Oral Administration of Recombinant Adeno-associated Virus-mediated Bone Morphogenetic Protein-7 Suppresses CCl4-induced Hepatic Fibrosis in Mice

Fibrogenesis and hepatocyte degeneration are the main pathological processes in chronic liver diseases. Transforming growth factor-beta 1 (TGF-beta 1) is the key profibrotic cytokine in hepatic fibrosis. Bone morphogenetic protein-7 (BMP-7) is a potent antagonist of TGF-beta 1 and an antifibrotic factor. In this study, we generated a recombinant adeno-associated virus carrying BMP-7 (AAV-BMP-7) and tested its ability to suppress carbon tetrachloride (CCl4-induced hepatic fibrosis when orally administered to mice. Our results show that the ectopic expression of BMP-7 in gastrointestinal (Cl) mucosa due to the AAV-BMP-7 administration led to the long-term elevation of serum BMP-7 concentrations and resulted in the drastic amelioration of CCl4-induced hepatic fibrosis in BALB/c mice. Immunostaining for alpha-smooth muscle actin (alpha-SMA) and desmin demonstrated that AAV-BMP-7 inhibited the activation of hepatic stellate cells (HSCs) in the fibrotic mouse liver. Moreover, the ectopic expression of BMP-7 promoted hepatocyte proliferation, as confirmed by an increase in the amount of proliferating cell nuclear antigen (PCNA)-positive hepatocytes in the mice that received AAV-BMP-7. Our results clearly indicate that BMP-7 is capable of inhibiting hepatic fibrosis and promoting hepatocyte regeneration. We suggest that oral AAV-BMP-7 could be developed into a safe, simple, and effective therapy for hepatic fibrosis. Received 19 November 2011; accepted 22 February 2012; advance online publication 31 July 2012. doi:10.1038/mt.2012.148