探讨脐带间充质干细胞（hUC-MSCs）对非酒精性脂肪肝病（NAFLD）大鼠肝脏损伤的作用及其与TLR4/NF-κB炎症通路和氧化应激的关系。

SD大鼠随机分为3组：正常对照组（NC组）、模型对照组（MC组）和hUC-MSCs治疗组（MC+hUC-MSCs组）。每组大鼠均为10只，分别喂食常规或高糖高脂饲料并给予相应治疗8周，其中MC+hUC-MSCs组每两周尾静脉注射含5×10⁶个hUC-MSCs。检测各组肝指数、谷丙转氨酶（ALT）、谷草转氨酶（AST）、甘油三酯（TG）、胆固醇（TC）、低密度脂蛋白（LDL）、高密度脂蛋白（HDL）和胰岛素抵抗指数（HOMA-IR）。光镜和电镜观察大鼠肝脏组织病理改变，评估NAFLD活动度积分（NAS）；Western Blot法检测大鼠肝脏组织超氧化物歧化酶（SOD）、8-羟基脱氧鸟苷（8-OHdG）、肿瘤坏死因子（TNF-α）、白介素-6（IL-6）Toll样受体4（TLR4）和核因子-κB （NF-κB）蛋白表达。组间比较采用单因素方差分析。

干预结束后，（1）NC组TG（0.96±0.29）?mmol/?L、TC（2.23±0.37）mmol/L、LDL（0.71±0.18）mmol/L、HDL（2.95±0.27）mmol/L，与MC组TG（5.79± 0.68）mmol/L、TC（6.08±0.79）mmol/L、LDL（6.06±0.31）mmol/L、HDL（0.75±0.18）?mmol/?L比较差异具有统计学意义（均P < 0.05）；与MC组比较，MC+hUC-MSCs组上述指标差异具有统计学意义（均P < 0.05）。（2）光镜下NC组肝细胞形态正常；MC组出现肝细胞脂肪变性、肝小叶排列不齐及炎症细胞浸润；而MC+hUC-MSCs组肝组织病理改变明显好转。与NC组比较，MC组肝组织NAS升高；与MC组比较，MC+hUC-MSCs组NAS降低[（0.36±0.16）分vs（8.72±0.35）分、（4.78±0.51）分，P < 0.05]。电镜下亦观察到与MC组比较，MC+hUC-MSCs大鼠肝细胞脂肪变性、胞核变形、内质网和线粒体形态异常明显改善。（3）与NC组比较，MC组大鼠TNF-α、IL-6、8-OHdG、TLR4和NF-κB蛋白表达均增高（均P < 0.05），SOD降低（P?< 0.05）；与MC组比较，MC+hUC-MSCs组大鼠上述指标改善（P < 0.05）。

hUC-MSCs通过抑制氧化应激和TLR4/NF-κB而保护NAFLD大鼠肝脏功能。

To evaluate the effect of human umbilical cord mesenchymal stem cells on liver injury and TLR4/NF-κB and oxidative stress of non-alcoholic fatty liver disease rats.

SD rats were randomly divided into three groups: control group (NC), non-alcoholic fatty liver disease model group (MC) and hUC-MSCs treatment group (MC+hUC-MSCs) (n = 10 for each group). The rats in the control group were fed with conventional feed, and the rats in MC and MC+hUC-MSCs group were fed with high glucose and high fat diet. Once every two weeks, the rats in hUC-MSCs group were injected 5×10⁶ hUC-MSCs by caudal vein. At the end of therapy, liver index, ALT, AST, TG, TC, LDL, HDL and HOMA-IR were measured. Liver tissues were observed with light microscope and transmission electronic microscope. The protein expressions of 8-OhdG, SOD, TNF-α, IL-6, TLR4 and NF-κB of liver tissues were detected by Western Blot.

(1)?At the end of therapy, parameters in the control group were as follow: TG (0.96±0.29) ?mmol/?L, TC (2.23±0.37) mmol/L, LDL (0.71±0.18) mmol/L, HDL (2.95±0.27) mmol/L; for the MC group, they were: TG (5.79±0.68) mmol/L, TC (6.08±0.79) mmol/L, LDL (6.06±0.31) mmol/L, HDL (0.75±0.18) ?mmol/?L compared with the control group, the value of the liver index, ALT, AST, TG, TC, LDL and HOMA-IR in the MC group were significantly increased (P < 0.05), and HDL decreased (P?< 0.05), which were reversed in the MC+hUC-MSCs group (P < 0.05). (2) HE staining showed fatty degeneration,disorder and inflammatory cell infiltration in the MC group.However,the above liver histopathology changes were improved in the MC+hUC-MSCs group. Compared with the control group, the value of NAS in the MC group significantly incresed. Compared with the MC group, the value of NAS was significantly declined in the MC+hUC-MSCs groups (0.36±0.16) vs (8.72±0.35)、(4.78±0.51), P < 0.05. Transmission electron microscope showed hepatocyte steatosis, cell nucleus deformation, endoplasmic reticulum and mitochondrial abnormalities were significantly improved in the MC+hUC-MSCs group. (3) Compared with the control group, the protein expression of the liver tissues TNF-α, IL-6, 8-OHdG, TLR4 and NF-κB by Western Blot increased, and SOD declined in the MC group, which were reversed in MC+hUC-MSCs groups (P < 0.05).

Human umbilical cord mesenchymal stem cells improved the liver damage of NAFLD by inhibitting TLR4/NF-κB and oxidative stress.