Enhancement of the mechanical and biological properties of a biomembrane for tissue engineering the ocular surface.

INTRODUCTION In this study, we have developed and optimised a novel gelatin-chitosan (GC) substrate for use as a cellular carrier for tissue-engineered conjunctival epithelium. MATERIALS AND METHODS The substrate was fabricated by casting and the mechanical properties of the substrate, including tensile strength and elongation, were measured. Using the MTT, cell proliferation assay with rabbit conjunctival fibroblasts, we optimised the G:C ratio to enhance cytocompatibility. Rabbit conjunctival epithelial cells were immunostained using monoclonal antibodies for keratin 4 and pancytokeratin to investigate the biological effects of the GC substrate on the proliferation and differentiation of epithelial cells. RESULTS We found that increasing the amount of gelatin resulted in an increase in elasticity (from 1:9 to 1:1 ratio), reaching a maximum (101.89% +/- 7.13%) at a ratio of 1:1. The MTT assay showed that the proliferation of conjunctival fibroblasts significantly increased from 0.068 +/- 0.017 to 0.177 +/- 0.011 (P = 0.014) as the gelatin was increased from 20% (1:4) to 50% (1:1). Additional studies using tissue-cultured conjunctiva explants showed that these explants grew well on the substrate, forming a multilayered epithelium. Cell morphology on this substrate was similar to that of cells grown on culture dishes alone. Positive staining of keratin 4 and pancytokeratin indicated that the substrate supported normal differentiation of conjunctival epithelial cells. CONCLUSION By enhancing the proportion of gelatin, both the mechanical and biological properties of the chitosan substrate were improved. The results also suggest that this GC biomembrane may be a useful candidate for reconstructive tissue engineering of the conjunctiva.