Ph-responsive polymersomes for matrix metalloproteinase-1 delivery as a promising therapeutic strategy for the treatment of liver fibrosis

Abstract

Background & Aims: Liver fibrosis is a growing health problem affecting millions of people worldwide. Chronic liver injury leads to the formation of scar tissue due to the excessive accumulation of extracellular matrix, mainly collagen-I and -III produced by activated hepatic stellate cells (HSCs). Currently, there are no therapies available for liver fibrosis. Matrix metalloproteinase-1 (MMP-1) is an enzyme that degrades the scar tissue by degrading collagen-I and -III favoring fibrolysis. We hypothesized liver-specific delivery of MMP-1 to degrade collagen as a promising approach for the treatment of liver fibrosis. Using state-of-the-art technologies, we synthesized innovative pH-responsive smart MMPsomes with the MMP1 decorated on the polymersome surface. Finally, we investigated the therapeutic efficacy of MMP1 and MMPsomes on human HSCs in vitro and on liver fibrosis mouse models in vivo, and ex vivo on fibrotic mouse livers. Methods: Polymersomes (Psomes) were fabricated using the pH switch method and MMP-1 post-loading at pH 5-6 was performed to increase the interaction between MMP-1 and the Psome membrane. Physiochemical analysis and enzymatic assays were performed to characterize the attachment and functionalization of enzyme on the Psomes. In vitro studies were performed on TGF-β activated human HSCs to evaluate the effects of MMP1 and MMPsomes on the cell viability, functionality and the gene and protein expression of collagen and HSCs activation marker α-SMA. Finally, the efficacy of MMP-1 and MMPsomes was tested in vivo and ex vivo on CCl4-induced liver fibrosis mouse models Results: Decoration of MMP-1 on the surface of the polymersome was successfully established with an affinity of 30%, without inhibition of function. Synthesized MMPsomes showed favorable size (~180nm at pH 6 and ~145 nm at pH 8) and charge (positive at pH 6 and negative at pH 8). MMP-1 and more significantly MMPsomes showed dose-dependent inhibition of collagen-I, -III and α-SMA gene expression, and collagen-I protein expression in TGF-β activated human HSCs with no significant effects on cell viability. The studies on CCl4-induced liver fibrosis mouse models have been performed, showed promising preliminary results with no in vivo toxicity however still under investigation. Conclusions: In conclusion, we present an innovative approach of MMP-1 delivery for the treatment of liver fibrosis.