Progression of fibrosis and the development of cirrhosis are responsible for the liver-related morbidity and mortality associated with chronic liver diseases. There is currently a great unmet need for effective antifibrotic strategies. Stem cells play a central role in wound-healing responses to restore liver homeostasis following injury. Here we tested the hypothesis that extracellular vesicles (EVs) isolated from induced pluripotent stem cells (iPSCs) modulate hepatic stellate cell (HSC) activation and may have antifibrotic effects. Human iPSCs were generated by reprogramming primary skin fibroblasts. EVs were isolated by differential centrifugation, quantified by flow cytometry (FACS), and characterized by dynamic light scattering and transmission electron microscopy (TEM). Primary human HSCs were activated with TGF-β (10 ng/mL) and exposed to iPSC-EVs. Efficacy of iPSC-EVs was tested on HSCs in vitro and in 2 murine models of liver injury (CCl4 and bile duct ligation). Characterization of iPSC-derived EVs by flow cytometry identified a large population of EVs released by iPSCs, primarily with a diameter of 300 nm, that could be visualized by TEM as round, cup-shaped objects. Fluorescent tracing assays detected iPSC-EVs in HSC cytosol after a short incubation, and EV uptake by HSCs resulted in both decrease of profibrogenic markers α–smooth muscle actin, CollagenIα1, fibronectin, and tissue inhibitor of metalloproteinases–1 and HSC profibrogenic responses, such as chemotaxis and proliferation. Genomics analyses of iPSC-EV miRNA cargo revealed 22 highly expressed miRNAs, among which miR-92a-3p was the most abundant. Transcriptome analysis identified 60 genes downmodulated and 235 upregulated in TGF-β–primed HSCs in the presence or absence of iPSC-EVs. Intravenous injection of iPSC-EVs in CCl4-induced and bile duct ligation–induced liver fibrosis resulted in antifibrotic effects at protein and gene levels. Results of this study identify iPSC-EVs as a potentially novel antifibrotic approach that may reduce or reverse liver fibrosis in patients with chronic liver disease.
Davide Povero, Eva M. Pinatel, Aleksandra Leszczynska, Nidhi P. Goyal, Takahiro Nishio, Jihoon Kim, David Kneiber, Lucas de Araujo Horcel, Akiko Eguchi, Paulina M. Ordonez, Tatiana Kisseleva, Ariel E. Feldstein