Ultrastructural assessment of cryopreserved hepatocytes after prolonged ectopic transplantation

Isolated adult rat hepatocytes were cryopreserved by cooling, in the presence of dimethyl sulfoxide, to low subzero temperatures and they were stored for 14 days at -196 C. The cells were then recovered and transplanted into the splenic pulp of the original donor animal. A similar transplant procedure was performed with hepatocytes which had not been cryopreserved. Ultrastructural assessment was made 1 month after transplantation. In general fewer hepatocytes survived ectopic transplantation after cryopreservation, but the surviving cells were ultrastructurally similar to ectopically transplanted cells not subjected to cryopreservation. Thus, the reduced metabolic activity measured previously in transplants of cryopreserved hepatocytes is likely to result from a smaller number of competent cells rather than from hepatocytes which have survived in an extensively damaged or abnormal state.