降温方法对硫酸软骨素保存的心脏瓣膜的影响

Effect of different cooling methods on cardiac valves cryopreserved in liquid nitrogen with chondroitin sulfate

目的观察不同降温方法对含硫酸软骨素的液氮深低温冷冻保存的同种异体心脏瓣膜的组织学结构和细胞活力的影响。方法将32只兔主动脉瓣随机分成4组，每组8只均经灭菌处理。对照组于灭菌后立即行瓣膜细胞活力测定及组织学检查；实验Ⅰ-Ⅲ组分别采用速冻法、阶梯降温法、程序控速降温法将瓣膜保存在含有硫酸软骨素的液氮深低温中1个月，复温后行瓣膜细胞活力测定、光镜及电镜检查。结果三种降温方法下冷冻保存的瓣膜均有损害，与对照组比较，实验Ⅰ组瓣膜组织学结构改变较重，细胞活力下降显著（P〈O．05）；实验Ⅱ组瓣膜组织学结构改变较轻，细胞活力下降显著（P〈O．05），实验Ⅲ组瓣膜组织学结构改变轻微，瓣膜细胞活力下降不明显（P〉O．05）。结论程序控速降温法是目前含硫酸软骨素的液氮深低温冷冻保存同种异体主动脉瓣的最佳降温方法，经此法保存的瓣膜组织学结构损伤轻微，细胞活力佳。

[ Objective ] To estimate the effect of different cooling methods on the histological structure and cy- toactive of cryopreserved homograft cardiac valves in liquid nitrogen with chondroitin sulfate （CS）. [ Methods ] 32 rabbit aortic valves were randomly divided into control and experiment groups（Ⅰ -Ⅲ）（n =8）. All the valves were ger- micidal treated. Then, the activity of endothelial cells in control group was immediately examined and the tissues were observed under light and electron microscopes. In the experiment groups, valves were eryopreserved in liquid nitrogen contained CS by three different cooling protocols. In group I, valves were immediately frozen to -196 de- grees C. In group II, valves were firstly frozen to 4 degrees C, then -80 degrees C after 2 h, and finally into liquid nitrogen after 8 h. In group III, valves were frozen with programmed freezing at a controlled rate of -1 degrees C/rain to-196 degrees C prior to liquid nitrogen. All valves in experiment groups were cryopreserved for 1 month. Then, the activities of endothelial cells in different groups were examined and the tissues were observed under light and elec- tron microscopes. [ Results ] Compared with control, cytoaetive in Group I was significantly declined （P 〈0.05） and severe morphologic changes occurred. In Group ]1, cytoactive was also significantly declined （P 〈0.05）, but morpho- logic changes were slight. In group Ill, cytoactive was slightly declined （P 〉0.05） and there were almost no morpho- logic changes. [ Conclusion ] Among all cooling protocols, the programmed cooling method is best, since the histo-logical structure and cytoactive were both cryopreserved well.