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Purpose To evaluate the effects of the vascular endothelial growth factor inhibitor conbercept (KH902) on corneal neovascularization and wound healing following penetrating keratoplasty in rabbits. Methods Conbercept was administered to New Zealand white rabbits through topical and subconjunctival routes. Corneal neovascularization and wound healing were examined by slit-lamp photography and histological analyses. The expressions of vascular endothelial growth factor inhibitor, α-smooth muscle actin, and keratocan in the corneal grafts were measured by real-time quantitative polymerase chain reaction (RT-qPCR). Results The anterior segment photographs demonstrated that corneal neovascularization started in the 2nd week. In the 4th week, histologically, the superficial corneal stroma layer showed disordered arrangement, and there were large numbers of dense inflammatory cells and blood vessels in the stroma layer. Vascular endothelial growth factor in the experimental groups was significantly decreased at all time points compared with the control group (both P = 0.001). Expression of α-smooth muscle actin in corneal grafts demonstrated an increase in time even it was lower in experimental groups, but the difference was not statistically significant (P equaled to 0.507 and 0.723, respectively). There were no significant differences with the expression of keratocan in all groups except that it significantly declined at the 4th week as to the second week in all groups and P values were 0.022, 0.020 and 0.014 in control (C), topical (E1), and subconjunctival (E2) group, respectively. Conclusion The study found that conbercept inhibited the formation of corneal neovascularization without affecting keratocan-mediated corneal wound healing and there were no significant differences between topical administration of different doses of conbercept on the rabbit corneal neovascularization after penetrating keratoplasty in this study.

Retinoic acid has recently been shown to control the phenotype and extracellular matrix composition of corneal stromal cells cultured in vitro as monolayers. This study set out to investigate the effects of retinoic acid on human corneal keratocytes within a 3D environment. Human corneal keratocytes were encapsulated in collagen gels, which were subsequently compressed under load, and cultured in serum-free media supplemented with 10 µM retinoic acid or DMSO vehicle for 30 days. Cell proliferation was quantified on selected days, while the expression of several important keratocytes markers was evaluated at day 30 using RT-PCR and immunoblotting. The weight and size of the collagen constructs were measured before and after hydration and contraction analyses. Retinoic acid enhanced keratocyte proliferation until day 30, whereas cells in control culture conditions showed reduced numbers after day 21. Both gene and protein expressions of keratocyte-characteristic proteoglycans (keratocan, lumican and decorin), corneal crystallins and collagen type I and V were significantly increased following retinoic acid supplementation. Retinoic acid also significantly reduced the expression of matrix metalloproteases 1, 3 and 9 while not increasing α-smooth muscle actin and fibronectin expression. Furthermore, these effects were also correlated with the ability of retinoic acid to significantly inhibit the contractility of keratocytes while allowing the build-up of corneal stromal extracellular matrix within the 3D constructs. Thus, retinoic acid supplementation represents a promising strategy to improve the phenotype of 3D-cultured keratocytes, and their usefulness as a model of corneal stroma for corneal biology and regenerative medicine applications.

