Developmental changes in patterns of expression of tenascin-C variants in the human cornea.

PURPOSE: To study patterns of expression of alternatively spliced tenascin-C (TN-C) variants believed to mediate cellular activities in human corneal development. METHODS: Serial sections of preterm, neonatal, child, and adult globes with normal anterior segments were labeled with monoclonal antibodies to TN-C. The antibodies included BC-4 and BC-8, which recognize epitopes in conserved domains of TN-C and can thus detect all TN-C variants, and BC-2, alpha-A2, alpha-A3, alpha-IIIB, TN11, and alpha-D, which bind to epitopes in alternatively spliced fibronectin type III repeats of TN-C. Bound antibodies were localized and visualized using an avidin-biotin complex-alkaline phosphatase technique. RESULTS: BC-4 and BC-8 showed similar patterns of staining, widely observed in preterm corneas, less so in neonatal corneas, and restricted to the limbus in the child and adult. BC-2, alpha-A2, alpha-A3, alpha-IIIB, TN11, and alpha-D staining was largely localized in corneal epithelium (preterm and neonatal), limbal epithelium, mast cells, and matrix surrounding limbal vessels (preterm, neonatal, child, and adult). CONCLUSIONS: TN-C may play a role in corneal development and in growth and differentiation of stem cells because it is widely expressed in the preterm cornea, less so in the neonate, and is restricted to the limbus in the child and adult. The differential patterns of expression of TN-C variants in normal corneas (preterm and neonatal), and in the limbus (preterm, neonatal, child, and adult), suggest specific roles played by each variant, and cell type-specific expression of the different variants.