常温灌注脂肪肝修复系统的作用和机制研究

Liver transplantation is known to be the most effective way to save end-stage liver disease. The increasing waiting list mortality as a result of ongoing organ shortage has led to the use of organs from extended criteria of moderate to severe steatotic donor livers. Our previous study on human and rat steattotic liver transplant demonstrated that steatotic livers were susceptible to cold ischemia preservation, which is the critical factor rendering steatotic livers nonviable. The presence of severe steatosis is correlated with the development of graft initial poor function and involved recipient and graft survival. The aim of this research is to develop a normothermic perfusion/defatting system. Oxygen and metabolic substance are added to maintain cellular aerobic metabolism within a physiological environment in porcine steatotic liver model. Perfusate containing 3,5-L-diiodothyronine, an effective defatting agent, upregulates both lipid oxidation and export throughout a short perfusion period. Porcine liver transplantation model is planed using steatotic graft which is preconditioned by the defatting system, to make sure if the survival can be improved in vivo. To further study its mechanism, the gene and protein changes of PPARγ/ADRP droplet pathway during extracorporeal perfusion and hepatocyte H2O2 culture are tested. Consequently, normothermic perfusion/defatting system can reduce the degree of hepatic graft steatosis to a certain extent. By restoring function in marginal steatotic donor organs, the donor pool might be greatly expanded.

肝移植是拯救终末期肝病最有效的手段，然而肝移植等候者因供肝短缺而死亡的概率逐年增加，导致边缘供肝逐渐纳入选择范围，其中中重度脂肪肝比例最高。我们前期在人和大鼠脂肪肝肝移植的研究中发现脂肪供肝对冷缺血保存极为敏感，供肝获取后冷保存时间延长会直接造成脂肪供肝的不可逆损伤，导致术后早期移植物功能不全，受体和移植物累计生存率下降。常温离体灌注系统为脂肪供肝提供氧和能量，维持肝细胞的有氧代谢，并具有移植前预处理的潜能。本课题拟利用常温灌注平台，在灌注液中加入二碘化甲状腺氨酸药物脱脂进行预处理，经过短时间的修复治疗，逐步将细胞内的脂质分解并排出，有效逆转供肝脂肪变，并在猪肝移植模型上，评估在体移植的生存率。通过离体灌注和氧自由基损伤实验，分析常温灌注系统对脂肪肝的修复作用中是否由PPARγ/ADRP脂滴信号通路介导。最终为临床合理保存和利用脂肪供肝，拓展供肝来源提供理论依据。

肝脏移植是救治终末期肝病的唯一有效手段。而供肝的严重短缺不仅制约了肝移植的发展，同时使众多亟需移植手术的患者丧失生命。而日益短缺的临床供肝中，相当一部分由于脂肪病变严重、移植后原发性移植物无功能而被舍弃，造成严重浪费。我们利用ECOM体外循环技术成功搭建了离体肝脏常温循环灌注系统，充分证明该系统可以有效维持离体肝脏稳定，减少肝脏、特别是脂肪肝脏的损伤，并通过探索优化的修复预处理，可以在短时间的循环灌注过程中，在一定程度上促进脂肪肝内脂质的代谢，显著减轻缺血再灌注损伤，提高脂肪供肝质量，为进一步扩大极度短缺的临床供肝来源提供了全新的思路和技术方案，本系统有望在不久的将来应用于临床，在一定程度上帮助解决供肝短缺难题，同时可有效延长肝脏保存时间，提升供肝质量，改善肝移植患者术后生存情况获益，造福广大肝移植受体。