Department of Infectious Diseases, Shenzhen People's Hospital (The Second Clinical Medical College, Jinan University; The First Affiliated Hospital, Southern University of Science and Technology), 1017 Dong Men Bei Road, Luo Hu District, Shenzhen, 518020, Guangdong Province, People's Republic of China.
Centre for Atherothrombosis and Metabolic Disease, Hull York Medical School, University of Hull, Hull, HU6 7RX, UK.
Stem Cell Res Ther. 2020 Sep 14;11(1):395. doi: 10.1186/s13287-020-01911-4.
Bone mesenchymal stem cells (MSCs) can promote liver regeneration and inhibit inflammation and hepatic fibrosis. MSCs also can serve as a vehicle for gene therapy. Smad7 is an essential negative regulatory gene in the TGF-β1/Smad signalling pathway. Activation of TGF-β1/Smad signalling accelerates liver inflammation and fibrosis; we therefore hypothesized that MSCs overexpressing the Smad7 gene might be a new cell therapy approach for treating liver fibrosis via the inhibition of TGF-β1/Smad signalling.
MSCs were isolated from 6-week-old Wistar rats and transduced with the Smad7 gene using a lentivirus vector. Liver cirrhosis was induced by subcutaneous injection of carbon tetrachloride (CCl) for 8 weeks. The rats with established liver cirrhosis were treated with Smad7-MSCs by direct injection of cells into the main lobes of the liver. The expression of Smad7, Smad2/3 and fibrosis biomarkers or extracellular matrix proteins and histopathological change were assessed by quantitative PCR, ELISA and Western blotting and staining.
The mRNA and protein level of Smad7 in the recipient liver and serum were increased after treating with Smad-MSCs for 7 and 21 days (P < 0.001). The serum levels of collagen I and III and collagenase I and III were significantly (P < 0.001) reduced after the treatment with Smad7-MSCs. The mRNA levels of TGF-β1, TGFBR1, α-SMA, TIMP-1, laminin and hyaluronic acid were decreased (P < 0.001), while MMP-1 increased (P < 0.001). The liver fibrosis score and liver function were significantly alleviated after the cell therapy.
The findings suggest that the MSC therapy with Smad7-MSCs is effective in the treatment of liver fibrosis in the CCl-induced liver cirrhosis model. Inhibition of TGF-β1 signalling pathway by enhancement of Smad-7 expression could be a feasible cell therapy approach to mitigate liver cirrhosis.
骨髓间充质干细胞（MSCs）可促进肝脏再生，抑制炎症和肝纤维化。MSCs 还可以作为基因治疗的载体。Smad7 是 TGF-β1/Smad 信号通路中的一个重要负调控基因。TGF-β1/Smad 信号的激活会加速肝脏炎症和纤维化；因此，我们假设过表达 Smad7 基因的 MSCs 可能通过抑制 TGF-β1/Smad 信号通路成为治疗肝纤维化的一种新的细胞治疗方法。
从 6 周龄 Wistar 大鼠中分离 MSCs，并使用慢病毒载体转染 Smad7 基因。通过皮下注射四氯化碳（CCl）8 周诱导肝硬化。用细胞直接注射到肝脏主要叶来治疗 Smad7-MSCs 诱导的肝硬化大鼠。通过定量 PCR、ELISA 和 Western 印迹及染色评估 Smad7、Smad2/3 和纤维化生物标志物或细胞外基质蛋白的表达和组织病理学变化。
Smad7-MSCs 治疗 7 和 21 天后，受体肝和血清中 Smad7 的 mRNA 和蛋白水平均升高（P<0.001）。Smad7-MSCs 治疗后，血清中 I 型和 III 型胶原及胶原酶 I 和 III 的水平显著降低（P<0.001）。TGF-β1、TGFBR1、α-SMA、TIMP-1、层粘连蛋白和透明质酸的 mRNA 水平降低（P<0.001），而 MMP-1 增加（P<0.001）。细胞治疗后，肝纤维化评分和肝功能明显改善。
研究结果表明，MSC 疗法联合 Smad7-MSCs 对 CCl 诱导的肝硬化模型中的肝纤维化治疗有效。通过增强 Smad-7 表达抑制 TGF-β1 信号通路可能是减轻肝硬化的可行细胞治疗方法。
