Ghrelin promotes neural differentiation of adipose tissue-derived mesenchymal stem cell via AKT/mTOR and -catenin signaling pathways

Adipose tissue-derived mesenchymal stem cells (ADSCs) are multipotent cells that can differentiate into various cell types. This study aimed to investigate the effect of ghrelin on the neural differentiation of rat ADSCs and underlying molecular mechanisms. Rat ADSCs were isolated and third-passage ADSCs were used in this study. The isolated ADSCs were characterized by flow cytometry analysis for MSCs' surface expression markers as evidenced by positive for CD90, CD44, and CD29 and negative for CD34, CD45, and CD11b/2f/c. The multilineage differentiation of ADSCs was confirmed by adipogenic, osteogenic, and neural differentiation. After induction of neurogenesis, the differentiated cells were identified by development of neuron-like morphology and expression of neural markers including glial fibrillary acidic protein, Nestin, MAP2, and beta-Tubulin III using immunofluorescence and western blot. Ghrelin concentration dependently elevated the proportion of neural-like cells and branching dendrites, as well as upregulated the expression of neural markers. Further, the expression of nuclear beta-catenin, p-GSK-3 beta, p-AKT, and p-mTOR was increased by ghrelin, indicating an activation of beta-catenin and AKT/mTOR signaling after the ghrelin treatment. Importantly, inhibition of beta-catenin or AKT/mTOR signaling suppressed ghrelin-induced neurogenesis. Therefore, we demonstrate that ghrelin promotes neural differentiation of ADSCs through the activation of beta-catenin and AKT/mTOR signaling pathways.