Hypoxia-Enhanced Wharton's Jelly Mesenchymal Stem Cell Therapy for Liver Fibrosis: A Comparative Study in a Rat Model

Liver fibrosis is a progressive disease that can lead to cirrhosis and liver failure, with limited treatment options. Wharton's jelly-derived MSCs (WJ-MSCs) have immunomodulatory and antifibrotic potential. Hypoxia preconditioning enhances MSC survival and paracrine activity, but its effects in liver fibrosis remain unclear. This study compares hypoxia and normoxia WJ-MSCs in a CCl₄-induced liver fibrosis rat model. Sprague-Dawley rats received chronic CCl₄ to induce fibrosis. At Week 8, normoxia or hypoxia WJ-MSCs were injected via the portal vein. Liver function was assessed using biochemical markers (ALT, AST, T-Bil, albumin), PET/MR imaging, and qPCR for IL-1β and IL-6. Fibrosis regression was evaluated via ultrasound, histology, and collagen quantification. Regeneration was analyzed through Ki67 immunostaining and qPCR for Ki67 and HGF. MSC engraftment was determined by hNA immunohistochemistry. Both normoxia and hypoxia WJ-MSCs improved liver function, with hypoxia WJ-MSCs showing greater AST and T-Bil reductions. PET/MR imaging demonstrated superior metabolic recovery in the hypoxia group, with greater ¹⁸F-FDG uptake reduction. Histological analysis confirmed more significant fibrosis regression and collagen reduction in the hypoxia group. Gene expression analysis showed stronger suppression of TGF-β, α-SMA, and collagen I. Liver regeneration markers Ki67 and HGF were significantly upregulated with a greater HGF increase in the hypoxia group. Additionally, hypoxia WJ-MSCs exhibited higher engraftment and reduced pulmonary entrapment, indicating improved liver homing. Both normoxia and hypoxia WJ-MSCs improved liver fibrosis, but hypoxia preconditioning further enhanced liver function, fibrosis regression, and metabolic recovery, supporting its therapeutic superiority.