The Chemical Inhibitory Effect of G9a Enzyme on Decrease of Proliferative Potential and Increase of the Adipogenic Propensity of Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) have unique properteis such as immunomodulatory function, secretion of cell survival factors, and the potential of bone , cartilage, and fat differentiation. All of the cellular processes including differentiation, proliferation, aging, and cell death are directly or indirectly regulated by epigenetic mechanisms such as histone methylation. G9a histone methyltransferase is one of the most important enzymes controlling cell behaviors. MSCs were isolated from rat bone marrow (BM-MSCs) and cultured in vitro. Bone marrow-derived MSCs (BM-MSCs) were treated with different doses of A366 (a specific G9a inhibtior) at the passages 1-3 of the primary culture. Then the proliferative capacity of BM-MSCs was analyzed using flowcytometry, assessment of the cell population doubling time, and studying the cell-cycle profile. The rate of adipogenic differentiation of A366-treated BM-MSCs was evaluated using oil red staining and fat gene expression analysis. Assessment of the PDT of BM-MSCs and cell-cycle profile showed that inhibition of G9a using low concentrations of A366 didn’t have any significant effect on BM-MSCs proliferative potential. However, the high doses of A366 increased the PDT and induced cell-cycle arrest. Moreover, A366 increased the adipogenic potential of BM-MSCs. Epigenetic regulators such as A366 that have been suggested for controlling cancers can affect BM-MSCs proliferative and differentiation behaviors. These regulators might also be used as a strategy for a more efficient proliferation and differentiation of MSCs to be used in cell therapy, tissue engineering, regeneration and tissue homeostasis.