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Various clinical disorders and injuries, such as chemical, thermal, or mechanical injuries, may lead to corneal loss that results in blindness. PURPOSE : The aims of this study were to differentiate human buccal mucosa (BMuc) into corneal epithelial-like cells, to fabricate engineered corneal tissue using buccal mucosal epithelial cells, and to reconstruct a damaged corneal epithelium in a nude rat model., Methods: BMuc were subjected to 10 d of induction factors to investigate the potential of cells to differentiate into corneal lineages., Results: Corneal stem cell markers β1-integrin, C/EBPδ, ABCG2, p63, and CK3 were upregulated in the gene expression analysis in induced BMuc, whereas CK3 and p63 showed significant protein expression in induced BMuc compared to the uninduced cells. BMuc were then left to reach 80% confluency after differential trypsinization. The cells were harvested and cultivated on a commercially available untreated air-dried amniotic membrane (AM) in a Transwell system in induction medium. The corneal constructs were fabricated and then implanted into damaged rat corneas for up to 8 weeks. A significant improvement was detected in the treatment group at 8 weeks post-implantation, as revealed by slit lamp biomicroscopy analysis. The structure and thickness of the corneal layer were also analyzed using histological staining and time-domain optical coherence tomography scans and were found to resemble a native corneal layer. The protein expression for CK3 and p63 were continuously detected throughout the corneal epithelial layer in the corneal construct., Conclusions: In conclusion, human BMuc can be induced to express a corneal epithelial-like phenotype. The addition of BMuc improves corneal clarity, prevents vascularization, increases corneal thickness and stromal alignment, and appears to have no adverse effect on the host after implantation.

Purpose: To report potentially pathogenic mutations in the keratin 3 (KRT3) and keratin 12 (KRT12) genes in two individuals with clinically diagnosed Meesmann corneal dystrophy (MECD)., Methods: Slit-lamp examination was performed on the probands and available family members to identify characteristic features of MECD. After informed consent was obtained, saliva samples were obtained as a source of genomic DNA, and screening of KRT3 and KRT12 was performed. Potentially pathogenic variants were screened for in 200 control chromosomes. PolyPhen-2, SIFT, and PANTHER were used to predict the functional impact of identified variants. Short tandem repeat genotyping was performed to confirm paternity., Results: Slit-lamp examination of the first proband demonstrated bilateral, diffusely distributed, clear epithelial microcysts, consistent with MECD. Screening of KRT3 revealed a heterozygous missense variant in exon 1, c.250C>T (p.(Arg84Trp)), which has a minor allele frequency of 0.0076 and was not identified in 200 control chromosomes. In silico analysis with PolyPhen-2 and PANTHER predicted the variant to be damaging to protein function; however, SIFT analysis predicted tolerance of the variant. The second proband demonstrated bilateral, diffusely distributed epithelial opacities that appeared gray-white on direct illumination and translucent on retroillumination. Neither parent demonstrated corneal opacities. Screening of KRT12 revealed a novel heterozygous insertion/deletion variant in exon 6, c.1288_1293delinsAGCCCT (p.(Arg430_Arg431delinsSerPro)). This variant was not present in either of the proband's parents or in 200 control chromosomes and was predicted to be damaging by PolyPhen-2, PANTHER, and SIFT. Haplotype analysis confirmed paternity of the second proband, indicating that the variant arose de novo., Conclusions: We present a novel KRT12 mutation, representing the first de novo mutation and the first indel in KRT12 associated with MECD. In addition, we report a variant of uncertain significance in KRT3 in an individual with MECD. Although the potential pathogenicity of this variant is unknown, it is the first variant affecting the head domain of K3 to be reported in an individual with MECD and suggests that disease-causing variants associated with MECD may not be restricted to primary sequence alterations of either the helix-initiation or helix-termination motifs of K3 and K12.

Purpose: To compare the effectiveness of three culture media for growth, proliferation, differentiation, and viability of ex vivo cultured limbal epithelial progenitor cells., Methods: Limbal epithelial progenitor cell cultures were established from ten human corneal rims and grew on plastic wells in three culture media: supplemental hormonal epithelial medium (SHEM), keratinocyte serum-free medium (KSFM), and Epilife. The performance of culturing limbal epithelial progenitor cells in each medium was evaluated according to the following parameters: growth area of epithelial migration; immunocytochemistry for adenosine 5'-triphosphate-binding cassette member 2 (ABCG2), p63, Ki67, cytokeratin 3 (CK3), and vimentin (VMT) and real-time reverse transcription polymerase chain reaction (RT-PCR) for CK3, ABCG2, and p63, and cell viability using Hoechst staining., Results: Limbal epithelial progenitor cells cultivated in SHEM showed a tendency to faster migration, compared to KSFM and Epilife. Immunocytochemical analysis showed that proliferated cells in the SHEM had lower expression for markers related to progenitor epithelial cells (ABCG2) and putative progenitor cells (p63), and a higher percentage of positive cells for differentiated epithelium (CK3) when compared to KSFM and Epilife. In PCR analysis, ABCG2 expression was statistically higher for Epilife compared to SHEM. Expression of p63 was statistically higher for Epilife compared to SHEM and KSFM. However, CK3 expression was statistically lower for KSFM compared to SHEM., Conclusions: Based on our findings, we concluded that cells cultured in KSFM and Epilife media presented a higher percentage of limbal epithelial progenitor cells, compared to SHEM.

Purpose: Juvenile epithelial corneal dystrophy of Meesmann (MCD, OMIM 122100) is a dominantly inherited disorder characterized by fragility of the anterior corneal epithelium and intraepithelial microcyst formation. Although the disease is generally mild and affected individuals are often asymptomatic, some suffer from recurrent erosions leading to lacrimation, photophobia, and deterioration in visual acuity. MCD is caused by mutations in keratin 3 (KRT3) or keratin 12 (KRT12) genes, which encode cornea-specific cytoskeletal proteins. Seventeen mutations in KRT12 and two in KRT3 have been described so far. The purpose of this study was to investigate the genetic background of MCD in a Polish family., Methods: We report on a three-generation family with MCD. Epithelial lesions characteristic for MCD were visualized with slit-lamp examination and confirmed by in vivo confocal microscopy. Using genomic DNA as a template, all coding regions of KRT3 and KRT12 were amplified and sequenced. Presence of the mutation was verified with restriction endonuclease digestion., Results: In the proband, direct sequencing of the polymerase chain reaction (PCR) product from amplified coding regions of KRT3 and KRT12 revealed a novel 1493A>T heterozygous missense mutation in exon 7 of KRT3, which predicts the substitution of glutamic acid for valine at codon 498 (E498V). Using PCR-Restriction Fragment Length Polymorphism (RFLP) analysis, the mutation was demonstrated to segregate with the disease (four affected members, three non-affected) and to be absent in 100 controls from the Polish population, indicating that it is not a common polymorphism., Conclusions: Location of the E498V mutation emphasizes the functional relevance of the highly conserved boundary motifs at the COOH-terminus of the alpha-helical rod domain in keratin 3 (K3).