摘要：急性肝衰竭是一個肝細胞短期大量壞死, 使肝功能快速不足且進展到衰竭, 常合併多重器官一起變差,死亡率甚高的疾病症候群。病生理上, 急性肝衰竭時大量肝細胞壞死會造成innate 免疫反應過度活化,大量的發炎物質(如TNFα, IL-1) 從肝臟溢出至全身, 引起個體的無菌systemic inflammatory responsesyndrome。隨後抑制發炎的細胞激素 (如IL-10,讓發炎過程趕快緩解並促進修復的代償反應) 跟著溢出肝臟外, 造成單核球對入侵體內細菌無感的免疫癱瘓及敗血症。Kupffer 細胞(肝內主要巨噬細胞) 從促進發炎態的M1 偏極化到促進炎緩解的M2 偏極化, 在其中佔有重要的角色。間質幹細胞可藉由生長激素, 細胞激素及細胞外間質交互作用緩解發炎, 支持肝細胞 (功能維持, 促進增生, 抑制死亡進行等)。文獻上間質幹細胞可調控巨噬細胞並和其交互作用。吾人假設在猛爆性肝炎大鼠進行間質幹細胞移植，可藉由調控Kupffer 細胞偏極化由M1 轉向M2, 提早減緩肝微環境發炎。此外, 用近致死肝毒D-gal 劑量(1.1~1.3 g/kg) 誘發大量肝細胞壞死的猛爆性肝炎動物模式, 先進行間質幹細胞移植提早緩解發炎, 再進行肝細胞移植補充肝源, 可大幅增進移植肝細胞的殖入率。吾人用附加不同螢光的間質幹細胞(紅)及肝細胞(綠)移植追蹤這些細胞在移植後短期的變化,兼看間質幹細胞、原生搖搖欲墜的肝細胞以及移植進入的健康肝細胞間的交互作用, 也將探討間質幹細胞對發炎微環境的影響。前述機制是否透過Kupffer 細胞偏極化進行以及對肝細胞的影響也將透過動物實驗及體外細胞培養實驗(間質幹細胞-Kupffer 細胞共養, 再取其上清培養液培養肝細胞的方法)進行驗證。吾人期望這個臨床前轉譯醫學研究結果可以提供間質幹細胞如何透過調控Kupffer 細胞及發炎微環境, 穩定肝細胞, 達到早期改善這種致命性高疾病的預後。
Abstract: Acute liver failure is a lethal syndrome characterized as liver decompensation and multi-organ functionaldeterioration in a short period of time. Pathophysiologically in acute liver failure, massive necrosis ofhepatocytes would result in overactivity of innate immune response and overflown of pro-inflammatoryfactors/cytokines from inflamed liver to all over the host body, which contribute to the aseptic systemicinflammatory response syndrome and multi-organ dysfunction. Then it is followed by anti-inflammatorycytokines overflowing, which caused immune paralysis of circulating monocytes and subsequent sepsis.Kupffer cells, the intrahepatic macrophages, plays a central role in the pathogenesis of acute liver failure andfulfils a diversity of roles in acute liver failure, from pro-inflammatory (M1 polarization) to pro-resolution(M2 polarization). Mesenchymal stem cells (MSCs) can ameliorate inflammation, support hepatocytefunctions, promote hepatocyte proliferation, and inhibit apoptosis by secreting growth factors, cytokines, andextracellular matrix. MSC can modulate and cross-talk with macrophages in literature. We hypothesized thattransplanted MSC can reduce hepatic micro-environment inflammation through modulating Kupffer cellpolarization (early change of macrophage from pro-inflammatory type to anti-inflammatory type) andstabilizing residual hepatocytes from dying in rats of fulminant hepatic injury (induced by 1.1~1.3 g/kgD-gal). Additionally, fulminant acute liver injury caused by this higher dose of D-gal will result in moremassive hepatocyte necrosis and demand more hepatocytes, which will create a survival advantage of donorhepatocytes to engraft after MSC (first) and then hepatocyte (later) transplantation. We will use differentfluorescent dyes labeling MSCs (red) and donor hepatocytes (green) to trace the early course (several hoursafter MSC transplantation to 2 days) of transplanted MSC or hepatocytes, interaction of MSC withhepatocytes (both native and/or donor origins) and microenvironment, and long-term transplanted cellrepopulation (1 week). The mechanism of how MSCs ameliorate inflammatory microenvironment bymodulating Kupffer cell polarization and so reduce necrosis and promote proliferation of hepatocytes aregoing to be exploited in vivo and in vitro (MSC-Kupffer co-culture study, and hepatocyte culture withco-culture medium). We hope this preclinical translational study can provide a fundamental understandinghow MSCs modulate Kupffer cell and inflammed micro-environment, stabilize hepatocytes (either native ortransplanted) and improve outcome of acute liver failure.
