Additive Effects of Mesenchymal Stem Cell-Conditioned Medium and Silymarin in Carbon Tetrachloride-Induced Liver Injury in Rats

Liver diseases remain one of the leading global causes of death, with increasing mortality over recent decades. Mesenchymal stem cells-conditioned medium (MSCs-CM), rich in cytokines, growth factors and extracellular vesicles, has shown anti-inflammatory and regenerative potential. This study evaluates the effect of MSCs-CM on carbon tetrachloride (CCl₄)- induced liver toxicity in Wistar rats and explores the combined effect of MSC-CM and silymarin using liver enzyme and antioxidant markers. This experimental animal study was conducted with sixty adults female Wistar rats. Liver toxicity was induced by intraperitoneal carbon tetrachloride (CCl₄, 1 ml/kg) thrice weekly for 28 days. Rats were randomly divided into six groups (n=10 each): normal control, CCl₄-only toxic control, CCl₄ + low-dose MSCs-CM, CCl₄ + high-dose MSCs-CM, CCl₄ + silymarin (100 mg/kg orally) and CCl₄ + silymarin + high-dose MSCs-CM. Low and high doses of MSC-CM (1 ml and 2 ml, respectively) were administered intraperitoneally over 4 weeks after hepatotoxicity induction. Therapeutic effects were evaluated by liver enzymes, antioxidant markers and histopathology. Treatment with low-dose MSCs-CM (Group 3) and high-dose MSCs-CM (Group 4) significantly reduced liver enzymes compared to the toxic control (p < 0.05). Silymarin (Group 5) and the combination of silymarin with MSCs-CM (Group 6) further reduced levels with group 6 showing the greatest reduction. Histological analysis of the normal control group showed intact hepatic architecture. CCl₄-treated rats exhibited periportal mononuclear cell infiltration and sinusoidal dilation. Low-dose MSC-CM treatment led to mild perivenular inflammation while high-dose MSC-CM showed reduced inflammation and improved hepatocyte structure. Silymarin-treated rats displayed moderate sinusoidal dilation. Notably, combined treatment with high-dose MSC-CM and silymarin restored near-normal liver architecture. MSCs-CM showed modest anti-hepatotoxic effects in CCl₄- induced model, improving liver enzymes and histology. These findings suggest its potential as a supportive therapy, especially in combination with other agents.