Peptide-Guided Nanoparticles Deliver Gene-Silencing Therapy to Reduce Liver Fibrosis by 65% in Mice

Chitosan nanoparticles decorated with a high density of PDGF-β binding peptide and loaded with anti-TGF-β1 siRNA significantly reduced hepatic TGF-β1 levels by approximately 65% and fibronectin levels by approximately 63% in a CCl4-induced liver fibrosis mouse model. Pretreatment with collagenase-loaded nanoparticles (to break down the dense scar tissue barrier) further reduced both markers by an additional ~10%. Histopathological evaluation confirmed reduced portal inflammation, absence of fibroblastic proliferation between hepatocytes, and decreased collagen deposition. The nanoparticles had 92.39% siRNA encapsulation efficiency, a diameter of 103 nm, and showed no organ-specific toxicity at doses up to 120 mg/kg over 4 weeks.

Researchers engineered chitosan nanoparticles (~103 nm diameter) modified with varying densities of PDGF-β receptor binding peptides as a targeting mechanism. The nanoparticles were loaded with anti-TGF-β1 siRNA (92.4% encapsulation efficiency). Safety was tested in healthy mice with biweekly dosing up to 120 mg/kg for 4 weeks. Biodistribution was assessed in both healthy and fibrotic mice. Efficacy was evaluated in a CCl4-induced liver fibrosis mouse model, with and without pretreatment using collagenase-loaded nanoparticles. Outcomes were measured by TGF-β1 and fibronectin levels plus Masson Trichrome histological staining.

Liver fibrosis progresses to cirrhosis and liver failure, and there are currently no approved anti-fibrotic drugs for the liver. The dense scar tissue itself creates a delivery barrier that prevents drugs from reaching the cells driving fibrosis. This study demonstrates a clever two-pronged approach — using peptide targeting to find the right cells and collagenase pretreatment to penetrate the scar tissue barrier — that could open a new therapeutic pathway.

Peptide-targeted nanoparticle delivery systems are an active frontier in treating fibrotic diseases across multiple organs. This study adds to evidence that targeting specific cell receptors with peptide-decorated nanoparticles can overcome the delivery challenges posed by fibrotic tissue. The approach could potentially extend beyond the liver to kidney, lung, or cardiac fibrosis.

This is a preclinical mouse study using a chemical (CCl4) fibrosis model, which may not perfectly replicate human liver fibrosis. The treatment duration was relatively short (4 weeks), and long-term efficacy and safety are unknown. Translation from mouse to human involves significant challenges in dosing, biodistribution, and immune response to nanoparticles. No comparison to existing fibrosis treatments was made.