Retinal pigment epithelium cells cultured on synthetic biodegradable polymers.
Alterations in the normal structure or functions of retinal pigment epithelium (RPE) can result in a number of ocular diseases. Implantation of RPE cells cultured on thin, biodegradable polymer films may provide a means of transplanting an organized sheet of RPE cells with distinct apical/basal characteristics for the restoration of normal RPE function. We have investigated the interactions of human RPE cells with different biodegradable polymer films to assess their suitability as substrates for RPE culture. Four biodegradable polymers were used: low molecular weight (MW) 50:50 poly(DL-lactic-co-glycolic acid) (PLGA); high MW 50:50 PLGA; 75:25 PLGA; and poly(L-lactic acid) (PLLA). Polymer film substrates were manufactured using a solvent casting technique. Human fetal RPE cells (10-16 weeks gestational) were plated on the polymer substrates and the cultures assessed with respect to cell attachment and proliferation. Histological and immunohistochemical studies were performed on the cells after 8 days in culture. RPE cells attached to all the polymers studied after 8 h in culture. After 8 h, 80.2 +/- 9.5% and 82.3 +/- 7.9% of the plated cells were attached to substrates of high MW 50:50 PLGA and 75:25 PLGA, respectively. The cells proliferated on all substrates, and there was about a threefold increase in cell number over the 8-day culture period on all the polymers studied. Immunohistochemistry after 8 days in culture demonstrated RPE cells labeled with a distinct reaction product for cytokeratin in the cell cytoplasm. All the polymers studied were suitable for RPE culture; however, high MW 50:50 PLGA and 75:25 PLGA proved to be the best in terms of manufacturing properties, cell attachment, and proliferation. These polymers can provide a suitable substrate for RPE cell culture and hold promise for the subretinal implantation of organized sheets of RPE cells.