Mesenchymal Stem Cell-Derived Exosomes Attenuate Hepatic Steatosis and Insulin Resistance in Diet-Induced Obese Mice by Activating the FGF21-Adiponectin Axis.

Exosomes derived from mesenchymal stem cells have shown promise in treating metabolic disorders, yet their specific mechanisms remain largely unclear. This study investigates the protective effects of exosomes from human umbilical cord Wharton's jelly mesenchymal stem cells (hWJMSCs) against adiposity and insulin resistance in high-fat diet (HFD)-induced obese mice. HFD-fed mice treated with hWJMSC-derived exosomes demonstrated improved gut barrier integrity, which restored immune balance in the liver and adipose tissues by reducing macrophage infiltration and pro-inflammatory cytokine expression. Furthermore, these exosomes normalized lipid metabolism including lipid oxidation and lipogenesis, which alleviate lipotoxicity-induced endoplasmic reticulum (ER) stress, thereby decreasing fat accumulation and chronic tissue inflammation in hepatic and adipose tissues. Notably, hWJMSC-derived exosomes also promoted browning and thermogenic capacity of adipose tissues, which was linked to reduced fibroblast growth factor 21 (FGF21) resistance and increased adiponectin production. This process activated the AMPK-SIRT1-PGC-1α pathway, highlighting the role of the FGF21-adiponectin axis. Our findings elucidate the molecular mechanisms through which hWJMSC-derived exosomes counteract HFD-induced metabolic dysfunctions, supporting their potential as therapeutic agents for metabolic disorders.