RELATED APPLICATION
FIELD OF THE INVENTION
[0002] The present disclosure relates to compositions and methods useful for the treatment
and/or prevention of conditions of the eye. In particular, the disclosure relates
to compositions and methods that can be used in augmenting and regenerating the cornea,
and in correcting refractive errors of the eye.
BACKGROUND OF THE INVENTION
[0003] It was previously believed that differentiated cells relinquished their ability to
regress to an earlier state. However, this view has been challenged by the induction
of pluripotent stem cells (cell reprogramming) and evidence showing that differentiated
cells can switch to another phenotype (Takahashi & Yamanaka 2006; Wemig et al. 2007;
Yamanaka & Blau 2010; Gurdon & Melton 2008; Peran et al. 2011). In addition, it is
now believed that the microenvironment for cells, which includes the surrounding cells,
extracellular matrix, and growth and differentiation factors, plays an important role
in bringing about the redirection of cellular differentiation (Häkelien and Collas
2002). With this information, researchers have begun to develop therapeutics that
utilise cell reprogramming and stem cell technologies.
[0004] The cornea of the eye accounts for more than two-thirds of the eye's total refractive
power (focusing power). Even small changes in corneal shape can have a dramatic effect
on the clarity with which an image is brought to focus on the retina. The stromal
layer of the cornea (the clear front surface of the eye) comprises the majority of
the corneal tissue and is composed of highly organised lamellae which are made up
of tightly packed collagen fibrils, mostly of collagen types I and V (Marshall et
al. 1993). The unique structure of the stromal layer as a result of the uniform alignment
of the collagen fibrils confers the properties of toughness and transparency on the
cornea (Funderburgh 2000).
[0005] When stromal cells (the corneal keratocytes) are removed from the cornea and cultured
in a monolayer they exhibit the morphological characteristics of fibroblasts and switch
from a stellate shaped cell to a multinucleate, fusiform shaped cell (Funderburgh
et al. 2001). Another commonly observed phenotype of keratocytes is the myofibroblast
form that is seen in the cornea after injury (Jester et al. 1987). Changes in exogenous
growth factors and cytokines are thought to bring about these phenotypic changes (Funderburgh
et al. 2001).
[0006] TGFβ family of growth factors are known to be the most potent inducers of chondrogenic
(cartilage) differentiation (Heng, Cao, & Lee 2004; Johnstone et al. 1998; Menetrey
et al. 2000). TGFβ1 stimulates the synthesis of collagens and fibronectin by chick
embryo fibroblasts (Ignotz and Massague 1986). For keratocytes, TGFβ1 and TGFβ2 are
known to cause ECM deposition associated with scarring, possibly due to conversion
of keratocytes into the myofibroblast phenotype (Funderburgh, Mann, Funderburgh, Corpuz,
& Roth 2001). In contrast, TGFβ3 has been shown to induce corneal fibroblasts to produce
ECM depositions made up of collagen type I without fibrosis or scarring (Karamichos,
Hutcheon, & Zieske 2011). Certain non-proteinaceous chemical compounds such as dexamethasone
(Johnstone, Hering, Caplan, Goldberg, & Yoo 1998), ascorbic acid (Farquharson, Berry,
Barbara Mawer, Seawright, & Whitehead 1998), and ethanol (Kulyk & Hoffman 1996) are
also known to promote chondrogenic differentiation
in vitro.
[0007] There are a number of conditions affecting the cornea, including various defects,
injuries, diseases, and degenerative conditions. Myopia results from excessive curvature
of the cornea so that light entering the eye focuses in front of the retina. It is
the most prevalent vision impairment worldwide affecting the vision of 70 to 90% of
people in some Asian countries and 30 to 40% in Europe and the United States (Frederick
2002). In most cases, myopia first occurs in school-age children and progresses until
about the age of 20. It is also associated with increased prevalence of macular degeneration,
retinal detachment, and glaucoma in adulthood (Ebenstein & Pruitt 2006).
[0008] Myopia is most commonly corrected by the use of prescription eye glasses or contact
lenses. However, these devices do not provide permanent treatment for the condition,
and they are unsuitable for use during certain activities. Contact lenses are also
associated with ophthalmic infections and more serious conditions, including corneal
abrasions and ulcers. In certain circumstances, refractive surgery or orthokeratology
is indicated for myopia. Still, these treatments provide only a temporarily correction
for mild to moderate myopia; they are not permanent treatments, and they are unsuitable
for severe cases.
[0009] Keratoconus is an ecstatic corneal dystrophy associated with stromal thinning and
disruption of the portion of the cornea known as Bowman's layer. The progressive thinning
of the corneal stroma typically occurs over decades and results in the cornea developing
a conical shape. This results in an impairment of vision due to irregular astigmatism
and myopia. The pathogenesis of keratoconus is still unknown but has been associated
with factors such as constant eye rubbing and contact lens wear (Krachmer, Feder,
& Belin 1984; Sherwin & Brookes 2004). It can appear as early as puberty and continues
to progress until the third or fourth decade of life.
[0010] The incidence of keratoconus has been estimated at approximately 1 in 2000 in the
general population worldwide (Rabinowitz 1998), with no predilection for either gender.
Since the onset of keratoconus is typically in early adulthood with continuation into
prime earning and child-rearing years, the loss of quality of life and the economic
burden of the treatment of keratoconus represent a significant public health concern.
Keratoconus is a major indication for cornea transplantation in the Western world,
determined by researchers to constitute 28.8% of corneal transplantation in France
(Legeais et al. 2001) and from 11.4% to 15.4% in the United States (Cosar et al. 2002;
Dobbins et al. 2000). There is an unusually high prevalence of keratoconus in New
Zealand, with a disproportionately high incidence in Pasifika and Maori populations
(Patel et al. 2005; Patel & McGhee 2013). In New Zealand, approximately 50% of all
corneal transplants performed are for keratoconus (Edwards et al. 2002).
[0011] Despite several studies on keratoconus, the underlying biochemical process remains
poorly understood. The familial occurrence of keratoconus suggests that one of the
aetiological factors is genetic (Ihalainen 1985). The condition has also been linked
to certain biochemical and biomechanical factors. For example, it has been determined
that the corneal thinning of keratoconus is a result of the loss of extracellular
matrix (ECM) components. However, this could be due to their destruction, their defective
formation, or a combination of these (Klintworth & Damms 1995; Klintworth 1999; Jhanji
et al. 2011). In the corneal stroma, changes associated with keratoconus include a
decrease in the number of lamellae and keratocytes (Ku, Niederer, Patel, Sherwin,
& McGhee 2008; Sherwin & Brookes 2004), and changes in organisation of the lamellae
and distribution of collagen fibrillary mass (Meek et al. 2005).
[0012] It is thought that the degradation of the stromal layer might be due to aberrant
proteolytic enzyme activity (Fukuchi, Yue, Sugar, & Lam 1994). Keratoconus corneas
are known to have decreased levels of enzyme inhibitors and an increased level of
degradative enzymes (Kenney & Brown 2003). Biomechanical factors include thinning
and decreased rigidity of the cornea due to oxidative damage caused by ultraviolet
radiation and mechanical trauma (Kenney & Brown 2003). Biomechanical investigation
of keratoconic corneas has revealed a decrease in elasticity and stiffness; however
the reasons for this remain unknown (Edmund 1988). It has been suggested that a reduction
in collagen cross-links could be a cause (Wollensak & Buddecke 1990). Currently there
is no satisfactory animal model for keratoconus and investigations have been largely
limited to an
ex vivo setting.
[0013] Depending on the severity of the condition, attempts to slow progression of keratoconus
include the use of special spectacles and contact lens. In severe cases, corneal implants,
intrastromal rings, or corneal transplants are necessary (Jhanji, Sharma, & Vajpayee
2011). Penetrating keratoplasty, a procedure in which the entire thickness of the
cornea is removed and replaced by donor corneal tissue, is the most commonly used
surgical procedure used to treat advanced cases of keratoconus (Rabinowitz 1998).
Keratoconus is the leading indication for corneal transplantation surgery worldwide,
with about 12-20% of those affected by keratoconus requiring a corneal transplant
(Pramanik, Musch, Sutphin, & Farjo 2006).
[0014] Early treatment options for keratoconus, such as customised gas permeable lenses
known as Rose K lenses, have been focussed on improving visual acuity. Newer treatments
aim to slow the progression of the disease. A treatment known as corneal collagen
crosslinking (CXL) looks at increasing corneal rigidity and biomechanical stability.
In this procedure, the epithelium is debrided, topical riboflavin drops are administered,
and the corneas are exposed to ultraviolet-A light at 370 nm for approximately 30
minutes (Ashwin & McDonnell 2010; G. Wollensak, Spoerl, & Seiler 2003). It is believed
that the UV-A light activates the riboflavin thereby producing reactive oxygen species
that induce the formation of covalent bonds between the collagen molecules in the
corneal stroma (Spoerl, Huhle, & Seiler 1998; G. Wollensak et al. 2003). This procedure,
however, is not recommended for the treatment of corneas thinner than 400 pm due to
the possibility of endothelial cell damage. Although this treatment leads to a stiffer
cornea, it does not address the problem of corneal thinning.
[0015] Therefore, there is an ongoing need for therapeutic compositions and methods for
addressing conditions of the eye, including conditions affecting the cornea. There
is a particular need for therapies that are relatively non-invasive and readily administered.
SUMMARY OF THE INVENTION
[0016] The inventors have developed compositions and methods for modulating corneal cells,
to alter collagen expression and extracellular matrix formation in corneal tissue.
These compositions and methods are useful for regenerating and/or augmenting the cornea,
and thereby treating and/or preventing various conditions of the cornea and refractive
errors of the eye.
[0017] Embodiments of the invention are set out in the appended set of claims.
[0018] In one aspect, the invention provides a composition comprising a TGFβ3 polypeptide,
and dexamethasone or any salts, esters, or hydrides thereof, for use in a method of:
(i) treating or preventing thinning or irregularity of a cornea of a subject; or (ii)
treating or preventing a refractive error of the eye of a subject,
wherein:
the TGFβ3 polypeptide comprises the amino acid sequence of SEQ ID NO: 1; or
the TGFβ3 polypeptide shares at least 90% sequence identity to the amino acid sequence
of SEQ ID NO: 1, or
the TGFβ3 polypeptide comprises at least 100 amino acids of the amino acid sequence
of SEQ ID NO: 1.
In another aspect, the invention provides a kit comprising: (i) a composition comprising
a TGFβ3 polypeptide, and dexamethasone or any salts, esters, or hydrides thereof;
and (ii) a contact lens, corneal insert, corneal implant, or intrastromal ring,
wherein:
the TGFβ3 polypeptide comprises the amino acid sequence of SEQ ID NO: 1; or
the TGFβ3 polypeptide shares at least 90% sequence identity to the amino acid sequence
of SEQ ID NO: 1, or
the TGFβ3 polypeptide comprises at least 100 amino acids of the amino acid sequence
of SEQ ID NO: 1.
[0019] In another aspect, the invention provides a combination of:
a composition comprising TGFβ3 polypeptide, and
a composition comprising dexamethasone or any salts, esters, or hydrides thereof,
for use in a method of: (i) treating or preventing thinning or irregularity of a cornea;
or (ii) treating or preventing a refractive error of the eye,
wherein:
the TGFβ3 polypeptide comprises the amino acid sequence of SEQ ID NO: 1; or
the TGFβ3 polypeptide shares at least 90% sequence identity to the amino acid sequence
of SEQ ID NO: 1, or
the TGFβ3 polypeptide comprises at least 100 amino acids of the amino acid sequence
of SEQ ID NO: 1.
[0020] In one aspect, the invention provides a composition comprising a TGFβ3 polypeptide,
and dexamethasone or any salts, esters, or hydrides thereof, for use in a method of
treating or preventing thinning or irregularity of a cornea of a subject,
wherein:
the TGFβ3 polypeptide comprises the amino acid sequence of SEQ ID NO: 1; or
the TGFβ3 polypeptide shares at least 90% sequence identity to the amino acid sequence
of SEQ ID NO: 1, or
the TGFβ3 polypeptide comprises at least 100 amino acids of the amino acid sequence
of SEQ ID NO: 1.
[0021] In various aspects:
The TGFβ3 polypeptide consists of the amino acid sequence of SEQ ID NO: 1.
[0022] The dexamethasone is dexamethasone phosphate.
[0023] The composition comprises 10 to 100 ng/ml of the TGFβ3 polypeptide.
[0024] The composition comprises 40 to 4000 ng/ml dexamethasone.
[0025] The composition is formulated as an eye drop.
[0026] The composition is formulated with gellan gum.
[0027] The composition is administered once daily or twice daily.
[0028] The composition is co-administered with one or more additional agents for the eye.
[0029] The one or more additional agents for the eye are selected from the group consisting
of: anaesthetic agents, anti-inflammatory agents, anti-microbial agents, and lubricants.
[0030] The composition for use is administered in conjunction with use of a contact lens,
corneal insert, corneal implant, or intrastromal ring.
[0031] The contact lens, corneal insert, corneal implant, or intrastromal ring is adapted
for moulding or holding corneal shape during and/or following treatment with the composition
for use.
[0032] The contact lens, corneal insert, corneal implant, or intrastromal ring is adapted
to act as a carrier for the composition for use or as a composition eluting device.
[0033] The composition for use is administered in conjunction with corneal collagen crosslinking.
[0034] The administration of the composition for use is prior to and/or subsequent to crosslinking.
[0035] The condition is selected from the group consisting of: keratoconus, myopia, and
astigmatism.
[0036] In an alternative aspect, the invention provides a combination of:
a composition comprising TGFβ3 polypeptide, and
a composition comprising dexamethasone or any salts, esters, or hydrides thereof,
for use in a method of: (i) treating or preventing thinning or irregularity of a cornea;
or (ii) treating or preventing a refractive error of the eye,
wherein:
the TGFβ3 polypeptide comprises the amino acid sequence of SEQ ID NO: 1; or the TGFβ3
polypeptide shares at least 90% sequence identity to the amino acid sequence of SEQ
ID NO: 1, or
the TGFβ3 polypeptide comprises at least 100 amino acids of the amino acid sequence
of SEQ ID NO:1.
[0037] In yet a further aspect, the invention provides a composition comprising a TGFβ3
polypeptide, and dexamethasone or any salts, esters, or hydrides thereof, for use
in a method of treating or preventing a refractive error of the eye of a subject,
wherein:
the TGFβ3 polypeptide comprises the amino acid sequence of SEQ ID NO: 1; or
the TGFβ3 polypeptide shares at least 90% sequence identity to the amino acid sequence
of SEQ ID NO: 1, or
the TGFβ3 polypeptide comprises at least 100 amino acids of the amino acid sequence
of SEQ ID NO: 1.
[0038] In various aspects:
The TGFβ3 polypeptide consists of the amino acid sequence of SEQ ID NO: 1.
[0039] The dexamethasone is dexamethasone phosphate.
[0040] The composition comprises 10 to 100 ng/ml of the TGFβ3 polypeptide.
[0041] The composition comprises 40 to 4000 ng/ml dexamethasone.
[0042] The composition is formulated as an eye drop.
[0043] The composition is formulated with gellan gum.
[0044] The composition is administered once daily or twice daily.
[0045] The composition is co-administered with one or more additional agents for the eye.
[0046] The one or more additional agents for the eye are selected from the group consisting
of: anaesthetic agents, anti-inflammatory agents, anti-microbial agents, and lubricants.
[0047] The composition for use is administered for use in conjunction with a contact lens,
corneal insert, corneal implant, or intrastromal ring.
[0048] The contact lens, corneal insert, corneal implant, or intrastromal ring is adapted
for moulding or holding corneal shape during and/or following treatment with the composition.
[0049] The contact lens, corneal insert, corneal implant, or intrastromal ring is adapted
to act as a carrier for the composition or as a composition eluting device.
[0050] The method is performed preceding or following refractive surgery.
[0051] The refractive error of the eye is associated with one or more of: myopia, hyperopia,
astigmatism, and presbyopia.
