Simplifying corneal surface regeneration using a biodegradable synthetic membrane and limbal tissue explants.

Currently, damage to the ocular surface can be repaired by transferring laboratory cultured limbal epithelial cells (LECs) to the cornea using donor human amniotic membrane as the cell carrier. We describe the development of a synthetic biodegradable membrane of Poly D,L-lactide-co-glycolide (PLGA) with a 50:50 ratio of lactide and glycolide for the delivery of both isolated LECs and of cells grown out from limbal tissue explants. Both isolated LECs and limbal explants produced confluent limbal cultures within 2 weeks of culture on the membranes without the need for fibroblast feeder layers. Outgrowth of cells from explants was promoted by the inclusion of fibrin. Membranes with cells on them broke down predictably within 4-6 weeks in vitro and the breakdown was faster for a lower molecular weight (MW) (44 kg/mol) rather than a higher MW (153 kg/mol) PLGA. Membranes could be reproducibly produced, sterilised with gamma irradiation and stored dry at -20 °C for at least 12 months, and the ability to support cell outgrowth from explants was retained. We demonstrate transfer of cells (both isolated LECs and of cells grown out from limbal explants) from the membranes to an ex vivo rabbit cornea model. Characterisations of the cells by immunohistochemistry showed both differentiated and stem cell populations. A synthetic membrane combined with limbal explants in theatre would avoid the need for tissue banked human amniotic membrane and also avoid the need for specialist laboratory facilities for LEC expansion making this more accessible to many more surgeons and patients.