Effect of function-enhanced mesenchymal stem cells infected with decorin-expressing adenovirus on hepatic fibrosis

Bone marrow-derived mesenchymal stem cells (BM-MSCs) are known to have an antifibrotic effect and could be used as vehicles for targeted gene delivery. Decorin plays a protective role against fibrogenesis by modulating the degradation of the extracellular matrix. The aim of this study was to determine whether the antifibrotic effect of a combination treatment consisting of BM-MSCs and decorin on hepatic fibrosis is superior to BM-MSCs alone. The effects of BM-MSCs infected with decorin-expressing adenovirus (DCN-MSCs) on hepatic fibrosis were examined in a rat model of thioacetamide (TAA)-induced cirrhosis. The effects of infection with decorin-expressing adenovirus and of incubation with the conditioned medium of DCN-MSCs on transforming growth factor-β (TGF-β) signaling were analyzed in immortalized human hepatic stellate cells (HSCs). According to the Laennec fibrosis scoring system, cirrhotic livers from rats treated with DCN-MSCs exhibited histological improvement compared with cirrhotic livers from rats treated with control adenovirus-infected MSCs (CA-MSCs). DCN-MSC treatment reduced hepatic collagen distribution, lowered the hydroxyproline content, and rescued liver function impairment in rats with TAA-induced cirrhosis. These protective effects were more potent with DCN-MSCs than with CA-MSCs. The upregulation of collagen-1, α-smooth muscle actin (α-SMA), TGF-β1, and Smad3 phosphorylation in cirrhotic livers was prevented by DCN-MSC administration. Intriguingly, medium from cultured DCN-MSCs blocked both Smad3 phosphorylation and exogenous TGF-β1 stimulated α-SMA synthesis in HSCs. DCN-MSCs exert strong protective effects against hepatic fibrosis by suppressing TGF-β/Smad signaling. Thus, treatment with DCN-MSCs is a potentially novel and efficient therapeutic approach for patients with intractable cirrhosis.