[0052] In an alternative aspect, the invention provides a combination of:
a composition comprising TGFβ3 polypeptide, and
a composition comprising dexamethasone or any salts, esters, or hydrides thereof,
for use in a method of: (i) treating or preventing thinning or irregularity of a cornea;
or (ii) treating or preventing a refractive error of the eye,
wherein:
the TGFβ3 polypeptide comprises the amino acid sequence of SEQ ID NO: 1; or the TGFβ3
polypeptide shares at least 90% sequence identity to the amino acid sequence of SEQ
ID NO: 1, or
the TGFβ3 polypeptide comprises at least 100 amino acids of the amino acid sequence
of SEQ ID NO: I.
[0053] In still a further aspect, the invention provides a kit comprising: (i) a composition
comprising a TGFβ3 polypeptide, and dexamethasone or any salts, esters, or hydrides
thereof; and (ii) a contact lens, corneal insert, corneal implant, or intrastromal
ring,
wherein:
the TGFβ3 polypeptide comprises the amino acid sequence of SEQ ID NO: 1; or
the TGFβ3 polypeptide shares at least 90% sequence identity to the amino acid sequence
of SEQ ID NO: 1, or
the TGFβ3 polypeptide comprises at least 100 amino acids of the amino acid sequence
of SEQ ID NO: 1.
[0054] In various aspects:
The contact lens, corneal insert, corneal implant, or intrastromal ring is adapted
for moulding or holding corneal shape during and/or following treatment with the composition.
[0055] The contact lens, corneal insert, corneal implant, or intrastromal ring act as a
carrier for the composition or as a composition eluting device.
[0056] The TGFβ3 polypeptide consists of the amino acid sequence of SEQ ID NO: 1.
[0057] The dexamethasone is dexamethasone phosphate.
[0058] The composition comprises 10 to 100 ng/ml of the TGFβ3 polypeptide.
[0059] The composition comprises 40 to 4000 ng/ml dexamethasone.
[0060] The composition is formulated as an eye drop.
[0061] The composition is formulated with gellan gum.
[0062] The composition is formulated for administration once daily or twice daily.
[0063] The composition is co-formulated with one or more additional agents for the eye.
[0064] The kit includes one or more additional agents for the eye.
[0065] The one or more additional agents for the eye are selected from the group consisting
of: anaesthetic agents, anti-inflammatory agents, anti-microbial agents, and lubricants.
[0066] The kit includes a contact lens solution.
[0067] The kit includes instructions for use.
[0068] The kit is used for the treatment or prevention of a refractive error of the eye.
[0069] The kit is used for the treatment or prevention of a corneal condition selected from
the group consisting of: keratoconus, myopia, hyperopia, astigmatism, presbyopia,
and stromal dystrophies.
[0070] The kit is used for the treatment of a corneal condition selected from the group
consisting of: an abrasion, tear, ulcer, bum, puncture, corneal melt, and surgical
injury.
[0071] The foregoing brief summary broadly describes the features and technical advantages
of certain embodiments of the present invention. Further technical advantages will
be described in the detailed description of the invention and examples that follows.
[0072] Novel features that are believed to be characteristic of the invention will be better
understood from the detailed description of the invention when considered in connection
with any accompanying figures and examples. However, the figures and examples provided
herein are intended to help illustrate the invention or assist with developing an
understanding of the invention, and are not intended to limit the invention's scope.
BRIEF DESCRIPTION OF THE DRAWINGS
[0073]
Figure 1A: Schematic showing myopia caused by an increased curvature of the cornea
such that light entering the eye is not focussed onto the retina.
Figure IB: View of a normal (A) and keratoconic (B) cornea, respectively. (C): Scheimpflug
image in severe keratoconus. Significant corneal thinning is appreciated in the central
cornea.
Figure 2: Organotypic slice culture set up.
Figure 3: Growth factor eye drops instilled in the eye of adult male Wistar rat.
Figure 4: Phoenix Micron IV in vivo eye imaging system set up specific for imaging
rat eyes.
Figure 5: Schematic of (A): a nanoindenter system, (B): a typical loaddisplacement
curve obtained during the indentation process which is used to calculate corneal elasticity
and hysteresis. Pmax = maximum load applied; hmax = penetration depth; hc = contact depth (the height of the contact between the tip and the sample); hf =
final depth; S = unloading stiffness.
Figure 6: Nanoindentation rigs designed to hold the human corneal button (A) and the
rat globe (B). The central section of the cornea is located by using the microscope,
(C), and once located the indenter probe is used, (D).
Figure 7: Corneal keratocytes seeded in chondrogenic differentiation medium. Keratocytes
cultured for 3 weeks in chondrogenic differentiation medium containing TGFβ3 and dexamethasone
formed spheres, which were labelled with: (A) nestin around the periphery of the spheres;
(B) collagen type II within the core. The culture medium was then switched to serum
containing fibroblast proliferation medium for 1 week, causing cells from the spheres
to spread out and populate the dish, (C). Cells in monolayer were negative for type
II collagen whereas the cell clusters remained positive for collagen type II, (D).
Figure 8: Corneal keratocytes seeded in serum containing fibroblast proliferating
medium. Keratocytes cultured in control fibroblast proliferation medium for 3 weeks
were negative for nestin (A), and collagen Type II (B). Confluent fibroblasts were
then cultured in chondrogenic differentiation medium containing TGFβ3 and dexamethasone
for 3 weeks, (C). The cells remained negative for collagen type II, (D). (E): pellet
culture of confluent fibroblasts in chondrogenic differentiation medium. After 3 weeks
in culture the cell pellet was sectioned and labelled positive for the keratocyte
marker keratocan, (F), and negative for the chondrocyte specific type II collagen,
(G).
Figure 9: Human corneal slices cultured for 2 weeks in control medium (A) and (D)
were negative for type II collagen and positive for type I collagen, respectively.
Human corneal slices cultured for 1 week, (B) and (E), and 2 weeks, (C) and (F), in
chondrogenic differentiation medium and labelled for collagen type II, (B) and (C),
and type I, (E) and (F). Strong labelling for type II collagen was seen in corneal
slices treated for 2 weeks whereas slices treated for only 1 week were negative for
type II collagen. Slices cultured in chondrogenic differentiation medium for both
the time periods, although less strongly labelled when compared to the control treated
slices, were positive for the native corneal collagen type I.
Figure 10: Human corneal slices cultured for 2 weeks in: (A) control medium and (B)
chondrogenic differentiation medium and labelled for collagen type II. Similar results
were obtained as shown by Figure 9. In vivo experiments showing (C): untreated corneas; (D) and (E): treated corneas with a widespread
labelling of type II collagen in the TGFβ3 and dexamethasone treated corneas of rats.
Stronger labelling was seen in the anterior (upper) part of the cornea, (D). Type
II collagen appeared fibrillar and was evenly distributed throughout the ECM.
Figure 11: Keratoconic corneal button cultured in vitro in control medium, (A), (C) and (E), and chondrogenic differentiation medium, (B),
(D) and (F), for 2 weeks and labelled for collagen type II (A) and (B), and vimentin
(C)-(F), respectively. Compared to the labelling in normal human corneas the labelling
of type II collagen in treated keratoconic corneas (B) was weaker. However, the deposition
of type II collagen had a similar pattern to that previously seen after in vitro and in vivo treatment of normal human and rat corneas. The fibroblast population in the treated
half of the keratoconic button (D) and (F) increased in number and the keratocytes
appeared healthier and intact with multiple, long cell processes (F), when compared
to the untreated half of the keratoconic cornea, (C) and (E).
Figure 12: Ex vivo cultured human keratoconic cornea cultured for 3 weeks in control medium, (A) and
(C), and chondrogenic differentiation media, (B) and (D), and labelled for alpha smooth
muscle actin (aSMA), (A) and (B), and type III collagen, (C) and (D). There was stronger
labelling for aSMA in stromal layer of corneas cultured in control medium (A), when
compared to corneas cultured in chondrogenic differentiation medium. Corneas cultured
in either of the two media did not label positively for type III collagen.
Figure 13: Corneal transparency of in vivo treated corneas. Treated, (A) and (C), and untreated, (B) and (D), corneas. After
3 weeks the treated and untreated corneas were indistinguishable from each other.
The front view of the corneas (A) and (B) reveal a clear cornea through which light
easily passes to reveal the blood vessels of the back of the eye very clearly. At
8 weeks the in vivo imaging of the cross section of the cornea reveals a clear, transparent cornea through
which light easily passes. There were no signs of corneal opacity or scarring.
Figure 14: Quantitative gene expression of collagen type II (A), and collagen type
I (B), in in vivo treated corneas. There was an initial increase in type II collagen expression upon
after 1 week of treatment. Upon withdrawal of the treatment there was a marked decrease
in type II collagen expression, (A). Native corneal collagen type I expression was
also initially upregulated, however upon long term treatment (up to 7 weeks) its expression
was comparable to the control untreated cornea, (B).
Figure 15: Comparison of 1 week in vivo treated and untreated corneas does not reveal a significant difference in hardness
(H) and reduced elastic modulus (Er).
Figure 16: Load deformation curves obtained for 3 week in vivo treated and untreated corneas from two rats. The corresponding graphs with the plotted
values clearly show an increase in elastic modulus (Er) and hardness (H) in the treated
corneas.
Figure 17: Comparison of elastic modulus and hardness of 8 week treated and control
human keratoconic cornea reveals a marked increase in both parameters in the treated
cornea.
Figure 18: Reshaping of the cornea in the sheep eye by combining in vivo cell reprogramming with a rigid contact lens to hold the desired corneal shape during
treatment.
Figure 19: (A) The Phoenix Micron IV in vivo eye imaging system. The imaging system enables measurement of corneal thickness,
curvature, and transparency. (B) An OCT attachment enables visualisation of the anterior
eye and measurement of corneal thickness and integrity, similar to the image seen
here. (C) A nanoindenter and (D) schematic representation of the set-up which will
be used to assess corneal biomechanics ex vivo in sheep. Output is shown as a load-displacement curve which can be analysed to obtain
Young's modulus of elasticity, and a measure of hardness. In large animals such as
sheep, corneal thickness (E) is indicated in microns and corneal curvature measurements
(F) are obtained using a portable Pentacam®. For corneal curvature (F), widely spaced colour contours indicate a large radius
of curvature; narrower contours indicate areas of steeper curvature. Numbers indicate
the radius of curvature at each point.
Figure 20: Only TGFβ3 combined with dexamethasone produces collagen type II deposition.
Sheep corneal tissue were cultured in (A) BMP6, (B) BMP6 + hydrocortisone, (C) TGFβ3
+ hydrocortisone, (D) BMP6 + dexamethasone, (E) TGFβ3 + prednisone, (F) TGFβ3 + Triesense®, (G) and (H) TGFβ3 + dexamethasone at 20X and 60X magnification, respectively, and
labelled for cartilage specific collagen type II. Figure 21: Dose response study for
combinations of TGFβ3 and dexamethasone. Sheep corneas were cultured for 3 weeks and
labelled for collagen type II.
DETAILED DESCRIPTION OF THE INVENTION
[0074] The following description sets forth numerous exemplary configurations, parameters,
and the like. It should be recognised, however, that such description is not intended
as a limitation on the scope of the present invention, but is instead provided as
a description of exemplary embodiments.
Definitions
[0075] In each instance herein, in descriptions, aspects, embodiments, and examples of the
present invention, the terms "comprising", "including", etc., are to be read expansively,
without limitation. Thus, unless the context clearly requires otherwise, throughout
the description and the claims, the words "comprise", "comprising", and the like are
to be construed in an inclusive sense as to opposed to an exclusive sense, that is
to say in the sense of "including but not limited to".
[0076] As used herein, "augmenting" refers to methods of increasing one or more of the thickness,
hardness, elastic modulus, tensile strength, and regularity of the cornea, including
the corneal tissue (e.g., the stromal layer). Augmentation may be used to impose a
particular shape to the cornea, i.e., corneal curvature. Augmentation methods may
be performed in the presence or absence of a particular condition of the eye, or of
the cornea. Augmentation may involve the increase in components in the extracellular
matrix of the cornea (e.g., collagen type II). Augmentation may also involve increasing
the number of cells (e.g., keratocytes) in the cornea. The number of cells may be
increased, for example, by altering the proliferative state of such cells from quiescent
to active.
[0077] "Co-administration" or "co-administering" refers to the combined use of agents, for
example, therapeutic agents for the eye, and includes the administration of coformulations
(i.e., combination formulations), as well as the simultaneous or sequential administration
of separate formulations. Similarly, "in conjunction" refers to the combined use of
a therapeutic composition and a therapeutic device/procedure. This can include use
of the composition preceding use of the device/procedure, simultaneously with the
device/procedure, and/or following use of the device/procedure.
[0078] A "condition" of the cornea refers to a state of disease, defect, damage, injury,
degeneration, or dysfunction of the cornea. The condition may affect the corneal tissue
(e.g., the stromal layer) or corneal cells (e.g., keratocytes). The condition may
be an acute condition, for example, an abrasion or ulceration, or may be a chronic
condition, for example, keratoconus or myopia.
[0079] The "cornea" as used herein refers to the transparent front part of the eye that
covers the iris, pupil, and anterior chamber of the eye. It includes the corneal epithelium,
Bowman's layer, corneal stroma, Descemet's membrane, and the corneal epithelium. Of
particular interest is the stromal layer (also called the
substantia propria) of the cornea, which comprises an extracellular matrix of regularly arranged collagen
fibres along with keratocytes,
[0080] A "derivative", as relating to a chemical derivative, refers to a compound that has
been chemically modified. The present disclosure encompasses each of the chemical
compounds described herein as well as any derivatives thereof, including chemically
modified forms such as salts, hydrides, esters, and other modifications of the original
compound.
[0081] "Isolated" as used herein, with particular reference to polypeptides, refers to a
molecule that is separated from its natural environment. An isolated molecule may
be obtained by any method or combination of methods as known and used in the art,
including biochemical, recombinant, and synthetic techniques. To obtain isolated components,
the polypeptides may be prepared by at least one purification or enrichment step.
Of particular interest are polypeptides and peptides obtained by artificial means,
i.e., non-natural, means. This includes but is not limited to, synthetic chemistry,
recombinant technology, purification protocols, etc. Included are polypeptides isolated
from natural, recombinant, or synthetic sources. Also included are polypeptides produced
by chemical synthesis, or by plasmids, vectors, or other expression constructs that
may be introduced into a cell or cell-free translation system. Such polypeptides are
clearly distinguished from polypeptides as they naturally occur, without human intervention.
[0082] The terms "protein" or "polypeptide" (e.g., SEQ ID NO.T), and other such terms, for
simplicity, refer to the molecules described herein. Such terms are not meant to provide
the complete characterization of these molecules. Thus, a protein or polypeptide may
be characterised herein as having a particular amino acid sequence, a particular 2-dimensional
representation of the structure, but it is understood that the actual molecule claimed
has other features, including 3-dimensional structure, mobility about certain bonds
and other properties of the molecule as a whole. It is the molecules themselves and
their properties as a whole that are encompassed by this disclosure. The terms "protein"
and "polypeptide" are used interchangeably herein.
[0083] A TGFβ3 "polypeptide" refers to polypeptides obtained from any source, e.g., isolated
naturally occurring polypeptides, recombinant polypeptides, and synthetic polypeptides,
and to include polypeptides having the naturally occurring amino acid sequence as
well as polypeptides having variant amino acid sequences, and fragments of such sequences,
as described in detail herein. TGFβ3 may also be referred to in the art as transforming
growth factor-beta3, TGFB3, ARVD, and FLJ16571.
[0084] Amino acid "sequence identity" refers to the amino acid to amino acid comparison
of two or more polypeptides. A test sequence may be identical to a reference sequence
(i.e., share 100% identity), or may include one or more amino acid substitutions.
In preferred aspects, amino acid substitutions may possess similar chemical and/or
physical properties such as charge or hydrophobicity, as compared to the reference
amino acid. Sequence identity may be typically determined by sequence alignments at
the regions of highest homology. Sequence alignment algorithms, for example BLAST
® sequence alignment programs, are well known and widely used in the art. Based on
the sequence alignment, the percent identity can be determined between the compared
polypeptide sequences.
