经液氮保存有活性同种带支架瓣膜的可行性研究

Feasibility of Viable Stented Homograft Valve Preserved in Liquid Nitrogen

目的:探讨经液氮保存的有活性的人同种带支架瓣膜的制作可行性。方法:将制作完成的瓣架液氮保存1个月后复温,进行几何形态检测(n=6)。所选用的涤纶包布及缝线经液氮保存1-3个月后复温,分别进行破坏应力实验,检测机械强度变化(n=6)。制作同种带支架瓣膜液氮保存3个月后,利用流式细胞仪技术,定量检测瓣叶细胞活性(实验组),新鲜采集同种瓣膜作为对照组(n=6)。结果:瓣架经液氮冷冻1个月后,其直径冷冻前为(21.10±0.06)mm,冷冻后为(21.10±0.05)mm(P>0.05),高度冷冻前为(14.03±0.02)mm,冷冻后为(14.04±0.03)mm(P>0.05),几何形态未发生明显变化。涤纶包布经液氮冷冻前其纵向纤维方向拉力强度为(19.05±1.64)MPa,冷冻1个月、3个月后分别为(17.29±1.79)MPa(P>0.05)和(18.23±1.60)MPa(P>0.05),其横向纤维冷冻前为(18.16±1.16)MPa,冷冻后分别为(16.81±0.97)MPa(P>0.05) 和(17.46±1.54)MPa(P>0.05)。包布物理强度未发生明显变化。缝线经液氮冷冻前拉力强度为(163.99±7.83) MPa,冷冻1个月、3个月后分别为(168.88±6.28)MPa(P>0.05)和(168.74±1.85)MPa(P>0.05),缝线物理强度未发生明显变化。实验组内皮细胞死亡率(10.24±1.71)%,对照组(9.09±2.72)%,两者之间无显著性差异(P=0.44)。实验组平滑肌细胞死亡率(8.76±1.82)%,对照组(7.84±0.59)%,两者之间无显著性差异(P=0.17)。实验组总细胞死亡率(8.79±1.44)%,对照组(7.40±0.49)%,两者之间无显著性差异(P=0.07)。结论:经液氮保存同种带支架瓣膜的材料选择符合技术要求,细胞活性保存良好,制作方法确实可行。

Objective： To develop a method of viable stented homograft valves preserved in liquid nitrogen. Methods： The frames （n=6） were put into liquid nitrogen, and preserved for one month. After thawing, their geometric shape was measured. Dacron cloth and thread （n=6） used to fabricate the stented homograft valve were put into liquid nitrogen, and cyropreserved for one to three months. After they thawed, we surveyed mechanical strength. We examined cell viability of the stented homograft valve preserved in liquid nitrogen using flow cytometer after 3 months of preservation （ experimental group）. Fresh homografts served as control group （ n = 6）. Results： The results revealed that the diameters before and after preservation were （21.10 ±0.06）ram and （21.10±0. 05） mm （P 〉 0. 05）, and the height before and after preservation were （ 14. 03 ± 0. 02） mm and （ 14. 04 ± 0.03 ）mm （P 〉 0.05 ）. The geometric shape of frames was not changed, Our outcomes showed that the tension along to longitudinal fibers of Dacron before and 1,3 months after preservation was（ 19. 05 ± 1.64） Mpa, （ 17.29 ±1.79） Mpa （P 〉 0. 05） and （ 18. 23 ± 1.60） Mpa （P 〉 0. 05 ）, respectively. The tension along to lateral fibers of Dacron before and 1,3 months after preservation was （18. 16 ± 1.16） Mpa, （ 16. 81 ± 0. 97） Mpa （ P 〉 0. 05 ） and （ 17.46 ± 1.54） Mpa （P 〉 0. 05 ）. The tension of thread before and 1,3 months after preservation were was（ 163.99 ± 7.83 ） Mpa, （ 168.88 ± 6. 28） Mpa （P 〉 0. 05） and （ 168.74 ± 1.85） Mpa （P 〉 0.05）. The mechanical strength of Dacron and thread was not significantly changed. The results revealed that the death ratio of endothelial cells was （ 10. 24 ＋ 1.71 ） % in the experimental group, and （9.09 ± 2. 72） % in the control group （P = 0.44）. The death ratio of fibroblast cells was （8.76 ± 1. 82） % in the experimental group, and （7.84 ± 0. 59） % （ P = 0. 17） in the control group. The death ratio of total cell was （8.79 ± 1.44） % in the experimental group, and （7. 40 ± 0. 49） % in the control group （P = 0. 07）. There were no significant differences between groups. Conclusion： The material of the stented homograft valve can be cyropreserved in liquid nitrogen. Liquid hydrogen can offer the benefit of cell viability of the stented homograft bioprosthetic valves.