非体外循环下组织工程心脏瓣膜体内实验动物模型的建立

Establishment of a in vivo tissue-engineered heart valve model without cardiopulmonary bypass in sheep

目的:寻求简单、经济的方法建立组织工程心脏瓣膜体内实验动物模型.方法:体质量20～30 kg成年绵羊9只,接受非体外循环下去细胞猪主动脉带瓣管道植入胸部降主动脉手术,并用自行研制的闭式主动脉瓣剪剪切造成自体主动脉瓣关闭不全.术中记录血压变化,术后观察植入瓣膜启闭功能,6个月后测量管壁厚度、管腔大小以及病理形态学改变.结果:术中自体主动脉瓣关闭不全后,收缩压升高,带瓣管道近心端舒张压比自体主动脉瓣关闭不全前显著降低,自体主动脉瓣脉压差明显增大,植入去细胞猪主动脉带瓣管道瓣膜两侧舒张期压力阶差增大.手术后2个月磁共振检查显示植入的瓣膜启闭功能良好,B超显示自体主动脉瓣中-重度关闭不全.术后6个月切取带瓣管道见:带瓣管道无扩张、血栓形成、瓣膜粘连、增厚、狭窄及关闭不全等改变,带瓣管道管壁厚度和管腔大小与术前无明显变化,但管壁明显僵硬,有局限性钙化现象.超微结构及病理学检查显示瓣膜和管道内表面均已内皮化,瓣叶和管道均有间质细胞存在,散在少许炎性细胞浸润.结论:通过非体外循环下将去细胞猪主动脉带瓣管道植入绵羊胸部降主动脉,并用自行研制的闭式主动脉瓣剪剪切使自体主动脉瓣关闭不全建立的组织工程心脏瓣膜体内研究动物模型,具有创伤小、术后生存率高、对实验干扰因素少以及节省人力、物力和财力等优点.

Objective：To explore a simple and economical method for establishing an in vivo animal model of tissue-engineered heart valve（TEHV） in sheep. Methods： Nine adult sheep, weighing 20-30kg, were implanted with decellularized porcine valvular conduits in thoracic descending aorta without cardiopulmonary bypass. The native aortic valves were cut by selfmade scissors to induce valve regurgitation. Arterial pressure of the sheep was monitored and recorded during the operation and the function of implanted conduits was evaluated by MRI. The animals were sacrificed 6 months later and pathological changes, thickness of conduit＇s wall, and lumenal diameter were observed by optical microscopy and scanning electron microscopy. Results： After native aortic valve was split, arterial systolic pressure increased and arterial diastolic pressure decreased. Pulse pressure increased in the proximal part of the implanted valve; the implanted valve pressure gradient was obviously increased during diastolic period. MRI showed that the implanted valve had excellent performance 2 months after operation and echocardiogram showed that the native aortic valve had moderate to severe regurgitation. There was no enlargement, thrombosis, valvular adhension, thickening, stenosis, and regurgitation in the implanted valvular conduits 6 months after operation. The aortic wall thickness and lumenal diameter had no significant change but obvious stiffness and calcification were found. Uhrastructure observation and pathological examination showed that the conduits and the valve leaflets were re-endothelialized with sparse inflammatory infiltration. Conclusion： Implanting decellularized porcine valvular conduits in thoracic descending aorta without cardiopulmonary bypass is a convenient and economical way for establishing an animal model of TEHV. Besides, this method is mini-invasive, more reliable and with high post operation survival rate.