How long can cryopreserved skin be stored to maintain adequate graft performance?

Skin graft preservation for the purpose of delayed application is still a basic tool in burn treatment and plastic and reconstructive surgery. As the demand for skin allografts has increased the responsibility for processing, storage and evaluation of graft performance of preserved skin has become an important issue of banking organizations. The present experiments were undertaken to determine how long can cryopreserved cadaveric skin be stored to maintain adequate graft performance? We applied a mouse recipient model, developed by us: Human cadaveric skin cryopreserved and stored for 5,6 or 7 years was grafted on Balb/c mice, and primary take was evaluated by gross observation and predetermined histologic criteria after 7 days. The results demonstrate that graft performance of cryopreserved skin decreased with time, as reflected in the lower percent of samples with high score of separate histologic criteria after prolonged storage. Nevertheless, paired comparison analysis between cryopreserved and fresh skin indicated that this decrease was not significant for storage of 5 years; whereas it was highly significant for 6 years of storage. Linear regression analysis indicated that there was no correlation between the score of the histologic criteria and storage period for upto 65 months. These results are in line with the paired comparison analysis. We feel that our in vivo model and analysis may be used as an evaluation procedure for transplantation performance of banked skin.