[0085] A "refractive error" as used herein, refers to error in the focusing of light by
the eye. Refractive errors may include spherical errors and cylindrical errors. Both
lower order aberrations and higher order aberrations are included. Specifically included
as refractive errors are the conditions of the eye noted as myopia, hyperopia, astigmatism,
anisometropia, and presbyopia.
[0086] "Regeneration", in relation to the cornea, refers to the restoration of one or more
of the shape, thickness, regularity, hardness, elastic modulus, and tensile strength
of the cornea, including that of the corneal tissue (e.g., the stromal layer). Methods
of regeneration may be used to impose a particular shape to the cornea, i.e., corneal
curvature. Regeneration methods may be performed in the treatment of a particular
condition of the eye, or of the cornea. Regeneration may involve the increase in components
in the extracellular matrix of the cornea (e.g., collagen type II). Regeneration may
also involve increasing the number of cells (e.g., keratocytes) in the cornea. The
number of cells may be increased, for example, by altering the proliferative state
of such cells from quiescent to active.
[0087] "Reprogramming" of cells, for example, for corneal cells (e.g., keratocytes) refers
to changes in the state of differentiation. Reprogramming is associated with one or
more changes in cell morphology, cellular gene expression (e.g., collagen expression,
including collagen type I and/or type II expression), or the cells proliferative state
(e.g., quiescent or active).
[0088] The term "subject" refers to a human or non-human animal.
[0089] "Preventing" refers to stopping or delaying the onset of a condition, for example
an eye condition, or particularly a corneal condition, such as a disorder or other
defect of the cornea. A preventative measure will result in the stoppage or delay
of one or more symptoms of the condition, or a lessening of symptoms if such do arise.
Prevention of a corneal condition may involve augmenting the cornea, as described
in detail herein.
[0090] "Treating" refers to reducing, ameliorating, or resolving a condition, for example
an eye condition, or particularly a corneal condition, such as a disorder or other
defect of the cornea. A treatment will result in the reduction, amelioration, or elimination
of one or more symptoms of the condition. Treatment of a corneal condition may involve
regeneration of the cornea, as detailed herein. The compositions for use of the invention
may be for treating various conditions, for preventing various conditions, or for
both treating and preventing various conditions, as described in detail herein.
Cell and tissue regeneration
[0091] Cell and tissue regeneration technologies hold considerable promise in therapeutic
treatments. As disclosed herein, the inventors have developed compositions and methods
for modulating cells using
in situ cell reprogramming in order to affect collagen type II expression and extracellular
matrix (ECM) deposition in corneal tissue. This, in turn, is used to strengthen and/or
augment the cornea of the eye. The inventors thereby provide a unique approach for
the
in situ /
in vivo regeneration and augmentation of the corneal stromal matrix.
[0092] Accordingly, the disclosed compositions, combinations and kits may be utilised in
in vivo tissue engineering therapy for treating or preventing thinning or irregularity of
the cornea associated with keratoconus or for treating or preventing a refractive
error of the eye associated with myopia. As noted above, myopia is characterised by
the excessive curvature of the cornea (Figure 1A),
while keratoconus is a progressive ectatic corneal dystrophy leading to a characteristic
pattern of corneal thinning (Figure IB; image adapted from Romero-Jimenez, Santodomingo-Rubido,
& Wolffsohn 2010).
[0093] Corneal keratocytes are relatively quiescent and normally only produce large amounts
of extracellular matrix (ECM) when they switch to a fibroblast or myofibroblast phenotype.
ECM deposition associated with those phenotypes usually leads to corneal fibrosis
and loss of transparency (Kadler, Baldock, Bella, & Boot-Handford 2007). Chondrocytes,
the cells that make up cartilage, secrete type II collagen which is a fibrillar collagen
similar to type I found in the cornea. Type II collagen is also expressed by keratocytes
during development of the chick cornea and it is only later replaced by type I in
the mature chick stroma (Linsenmayer et al. 1990).
[0094] The inventors have previously shown that stromal cells from adult human and rat corneas
can be reprogrammed to produce neuron specific proteins when treated with neuronal
lineage specifying growth factors (Greene et al. 2013). This data demonstrates that
an adult cell population can be reprogrammed simply by the modulation of the growth
factor environment both
in vitro and
in vivo.
[0095] Now, as demonstrated herein, the inventors show that corneal stromal cells can be
induced
in vitro and
ex vivo to produce cartilage specific fibrillar collagen, collagen type II, by treating the
cells with transforming growth factor β3 (TGFβ3) and dexamethasone (Examples 8 and
9). In particular, the inventors have demonstrated that keratocytes in human keratoconic
corneal biopsies express collagen type II when treated with these two compounds (Example
8). In addition, with animal studies, the inventors have demonstrated that the two
compounds of TGFβ3 and dexamethasone can be delivered
in vivo using eye drops to stimulate collagen II deposition (Example 9). Notably, the deposition
of collagen type II was uniform, improving the biomechanics of the cornea, with no
fibrosis or scarring, and no effect on corneal transparency (Examples 11 and 13).
[0096] Without wishing to be bound by theory, it is hypothesised that the collagen deposition
is brought about by the reprogramming of cells within the stroma to a chondrocyte
phenotype. It is known that chondrocytes secrete type II collagen which is not only
a fibrillar collagen similar to type I found in the cornea, but is also expressed
during development of the chick cornea (Linsenmayer et al. 1990). It is only later
replaced by collagen type I in the mature stroma (Linsenmayer et al. 1990).
[0097] In the results described herein, an initial increase in collagen type I expression
was observed upon treatment of corneal keratocytes with TGFβ3 and dexamethasone (Example
12). However, the inventors consider that the observed level of collagen type I deposition
would be insufficient to stiffen/reshape a cornea. Furthermore, the deposition of
collagen type II is deemed more feasible as a treatment strategy. It is noted that
collagen type II is less susceptible to enzymatic degradation, for example, by enzymes
present in a keratoconic cornea.
[0098] In accordance with the inventors' results, it is possible to use the reprogramming
of keratocytes to produce new ECM molecules as an effective treatment to improve the
biomechanical characteristics of the cornea. This approach is considered advantageous,
as it reduces susceptibility to degradation by corneal enzymes, as noted above. The
disclosed treatment module aims not only to stabilise the cornea, but also to provide
remedial aid for conditions of the eye, including various corneal conditions and refractive
errors of the eye. Thus, the compositions for use of the invention may be, for example,
for the treatment of keratoconic keratocytes in the ectatic cornea. Additionally,
the compositions for use of the invention may be for the treatment of myopia and various
other conditions of the cornea, as described in detail herein.
Conditions affecting the eye and cornea
[0099] The compositions and combinations for use of the invention are for use in treating
or preventing thinning or irregularity of a cornea of a subject, or treating or preventing
a refractive error of the eye of a subject. Exemplary conditions include keratoconus,
as described in detail herein, and related conditions, which include corneal ectasias
such as keratoglobus, pellucid marginal degeneration, and posterior keratoconus (see,
e.g., Arffa 1997; Krachmer et al. 1984; Rabonitz 2004; Jinabhai et al. 2010). Specifically
included as defects are myopia, presbyopia, and also astigmatisms, which encompass
regular and irregular astigmatisms. Congenital defects of the cornea are also included.
Amongst these are cornea plana and microcomea, the latter of which may be associated
with fetal alcohol syndrome, Turner syndrome, Ehlers-Danlos syndrome, Weill-Marchesani
syndrome, Waardenburg's syndrome, Nance-Horan syndrome, and Cornelia de Lange's syndrome.
Included also is keratoglobus (mentioned above) that may be associated with Ehlers-Danlos
syndrome type IV.
[0100] In certain situations, the compositions for use of the invention may be to prevent
corneal damage. Damage or degeneration may be associated with a particular condition
of the cornea. Specifically included is corneal melt, for example, corneal melt associated
with an inflammatory disorder, such as rheumatoid arthritis. Other exemplary conditions
include keratitis, such as marginal keratitis, stromal keratitis, exposure keratitis,
neurotrophic keratitis, filamentary keratitis, rosacea keratitis, viral keratitis
including herpes keratitis, fungal keratitis, protozoal keratitis, and other infectious
keratitis, such as luetic interstitial keratitis, microsporidial keratitis, Thygeson's
keratitis, and infectious crystalline keratopathy. Included also is ulcerative keratitis,
also called peripheral ulcerative keratitis (PUK), which includes ulcerative keratitis
that is associated with a systemic disease, such as rheumatoid arthritis Wegener's
granulomatosis, systemic lupus erythematosus, relapsing polychondritis, and polyarteritis
nodosa. Endophthalmitis is also included. Included as well are chronic corneal edema,
Mooren's ulcer, dellen, phlyctenulosis, Terrien's degeneration, Salzman's degeneration,
spheroidal degeneration, and Fuch's dystrophy. Such conditions are well known and
well characterised in the art. See, e.g., Jackson 2008; Denniston 2009; and Willshaw
et al. 2000. Additionally included are stromal dystrophies, for example, lattice corneal
dystrophy (e.g., type 1 and type 2), granular corneal dystrophy (e.g., type 1 and
type 2), macular corneal dystrophy, Schnyder corneal dystrophy, congenital stromal
corneal dystrophy, and fleck corneal dystrophy.
[0101] In even further aspects, the invention encompasses compositions for use in treating
or preventing refractive errors of the eye. Such refractive errors may be associated
with particular conditions, including myopia, hyperopia, presbyopia, anisometropia,
higher order aberrations, and various astigmatisms. Higher order aberrations include,
but are not limited to, comas, trefoils, quadrafoils, spherical aberrations, and aberrations
identified by mathematical expressions (e.g., Zemike polynomials).
[0102] Conditions of the cornea may be diagnosed by various methods, including fluorescein
staining, which may include a Seidel's test, specular microscopy, corneal topography,
isometric tomography, pachymetry, ultrasound, slit lamps, corneal scrapes, and biopsies.
Diagnosis may also involve assessments for visual acuity and/or opacification. Corneal
conditions may be associated with one or more symptoms of: pain, photophobia, foreign
body sensation, reduced visual acuity, oedema, white cell infiltrate, fluorescein
uptake, vascularisation, redness, and systemic symptoms such as headaches, nausea,
and fatigue. Similarly, symptoms of refractive errors may include but are not limited
to: reduced visual acuity as well as blurry vision, double vision, haziness of vision,
visual fatigue, foreign body sensation, problematic glare or halos, starburst patterns,
ghost images, impaired night vision, squinting, excessive staring, excessive blinking,
headaches, eye rubbing, eye strain, eye surface dessication, eye irritation, redness,
and spasms of the eye.
Therapeutic compositions
[0103] In various aspects, the composition for use may be formulated to include the noted
combination of components (a TGFβ3 polypeptide plus dexamethasone (or any salts, esters,
or hydrides thereof)), or may be formulated to include a first component (a TGFβ3
polypeptide or alternatively dexamethasone (or any salts, esters, or hydrides thereof))
with the second component to be added in prior to administration. Alternatively, a
combination for use may be formulated to include a first component (a TGFβ3 polypeptide
or alternatively dexamethasone (or any salts, esters, or hydrides thereof)), which
is used in simultaneous or sequential administration with a formulation that includes
the second component.
[0104] In one aspect, the TGFβ3 polypeptide may include at least the following amino acid
sequence: ALDTNYCFRN LEENCCVRPL YIDFRQDLGW KWVHEPKGYY ANFCSGPCPY LRSADTTHST VLGLYNTLNP
EASASPCCVP QDLEPLTILY YVGRTPKVEQ LSNMVVKSCK CS (SEQ ID NO:1) (GenBank Reference CAR70088.1).
The TGFβ3 polypeptide may include at least 112 amino acids shown above, and may have
a molecular mass of 25.5 kDa. Alternatively, the TGFβ3 polypeptide may be derived
from amino acids 644-850 (207 amino acids) of the precursor polypeptide sequence identified
in GenBank Reference CAA33024.1; GenBank Accession No. CAA33024; or NCBI Reference
Sequence NP_003230.1.
[0105] In other aspects, the TGFβ3 polypeptide shares at least 90% sequence identity to
the amino acid sequence of SEQ ID NO: 1
[0106] In further aspects, the TGFβ3 polypeptide comprises at least 100 amino acids of the
amino acid sequence of SEQ ID NO: 1.
[0107] In a particular aspect, the TGFβ3 polypeptide or the variant or fragment thereof
may be provided as a recombinant polypeptide. For example, the polypeptide may be
expressed in cell or cell-free expression systems as widely known and used in the
art. Included amongst these are bacterial, fungal, plant, and mammalian expression
systems. Expression systems using
E. coli cells, CHO cells, HEK cells, and
Nicotiana benthamiana cells are specifically included. The TGFβ3 polypeptide or the variant or fragment
thereof may be provided as a human recombinant polypeptide expressed in human or non-human
expression systems. The TGFβ3 polypeptide or the variant or fragment thereof may be
provided as a disulfide-linked homodimeric, non-glycosylated, polypeptide chain, in
accordance with known methods.
[0108] The TGFβ3 polypeptide or the variant or fragment thereof may be isolated from recombinant
expression systems by standard methods, including well known chromatographic techniques.
The TGFβ3 polypeptide or the variant or fragment thereof may include a sequence tag
to facilitate cleavage, isolation, and/or localisation of the polypeptide. In accordance
with the present invention, the TGFβ3 polypeptide may be obtained from various commercial
sources. For example, recombinant human TGFβ3 may be obtained from R&D Systems (Catalogue
Nos. 243-B3-002; 243-B3-010), BioVision, Inc. (Catalogue Nos. 4344-500; 4344-50; 4344-5),
or Prospec Protein Specialists (Catalogue Nos. CYT-113; CYT-319).
[0109] The biological activity of the TGFβ3 polypeptide or the variant or fragment thereof
may be measured in accordance with widely known and used methods. For example, biological
activity may be measured in culture by the polypeptides ability to inhibit the mink
lung epithelial (MvlLu) cells proliferation (see, e.g., Premaraj et al. 2006). Exemplary
activity by this measurement is shown by an ED50 of < 50 ng/ml. Alternatively, biological
activity may be measured by the dose-dependent inhibition of IL-4 induced proliferation
of mouse HT-2 cells (BALB/c spleen activated by sheep erythrocytes in the presence
of IL-2) (see, e.g., Tsang et al. 1995). Exemplary activity by this measurement is
typically 0.1 to 0.5 ng/ml. Alternatively, the composition that includes the combination
of agents described herein may be measured for biological activity using the methods
noted below. For example, induction of collagen type II (e.g., collagen type II, alpha
1) in keratocytes can be assessed by one or more of: immunohistochemical assays, protein
assays, Western blot analysis, polymerase chain reaction (PCR) analysis, and quantitative
PCR technologies.
[0110] As described herein, the composition may also include dexamethasone, or any salts,
esters, or hydrides thereof. Dexamethasone is characterised as having the following
chemical structure:

[0111] The trade names for dexamethasone include, for example, Decadron
®, Dexasone
®, Diodex
®, Hexadrol
®, Maxidex
®, and Minims
®.
[0112] In various aspects, derivatives of dexamethasone may be used, including any esters
and salts thereof. Exemplary derivatives include but are not limited to: dexamethasone-17-acetate
(
CAS RN: 1177-87-3), dexamethasone disodium phosphate (
CAS RN: 2392-39-4), dexamethasone valerate (
CAS RN: 14899-36-6), dexamethasone- 21-isonicotinate (
CAS RN: 2265-64-7), dexamethasone palmitate (
CAS RN: 33755-463), dexamethasone propionate (
CAS RN: 55541-30-5), dexamethasone acefurate (
CAS RN: 83880-70-0), dexamethasone-21-galactoside (
CAS RN: 92901-23-0), dexamethasone 21-thiopivalate, dexamethasone 21-thiopentanoate, dexamethasone 21-
thiol-2-methyl-butanoate, dexamethasone 21-thiol-3-methyl-butanoate, dexamethasone
21-thiohexanoate, dexamethasone 21-thiol-4-methyl-pentanoate, dexamethasone 21- thiol-3,3
-dimethyl-butanoate, dexamethasone 21 -thiol-2-ethyl-butanoate, dexamethasone 21-thiooctanoate,
dexamethasone 21-thiol-2-ethylhexanoate, dexamethasone 21-thiononanoate, dexamethasone
21-thiodecanoate, dexamethasone 21- p-fluorothiobenzoate or a combination thereof.
