[Cultured human corneal endothelial cell transplantation]

Researchers have demonstrated the feasibility of transplanting human cultured corneal endothelial cells (HCEC) in various animal models. This review provides an overview of recent advances in our understanding of cultured corneal endothelial cell transplantation. We propose HCEC transplantation with a collagen sheet as the substitute carrier of HCEC. We also propose a novel strategy for corneal endothelial cell deficiency with the injection of adult human corneal endothelial precursors (HCEP). Using white rabbits or nude rats as keratopathy models, cultured HCEC were seeded on a collagen sheet. Descemetorhexis was performed on rabbit eyes. The HCEC collagen sheet was brought into the anterior chamber and fixed to the posterior stroma (HCEC group). Rabbit corneas with collagen sheet transplantation after descemetorhexis(collagen group) and with only descemetorhexis(no transplantation group) were the controls, respectively. As for HCEP transplantation, HCEP, isolated from rabbit corneal endothelial cells by sphere-forming assay, were injected into the anterior chamber and a face-down position was maintained for 24 hours in the rabbits (HCEP group). Pump function parameters of the HCEC sheets were 76-95% of those of human donor corneas. Mean corneal thickness in the HCEC group was significantly less than in the collagen and no transplantation groups 1, 3, 7, 14, 21, and 28 days (p< 0.05) after surgery. Cells were spread over the rear corneal surface in the HCEC group. In HE staining, marked stromal edema was present in the collagen and in the no transplantation groups, but not in the HCEC group with collagen sheets bearing monolayer cells. In the HCEP group, injected spheres were spread over the rear surface of the cornea and corneal edema was markedly suppressed. Our findings indicate that transplantation of cultured HCEC from adult human donor cornea by means of a collagen sheet can maintain the function of corneal dehydration. This suggests the feasibility of transplantation using cultured HCEC with a collagen sheet for corneal endothelial cell dysfunction. Additionally, adult precursor injection therapy can be also an effective strategy for corneal endothelial cell deficiency in place of conventional full-thickness corneal transplantation.