BASEMENT-MEMBRANE SYNTHESIS BY HUMAN CORNEAL EPITHELIAL-CELLS IN-VITRO

Purpose. Collagen gels may prove to be potential carriers for transplantation of cultured corneal epithelial cells. The purpose of this study was to evaluate the suitability of collagen gels in comparison with corneal stromal blocks as the substrate to support the growth of human corneal epithelial cells in culture and the synthesis and deposition of the basement membrane components by these cells. Methods. Corneal epithelial sheets, freed from the culture dishes using Dispase II (Boehringer Mannheim, Indianapolis, IN), were cultured on corneal stromal blocks. Deposition of laminin, type IV collagen, type VII collagen, and perlecan (heparan sulfate proteoglycan) were evaluated immunohistochemically after 4 days, 7 days, 2 weeks, and 3 weeks. Human limbal explant cultures were established on collagen gels prepared from bovine type I collagen with or without addition of cultured human corneal fibroblasts. After 1, 2, 3, and 4 weeks, the deposition of the basement membrane components was evaluated immunohistochemically. Results. Corneal epithelial cells, cultured on corneal stromal blocks as well as on collagen gels with or without fibroblasts, deposited laminin, type IV collagen, perlecan, and type VII collagen at the interface of the cells and the substrates. However, different substrates differentially influenced the temporal pattern of the deposition of various basement membrane components. On the stromal blocks, deposition of laminin, type IV collagen, and perlecan by the epithelial cells was evident at 1 week. Type VII collagen was detected at 2 weeks. On the collagen gels with fibroblasts, deposition of laminin, type IV collagen and perlecan was detectable at 1 week. In the epithelial cultures on the collagen gels without fibroblasts, only perlecan was detectable at 1 week. At 2 weeks, all of the basement membrane components, including type VII collagen were detectable on the collagen gels, either with or without fibroblasts. Conclusion. Human corneal epithelium cultured on collagen gels or on corneal stromal blocks can synthesize and deposit basement membrane components, including laminin, type IV collagen, type VII collagen, and perlecan within 2 weeks in culture. Therefore, collagen gels may serve as potential carriers for human corneal epithelial transplantation.