| The heart valve lesion is one of the main causes harmful to human health.There have been approximate 100 prosthetic heart valves since 1960s,but they couldn't overcome the disadvantages of themselves.In 1962,valve graft were used in aortic or pulmonary valve replacement.Its'advantages,such as favorable biologic characteristics and excellent hemodynamic performance,were excited.In recent years,the cryopreservation and the application of vavle graft have been spread at home and overseas.But the actual preservation shows differences,as a result of all the different technical approaches.Objective:Under the same conditions,compare the different cooling and warming methods of the valve graft cryopreserved in liquid nitrogen,to research the better way to prepare and preserve the valve graft,discuss the influencing factors of injury valve graft,find the measures to minimize the injury to the cells.Methods:obtain aortic and pulmonary valves with blood vessels from 20 donor hearts (porcin).After sterilizing,specimens were divided into 2 groups(control and test group).The test group was hypothermied at-1℃/min while the control group were hypothermied at -0.5℃/min,and then cryopreserved in liquid nitrogen for 6 months.The test group was thawed fast,compared with the control group thawed step by step.The morphological and immunohistochemistry staining were used to observe the differences of valve graft.Results:The endotheliocyte can be found in both groups,collagen fiber and elastic fibers kept clear.The viability of endotheliocyte in the test group was higher than that in the control group and the structural damage was also lighter,P＜0.05(Z=-3.053,P=0.002).The expressions of vimentin were higher in the test group,P＜0.05(Z=-2.881,P=-0.004).The electron microscope showed endotheliocyte was kept more integral in the test group,internal elastic layer also suffered less damage.Conclusions:The valve graft cryopreserved in liquid nitrogen had better effect by hypothermyed at -1℃/min and thawed fast.
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