Ultrasound-Responsive Dual-Prodrug Nanoassembly for "Fenestrae-Restoration Strategy" in Liver Fibrosis Therapy.

Liver fibrosis is a serious yet reversible intermediate stage in the progression of liver disease, which can ultimately advance to cirrhosis and hepatocellular carcinoma. Targeted and selective inhibition of activated hepatic stellate cells (aHSCs) has emerged as a promising therapeutic strategy for the treatment of liver fibrosis. However, the capillarization of liver sinusoidal endothelial cells (LSECs) characterized by the loss of fenestrae and continuous formation of basement membrane presents a significant barrier to effective delivery of anti-fibrotic agents. In this study, we propose a novel "fenestrae-restoration strategy" employing ultrasound-responsive polymeric dual prodrug nanoassembly (PMS) co-loaded with nitric oxide prodrug (mSNO) and poly-metformin (PMet). PMS is engineered for controllable, ultrasound-triggered release of nitric oxide from mSNO, which activates soluble guanylate cyclase. This results in upregulation of intracellular cyclic guanosine monophosphate that facilitates the reversal of LSECs capillarization, restoring fenestrae and enhancing endothelial permeability. This restoration enables PMS to traverse the hepatic sinusoidal barrier, followed by accumulation in fibrotic tissue, where PMet is internalized by aHSCs. In lysosomes, metformin released from PMet ultimately inhibits aHSCs proliferation and migration via the AMPK-mTOR pathway deregulation. The therapeutic efficacy and underlying mechanisms of "fenestrae-restoring strategy" were comprehensively validated in preclinical CCl(4)-induced murine model of liver fibrosis. These findings provide interesting insights into the combination therapy of liver fibrosis and paves new avenues for future development of smart therapeutic modalities utilizing stimuli-responsive biosafe nanotherapeutics.