Viability of cryopreserved semilunar valves: an evaluation of cytosolic and mitochondrial activities

Background. Despite long-standing, widespread use of cryopreserved allografts, the basic cellular biology of these tissues is still yet unknown. The present investigation was undertaken to study cryopreserved heart valves from the standpoint of cytosolic esterase and mitochondrial dehydrogenase activities. Methods. Cryopreserved porcine aortic cusps were observed in an unfixed fresh condition with a confocal laser scanning microscope using fluorescent dye. Porcine cusps and cultured human umbilical vein endothelial cells were divided into three groups, including fresh, cold-preserved, and cryopreserved specimens, and cytosolic esterase activity and mitochondrial dehydrogenase activity were analyzed in each. Results. Confocal laser scanning microscope findings disclosed a widely distributed fluorescence in the cusp. Cytosolic esterase activity within human umbilical vein endothelial cells (28% ± 9.0%) after cryopreservation was significantly less than that it was in the cusps (72% ± 21%). Mitochondrial dehydrogenase activity of cryopreserved human umbilical vein endothelial cells and that of cusps fell to 44% ± 6.1% and 64% ± 17% respectively; the difference between the two values was not significant. Conclusions. Cryopreservation appeared to produce serious damage to cytosolic and mitochondrial functions of endothelial cells. The cytosolic function of cusps, mainly consisting of fibroblasts, was comparatively preserved after cryopreservation, but mitochondrial function of the cusps was more diminished.