Flk-1+Sca-1- mesenchymal stem cells: functional characteristics in vitro and regenerative capacity in vivo

Objectives: Mesenchymal stem cells (MSCs) represent a powerful tool in regenerative medicine because of their differentiation and migration capacities. We aimed to investigate the possibility of Flk-1(+)Sca-1(-) mesenchymal stem cells (Flk-1(+)Sca-1(-) MSCs) transplantation to repair erectile function in patients suffering from diabetes mellitus (DM)-associated erectile dysfunction (ED). Methods: In this study, we isolated Flk-1(+)Sca-1(-) MSCs from bone marrow (bMSCs). Then, newborn male rats were intraperitoneally injected with 5-ethynyl-2-deoxyuridine for the purpose of tracking endogenous Flk-1(+)Sca-1(-) MSCs. Eight weeks later, 8 of these rats were randomly chosen to serve as normal control (N group). The remaining rats were injected intraperitoneally with 60 mg/kg of streptozotocin (STZ) to induce DM. Eight of these rats were randomly chosen to serve as DM control (DM group) while another 8 rats were subject to Flk-1(+)Sca-1(-) MSCs treatment (DM+MSC group). All rats were evaluated for erectile function by intracavernous pressure (ICP) measurement. Afterward, their penile tissues were examined by histology. Results: Flk-1(+)Sca-1(-) MSCs could differentiate into skeletal muscle cells and endothelial cells in vivo and in vitro. Engrafted Flk-1(+)Sca-1(-) MSCs were shown to home to injured muscle, participate in myofibers repair and could partially reconstitute the sarcolemmal expression of myocardin and ameliorate the level of related specific pathological markers. Conclusion: Flk-1(+)Sca-1(-) MSCs could be used in the treatment erectile function in diabetes mellitus associated erectile dysfunction by promoting regeneration of nNOS-positive nerves, endothelium, and smooth muscle in the penis.