Human umbilical cord-derived mesenchymal stem cells ameliorate non-alcoholic fatty liver disease via activating TFEB-mediated autophagy in male mice.

Abstract

Non-alcoholic fatty liver disease (NAFLD) is characterized by abnormal lipid accumulation in hepatocytes and defective autophagy has been implicated in its pathogenesis. Human umbilical cord-derived MSCs (hUC-MSCs) have shown therapeutic potential in treating NAFLD, while underlying molecular mechanisms remained largely unknown. Male C57BL/6J mice fed a choline-deficient high fat diet (CD-HFD) and HepG2 cells exposed to palmitic acid/oleic acid were established as in vivo and in vitro models of NAFLD, respectively. Both models were subjected to treatment with human umbilical cord-derived MSCs (hUC-MSCs). Lipid content, proinflammatory cytokines, fibrosis markers and the hepatic transcriptome were assessed to determine the effect of hUC-MSCs. Here, hUC-MSCs decreased hepatic lipid content and alanine aminotransferase/aspartate aminotransferase levels, as well as attenuated inflammation and fibrosis in choline-deficient high-fat diet (CD-HFD)-induced NAFLD mice. Mechanistically, hUC-MSCs restored impaired autophagic flux and mitigated liver steatosis through the AMPK-mTOR-TFEB pathway in both NAFLD mice and oleic acid/palmitic acid-induced "fatty" HepG2 cells. Of note, hUC-MSCs have been found to promote nuclear translocation of TFEB in PA/OA-induced HepG2 cells. Additionally, TFEB knockdown partially attenuated the effect of hUC-MSCs on enhancing autophagy and lipid metabolism in vitro. This study suggests that hUC-MSCs represent a potential therapeutic approach to treating NAFLD through activating TFEB-mediated autophagy.