To determine the genetic basis of autosomal dominant cornea plana (CNA1) through the performance of a genome-wide linkage analysis and screening of the decorin (DCN), dermatan sulfate proteoglycan 3 (DSPG3), forkhead box C1 (FOXC1), keratocan (KERA), lumican (LUM,) and paired-like homeodomain transcription factor 2 (PITX2) genes in members of an affected multigenerational family.Cycloplegic refraction, slit lamp biomicroscopy, corneal pachymetry, and corneal topography were performed to determine each patient's affected status. DNA was obtained from affected and unaffected subjects for the performance of a genome-wide linkage analysis as well as PCR amplification and sequencing of DCN, DSPG3, FOXC1, KERA, LUM, and PITX2.Five affected and three unaffected individuals were examined and provided a peripheral blood sample for DNA isolation. All affected individuals demonstrated an average corneal dioptric power less than 39 D, as well as one or more of the following anomalies: high hyperopia, strabismus, microcornea, posterior embryotoxon, iridocorneal adhesions, iris atrophy, and pupillary irregularities. A genome-wide linkage analysis did not indicate or exclude linkage to the region on chromosome 12 to which CNA1 has been previously mapped, and did not provide a single or multipoint LOD score greater than 2.0 for any of the 400 microsatellite markers. Screening of DCN, DSPG3, FOXC1, KERA, LUM, and PITX2 revealed 12 previously described single nucleotide polymorphisms, 2 previously described duplications, and 1 previously described insertion. None of the mutations previously associated with autosomal recessive cornea plana (CNA2) were identified. Seven novel sequence variants were described, including 5 single nucleotide substitutions, 1 insertion and 1 deletion. None of the identified sequence variants demonstrated complete segregation with the affected phenotype in the pedigree.Although missense and nonsense mutations in KERA are associated with CNA2, we did not identify any of the previously described mutations or novel mutations that segregated with the disease phenotype in a family with CNA1. In addition, no pathogenic sequence variations were found in DCN, DSPG3, LUM, PITX2 and FOXC1, which have also been implicated in corneal and anterior segment dysgenesis.

Purpose:To report a novel KERAmutation associated with autosomal recessive cornea plana in members of a nuclear family and to describe their ophthalmic phenotypes. Methods:Ophthalmic examination, biometry, and direct sequencing of KERA. Results:Five of the 6 siblings were affected and had small flat corneas, variable anterior chamber depths, and short axial lengths. The remaining brother and the 2 parents had normal ophthalmic examinations. Genetic testing revealed a novel homozygous nonsense mutation in exon 3 [937C>T] in the clinically affected individuals. The clinically unaffected parents were confirmed as carriers. The clinically unaffected sibling had no KERAmutation. This mutation leads to replacement of an arginine by a stop codon at position 313 of keratocan protein. Conclusions:This novel point mutation in KERAis the fourth thus far described. The ocular phenotype is characteristic of autosomal recessive cornea plana.

The cornea is a transparent and avascular tissue that functions as the major refractive structure for the eye. A wide variety of growth factors, chemokines, cytokines and their receptors are synthesized by corneal epithelial and stromal cells, and are found in tears. These molecules function in corneal wound healing and in inflammatory responses. Proteoglycans and glycoproteins are essential for normal corneal function, both at the air-epithelial interface and within the extracellular matrix. The ocular MUC mucins may play roles in forming the mucus layer of the tear film, in regulating tear film spread, and in inhibiting the adhesion of pathogens to the ocular surface. Lumican, keratocan and mimecan are the major keratan sulfate proteoglycans of the corneal stroma. They are essential, along with other proteoglycans and interfibrillar proteins, including collagens type VI and XII, for the maintenance of corneal transparency. Corneal epithelial cells interact with a specialized extracellular matrix structure, the basement membrane, composed of a specific subset of collagen type IV and laminin isoforms in addition to ubiquitous extracellular matrix molecules. Matrix metalloprotein-ases have been identified in normal corneal tissue and cells and may play a role in the development of ulcerative corneal diseases. Changes in extracellular matrix molecule localization and synthesis have been noted in other types of corneal diseases as well, including bullous keratopathy and keratoconus.

Keratocan is one of the three major keratan sulfate proteoglycans characteristically expressed in cornea. We have isolated cDNA and genomic clones and determined the sequence of the entire human keratocan (Kera) gene. The gene is spread over 7.65 kb of DNA and contains three exons. An open reading frame starting at the beginning of the second exon encodes a protein of 352 aa. The amino acid sequence of keratocan shows high identity among mammalian species. This evolutionary conservation between the keratocan proteins as well as the restricted expression of Kera gene in cornea suggests that this molecule might be important in developing and maintaining corneal transparency.