Reactive oxygen species-responsive micelles targeting activated hepatic stellate cells for treating liver fibrosis

Effectively mitigating the progression of liver fibrosis is crucial for preventing the advancement of chronic liver diseases to end-stage cirrhosis and hepatocellular carcinoma. Targeted delivery to hepatic stellate cells (HSCs) has demonstrated promising potential in the treatment of liver fibrosis. However, the development of HSC-targeted drug delivery systems faces significant challenges due to the inefficiency of nano-delivery systems in achieving adequate cellular entry and the limited controllability of drug release. Here, we designed a targeted penetrating peptide, cRGDfK-R6, which comprises the integrin αvβ3-targeting peptide segment cRGDfK and the cell-penetrating peptide R6, conjugated to micelles that are cleavable in response to high levels of reactive oxygen species (ROS) within activated HSCs (aHSCs), aiming to achieve sequential delivery that penetrates the cell membrane and specifically releases the payload upon targeting aHSCs. We synthesized an amphiphilic block copolymer linked by thioketal (TK) and successfully conjugated it with cRGDfK-R6, subsequently self-assembling with betulin (Bt) to form stable and biocompatible Bt/cRGDfK-R6-PPMs^TK. Compared with micelles lacking cell-penetrating action or non-ROS-responsiveness, Bt/cRGDfK-R6-PPMs^TK demonstrated enhanced drug accumulation in aHSCs and anti-fibrotic activity both in vitro and in fibrotic mouse models. In summary, this work indicates that Bt/cRGDfK-R6-PPMs^TK provides an efficient and precise innovative platform for drug delivery to aHSCs in treating liver fibrosis.