Experimental corneal cryopreservation: impact of postmortem time on corneal endothelial cell survival.

Clinical and experimental studies with rabbit and human corneas have shown the correlation between short postmortem times and successful corneal cryopreservation. In this experimental study we investigated this phenomenon considering the latent freeze-thaw-induced cell damage. Enucleated eye-balls of freshly slaughtered pigs were stored in moist chambers at 4 degrees C for 2, 4, 8, 16, 32, and 72 h before cryopreservation. After thawing, the corneas were organ-cultured for 1 day. After staining with trypan blue and alizarin red S the tissue was evaluated morphometrically, calculating the amount of necrotic areas on the central corneal surface and the endothelial cell density. Corneas stored up to 32 h before cryopreservation showed no difference regarding the amount of necrosis and endothelial cell density compared to freshly cryopreserved tissue. Corneas stored 72 h before cryopreservation revealed no endothelial cell survival. We conclude that a post-mortem time of up to 32 h before corneal cryopreservation has no influence on endothelial cell survival.