Specifically included are dexamethasone alcohol and dexamethasone sodium phosphate.
Dexamethasone derivatives are also included, as described in
US 4177268.
[0113] The composition may include related steroidal agents in addition to dexamethasone.
For example, other corticoid steroids may be utilised, along with dexamethasone. Preferred
for use as related steroids are Group C steroids according to Coopman classification,
which includes betamethasone-type steroids, such as dexamethasone, dexamethasone sodium
phosphate, betamethasone, betamethasone sodium phosphate, and fluocortolone. Other
related steroidal agents include but are not limited to: fluoromethalone, lotoprendol,
medrysone, prednisolone, prednisone, rimexolone, hydrocortisone, lodoxamide, or any
derivative or combination thereof. Specifically included are fluoromethalone acetate,
fluoromethalone alcohol, prednisolone acetate, prednisolone sodium phosphate, lotoprendol
etabonate, hydrocortisone acetate, and lodoxamide tromethamine.
[0114] The composition may include, for example, 0.04 ng/ml to 4 ng/ml; or 0.04 ng/ml to
0.4 ng/ml; or 0.4 ng/ml to 4 ng/ml; or 4 to 40 ng/ml; or 40 ng/ml to 400 ng/ml, or
40 ng/ml to 4000 ng/ml dexamethasone, or derivative thereof or related steroidal agent;
or about 0.04 ng/ml, about 0.08 ng/ml, about 0.12 ng/ml, about 0.4 ng/ml, about 0.8
ng/ml, about 1.2 ng/ml, about 4 ng/ml, about 12 ng/ml, about 24 ng/ml, about 40 ng/ml,
about 80 ng/ml, about 120 ng/ml, about 240 ng/ml, about 400 ng/ml, about 800 ng/ml,
about 1000 ng/ml, about 1600 ng/ml, about 2000 ng/ml, about 2400 ng/ml, about 3200
ng/ml, or about 4000 ng/ml dexamethasone, or any salt, ester, or hydride thereof.
[0115] As further examples, the composition may include 0.4 pg/ml to 40 pg/ml; or 0.4 p.g/ml
to 4 pg/ml; or 4 pg/ml to 40 pg/ml dexamethasone, or derivative thereof or related
steroidal agent; or about 0.4 pg/ml, about 0.8 pg/ml, about 1 pg/ml, about 1.2 pg/ml,
about 2 pg/ml, about 4 pg/ml, about 8 pg/ml, about 12 pg/ml, about 20 Ug/ml, or about
40 pg/ml dexamethasone, or any salt, ester, or hydride thereof.
[0116] As yet further examples, the composition may include 0.1 mg/ml to 1 mg/ml; or 0.5
mg/ml to 5 mg/ml; or 1 mg/ml to 10 mg/ml; dexamethasone, or any salt, ester, or hydride
thereof; or about 0.1 mg/ml, about 0.5 mg/ml, about 1 mg/ml, about 2 mg/ml, about
5 mg/ml, or about 10 mg/ml dexamethasone, or any salt, ester, or hydride thereof.
[0117] The composition may include, for example, 1 ng/ml to 1 pg/ml; or 1 ng/ml to 10 ng/ml;
or 10 ng/ml to 100 ng/ml; or 100 ng/ml to 1 pg/ml TGFβ3 polypeptide as defined herein,
or about 1 ng/ml, about 5 ng/ml, about 10 ng/ml, about 20 ng/ml, about 50 ng/ml, about
100 ng/ml, about 200 ng/ml, about 500 ng/ml, about 800 ng/ml, or about 1 ug/ml TGFβ3
polypeptide. In particular aspects, the composition may include at least 40 ng/ml
dexamethasone, or derivative thereof or related steroidal agent, along with at least
4 ng/ml TGFβ3 polypeptide.
[0118] The composition may also include one or more anti-inflammatory agents. Exemplary
anti-inflammatory agents include ketotifen fumarate, diclofenac sodium, flurbiprofen
sodium, ketorlac tromethamine, suprofen, celecoxib, naproxen, rofecoxib, or any derivative
or combination thereof. Particularly included are nonsteroidal anti-inflammatory drugs
(NSAIDs). The composition may additionally include one or more anaesthetic agents.
Exemplary anaesthetics include topical anaesthetics such as proparacaine, lidocaine,
and tetracaine, and any derivative or combination thereof. Other agents for the eye
may be selected for inclusion with the composition; these may be chosen by the skilled
artisan based on the condition and needs of the subject under treatment.
[0119] The compositions as described herein may be formulated for topical administration,
as described herein and in accordance with known methods. In certain circumstances,
intraocular administration may be desirable. The composition may be provided in any
form suitable for administration to the eye. Exemplary formulations include, at least,
solutions, suspensions, emulsions (dispersions), gels, creams, or ointments in a suitable
ophthalmic vehicle. For example, the composition may be provided in the form of eye
drops, a semisolid gel, or a spray. In certain aspects, moulding contact lenses or
other inserts/implants may be impregnated with the composition for use of the invention.
In this manner, the composition can be delivered to the cornea continuously and in
a time-release manner as the subject is wearing the contact lenses.
[0120] For topical administration to the eye, the compositions may be formulated with a
pH range of 5.0 to 8.0. This pH range may be achieved by the addition of buffers to
the solution. It is preferred that the formulations are stable in buffered solutions.
That is, there is no adverse interaction between the buffer and the active agents
that would cause the composition to be unstable, e.g., by precipitation or aggregation.
The composition may be hypertonic (5% to 40%, preferably approximately 10, 20, 30,
or 40%) or hypotonic (0% to 5%, preferably approximately 1, 2, 3, or 4%) depending
on the needs of the subject (e.g., working needs, rest hours, sleeping, etc.) A hypertonic
composition (e.g., 40%) may be used when combined with moulding contact lenses, as
described in detail herein.
[0121] The compositions may include one or more suitable preservatives as optional ingredients.
Suitable preservatives may be added to prevent contamination, for example, bacterial
contamination. Such agents may include, but are not limited to, benzalkonium chloride,
thimerosal, chlorobutanol, methyl paraben, propyl paraben, phenylethyl alcohol, EDTA,
sorbic acid, Onarner
® M, and other agents known to those skilled in the art, or any combination thereof.
Such preservatives may be typically employed at a level of 0.001% to 1.0% by weight
of the composition.
[0122] The compositions may contain an optional co-solvent. The solubility of the components
of the present compositions may be enhanced by a surfactant or other appropriate co-solvent
in the composition. Such co-solvents/surfactants include, for example, polysorbate
20, 60, and 80, polyoxyethylene/polyoxypropylene surfactants (e.g. Pluronic
® F-68, F-84, and P-103), cyclodextrin, tyloxapol, and other agents known to those
skilled in the art, and any combination thereof. Such co-solvents may be typically
employed at a level of 0.01% to 2% by weight of the composition.
[0123] Penetration enhancing agents may be used to increase uptake of the composition into
the eye. Exemplary agents include, at least, cetylpyridinium chloride, ionophores
such as lasalocid, benzalkonium chloride, Parabens, Tween 20, saponins, Brij 35, Brij
78, Brij 98, ethylenediaminetetraacetic acid, bile salts, and bile acids (such as
sodium cholate, sodium taurocholate, sodium glycodeoxycholate, sodium taurodeoxycholate,
taurocholic acid, chenodeoxycholic acid, and ursodeoxycholic acid), capric acid, azone,
fusidic acid, hexamethylene lauramide, saponins, hexamethylene octanamide, and decylmethyl
sulfoxide.
[0124] In addition, bioadhesive polymers may be used to adhere to the mucin coat covering
the eye, to prolong contact of the composition with the eye. Bioadhesive polymers
may be macromolecular hydrocolloids with numerous hydrophilic functional groups, such
as carboxyl-, hydroxyl-, amide, and sulphate capable of establishing electrostatic
interactions. Exemplary agents include, at least, polyarylic acid (e.g., carbopol,
carbophil, and polycarbophil) and carboxymethyl cellulose.
[0125] Controlled release systems may also be used; such systems may involve
in situ gels, colloidal particles, nanoparticles, and/or niosomes. Other drug delivery systems
include but are not limited to: non-erodible ocular inserts, erodible ocular inserts,
hydrogels, collagen shields, liposomes, drug-loaded films (e.g., NOD
®), and ionotophoresis.
[0126] The compositions may include, also, an optional agent to increase viscosity. Viscosity
increased above that of simple aqueous solutions may be desirable to increase ocular
absorption of the active compounds, to decrease variability in dispensing the formulation,
to decrease physical separation of components of a suspension or emulsion of the formulation
and/or to otherwise improve the ophthalmic formulation. Such viscosity builder agents
include as examples polyvinyl alcohol, polyvinyl pyrrolidone, methyl cellulose, hydroxy
propyl methylcellulose, hydroxyethyl cellulose, carboxymethyl cellulose, hydroxy propyl
cellulose, other agents known to those skilled in the art, or a combination thereof.
Such agents may be typically employed at a level of 0.01% to 2% by weight of the composition.
[0127] In particular aspects, the compositions include a gelling agent, for example, high
molecular weight water-soluble polysaccharides such as gellan gum. Gellan gum may
be obtained from various commercial sources, for example, as sold under the trade
name Kelcogel
®. In particular, Kelcogel
® LT 100 may be used as a fine mesh, high acyl gellan, which forms soft, elastic, non-brittle
gels. In specific aspects, the gellan gum based composition is formulated as a 0.5%
eye drop
[0128] Other agents may be used to further stabilise or otherwise enhance the composition.
For example, one or more of EDTA, sodium chloride, tyloxapol, sodium sulfate, and/or
hydroxyethylcellulose may have additional beneficial effects of further stabilising
the composition.
Therapeutic methods
[0129] The compositions for use are used to treat or prevent thinning or irregularity of
a cornea of a subject; or treating or preventing a refractive error of the eye of
a subject. Thus, the compositions described herein may be used to address various
conditions of the cornea and correct refractive errors of the eye, and may be used
as adjunct therapy with other eye treatments.
[0130] As previously noted, the composition for use may be formulated in any suitable means
for administration to the eye. Included as formulations are ophthalmic solutions,
creams, emulsions, ointments, and gels. Specifically noted are formulations that are
made as eye drops. In a particular aspect, the composition for use may be administered
as an eye drop using any of the many types of eye drop dispensers on the market. As
exemplifications, the container for the compositions for use of the invention may
be clear, translucent, and opaque and may contain other properties or combination
of properties such as being glass lined, tamper proof, packaged in single or few dose
aliquots, and any combination thereof.
[0131] The composition for use may be administered in therapeutically effective amounts
to a subject to achieve a desired medical outcome. In particular, the composition
for use may be administered in amounts to address an ophthalmic condition described
herein, or at least mitigate one or more symptoms of such condition. The precise dosage
of the composition for use (i.e., amount and scheduling) may be determined by a clinician,
based on the subject and the condition presented. Exemplary formulations (e.g., eye
drops) may be administered 1 to 24 times per day, or 1 to 12 times per day, or 1 to
6 times per day, or 1 to 4 times per day, or 1 to 3 times per day, or 1 to 2 times
per day, or 1, 2, 3 4, 6, 8,12, 18, or 24 times per day. The composition for use may
be topically applied as an eye drop by placing one drop in each eye to be treated.
Alternatively, 2 to 3 drops may be applied to each eye.
[0132] For the described composition for use, the dosage range may be, for example, 0.2
pg to 2.4 ng; or 2 pg to 2.4 ng of dexamethasone, or any salt, ester, or hydride thereof;
or about 0.2 pg, about 0.4 pg, about 0.6 pg, about 0.8 pg, about 1.2 pg, about 2.4
pg, about 2 pg, about 4 pg, about 6 pg, about 8 pg, about 12 pg, about 18 pg, about
24 pg, about 0.2 ng, about 0.26 ng, about 0.4 ng, about 0.6 ng, about 0.8 ng, about
1.2 ng, about 1.8 ng, or about 2.4 ng of dexamethasone, or any salt, ester, or hydride
thereof, per eye for one dose.
[0133] As other examples, the dosage range may be 12 ng to 1.3 pg; or 6 ng to 600 ng dexamethasone,
or derivative thereof or related steroidal agent; or about 6 ng, about 8 ng, about
12 ng, about 16 ng, about 18 ng, about 24 ng, about 26 ng, about 30 ng, about 36 ng,
about 40 ng, about 48 ng, about 52 ng, about 54 ng, about 60 ng, about 72 ng, about
78 ng, about 80 ng, about 90 ng, about 120 ng, about 130 ng, about 160 ng, about 180
ng, about 240 ng, about 260 ng, about 300 ng, about 360 ng, about 400 ng, about 480
ng, about 520 ng, about 540 ng, about 600 ng, about 720 ng, about 780 ng, about 900
ng, about 1.2 µg, about 1.3 µg of dexamethasone, or any salt, ester, or hydride thereof,
per eye for one dose.
[0134] As still other examples, the dosage range may be 1.5 pg to 150 pg; 2.6 pg to 260
pg; or 6.5 pg to 650 pg of dexamethasone, or derivative thereof or related steroidal
agent; or about 1.5 pg, about 2 pg, about 3 pg, about 4.5 pg, about 6 pg, about 6.5
pg, about 7.5 pg, about 10 pg, about 15 pg, about 22.5 pg, about 32.5 pg, about 20
pg, about 26 pg, about 30 pg, about 40 pg, about 45 pg, about 60 pg, about 65 pg,
about 75 pg, about 80 pg, about 90 pg, about 100 pg, about 120 pg, about 130 pg, about
150 pg, about 180 pg, about 225 pg, about 240 pg, about 260 pg, about 200 pg, about
300 pg, about 325 pg, about 450 pg, about 600 pg, or about 650 pg dexamethasone, or
any salt, ester, or hydride thereof, per eye for one dose. It will be recognised that
specific formulations of dexamethasone are commercially available, and such may be
utilised in accordance with accepted dosage amounts and scheduling.
[0135] Any of the above noted dosages of dexamethasone may be co-administered with a dosage
range of, for example, 5 pg to 65 ng; or 0.5 ng to 65 ng of TGFβ3 polypeptide, or
variants or fragments thereof; or about 5 pg, about 10 pg, about 15 pg, about 20 pg,
about 30 pg, about 45 pg, about 60 pg, about 0.05 ng, about 0.1 ng, about 0.15 ng,
about 0.2 ng, about 0.3 ng, about 0.45 ng, about 0.5 ng, about 0.6 ng, about 0.65
ng, about 1 ng, about 1.5 ng, about 2 ng, about 3 ng, about 4 ng, about 4.5 ng, about
6 ng, about 6.5 ng, about 7.5 ng, about 9 ng, about 10 ng, about 12 ng, about 13 ng,
about 15 ng, about 16 ng, about 20 ng, about 22.5 ng, about 24 ng, about 30 ng, about
32.5 ng, about 36 ng, about 40 ng, about 45 ng, about 48 ng, about 50 ng, about 52
ng, about 60 ng, or about 65 ng of TGFβ3 polypeptide as defined herein, per eye for
one dose.
[0136] Dosage for one eye may be about one drop of the disclosed composition for use. One
drop of composition may be 10 pl to 200 pl, 20 pl and 120 pl, or 50 pl to 80 pl or
any values in between. For example, dispensers such as pipettors can dispense drops
from 1 pl to 300 pl and any value in between. Preferably, the dispenser metes out
about 15 pl, about 20 pl, about 30 pl, about 45 pl, about 60 pl, or about 65 pl per
drop of the disclosed composition.
