In vitro expanded corneal endothelial cell sheets: towards a new therapeutic approach

Corneal transplantation is currently the only effective treatment solution to restore corneal clarity in patients with endothelial disorders. Descemet membrane endothelial keratoplasty (DMEK) is the most recent corneal transplantation technique that selectively replaces only Descemet membrane (DM) and endothelium with the same layers of a healthy donor. However, its application is limited by shortage of high‐quality healthy donor tissue. In order to increase the pool of endothelial grafts, new strategies have been developed, which include surgical‐based and tissue‐engineering based approaches. Tissue‐engineered approaches such as endothelial cell sheet transplantation and cell injection rely on the in‐vitro expansion of cultured corneal endothelial cells (CEC). For endothelial cell sheet transplantation suitable cell carriers are required, which could either be natural carriers (e.g. human anterior lens capsules (HALC)) or bioengineered matrices (e.g. 20 µm thick collagen‐based carriers (LK20)). Within the ARREST BLINDNESS project, CEC were cultured on different carriers and the suitability of the cell‐carrier sheets as tissue‐engineered grafts for DMEK‐like procedures was evaluated by performing in‐vitro surgeries. Upon in‐vitro DMEK surgery, CEC‐HALC sheets behaved similarly to a standard DMEK‐graft on all scored aspects such as graft implantation, unfolding and adherence to bare stroma, whereas graft adhesion and surgical handling, respectively, are issues that still need to be addressed for CEC‐LK20 and CEC‐‘denuded DM’ sheets. First results of in‐vivo tests in an animal model will be presented as well as measures to approach legislative issues.