Comparison between the Regenerative and Therapeutic Impact of BM-MSCs and AD-MSCs Pre-treated with Melatonin on Liver Fibrosis

Background The distinctive feature of liver fibrosis is the progressive replacement of healthy hepatic cells by extracellular matrix protein, which is abundant in collagen I and III with impaired matrix remodelling. The activation of myofibroblastic cells enhances a fibrogenic response of complex interactions of hepatic stellate cells, fibroblasts and inflammatory cells to produce excessive deposition of extracellular protein matrix. This process is activated by multiple fibrogenic mediators and cytokines such as TNF-α and IL-1ß with decrease in the anti-fibrogenic factor NF-ҡß. Mesenchymal stem cells (MSCs) represent a promising therapy for liver fibrosis giving more advanced regenerative influence when cultured with extrinsic or intrinsic proliferative factors, cytokines, anti-oxidants, growth factors, and hormones such as Melatonin (MT). However, previous studies showed conflicted findings concerning the therapeutic effects of adipose (AD) and bone marrow (BM)-MSCs, therefore, the present work aimed to accomplish a comparative and comprehensive study investigating the impact of MT pre-treatment on the immunomodulatory, anti-inflammatory and anti-apoptotic effects of AD and BM-MSCs and to critically analyse whether MT pre-treated both AD-MSCs and BM-MSCs reveal equal or different therapeutic and regenerative potentials in CCl4-injured liver of experimental rat models. Materials and methods Six groups of experimental rats were used with ten rats in each group; group I (control group), group II (CCl4-treated group), group III (CCl4 and BM-MSCs treated group), group IV (CCl4 and MT pre-treated BM-MSCs group), group V (CCl4 and AD-MSCs treated group) and group VI (CCl4 and MT pre-treated AD-MSCs group). Liver function tests, gene expression of inflammatory, fibrogenic, apoptotic and proliferative factors were analysed. Histological and immunohistochemical changes were assessed. Results The present study compared the capability of AD and BM-MSCs, with and without the pre-treatment of MT, to reduce hepatic fibrosis. Both types of MSCs improved hepatocyte function by reducing the serum levels of (ALT), aspartate aminotransferase (AST), alkaline phosphatase (AKP), and total bilirubin (TBIL). In addition, the changes in the hepatocellular architecture including the hepatocytes, liver sinusoids, central veins, portal veins, biliary ducts and hepatic arteries showed decrease hepatocyte injury and cholestasis with reduction of inflammation, apoptosis and necrosis of the hepatic cells together with inhibition of liver tissue fibrosis. These results were augmented by the analysis of the expression of the anti-inflammatory cytokines TNFα and IL-1β, the anti-fibrogenic factor NF-ҡß, the apoptotic factor caspase-3 and the proliferative indicators antigen Ki-67 and proliferating cell nuclear antigen (PCNA). These findings were found statistically significant, with the best results in the rats received AD-MSCs pre-treated with MT, denoting better regenerative and therapeutic effects. Conclusion AD-MSCs, pre-treated with MT, are superior to BM-MSCs due to their better efficacy in improving hepatic fibrosis and promoting the therapeutic and regenerative capability of liver tissue. They represent a very significant tool for future stem cell use in tissue regeneration strategy for the treatment of liver diseases.