STRUCTURAL, ULTRASTRUCTURAL AND FUNCTIONAL STUDIES OF HUMAN CARDIAC VALVE ALLOGRAFTS THAT SUFFERED AN INCREMENT OF THE CRYOSTORAGE TEMPERATURE

Human cardiac valve allografts (HVAs) suffer injuries during the cryopreservation period. Here, we described structural, ultrastructural and functional damages suffered by HVAs after an increment of their cryostorage temperature (100°C). Two experimental groups of pulmonary and aortic HVAs were compared: cryopreserved (HVA cryo ) and cryopreserved with temperature changes (HVA T ). Transmission electron microscopy (TEM) was used to analyze valve fibroblasts and extracellular matrix morphology. Total collagen amount was estimated using two different methods and fibroblast viability was assessed measuring their oxygen consumption rate. Porcine heart grafts valves were used to set the techniques. Disorganized collagen network was seen in HVA T by TEM. Fibroblasts showed damages in the cellular membrane and many secretor vesicles. Mitochondria and chromatin were also altered. HVA T had less amount of collagen and fibroblasts showed an oxygen consumption rate markedly diminished compared to HVA cryo . The increment of 100°C suffered by HVAs caused damages that made them unsuitable for clinical purposes.