[0137] Where the composition for use is administered via a contact lens or another insert/implant
device, the contact lens or insert/implant may include, for example, 0.01 mg to 10
mg of dexamethasone, or any salt, ester, or hydride thereof; or about 0.01 mg, about
0.1 mg, about 0.5 mg, about 0.7 mg, about 1 mg, about 5 mg, or about 10 mg of dexamethasone,
or any salt, ester, or hydride thereof. Alternatively, the contact lens or insert/implant
may include 10 ng to 100 ng of dexamethasone, or any salt, ester, or hydride thereof;
or about 1 ng, about 5 ng, about 10 ng, about 20 ng, about 50 ng, about 80 ng, or
about 100 ng dexamethasone, or any salt, ester, or hydride thereof. As further examples,
the contact lens or insert/implant may include about 10 ng to 1 pg of TGFβ3 polypeptide;
or about 10 ng, about 50 ng, about 100 ng, about 200 ng, about 500 ng, about 800 ng,
or about 1 pg TGFβ3 polypeptide as defined herein.
[0138] The compositions for use described herein may be used in conjunction with various
surgical procedures or other treatments. For example, the compositions for use can
be used along with surgical and non-surgical methods for the refractive correction
of the eye. Exemplary methods include but are not limited to: radial keratotomy (RK),
including mini asymmetric radial keratotomy (MARK), hexagonal keratotomy (HK), photorefractive
keratectomy (PRK), keratomilleusis, laser
in situ keratomileusis (LASIK), e.g., intraLASIK
®, laser epithelial keratomileusis (LASEK), e.g., Epi- LASEK, automated lamellar keratoplasty
(ALK), laser thermal keratoplasty (LTK), conductive keratoplasty (CK), limbal relaxing
incisions (LRI), astigmatic keratotomy (AK), epikeratophakia, anterior ciliary sclerotomy
(ACS), scleral reinforcement surgery, presbyopia reversal, laser reversal of presbyopia
(LRP), intracorneal rings (ICR), intrastromal corneal ring segments (e.g., INTACTS
®), implantable contact lenses, scleral expansion bands (SEB), and Kamra
™ inlays. Also included are thermokeratoplasty, orthokeratology, enzyme orthokeratology,
and chemical orthokeratology.
[0139] The compositions for use may be used in conjunction with surgical correction of non-refractive
conditions, for example, surgical correction of a corneal tear. In particular aspects,
the compositions for use described herein may be used in conjunction with specific
surgical methods performed on the cornea. Exemplary methods include but are not limited
to: corneal transplant surgery, penetrating keratoplasty (PK), phototherapeutic keratectomy
(PTK), pterygium excision, corneal tattooing, keratoprosthesis insertion (e.g., KPro
or Dohlman-Doane), and osteo-odonto-keratoprosthesis insertion (OOKP).
[0140] The compositions for use may be used in conjunction with corneal collagen crosslinking.
Corneal crosslinking typically involves the use of riboflavin solution activated by
exposure to UV-A light. Noted crosslinking methods include but are not limited to:
corneal crosslinking with the epithelium removed (Dresden protocol, or epi- off),
transepithelial crosslinking (epi-on), and accelerated crosslinking. Crosslinking
procedures are generally available, and marketed as CXL, C3-R
® CCL
® and KXL
® corneal crosslinking, amongst others. Administration of the composition may be prior
to, and/or subsequent to, the crosslinking procedure. It is proposed that the disclosed
compositions can be used to avoid or counter the deleterious effects of crosslinking
procedures, such as stromal haze and cell loss (described in more detail, below).
Moreover, corneal regeneration with the disclosed compositions can allow crosslinking
to be performed on subjects who were previously ineligible for such procedures, e.g.,
those with corneal thickness less than 400 pm. Furthermore, the disclosed compositions
can be used to slow or halt progressive corneal thinning, which would not be addressed
by the use of crosslinking on its own.
[0141] The compositions for use described herein may be co-administered with one or more
additional agents for the eye. In various aspects, co-administration may be by simultaneous
or subsequent administration with such agents, or by co-formulation with such agents.
Depending on the condition being treated or prevented, the compositions for use described
herein may be co-administered with one or more agents, which include but are not limited
to: antihistamines, sympathomimetics, beta receptor blockers, parasympathomimetics,
parasympatholytics, prostaglandins, nutrients, vasoconstrictors, lubricants, anti-microbials,
and anaesthetics. Specifically included are various antiinflammatory agents, including
nonsteroidal anti-inflammatory drugs (NSAIDs). The compositions for use may also be
co-administered with eye lubricating solutions and tearreplacing solutions.
[0142] Non-limiting examples of anaesthetics include: benzocaine, bupivacaine, cocaine,
etidocaine, lidocaine, mepivacaine, pramoxine, prilocalne, chloroprocaine, procaine,
proparacaine, ropicaine, and tetracaine. Non-limiting examples of antiinflammatory
agents include: aspirin, acetaminophen, indomethacin, sulfasalazine, olsalazine, sodium
salicylate, choline magnesium trisalicylate, salsalate, diflunisal, salicylsalicylic
acid, sulindac, etodolac, tolmetin, diclofenac, ketorolac, ibuprofen, naproxen, flurbiprofen,
ketoprofen, fenoprofen, suprofen, oxaproxin, mefenamic acid, meclofenamic acid, oxicams,
piroxicam, tenoxicam, pyrazolidinediones, phenylbutazone, oxyphenthatrazone, pheniramine,
antazoline, nabumetone, COX-2 inhibitors (Celebrex
®), apazone, nimesulide, and zileuton. Glucocorticoids such as hydrocortisone, prednisolone,
fluorometholone, and dexamethasone may also be used as anti-inflammatory agents.
[0143] Exemplary anti-microbial agents include but are not limited to: bacitracin zinc,
chloramphenicol, chlorotetracycline, ciprofloxacin, erythromycin, gentamicin, norfloxacin,
sulfacetamide, sulfisoxazole, polymyxin B, tetracycline, tobramycin, idoxuridine,
trifluridine, vidarabine, acyclovir, foscamet, ganciclovir, natamycin, amphotericin
B, clotrimazole, econazole, fluconazole, ketoconazole, miconazole, flucytosine, clindamycin,
pyrimethamine, folinic acid, sulfadiazine, and trimethoprimsulfamethoxazole. Exemplary
vasoconstrictors include but are not limited to: dipivefrin (Propine
®), epinephrine, phenylephrine, apraclonidine, cocaine, hydroxyamphetamine, naphazoline,
tetrahydrozoline, dapiprazole, betaxolol, carteolol, levobunolol, metipranolol, and
timolol. Nutrients include vitamins, minerals, and other beneficial agents such as
vitamin A, vitamin Bi, vitamin Bö, vitamin B 12, vitamin C (ascorbic acid), vitamin
E, vitamin K, and zinc.
[0144] In specific aspects, the composition for use described herein is formulated as eye
drops, and such eye drops are used in conjunction with other eye drop formulations.
Such other eye drops may include but are not limited to: rinse/lubricating eye drops,
dry eye treatments, steroid and antibiotic eye drops, glaucoma eye drops, allergy/anti-
inflammatory eye drops, and conjunctivitis eye drops.
[0145] The compositions for use may be used in conjunction with contact lenses, corneal
inserts, corneal implants, or intrastromal rings, to assist in supporting or reshaping
the subject's cornea. Included amongst corneal inserts are corneal inlay and corneal
onlay devices. For example, contact lenses, intrastromal rings, or other inserts/implants
may be used for moulding or holding corneal shape preceding, during, and/or following
treatment with the composition. It is noted that a corneal 'insert' typically refers
to a temporary device inserted into the cornea, while a corneal 'implant' typically
refers to a more permanent device. However, many well known devices are described
interchangeably in the art as implants/inserts. Therefore, the terms 'insert/implant'
as used herein are not to be deemed as strictly limiting based on time of usage.
[0146] The contact lens, corneal insert, corneal implant, or intrastromal ring may be used
as a kit with the disclosed composition in treating or preventing thinning or irregularity
of a cornea of a subject; or treating or preventing a refractive error of the eye
of a subject. In various aspects, the contact lens, corneal insert, corneal implant,
or intrastromal ring may act as a carrier for the composition or as a composition
eluting device. In other aspects, the contact lens, intrastromal ring, or other corneal
insert/implant may be utilised with the composition that is suitable for administration
to the eye, e.g., eye drops, as described in detail herein. In certain aspects, computer
software may be used to determine the contact lenses, corneal inserts, corneal implants,
or intrastromal rings that are most suitable for the subject and/or to determine the
formulation of the composition. In particular aspects, treatment utilising contact
lenses, corneal inserts, corneal implants, or intrastromal rings along with the composition
described herein is used preceding or following eye surgery, e.g., refractive or transplant
surgery.
[0147] The treatment may involve assessing the subject (e.g., age, working needs of the
subject, eye defect or disease, etc.), prescribing the use of moulding contact lenses,
corneal inserts, corneal implants, or intrastromal rings to assist with the needed
changes in the radius of curvature of the anterior surface of the cornea, and prescribing
the composition described herein to be used in conjunction with the contact lenses
or implants/inserts. The contact lenses or implants/inserts which are prescribed and
utilised by the subject can be used exert a mechanical force on the cornea thereby
inducing a change in shape, i.e., the refractive power, of the cornea.
[0148] In certain preferred aspects, the cornea may be supported or shaped by use of a corneal
insert, corneal implant, or intrastromal ring in conjunction with the disclosed composition.
Examples of commercially available devices include INTACS
® and KeraRing intrastromal corneal rings. In another aspect, a moulding contact lens
may be used in conjunction with the disclosed composition. The contact lens may be
hard or rigid, or it may be a soft lens. Alternatively, the contact lens may comprise
both hard and soft portions. If a soft contact lens is used, more positive or negative
curvature can be induce in the cornea, and the discomfort in the subject's eyes will
diminish as he or she adapts to the contact lenses. If a hard contact lens is used,
more mechanical pressure can be exerted on the cornea. The contact lenses may be gas
permeable. Moulding contact lenses may be obtained from commercial sources. Examples
of commercially available lenses include, at least, DreamLite, OK Lens, EyeDream,
MiracLens, DreamLens, i-GO OVC, GOV, Wake and See, CRT, Fargo/iSee, Emerald and Wave
Contact Lens System lenses.
[0149] Once the contact lens, corneal insert, corneal implant, or intrastromal ring is placed
on/into the eye of the subject, the composition described herein (e.g., eye drops)
may be ad
ministered to the eye. In certain circumstances, it may be desirable to preadminister
the composition prior to placement of the contact lens, corneal insert, corneal implant,
or intrastromal ring. Advantageously, the contact lenses, intrastromal rings, or other
inserts/implants and the composition may be used in conjunction to produce a change
in the shape, and thereby the refractive power, of the cornea. The composition may
be administered more frequently to allow the cornea to adopt the desired change in
shape. In certain aspects, the composition is administered at least every 24,12, or
8 hours. In other aspects, the composition is administered every 6 hours. In certain
other aspects, the composition is administered approximately every 3 hours. In yet
other aspects, the composition is administered approximately every 2 hours. In still
other aspects, the composition is administered every hour.
[0150] Without wishing to be bound by any particular theory, the combined use of contact
lenses, corneal inserts, corneal implants, or intrastromal rings and the composition
described herein may induce changes in the molecular structure of the cornea and may
induce changes in the cells and proteins such as collagen (e.g., collagen type II)
found in the corneal stroma. The surface of the cornea is thereby made more uniform.
By reducing irregularities in the surface of the cornea, the quality and clearness
of all images (i.e., visual acuity) is improved.
[0151] For the calculation of the moulding contact lenses the flattest keratometry is taken.
One of skill in this art could also use the steeper keratometry or an average of both
and based on this corneal curvature make the necessary calculations to flatten or
steepen the radius of curvature of the anterior surface of the cornea and thus correct
the refractive defect of the eye. The base curve of the moulding contact lens may
be calculated based on the change in the refractive power for each eye separately.
In particular aspects, the base curve of the moulding contact lens may be calculated
starting with one to four flatter or steeper diopters, more preferably one to three
flatter or steeper diopters, even more preferably one to two flatter or steeper diopters,
depending on the refractive error that is required. The peripheral base curve depends
on the adaptation of the moulding contact lens and is calculated to be 0.5 mm of radius
greater than the central zone, but can vary depending on the design.
[0152] The diameter of the moulding contact lens used in accordance with the invention may
be from 8.0 mm to 18.0 mm. Commercially available lenses are produced with such diameters.
In certain aspects, the moulding contact lens may be a hard contact lens with a diameter
ranging from 8.0 mm to 12.0 mm. In other aspects, the moulding contact lens may be
a soft contact lens with a diameter ranging from 13.0 mm to 15.0 mm. Soft contact
lenses may cover the entire cornea and go from sclera to sclera. In still other aspects,
the moulding contact lens may be comprised of hard and soft materials. The contact
lens may be hard in the centre, out to approximately 12.0 mm, 13.0 mm, 14.0 mm, or
15.0 mm, and then soft in the periphery out to 16.0 mm, 17.0 mm, and 18.0 mm. A larger
contact lens, preferably a soft contact lens, may be used at night as a moulding contact
lens.
[0153] The power of the moulding contact lenses can be determined to the nearest possible
refractive power that the subject requires to see comfortably. During the adaptation
process with the moulding contact lenses, if the vision is not adequate for the needs
of the subject, the subject is prescribed eyeglasses while the subject is undergoing
treatment. As the cornea is being reshaped or has been reshaped, various optometric
measurements may be repeated to confirm that the treatment is progressing as planned
and is adequate. Such measurements may include assessment of visual acuity for near
and far vision, orthotypes, keratometry measurements, objective and subjective retinoscopy,
diagrams of the adaptation of the moulding contact lens, movement of the moulding
contact lens, and comfort of the moulding contact lens.
[0154] After the measurements are taken, changes may be made to the treatment program based
on these measurements. With each evaluation, a decision may be made whether to continue
with the same moulding contact lens or whether a new contact lens should be used.
In addition, the same decision can be made with regard to the composition being used
with the moulding contact lenses. Changes in the moulding contact lenses and/or in
the composition can be made to induce the desired reshaping of the cornea over several
weeks. In certain aspects, weekly periodic revisions are performed during the first
8 weeks after beginning treatment.
[0155] The composition as described herein induces changes in the collagen content of the
cornea (e.g., collagen type II). Other aspects of the anatomy, histology, and physiology
of the cornea may also be affected by composition. The composition may be hypertonic
or hypotonic to induce changes in corneal hydration. The composition may change the
molecular structure of the cornea (e.g., the extracellular matrix) and in this way
augment or repair the cornea, or reshape the cornea to the desired curvature.
[0156] When reshaping the cornea, it may be desirable to co-administer one or more enzymes
to soften the cornea. Exemplary enzymes include but are not limited to hyaluronidase,
chondroitinase ABC, chondroitinase AC, keratanse, and stromelysin, which have been
shown to work on various proteoglycan components of the cornea. Included also are
the enzyme collagenase, matrix metalloproteinase 1 (interstitial collagenase), and
matrix metalloproteinase 2 (gelatinase). Where the composition for use is coadministered
with any such enzymes, it may be desirable to include a vehicle such as a polymer
(e.g., methylcellulose, polyvinyl alcohol, cellulose, etc.) in the composition for
use to enhance the working of such enzymes. Additional agents may be included to activate
metalloproteinase enzymes, e.g., interleukin-la, tumour necrosis factor a/β and any
subtypes thereof, monosodium urate monohydrate, 4-amino phenylmercuric acetate, human
serum amyloid A, human B2 microglobin, and copper chloride. Also included may be carbamide
(urea). Any combination of these agents may also be used.
[0157] The composition for use may also be co-administered with one or more enzymes that
degrade other sugars or proteins found in the cornea. The composition for use may
be co-administered with one or more anaesthetics used to reduce the irritation of
the moulding contact lens or any corneal insert/implant to the cornea. The composition
for use may be co-administered with one or more lubricants to improve the comfort
of the subject during the treatment. In other aspects, the composition for use may
be co-administered with one or more anti-microbial agents such as anti-bacterial,
anti-viral, and/or anti-fungal agents. The composition for use may also be co-administered
with one or more vasoconstrictors. The person of skill in the art can determine the
appropriate agents for co-administration to the subject based on the condition being
treated.
