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Cryopreserved allograft valves are increasingly being used as valvular replacements. This study was conducted to characterize the ultrastructural damage on the allograft valves obtained by a current standard protocol of valve procurement, antibiotic exposure, and cryopreservation, as a basis for future studies on allograft valve preservation. Materials used were seven aortic and seven pulmonary fresh porcine valves, which were cryopreserved according to the requirements of the American and European Associations of Tissue Banks. The samples were randomly assigned into four groups: (1) fresh, untreated; (2) fresh, treated with antibiotics for 24 h.; (3) treated with antibiotics and exposed to dimethyl sulfoxide (without freezing); and (4) treated with antibiotics, exposed to dimethyl sulfoxide, and then cryopreserved and stored until the study. All tissue samples were processed simultaneously for routine light microscopy and transmission electron microscopy. Fresh-untreated, antibiotic-treated, and dimethyl sulfoxide-exposed valves showed adequate preservation of cellular components. However, after cryopreservation significant damage was observed in fibroblasts with signs of apoptotic cellular injury. Our observation suggests that apoptosis occurs during valve processing. This apoptotic process may be related to various factors, including chemical injury or hypoxia., (Copyright 2001 Elsevier Science.)

To evaluate whether amphotericin B has a detrimental effect on the viability of cryopreserved skin, human skin samples were incubated during 7 and 24 h in three different media: 0.9% phosphate-buffered saline and Medium 199 with and without 10 micrograms/ml amphotericin B. The viability of the tissue was assessed by measuring the tetrazolium reductase activity before and after cryopreservation. A significant decrease in cryopreserved human skin viability was observed after 7 and 24 h incubation with amphotericin B. These results indicate that in the processing of skin preservation, the beneficial effect of using amphotericin B as an antifungal agent may be reduced by its negative effect on tissue viability.