[Application of experimental findings of cryopreservation of animal tissue to results of cryopreservation of human tissue].

In order to compare the results after experimental corneal cryopreservation of porcine corneas to human tissue we cryopreserved several human corneas that were not suitable for transplantation. The corneas were frozen in a medium containing 2% chondroitin sulfate, 15% DMSO, and 20% fetal calf serum in MEM-medium to -196 degrees C and thawed at 37 degrees C in a waterbath. Subsequently they were kept in organ culture for 24 h. After vital staining with trypan blue and alizarin red S they were evaluated morphometrically. Endothelial cell densities after the experiment ranged between 47% and 64% of the endothelial cell counts revealed before cryopreservation. Human corneal endothelium showed enlargement of single nucleated cells, and large numbers of giant cells with one or two nuclei but only few multinucleated giant cells and only few necrotic spots compared to porcine tissue in which multinucleated giant cells and large necrotic areas were a frequent finding. We conclude that human corneal endothelium is less sensitive to the freeze-thaw trauma than porcine tissue. Porcine tissue can be used as a susceptible model for the development of new methods of corneal cryopreservation.