[0158] In certain aspects, the composition may be provided in a kit as defined in the claims.
The kit may include one or more of; moulding contact lenses, lubricating eye drops,
cleaning or other solutions for the contact lenses, a contact lens carrying case,
an extra pair of contact lenses, and instructions for wearing the contact lenses and
using the composition. The composition provided with the kit may be formulated to
include the noted combination of components (a TGFβ3 polypeptide as defined herein
plus dexamethasone (or any salt, esters, or hydrides thereof)).
EXAMPLES
[0159] The examples described herein are provided for the purpose of illustrating specific
embodiments and aspects of the invention and are not intended to limit the invention
in any way. Persons of ordinary skill can utilise the disclosures and teachings herein
to produce other embodiments, aspects, and variations without undue experimentation.
Example 1: Overview of experiments
[0160] In previous experiments, the inventors have shown that it is possible to direct keratocytes
to differentiate down a neuronal lineage. The experiments described herein have aimed
to investigate the potential of keratocytes to switch to a chondrocyte-like cells
that secrete cartilage specific collagen type II. This type of cartilage is thought
to be expressed during development (Linsenmayer et al. 1990). A further aim has been
to establish whether collagen type II deposition could be induced
in vivo in the corneas of live rats and whether this treatment positively affected the optical
properties of the corneas. A still further aim has been to determine whether keratocytes
in keratoconic tissue could be amenable to this method of cell reprogramming and subsequent
production of collagen type II rich ECM. Finally, the experiments have aimed to evaluate
the effect of type II collagen deposition on the biomechanical properties of the
in vivo and
ex vivo treated corneas using nanoindentation testing, a bioengineering approach that enables
analysis of hardness and elastic modulus.
Example 2: Tissue samples
Human tissue
[0161] Cadaveric whole human corneas, keratoconic corneas obtained at the time of transplant
surgery, human limbal rims and surgeon cut DSEK caps (excess stromal tissue from Descemets
stripping endothelial keratoplasty) were obtained from donors sourced through the
New Zealand National Eye Bank (Auckland, New Zealand). Human limbal rims were collected
after the central corneal button had been removed for corneal transplantation surgery
leaving a 2 mm corneal margin from the limbal junction. Prior to the use of tissue,
research ethics approval and consent was obtained from the Northern X Regional Human
Ethics Committee. All tissue, until use, was stored in New Zealand Eye Bank medium
(2% FCS, 2 mM L-glutamine, 1 × Anti-Anti in Eagles MEM) and transported in New Zealand
Eye Bank transport medium (Eye Bank medium supplemented with 5% dextran).
Animal tissue
[0162] Ethics approval for animal studies was obtained from the University of Auckland Animal
Ethics Committee (application number R856). Eyes and cartilage from 6-8 week old adult
male Wistar rats were obtained after euthanisation using a carbon dioxide chamber.
The whole eye was removed from the animal and the cornea was carefully dissected out
using surgical scissors with the aid of a dissecting microscope. The xiphoid process,
which is part of the sternum that contains a thin, broad plate of cartilage at its
end, was dissected out using a scalpel blade. The animal tissue was washed with povidone-iodine
(PVP-I) and sodium thiosulphate. The excess fat and tissue covering the cartilage
was scraped away with a blade. Freshly harvested eyes and cartilage were stored for
a minimal amount of time in phosphate buffered saline solution until use.
Example 3: Histological analysis
Tissue preparation and cryosectioning
[0163] Corneal and cartilage pieces (2 mm × 2 mm) were embedded in Optimal Cutting Temperature
compound (OCT, Tissue-Tek, Sakura, The Netherlands) before being snap frozen in liquid
nitrogen. Sections 10-15 µm thick were cut using a Microm HM550 Cryostat (Thermo-Scientific,
USA) and mounted on SuperFrost
™ Plus electrostatic slides (Menzel-Glenser, Germany). Cryosections were stored at
-20°C until further use.
Cell and Tissue Culture
Tissue digestion and cell preparation from human and rat corneas
[0164] Limbal rims were dissected to isolate stroma from sclera in a class II laminar flow
hood. Following this, the corneal epithelium and endothelium was gently scraped off
with a keratome and discarded. DSEK caps also received gentle scraping with a keratome
to remove the epithelium. Remaining stromal tissue was then digested in 0.4% type
II collagenase (Sigma-Aldrich), in Hanks balanced salt solution (GIBCO
®, Life Technologies) at 37°C with gentle mixing on an orbital shaker. A variety of
digestion times were used with 5 hours being the time required for optimal tissue
digestion and cell viability.
[0165] After tissue digestion was complete the cells were pelleted by centrifuging at 1200
rpm for seven minutes. The cells were then resuspended in a minimal amount of an appropriate
cell culture medium and counted using a Leica DM IL bench top inverted microscope
and a Neubauer hemocytometer. A 1:1 ratio of cell suspension added to trypan blue
solution (0.04% trypan blue stock in PBS) was used with a minimum of three counts
per sample and the average value taken.
Cell culture of corneal keratocytes
[0166] All cell manipulations were performed in a class II laminar flow hood using aseptic
technique. Isolated keratocytes were cultured in either 12 or 24 well cluster plates
(Falcon) on plastic or glass coverslips in 2-3 ml of cell culture media. Cells were
kept in a humidified incubator at 37°C with 5% CO
2. Culture media was changed after 24 hours then every two days subsequently or more
frequently if required. Cultures were viewed daily with a Leica DM IL bench top inverted
microscope. For cell pellet culture, freshly obtained cells after tissue were pelleted
by centrifuging at 300 g for 7 minutes at 20°C in a plastic conical tube. Appropriate
culture media was added to the tubes. After 24 hours of incubation at 37°C, the cells
had contracted and formed a pellet which did not adhere to the walls of the tube.
The pellets were cultured in 2 ml of media in a humidified atmosphere of 5% CO
2 at 37°C for three weeks. Media was changed every other day.
Organotypic slice culture
[0167] Human and rat corneal and cartilage tissue was thin-sliced (1-2 mm) in an anteroposterior
plane with a blade and the slices were placed in an organotypic air-liquid interphase
culture system (Figure 2). Briefly, the explants of healthy tissue were cultured on
0.4 µm pore size cell culture inserts (Millicell, France) at the interface between
culture medium and a CO
2 rich environment. Corneal sections were placed epithelium side up on cell culture
plate inserts with 3 ml of culture medium. The culture media was changed every other
day.
Example 3: In vitro reprogramming
Culture media
[0168] Several custom made media were used as described in the table below.
Table 1: Cell culture media used
| Name |
Medium Base |
Other Components |
| Fibroblast proliferation medium |
Dulbecco's Modified Eagle Medium (DMEM) (Life Technologies, GIBCO®) |
10% FBS, 1% Anti-anti (100X stock), 1% GlutaMAX™ (100X stock) |
| Chondrogenic reprogramming medium |
Advanced DMEM (Life Technologies, GIBCO®) |
10 ng/ml TGFβ3 (Abeam, ab52313), 10-7 M dexamethasone (Abeam, ab120743), 1% GlutaMAX™ (Life Technologies, GIBCO®) (100X stock), 1% Anti-Anti (100X stock) (Life Technologies, GIBCO®) |
| Control medium |
Dulbecco's Modified Eagle Medium (DMEM) |
1% GlutaMAX™ (100X stock), 1% Anti-Anti (100X stock) |
Chondrogenic reprogramming of keratocytes
[0169] Tissue slices were cultured in the chondrogenic differentiation medium for varying
time intervals to determine the optimum time required for the growth factor treatment.
Samples were collected for each time point (Table 2). For obtaining a monolayer of
cells, keratocytes were seeded on glass coverslips at a density of 15 × 10
4 per cm
2. The cells were allowed to attach to the coverslips for 24 hours and culture media
was changed every other day. Cultures were maintained for up to 3 weeks.
Table 2: Experimental time points for corneal tissue slice culture
| |
Time point 1 Week 1 |
Time point 1 Week 2 |
Time point 1 Week 3 |
| Sample 1 |
chondrogenic differentiation medium |
control medium |
control medium |
| Sample 2 |
chondrogenic differentiation medium |
chondrogenic differentiation medium |
control medium |
| Sample 3 |
chondrogenic differentiation medium |
chondrogenic differentiation medium |
chondrogenic differentiation medium |
| Sample 4 |
control medium |
control medium |
control medium |
Example 4: In vivo reprogramming
Gel eye drop formulation for growth factor delivery
[0170] Eye drops were formulated using gellan gum which is a water soluble polysaccharide
produced by the bacterium,
Pseudomonas elodea. The use of gel base formulation allows a prolonged corneal residence time and increased
ocular bioavailability of the therapeutic agent. Since polymeric gellan gum is an
anionic polymer it undergoes
in situ gelling in the presence of mono- and divalent cations such as Ca
2+, Mg
2+, K
+, and Na
+ (Bakliwal, & Pawar 2010) . The electrolytes present in the tear fluid cause the gelation
of the polymer when it is instilled in the eye and this in turn results in a longer
residence time and increased bioavailability of the drug (Ludwig 2005). Based on previous
formulation studies, the polymer formulation is a non-irritant and safe for
in vivo use (Rupenthal, Green, & Alany 2011).
[0171] A 0.5% solution was prepared by first heating distilled water to 80°C followed by
the addition of gellan gum (Kelcogel
™ USA) with constant stirring. Once the powder was completely dissolved, the solution
was cooled and stored at 4°C. The appropriate amounts of growth factors were added
to the runny gel with constant stirring. A ten times higher concentration of growth
factors than that used in the culture medium was used to make up for the drug lost
through naso-lacrymal drainage and blinking. The eye drop gel included a final concentration
of 100 ng/ml TGFβ3 and approximately 4 µg/ml dexamethasone.
Treatment with neurogenic and chondrogenic factors
[0172] The animals were manually restrained and approximately 15 µL of the eye drops were
instilled in the right eye (Figure 3). The contra lateral eye was used as the control
eye. Thrice daily eye drops were administered for up to 5 days for neuronal specification
and for up to 8 weeks for chondrogenic specification.
Example 5: Immunohistochemical (IHC) analysis
Tissue harvesting and treatment
[0173] At the end of the treatment the animals were euthanised using a carbon dioxide chamber.
The eyes were harvested and rinsed in phosphate buffered saline. The corneas were
then dissected out carefully and fixed in 4% paraformaldehyde (PFA) for 1 hour and
treated with sucrose solution in order to cryoprotect the tissue before freezing and
sectioning. Sucrose as a cryoprotection is a dehydrant that prevents the formation
of ice crystal artefact in frozen tissue sections. In the case of slow freezing of
the tissue cryoprotection is particularly important.
[0174] Briefly, the corneas were immersed in 20% sucrose solution for 5 hours at 4°C and
then moved to a 30% sucrose solution and kept at 4°C until the tissue sinks (usually
overnight). The corneas were then embedded in OCT compound and immersed in liquid
nitrogen to bring about rapid freezing. The frozen blocks of tissue were stored at
-80°C until further use. Approximately 10-15 µm thick cryostat sections were mounted
on SuperFrost
™ Plus slides and the slides were stored at -80°C until needed. In the case of cell
cultures, the cells cultured on coverslips were rinsed with PBS and fixed with 4%
PFA for 15 minutes. Coverslips were immersed in PBS until further use.
Immunohistochemistry
[0175] For tissue cryosections, before carrying out immunohistochemistry, the slides were
kept at room temperature for 15-20 minutes. The OCT was washed off using PBS and the
zone around the tissue demarcated using a wax pen. The tissue slices were first incubated
with a blocking solution of 10% normal goat serum for 1 hour followed by overnight
incubation with the appropriate dilution of primary antibody at 4°C. The slides were
then rinsed three times in PBS before incubation with the appropriate dilution of
secondary antibody. The secondary antibody was left on for 2 hours at room temperature.
Slices were counterstained with the nuclear marker 4', 6'-diamidino-2-phenylindol
(DAPI) and mounted in Citifluor antifade agent (ProSciTech, Australia). An Olympus
FluoView
™ FV-1000 confocal laser scanning microscope (405 nm, 473 nm, and 559 nm wavelength
lasers) and Leica DMRA fluorescence microscope were used for imaging.
Table 3: Antibodies used
| Antibody |
Supplier/Cat. No. |
Dilution used |
| Primary antibodies |
| Mouse anti Collagen Type I |
Abcam/ab63080 |
1:2000 |
| Mouse anti Collagen Type II |
Millipore/MAB8887 |
1:200 |
| Mouse anti Collagen Type III |
Biogenesis/2150-0081 |
1:100 |
| Mouse anti Vimentin |
Sigma/V6630 |
1:1000 |
| Mouse anti α Smooth muscle actin |
Novocastra/NCL-SMA |
1:100 |
| Secondary antibodies |
| Goat anti mouse Alexa 568 |
Molecular probes®/A-11031 |
1:500 |
| Goat anti rabbit Alexa 488 |
Molecular Probes®/A-11034 |
1:500 |
| Goat anti mouse Alexa 488 |
Molecular Probes®/A-11001 |
1:500 |
Example 6: Gene expression analysis
RNA isolation and cDNA synthesis
[0176] The mRNA extraction from samples was carried out using the PureLink
® RNA MicroKit (Invitrogen). In brief, tissue samples were mixed with 0.75 ml TRIzol
® and carrier RNA and homogenised using a hand held homogeniser (PRO Scientific, Inc.).
The samples where then incubated with 0.2 ml of chloroform followed by centrifugation
at 12000 rpm and 4°C for 15 minutes. The upper phase was separated and was mixed with
ethanol and then transferred to the collection column tube.
[0177] The RNA was collected on the column by centrifuging at 12000 rpm for 1 minute. The
flow-through was discarded and the extracted RNA treated with deoxyribonuclease (DNAse).
The column was washed several times with the buffers provided and the RNA was finally
dispersed in ribonuclease (RNAse) free water. The concentration was determined using
a NanoDrop
® (Thermo Scientific) and the mRNA was stored at -80°C.
[0178] The SuperScript
® VILO
™ cDNA Synthesis Kit (Invitrogen
™, Life Technologies) was used to prepare cDNA. Briefly, 100 ng of RNA was incubated
at 25°C for 10 minutes with VILO
™ Reaction Mix, SuperScript
® Enzyme Mix, and RNAse free water. The samples were then incubated at 42°C for 120
minutes followed by 85°C incubation for 5 minutes. The cDNA was stored at -20°C.
Quantitative PCR using TaqMan® gene expression assays
[0179] TaqMan
® Gene Expression Assays for the genes of interest were obtained. In the PCR step,
10 µL of TaqMan
® Universal Master Mix II was combined with 1 µL of the assay, approximately 25 ng
of cDNA and 9 µL water to make up a volume of 20 µL. The tubes were vortexed and centrifuged
briefly to spin down the contents. Each cDNA sample was prepared in triplicate and
pipetted into a 3 84 well plate. 20 µL of each reaction mixture was loaded into each
well of a MicroAmp
® Optical 384-Well Reaction Plate (Applied Biosystems). The plate was then covered
with a MicroAmp
® Optical Adhesive Film (Applied Biosystems) and the plate was centrifuged briefly
to eliminate air bubbles. The plate was transferred to the 7900HT Fast Real-Time PCR
System and was run using the following thermal cycling parameters, 50°C for 2 min,
95°C for 10 minutes followed by 40 cycles of 95°C at 15 sec and 60°C at 1 minute.
Results were analysed as described in the previous section.
