Development of Transparent Acellular Dermal Matrix as Tissue-Engineered Stroma Substitute for Central Lamellar Keratoplasty

PURPOSE: To improve the transparency of the acellular dermal matrix (ADM) and investigate the optical, mechanical and histologic properties and biocompatibility of transparent ADM (TADM) in lamellar keratoplasty. METHODS: A stepwise sectioning strategy was applied to determine the transparency distribution of the ADM, and TADM was fabricated accordingly. Transmittance measurements, uniaxial tension testing, and histologic staining were applied to detect its properties. Lamellar keratoplasty was performed in rabbits with TADM, and postoperative evaluations were conducted including the transmittance of the transplant area and histologic staining. RESULTS: The transmittance of the ADM increased with increasing depth, and TADM was isolated mechanically at the deepest level. There was a significant improvement in the transmittance of the TADM compared with the ADM, and no significant difference in transmittance between dehydrated TADM and cornea was observed. The elastic modulus of TADM was significantly stronger than that of normal cornea (P = 0.004). TADM consisted of dense collagen fibrils, mainly collagen type I, and the collagen fibril diameter and interfibrillar spacing were determined to be larger than corneal stroma. After lamellar keratoplasty in rabbits, the TADM was well integrated with the host cornea, and transparent cornea without neovascularization was observed at 6 months. Re-epithelization was completed at 1 month, and keratocyte repopulation and collagen remodeling were observed in the graft 3 and 6 months after surgery. CONCLUSIONS: This study presents the transparency distribution of the ADM and a method for obtaining TADM, which demonstrates ideal transparency, strong mechanical properties, and satisfactory biocompatibility when applied in lamellar keratoplasty.