Cultivated Limbal Epithelial Transplantation (CLET)

Cultivated limbal epithelial transplantation (CLET) is the latest advanced cell therapy applied to the treatment of limbal stem-cell deficiency (LSCD). It has been shown to be an effective and safe procedure for treating severe limbal stem-cell deficiency when there is an undamaged, even small (1–2 mm2 are sufficient) portion of the limbus that will provide donor cells to be expanded in vitro. Unilateral and non-total bilateral limbal deficiency can therefore be successfully treated with long-term survival and without the need for systemic immunosuppression. It has several advantages over direct limbal transplantation: (1) minimum risk for the donor’s eye, (2) the procedure can be repeated due to the reduced size of the biopsy and (3) partial bilateral LSCDs can be treated. It is a GMP-validated procedure and has recently been approved in Europe by the European Medicine Agency (EMA) Competent Authority and is now available for clinical use. For total bilateral LSCD, allogeneic cultivated limbal epithelial does not guarantee long-term survival, stability, and avascularity of the epithelium: a viable solution for these cases is still missing.