Table 4: TaqMan® gene assays used for QPCR
| Gene symbol |
Gene name |
Assay ID |
| Colla1 (Rat) |
Collagen, type I, alpha 1 |
Rn01463848_m1 |
| Col2a1 (Rat) |
Collagen, type II, alpha 1 |
Rn01637085_m1 |
| Col2a1 (Rat) |
Collagen, type II, alpha 1 |
Rn01637087_m1 |
| Pop4 (Rat) |
Ribonuclease P protein subunit p29 (housekeeping gene) |
Rn02347225_m1 |
| COL2A1 (Human) |
Collagen, type II, alpha 1 |
Hs00264051_m1 |
| CDKN1A (Human) |
Cyclin-Dependent Kinase Inhibitor 1 (housekeeping gene) |
Hs00355782_m1 |
Example 7: Testing of biomechanical and optical properties of corneas following in situ stromal ECM protein deposition
Examination of anterior segment (frontal structures) of the rodent eye
[0180] Corneal biomechanics have been shown to be relevant in the diagnosis and treatment
of various corneal diseases and provide insight into the structure of the cornea and
its relation to corneal physiological function. Corneas that have undergone treatment
to bring about the deposition of ECM protein also need to be tested for corneal opacity
as reduced transparency would be undesirable.
[0181] The Phoenix Micron IV Rodent eye Imaging System (Phoenix Research Labs) was used
to examine the corneas of treated rats. Rats were first sedated using an intra-peritoneal
injection of ketamine and Domitor
® (3:2). The slit-lamp attachment of the Micron IV imaging system was used to examine
the layers of the cornea in detail and check corneal integrity and transparency. Retinal
imaging was also done to check corneal transparency. Following imaging, the rats were
administered Antisedan
® (atipamezole) for reversal of the sedative.
Nanoindentation measurements of in vitro and in vivo treated corneas
[0182] Nanoindentation provides mechanical measurements of materials of interest through
the application of ultra-small forces perpendicular to the sample plane of interest
and measurement of the resultant sample indentation (Dias & Ziebarth 2013). Nanoindentation
has recently emerged as a powerful tool for measuring nano- and microscale mechanical
properties in tissues and other biomaterials (Ebenstein & Pruitt 2006). The more recent
advancement of
in situ scanning probe microscopy (SPM) imaging, where the nanoindenter tip is simultaneously
used as a 3D imaging device combined with nanoindentation has enabled a new wave of
novel materials research (Dickinson & Schirer 2009). Force, displacement, and time
are recorded simultaneously while a nanoindentation tip is pushed into the corneal
tissue under a controlled load. The forces applied during nanoindentation can be as
small as a few nanoNewtons or as large as several Newtons enabling a range of size
scales to be studied. Nanoindentation tests are output as a load-displacement curve
which can be analysed using well defined equations to calculate the mechanical properties
relating to rigidity, integrity, and elasticity of the cornea.
[0183] Human keratoconic corneas were put into organotypic culture either in control medium
or in medium containing the specific ECM protein inducing reprogramming factors. Nanoindentation
measurements were then taken at the end of the treatment time. For the
in vivo study, the animals were manually restrained and approximately 15 µL of the gel eye
drop formulation containing the reprogramming factors were instilled in the right
eye of each Wistar rat. The contra lateral eye was used as the control eye. Eye drops
were administered thrice daily for up to seven weeks. Nanoindentation measurements
were recorded after week 1, week 3, or week 7 of the treatment period on isolated
eyes.
[0184] Nanoindentation testing was carried out at the Chemical and Materials Engineering
lab at the University of Auckland. In order to test the cornea in its natural position,
a mould was required for nanoindentation. Previous studies have used polystyrene and
blue tack to hold the corneas in place. The effect of the mould deforming under the
load was a potential source of error so a hard mould was decided on for testing. The
first material that was used to create a mould was conventional play dough. This was
formed to the exact shape and curvature of human cornea samples (Figure 6(A)). The
play dough was then left to harden over the next two days before being used in testing.
The testing of the rat eyes was slightly different as the entire globe was used. To
hold the globes in place a petri dish filled with a resin and having small indent
to hold the globe was used (Figure 6(B)). PBS was used to keep the samples from drying
out.
[0185] Because the samples are very soft biological samples a conospherical fluid tip was
used for all nanoindentation testing. The indent load used for the human samples was
50 µN. For the rat globes a range of loads between 3 and 5 µN were used. The fibre
optic light was switched on and the sample placed directly under the stream of light
from the microscope. The central section of the cornea was placed directly in the
stream of light as accurately as possible (Figure 6(C)). The sample was focused by
adjusting the Z slider until the surface of the cornea could be observed in good resolution.
To ensure that the focus was on the central highest point of the cornea sample, the
view was moved in the x and y directions to observe how the focus changed.
[0186] Once the data collection point was focused on the centre of the cornea, the sample
boundary was defined and a quick approach was performed. Before indenting the load
function had to be set up correctly. The actual indentation process is automated by
the Hysitron Triboindenter
® (Figure 6(D)). The pre-defined load was placed on the indenter tip which penetrates
the sample until it reaches a defined limit. The tip was then held for 10 seconds
before the tip was unloaded from the sample. The hardness of the sample is determined
by the area of residual indentation (Ar) after the tip is unloaded.

[0187] Where P
max is the maximum indentation load and Area is the contact area of the conospherical
tip with the sample. The reduced elastic modulus is a representation of the elastic
modulus in both the sample and the indenter tip as shown by the following equation:

[0188] Where i referrers to the indenter and
m refers to the sample material. The reduced elastic modulus tells us how elastic a
sample is. Because the same indenter tip is used for each test the reduced elastic
modulus can be used to compare the elasticity in each sample being tested.
Example 8: Adult human corneal keratocytes produce cartilage specific collagen type
II upon treatment with exogenous TGFβ3 and dexamethasone
[0189] It is known that one growth factor may act on several types of cells with similar
or varied effects whilst more than one growth factor may share similar biological
functions. When choosing growth factors, cytokines, and chemicals that might bring
about collagen deposition in the corneal stroma it was important to consider the known
effects of certain exogenous factors. In the present experiments, a combination treatment
of TGFP3 and dexamethasone was utilised.
[0190] Most of the evidence for the effects of TGFβ3 and dexamethasone has been obtained
by studies done on their effects on stem/progenitor cells (Schuldiner, Yanuka, Itskovitz-Eldor,
Melton, & Benvenisty 2000; Worster, Nixon, Brower-Toland, & Williams 2000). A combination
of TGFβ and dexamethasone has been previously used to induce progenitor cells to differentiate
into chondrocytes
in vitro (Diekman, Rowland, Lennon, Caplan, & Guilak 2009; Johnstone et al. 1998; Kolambkar,
Peister, Soker, Atala, & Guldberg 2007; Winter et al. 2003). Furthermore, dexamethasone,
a synthetic steroid drug has been used to treat inflammatory eye conditions. Therefore
a combination of TGFβ3 and dexamethasone was used in the chondrogenic differentiation
medium to drive the differentiation of keratocytes towards a chondrocyte phenotype.
[0191] In the present experiments, the expression of type I and type II collagen was specifically
noted. It is known that fibrillar types of collagen such as types I and II self-assemble
and crosslink to form highly crystalline fibres exhibit a very high stiffness, low
extensibility and a remarkable elastic energy storage capacity (Wells 2003). It is
the crosslinking which contributes towards the stiffness and tensile strength of the
fibres.
[0192] The corneal stromal extracellular matrix (ECM) is composed of tightly packed heterotypic
collagen fibrils made up mostly of collagen types I and V. Similar to corneal fibrils,
cartilage fibrils are heterotypic (made up of types II and XI) and have a uniform
diameter of 25 nm (slightly smaller than corneal fibrils) (Mendler, Eich-Bender, Vaughan,
Winterhalter, & Bruckner 1989). Collagen II is the major fibril component of cartilage
and is similar to collagen I in that the molecule essentially consists of a single
uninterrupted helical domain 300 nm in length. Owing to their similarities, collagens
II and XI are considered to be the cartilage analogues of collagens I and V (corneal
stroma collagens) in other tissues.
[0193] In the present experiments, corneal keratocytes from adult corneas were seeded in
either the chondrogenic differentiation medium containing TGFβ3 and dexamethasone
or a standard fibroblast proliferation medium. Within 2-3 days the keratocytes seeded
in the chondrogenic differentiation media formed cell aggregations/spheres (Figure
7(A)) approximately 50-100 µm in diameter. The spheres labelled for the chondrocyte
specific collagen type II in the central portion and nestin around the periphery (Figure
7(B)). Furthermore, once the spheres were placed in the fibroblast proliferation media
cells from the spheres started spreading outwards (Figure 7(C)) to populate the culture
dish thereby forming a cell monolayer. The regions where the cells had once been aggregated
labelled for collagen type II whereas the cells in monolayer did not (Figure 7(D)).
[0194] Keratocytes seeded in the fibroblast proliferating medium formed an even monolayer
of fibroblast-like cells (Figure 8(A)) which did not label for either nestin or collagen
type II (Figure 8(B)). When the media was changed to chondrogenic differentiation
medium there were no changes in the appearance of the culture and cells remained collagen
type II negative. These results suggest that cell aggregation appears to be important
for cartilage-like ECM production. Keratocytes seeded into fibroblast proliferation
medium failed to form the necessary cell aggregations. Therefore, in order to form
fibroblast clusters, the confluent fibroblasts were dissociated from the culture dish,
pelleted, and grown as a pellet culture in chondrogenic differentiation medium for
a further three weeks. Cell pellets labelled positive for the corneal stroma specific
ECM protein keratocan but not the cartilage specific ECM protein type II collagen
(Figure 8(F) and (G)).
Example 9: Keratocytes in adult human corneas and adult rat corneas secrete collagen
type II containing ECM when treated with TGFβ3 and dexamethasone
[0195] Slices of adult human cornea were placed in organotypic slice culture in either control
medium or chondrogenic differentiation medium for two weeks. The tissue slices were
then labelled for the chondrocyte specific ECM protein collagen type II and the native
corneal collagen type I. Positive labelling was seen only in the TGFβ3 and dexamethasone
treated corneas (Figure 9(C) and 10(B)). It was found that a treatment period of two
weeks resulted in deposition of type II collagen within the stromal ECM of treated
corneas (Figure 9(C)). Treatment for 1 week did not result in any visible deposition
of type II collagen in the stromal ECM (Figure 9(B)).
[0196] The amount and pattern of the native collagen type I appeared to be slightly altered
in the treated corneas. In general, the intensity of the labelling was similar but
the distribution was more extensive and the amount of labelling was higher in the
untreated corneas (Figure 9(D)). Furthermore, the newly produced type II collagen
was laid evenly and in an ordered fashion in the ECM without forming any large masses
or aggregates. The labelling was clearly seen along the pre-existing collagen framework
of the corneal stroma and was distributed across the entire thickness of the stromal
layer.
[0197] The
in vitro human corneal tissue experiment was then extended to an
in vivo rodent study wherein the right corneas of male Wistar rats were treated for two weeks
with a thrice daily administration of 15 µl of a gellan gum based eye drop formulation
of TGFP3 and dexamethasone. After two weeks the rats were euthanised and the corneas
processed for immunohistochemistry. Only the treated corneas labelled positive for
collagen type II with a higher degree of deposition observed in the anterior part
of the cornea (Figure 10(D) and (E)). Thus, only corneal slices cultured in the chondrogenic
differentiation medium were positive for type II collagen. Furthermore, type II collagen
was laid down in uniform layers along the pre-existing collagen framework of the stroma.
Example 10: Induction of collagen type II deposition in keratoconic corneas
[0198] The inventors next looked to confirm that the
in vivo reprogramming observed in their studies could be utilised in treatments for keratoconus.
Experiments were carried out to affirm that keratocytes in keratoconic corneas were
amenable to the induction of collagen type II deposition. Keratoconic corneal buttons
obtained after corneal transplant surgery were placed into culture as soon as they
were obtained. Half of each button was put into control medium and the other half
placed in chondrogenic differentiation medium and maintained for 2 weeks. After 2
weeks the tissue was processed for either immunohistochemistry or mRNA extraction.
The stromal ECM of only the treated half of the cornea was positive for type II collagen
(Figure 11(B)). Although the intensity of the labelling was lower in keratoconic tissue
when compared to normal corneal tissue, the labelling pattern was similar and followed
an ordered arrangement along the backbone of pre-existing collagen lamellae.
[0199] Vimentin labelling revealed stark differences between keratocytes in the untreated
and treated keratoconic corneas. In general the keratocyte density was lower in the
untreated corneas with a scarcity of cells in the posterior part of the cornea (Figure
11(C)). Also, the keratocytes in treated corneas appeared more filamentous and complete
in morphology when compared to keratocytes in untreated corneas (Figure 11(E) and(F)).
Keratocytes in treated corneas were longer and had a larger number of cell processes
which labelled strongly for Vimentin when compared to the keratocytes in the untreated
corneas.
Example 11: TGFβ3 and dexamethasone treatment does not induce deposition of fibrotic
proteins or cause corneal opacity
[0200] Human corneas cultured in the chondrogenic differentiation medium for up to three
weeks were labelled for collagen type III and αSMA which are associated with fibrosis
and scarring (Gabbiani 2003; Karamichos et al. 2012). There was no evidence of any
fibrotic matrix deposition, on the other hand there was a higher degree of αSMA labelling
in the control tissue (Figure 12). These results confirm previous findings that, unlike
TGFβ1 and TGFβ2, TGFβ3 does not induce the differentiation of corneal keratocytes
into myofibroblasts.
[0201] Slit lamp examination was performed on the live rats throughout the study period.
Upon examination, treated and untreated corneas were indistinguishable with no signs
of scarring or opacity. Back of the eye imaging to reveal the blood vessels showed
clear corneas which did not obstruct the passage of light (Figure 13(A) and (B)) and
in vivo cross section imaging of the rat cornea using the Micron IV lens revealed transparent
corneas through which light easily passed (Figure 13(C) and (D)). There was no sign
of any corneal opacity or cloudiness which would lead to the obstruction of light
passing through the cornea.
Example 12: Change in mRNA expression of collagen type II and type I upon treatment
in vivo
[0202] Rat corneas which were treated
in vivo for 1 week, 7 weeks, and 3 weeks followed by a non-treatment period of 4 weeks were
subjected to quantitative gene expression analysis. The aim was to determine whether
type II collagen expression decreases again and/or permanently ceases after growth
factor treatment is withdrawn. The effect of the treatment on native corneal collagen
type II was also investigated.
[0203] When compared to the 7 weeks treated corneas, the 1 week treated corneas expressed
very high levels of type II collagen. The expression levels dropped considerably upon
withdrawal of the treatment as indicated by the first graph in figure 35. For type
I collagen expression, the 1 week and 7 week treated corneas were each compared to
their untreated corneas. It was found that there was an initial spike in type I Collagen
expression after 1 week treatment but by week 7 type I Collagen expression was significantly
lower and comparable to its expression in the untreated cornea (Figure 14 (B)).
Example 13: Change in biomechanical properties of in vitro and in vivo treated corneas
[0204] It was hypothesised that the laying down of type II collagen would affect the stiffness
and elasticity of the corneas. In order to evaluate these changes, the
in vivo rat corneas and
ex vivo treated human corneas and their matching controls were subjected to nanoindentation
testing.
[0205] When compared to the untreated controls the 1 week
in vivo treated rat corneas did not have a significant increase in either hardness or elasticity
(Figure 15). In the 3 week
in vivo treated corneas, there was a clear difference between the treated and control eye.
Each of the corneas was tested up to eight times and the resulting load deformation
graphs obtained showed good reproducibility (Figure 16). In the right eye exposed
to the growth factor treatment, both the hardness and reduced elastic modulus were
markedly higher. A matched pair of keratoglobus corneas that were cultured
ex vivo in either the control medium or the chondrogenic differentiation medium for 6 weeks
were also subjected to the same biomechanical testing. Once again, testing revealed
a significant increase in hardness and elastic modulus in the treated cornea (Figure
17).
Example 14: Comparative combinations of growth factors and steroids
[0206] An
ex vivo study on sheep corneas was carried out in order to investigate the efficacy of other
growth factor-steroid combinations in chondrogenic differentiation of corneal keratocytes.
[0207] Fresh sheep eyes were obtained from Auckland Meat Processors. The corneas were immediately
excised and washed with povidone-iodine (PVP-1) and sodium thiosulphate solution.
Then, 8 mm discs of sheep corneal tissue were cut using a trephine. One sheep corneal
disc was placed in each of the culture conditions (outlined in Table 5) for 3 weeks.
