Exosomes derived from miR‐181‐5p‐modified adipose‐derived mesenchymal stem cells prevent liver fibrosis via autophagy activation

Proliferating hepatic stellate cells ( HSC s) respond to liver damage by secreting collagens that form fibrous scar tissue, which can lead to cirrhosis if in appropriately regulated. Advancement of micro RNA (mi RNA ) hepatic therapies has been hampered by difficulties in delivering mi RNA to damaged tissue. However, exosomes secreted by adipose‐derived mesenchymal stem cells ( ADSC s) can be exploited to deliver mi RNA s to HSC s. ADSC s were engineered to overexpress mi RNA ‐181‐5p (miR‐181‐5p‐ ADSC s) to selectively home exosomes to mouse hepatic stellate ( HST ‐T6) cells or a CC l4‐induced liver fibrosis murine model and compared with non‐targeting control Caenorhabditis elegans miR‐67 (cel‐miR‐67)‐ ADSC s. In vitro analysis confirmed that the transfer of miR‐181‐5p from miR‐181‐5p‐ ADSC s occurred via secreted exosomal uptake. Exosomes were visualized in HST ‐T6 cells using cyc3‐labelled pre‐mi RNA ‐transfected ADSC s with/without the exosomal inhibitor, GW 4869. The effects of mi RNA ‐181‐5p overexpression on the fibrosis associated STAT 3/Bcl‐2/Beclin 1 pathway and components of the extracellular matrix were assessed. Exosomes from miR181‐5p‐ ADSC s down‐regulated Stat3 and Bcl‐2 and activated autophagy in the HST ‐T6 cells. Furthermore, the up‐regulated expression of fibrotic genes in HST ‐T6 cells induced by TGF ‐β1 was repressed following the addition of isolated miR181‐5p‐ ADSC exosomes compared with miR‐67‐ ADSC exosomes. Exosome therapy attenuated liver injury and significantly down‐regulated collagen I, vimentin, α‐ SMA and fibronectin in liver, compared with controls. Taken together, the effective anti‐fibrotic function of engineered ADSC s is able to selectively transfer miR‐181‐5p to damaged liver cells and will pave the way for the use of exosome‐ ADSC s for therapeutic delivery of mi RNA targeting liver disease.