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目的比较犬内皮祖细胞内衬脱细胞带瓣膜静脉支架与犬天然静脉瓣膜在生理条件下的闭合机制。方法普通雄性杂种犬36只,体重15～18kg,取12只犬左侧带瓣膜股静脉制备脱细胞带瓣膜静脉支架。将余24只动物随机分为实验组和对照组(n=12),取实验组骨髓进行体外扩增培养获取内皮祖细胞,取第3代细胞以5×106个/mL密度种植于支架上,行种植细胞前后支架大体及HE染色观察。实验组于左侧股静脉部位移植同种异体内皮祖细胞内衬脱细胞带瓣膜静脉支架,对照组原位移植自体带瓣膜静脉。术后4周通过彩色超声多普勒检查,比较动物由平卧位升至头高脚低位,瓣膜关闭前后瓣膜远端血流方向和流速的改变,以及瓣窦部位静脉管径的变化情况。结果种植细胞前后支架大体及HE染色示,经脱细胞处理的带瓣膜静脉支架能较好地保留其纤维和胶原结构,经生物反应器可于体外成功将内皮祖细胞种植于脱细胞支架上。动物于头高脚低位至瓣膜开始关闭时,实验组均出现血液返流现象,返流流速(1.4±0.3)cm/s;对照组未出现血液返流现象,但血液流速下降,由高峰流速(21.3±2.1)cm/s减至(18.2±3.3)cm/s。对照组瓣膜的活动周期、开始闭合时间及瓣膜从开始闭合到完全闭合的时间分别为(918±46)、(712±48)、(154±29)ms,实验组分别为(989±53)、(785±43)、(223±29)ms,两组比较差异均有统计学意义(P<0.05)。瓣膜关闭完全后,两组均未见返流。实验组和对照组瓣膜关闭前后瓣膜窦部静脉管径均有所增大,增大比例分别为116.8%±2.0%和118.5%±2.2%(P>0.05)。结论犬内皮祖细胞内衬脱细胞带瓣膜静脉支架与天然静脉瓣膜在生理条件下的闭合条件有明显差异,前者依赖于血液返流,后者与血液流速减慢及瓣窦段静脉压力增高有关。
Objective To compare the occlusion mechanism of endothelial progenitor cells (EPCs) with canine ventricular valves and canine natural venous valves in physiological conditions. Methods Thirty - six male commonbred dogs (weighing 15 ~ 18kg) were enrolled in this study. Twenty-four animals were randomly divided into experimental group and control group (n = 12). The bone marrow of the experimental group was used for in vitro expansion culture to obtain endothelial progenitor cells. The third generation of cells were seeded on the scaffold at a density of 5 × 106 / mL , Before and after planting cells were scaffold and HE staining observed. In the experimental group, allogeneic EPCs were transplanted in the left femoral vein. The control group received autologous valvular vein graft. Four weeks after operation, color Doppler ultrasound examination was performed to compare the changes of the direction and velocity of the distal blood flow and the diameter of the vein in the valvular sinus before and after the valve was closed. Results Before and after the implantation of cells, HE and HE staining showed that the acellular valve-covered venous scaffolds could well preserve the fiber and collagen structure. The endothelial progenitor cells could be successfully seeded on the decellularized scaffolds via bioreactor in vitro. When the animal was in the head-to-feet low position and the valve started to close, the blood reflux occurred in the experimental group with a reflux flow rate of (1.4 ± 0.3) cm / s. No blood reflux was observed in the control group, but the blood flow decreased from peak to peak (21.3 ± 2.1) cm / s to (18.2 ± 3.3) cm / s. In the control group, the activities of the valve, the time of onset of closure and the duration of valve closure from the initial closure to complete closure were (918 ± 46), (712 ± 48) and (154 ± 29) ms, respectively, and were 989 ± 53 , (785 ± 43) and (223 ± 29) ms, respectively. There was significant difference between the two groups (P <0.05). Valve closed completely, no reflux in both groups. The diameter of valvular venous veins in both experimental group and control group before and after valve closure were increased, with the increasing ratio being 116.8% ± 2.0% and 118.5% ± 2.2%, respectively (P> 0.05). Conclusions There are significant differences in the closure conditions of the aortic valve-bearing aortic valve-bearing aortic valve with natural venous valves under the physiological conditions. The former depends on the blood reflux and the latter is related to the slowed blood flow and the increased venous pressure in the valve segment .