The corneal discs were then placed in an organotypic air-liquid interphase culture
system.
[0208] Briefly, the explants of healthy tissue were cultured on 0.4 µm pore size cell culture
inserts (Millicell, France) at the interface between culture medium and a CO
2 rich environment. Corneal sections were placed epithelium side up on cell culture
plate inserts with 3 ml of culture medium. The culture media was changed every other
day. The basal medium used was Dulbecco's Modified Eagle Medium (DMEM) supplemented
with 1% Anti-Anti (antibiotic-antimycotic solution) and 1% GlutaMAX
™ (GIBCO
®). At the end of 3 weeks, each corneal disc was fixed in 4% paraformaldehyde (PFA)
for 1 hour and treated with sucrose solution in order to cryoprotect the tissue before
freezing and sectioning.
[0209] In brief, the corneas were immersed in 20% sucrose solution for 5 hours at 4°C and
then moved to a 30% sucrose solution and kept at 4°C until the tissue sank (usually
overnight). The corneas were then embedded in OCT (optimal cutting temperature) compound
and immersed in liquid nitrogen to bring about rapid freezing. The frozen blocks of
tissue were stored at -80 °C until further use. Approximately 4-6 40 µm thick cryostat
sections were mounted on SuperFrost
™ Plus slides and the slides were stored at -80 °C until needed. The corneal sections
were then labelled for collagen type II.
[0210] For immunohistochemistry, the slides were kept at room temperature for 15-20 minutes.
The OCT was washed off using PBS and the zone around the tissue was demarcated using
a wax pen. The tissue slices were first incubated with a blocking solution of 10%
normal goat serum for 1 hr followed by overnight incubation with mouse anti collagen
II antibody (Millipore/MAB8887) at 4°C. The slides were then rinsed three times in
PBS before incubation with the appropriate dilution of goat anti mouse Alexa Fluor
® 488 secondary antibody (Molecular Probes
®/A-11001). The secondary antibody was left on for 2 hours at room temperature. Slices
were counterstained with the nuclear marker 4', 6'-diamidino-2-phenylindol (DAPI)
and mounted in Citifluor antifade agent (ProSciTech, Australia). An Olympus FluoView
™ FV-1000 confocal laser scanning microscope (405 nm, 473 nm and 559 nm wavelength
lasers) and Leica DMRA fluorescence microscope were used to visualise labelling.
[0211] Table 5 depicts the findings from this study. Figure 20 shows representative images
of collagen type II labelling in corneal sections, in each of the conditions.
Table 5: Tested combinations of growth factors and steroids
| Growth factor-steroid combination |
Collagen type II deposition (Y/N) |
Representative image |
| BMP6 |
N |
Figure 20A |
| BMP6 + hydrocortisone |
N |
Figure 20B |
| TGFβ3 + hydrocortisone |
N |
Figure 20C |
| BMP6 + dexamethasone |
N |
Figure 20D |
| TGFβ3 + prednisone |
N |
Figure 20E |
| TGFβ3 + Triesense® |
N |
Figure 20F |
| TGFβ3 + dexamethasone |
Y |
Figure 20G-H |
[0212] The results confirmed that the combination of TGFβ3 and dexamethasone is the only
tested combination that elicited the desired response from the target cells (Figure
20, panels G-H). The other growth factor-steroid combinations failed to produce the
desired changes in collagen type II in keratocytes (Figure 20, panels A-F). The results
also confirmed the reprogramming of keratocytes in sheep corneas (Figure 20, panels
G-H).
[0213] Previous studies have shown other growth factors and other steroid compounds to be
unsuitable for corneal treatment and repair. TGFβ1 and TGFβ2 both produce fibrotic
scarring (Carrington, Albon et al. 2006; Desmouliere, Chaponnier et al. 2005; Jester,
Huang et al. 2002; Cowin et al. 2001; Shah et al. 1995). EGF negatively regulates
chondrogenesis (Yoon 2000). Estrogen also negatively regulates chondrogenesis (Kato
& Gospodarowicz 1985). Hydrocortisone has been shown to promote adipogenic rather
than chondrogenic differentiation (Ghoniem et al. 2015; Lee, Kuo et al. 2004). These
earlier studies show the significance of the present findings on TGFβ3 and dexamethasone,
which act together to promote chondrogenic differentiation of corneal keratocytes
and scar free corneal healing.
Example 15: Comparative dosages for TGFβ3 and dexamethasone
[0214] Prior to an
in vivo study, experiments were performed to identify the various effective dosages for
ex vivo treatments. A dose range study was carried out for TGFβ3 and dexamethasone by culturing
sheep corneas in culture media containing these two factors in varying concentrations.
[0215] Fresh sheep eyes were obtained and corneas were excised and treated as noted in Example
14. One sheep corneal disc was placed in each of the 16 culture conditions (Figure
21) for 3 weeks. The corneal discs were cultured and then subjected to immunohistochemical
and microscopic analysis as noted in Example 14. Figure 21 shows representative images
of collagen type II labelling in corneal sections in each of the conditions.
[0216] This study revealed that lower concentrations of TGFβ3 (2-4 ng/mL) and dexamethasone
(1-10 nM) had lower efficacy
ex vivo (Figure 21, first and second rows). Higher doses, i.e., 8-10 ng/mL TGFβ3 and 100-1000
nM dexamethasone were efficient in inducing collagen type II deposition (Figure 21,
third and fourth rows).
[0217] These results confirmed the use of 100 nM dexamethasone and 10 ng/mL TGFβ3 as effective
concentrations (Figure 21, third row). Higher concentrations of dexamethasone (1000
nM, i.e., 400 ng/mL) were also shown to be effective (Figure 21, fourth row). It was
noted that the dexamethasone concentrations tested in this study were considerably
lower than the concentrations used in commercially available eye drops (i.e., 1 mg/mL
dexamethasone).
Example 16: Overview of experimental observations and results
[0218] A combination of TGFβ1 and dexamethasone has been previously used to induce progenitor
cells to differentiate into chondrocytes
in vitro (Diekman et al. 2009; Johnstone et al. 1998; Kolambkar et al. 2007; Winter et al.
2003). In other studies, a side population of corneal stromal cells has been shown
to produce a matrix made up of the cartilage specific collagen II under similar chondrogenic
differentiation conditions (Du, Funderburgh, Mann, SundarRaj, & Funderburgh 2005).
It has also been reported that scleral cells after four weeks in a chondrogenic differentiation
medium containing TGFβ1 and BMP2 expressed cartilage specific markers including aggrecan,
and collagen type II. Furthermore, human scleral cells have been shown to retain their
chondrogenic potential
in vivo after being transplanted into a rat cartilage defect (Seko et al. 2008). It is known
that the fibroblastic cells of the sclera and the corneal stroma share a common embryological
origin.
[0219] As shown herein, keratocytes seeded in culture medium containing TGFβ3 and dexamethasone
and in the absence of serum spontaneously formed cell spheroids within 2-3 days by
cell aggregation and by three weeks these cell clusters labelled positive for cartilage
specific type II collagen. Initially upon treatment with TGFβ3 and dexamethasone,
type I collagen expression was also increased. When the medium was changed to a control
medium containing fetal calf serum the cell clusters dispersed into a monolayer of
cells. Cells growing in the monolayer no longer expressed type II collagen. These
results suggest that cell aggregation or environment might be important in collagen
type II induction.
[0220] Notably, keratocytes which were first proliferated as fibroblasts in serum containing
medium did not secrete collagen type II when the medium was changed to the TGFβ3 and
dexamethasone containing chondrogenic differentiation medium. This suggests that once
proliferated as fibroblasts the cells lose the ability to differentiate along a chondrogenic
pathway. Further to this, fibroblasts grown in three-dimensional culture in chondrogenic
differentiation medium as a pellet also failed to express cartilage specific collagen
type II. These results suggest that the quiescent keratocyte phenotype and cell aggregation
are important to chondrogenic differentiation.
[0221] It is shown herein that
ex vivo culture of normal and keratoconic corneas in chondrogenic differentiation media revealed
uniform deposition of type II collagen along the stromal lamellae. Every keratocyte
within the corneal stroma was associated with the collagen type II labelling, once
again suggesting that the reprogramming into a chondrogenic phenotype is stochastic
and confirming that results obtained from the
in vitro cell culture were not as a result of proliferation of a side population of progenitor
cells. Furthermore,
in vivo treatment of corneas in rats also caused the deposition of type II collagen in a
manner similar to that seen in
ex vivo culture. However, stronger immunolabelling of type II collagen was seen in the anterior
part of the cornea when treated
in vivo, most probably reflecting easier diffusion of growth factors into the anterior layers
of the stroma from the ocular surface.
[0222] Studies looking at differences in keratocyte density in keratoconic corneas have
reported an overall decrease in cell density. The results here also confirm this.
However, unlike other studies which have reported a marked decrease in cell density
in the anterior part of the stroma (Hollingsworth, Efron, & Tullo 2005; Ku et al.
2008; Mencucci et al. 2010; Niederer et al. 2008), the results here indicate a marked
decrease in keratocyte density in the posterior part of the stroma of the untreated
keratoconic cornea also. In keratoconus there is a general thinning of the cornea.
It is not known, however, whether this is due to the apoptosis of keratocytes and
subsequent decreased production of ECM or whether keratocyte apoptosis is secondary
to the process of corneal thinning.
[0223] As shown herein, the treated half of the keratoconic cornea which was cultured in
the chondrogenic medium containing TGFβ3 and dexamethasone had an increased keratocyte
density when compared to the control. Furthermore, the posterior region of the stroma
appeared to be repopulated by keratocytes. The keratocytes in the treated half also
appeared to look healthier with large prominent nuclei and several cell processes.
This indicates that the treatment with the two factors have possibly caused keratocytes
to proliferate and repopulate the stroma, in particular the posterior part which was
devoid of keratocytes.
[0224] Collagen crosslinking, one of the current treatments for keratoconus, results in
an initial period of keratocyte apoptosis in the anterior part of the stroma. This
is then followed by a period of repopulation of the stroma by the keratocytes. Keratocyte
cell death is generally seen in response to an injury and in the case of crosslinking
is understood to be as a result of UVA-induced cellular damage. This apoptotic response
is thought to have evolved in order to protect the cornea from further inflammation
(Wilson, Netto, & Ambrosio 2003).
[0225] Stromal haze which can last up to several months is also observed after the crosslinking
treatment. It has been attributed to the increase in collagen diameter and spacing
between the collagen fibrils which results in the modification of the corneal microstructure.
Most studies have reported a decrease in corneal haze between 6-12 months after the
treatment (Greenstein, Fry, Bhatt, & Hersh 2010; Mazzotta et al. 2008). Although there
have been several clinical observations of the corneas carried out after the crosslinking
treatment there is ambiguity regarding the cause of the corneal haze and other possible
downstream effects of the treatment. The fact that it takes several months for corneas
to be repopulated and become clear suggests that the crosslinking might be triggering
a wound healing response within the stroma.
[0226] In this study, even upon long term (up to 8 weeks)
in vitro and
in vivo treatment there was no evidence of corneal opacity. This is probably due to the deposition
of the collagen II in uniform layers along the pre-existing collagen lamellae. Deposition
of collagen type III (associated with fibrosis) and alpha-smooth muscle actin (during
myofibroblast formation) leads to opacity and scarring. Both these are seen during
corneal wounding. Neither of these proteins was expressed in the treated corneas suggesting
that wound healing cascades which could bring about scarring were not being triggered.
[0227] As described herein, quantitative measurement of type II collagen mRNA expression
showed that its expression was significantly lowered upon withdrawal of TGFβ3 and
dexamethasone. This suggests that the reprogramming of keratocytes is not irreversible
and the subsequent deposition of type II collagen in the ECM can potentially be controlled.
This is important for the development of therapeutic methods, as it would not be desirable
to induce irrepressible ECM deposition.
[0228] Nanoindentation has been employed in the assessment of postoperative therapeutic
methods such as crosslinking for keratoconus (a corneal dystrophy) and post-LASIK
ectasia in the eye. In one study done on human cadaver corneas it was found that collagen
crosslinking caused a two-fold increase in the elastic modulus in the anterior corneal
stroma while the posterior stroma was unaffected by the treatment (Dias, Diakonis,
Kankariya, Yoo, & Ziebarth 2013). In this study, anterior corneal elasticity was measured.
In addition, the results in this study do indicate that posterior stroma keratocyte
density was altered in the TGFβ3 and dexamethasone treated corneas.
[0229] While nanoindentation does not measure the properties of the individual collagen
fibrils it can measure the changes in the inherent elastic property of the cornea
which will be altered on collagen II deposition with a subsequent increase in collagen
crosslinking. Structural differences within the stroma are reflected in the corresponding
differences in biomechanical properties. The results here show that there was almost
a three-fold increase in elastic modulus and hardness in the growth factor treated
rat corneas. These results indicate that the treatment results in a stiffer cornea
with higher elasticity. The elastic modulus is a measure of a substance's resistance
to being deformed elastically and therefore a higher elastic modulus indicates that
a material is more difficult to deform. In this study, a significant increase in hardness
and elastic modulus in 3 week treated corneas when compared to 1 week treated corneas
is consistent with the immunohistochemical labelling results that show at least 2-3
weeks of treatment is required for the laying down of detectable layers of type II
collagen.
[0230] The immunohistochemical labelling results coupled with the gene expression studies
and biomechanical testing show that keratocytes within an intact cornea are amenable
to reprogramming along a chondrogenic pathway by treatment with TGFβ3 and dexamethasone.
The reprogramming by combined TGFP3 and dexamethasone treatment is stochastic and
may be controlled via the modulation of the growth factor treatment period to result
in stiffer, more elastic corneas. Notably, administration of both agents is required;
when TGFβ3 and dexamethasone are tested separately, no collagen type II production
in keratocytes is observed. A novel treatment is therefore proposed for keratoconus
and other eye conditions using
in vivo tissue engineering, by administration of TGFβ3 and dexamethasone, as described herein.
Example 17: Large animal model to investigate reshaping of the cornea
Reshaping the cornea whilst delivering the optimal regimen in a sheep model
[0231] Additional experiments are carried out to use a large animal model to demonstrate
reshaping of the cornea. For these experiments, a large animal model is used to allow
placement of prescription contact lenses. Sheep are used as a model animal, as their
eyes are comparable in size and physiology to that of humans. In addition, housing
facilities are available at Lincoln University, Christchurch. It is noted also that
sheep have a mild temperament, and are amenable to handling.
[0232] Sheep are sedated in accordance with standard operating procedure in the housing
facility. The eye drop formulation with optimal TGFβ3 and dexamethasone concentrations
(volume scaled) based upon the rodent dose optimisation studies are instilled in the
right eye followed by the placing of corneal INTACS
® (or similar scleral rings) to hold the desired curvature of the cornea during collagen
deposition (Figure 18). Eye drops are continued to be administered either once or
twice daily (as determined in rodent optimisation studies) for a period of three weeks.
The INTACS
® are then removed and the animals are continued to be housed for a further three weeks
or six months.
[0233] Before treatment and at the end of the treatment (when the INTACS
® are removed), corneal thickness and curvature measurements are taken. The portable
corneal pachymeter is used to detect changes in corneal thickness of treated versus
control contralateral corneas
in vivo. A portable Pentacam
® is used to measure corneal curvature as well as corneal thickness of the sheep eyes
before and after treatment (Figures 19(E)and (F)). Corneal measurements are repeated
again at three weeks after lenses removal with the final (most accurate) Pentacam
® measurements. These are taken after killing the animal but prior to eye removal for
immunohistological and biomechanical analysis as described above for rodent corneas.
In the unlikely event that the sheep are unable to tolerate a hard contact lens (signs
of infection, inflammation or irritability), the study is continued without lenses,
which allows completion of key parameters such as type II collagen deposition and
distribution, and biomechanical properties.
[0234] In view of the results, it is proposed to use
in vivo tissue engineering as described in detail herein, in combination with of a rigid
gas permeable OrthoK contact lenses (or similar) to permanently reshape and stabilise
the cornea, providing treatment for common corneal defects, including myopia.
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