Testosterone stimulates proliferation and preserves stemness of human adult mesenchymal stem cells and endothelial progenitor cells.

Human adult stem and progenitor cells are promising cell types widely studied for their clinical benefits. A reduced number of stem cells present in the human body are associated with numerous dysfunctions. Since androgens have a profound effect on different cell types, we questioned whether testosterone (T), one of the main androgens, influence and are involved in the proliferation of stem cells and÷or affect their stemness potential. Isolated mesenchymal stem cells (MSCs) and endothelial progenitor cells (EPCs) were cultured and then stimulated with different concentration of testosterone (10-100 nM). The cellular proliferation rate, adhesion, and viability were measured in real-time using xCELLigence system and DNA-cell proliferation assay. The immunophenotype of the stimulated cells versus non-stimulated cells was determined by flow cytometry. The maximal effect on MSCs and EPCs proliferation was obtained at 40 nM testosterone; this concentration was used in further experiments. The cellular index measured in real-time by impedance-based dynamic measurements revealed that 40 nM testosterone had a proliferative effect on both MSCs and EPCs, having a proliferative index of ˜50% above the control (non-stimulated) cells. Furthermore, flow cytometry assay indicated that testosterone stimulation did not alter the phenotype of MSCs and EPCs, both cell types preserving the expression of the characteristic surface markers. Testosterone stimulation increases the proliferation and preserves stemness of MSCs and EPCs suggesting that, besides other factors, the hormone may engineer these cells and increase their therapeutic potential.