Purpose: The possibility of providing cultured corneal endothelial cells (CECs) for clinical transplantation has gained much attention. However, the worldwide need for human (h) donor corneas far exceeds supply. The pig (p) might provide an alternative source. The aim of this study was to compare the proliferative capacity of CECs from wild-type (WT) pigs, genetically-engineered (GE) pigs, and humans. Methods: The following CECs were cultured: hCECs from donors (i) ≤36 years (young), (ii) ≥49 years (old), and WT pCECs from (iii) neonatal (<5 days), (iv) young (<2 months), and (v) old (>20 months) pigs, and CECs from young (vi) GE pigs (GTKO/CD46 and GTKO/CD46/CD55). Proliferative capacity of CECs was assessed by direct cell counting over 15 days of culture and by BrdU assay. Cell viability during culture was assessed by annexin V staining. The MTT assay assessed cell metabolic activity. Results: There was significantly lower proliferative capacity of old CECs than of young CECs (p < 0.01) in both pigs and humans. There was no significant difference in proliferative capacity/metabolic activity between young pCECs and young hCECs. However, there was a significantly higher percentage of cell death in hCECs compared to pCECs during culture (p < 0.01). Young GE pCECs showed similar proliferative capacity/cell viability/metabolic activity to young WT pCECs. Conclusions: Because of the greater availability of young pigs and the excellent proliferative capacity of cultured GE pCECs, GE pigs could provide a source of CECs for clinical transplantation. Copyright © 2012 S. Karger AG, Basel.