Sex steroid-mediated reprogramming of vascular smooth muscle cells to stem cells and neurons: possible utilization of sex steroid combinations for regenerative treatment without utilization of in vitro developed stem cells.

Previous work from our laboratory demonstrated that sex steroid combinations, but not individual sex steroids alone, cause transdifferentiation of ovarian epithelial cells--ovarian surface epithelium (OSE) and follicular granulosa cells--into neural stem cells (NSC) and differentiating neurons. In the present study we have chosen primary culture of human vascular smooth muscle cells (SMC), a non-epithelial mesenchymal cells in order to test them as a control cell type regarding their morphology and expression of NSC and neuronal markers. Utilization of estradiol (E2), progesterone (PG) or testosterone (TS) alone did not induce the emergence of neurons from the vascular SMC. However, the treatment with sex steroid combinations (PG + TS or E2 + PG + TS) caused transdifferentiation into neural/neuronal type cells. By immunohistochemistry, these cells exhibited strong expression of stem cell markers and neural/neuronal glycoconjugates SSEA-1, SSEA-4, Thy-1, NeuN and NCAM. In the Neurobasal/B27 medium both, the OSE and vascular SMC also transdifferentiated into neuronal cells. Western blot analysis has shown significant increase of NeuN 48-kDa species after E2 + PG or PG + TS treatment. Secretion of E2 increased significantly in vascular SMC cultures pretreated with TS, PG or TS + PG. Unlike OSE cells, the vascular SMC accompany as pericytes all vessels, including CNS microvasculature. We also observed that sex steroid combinations could produce SMC stem type cells which differentiated within a few days back to mature vascular SMC. This is of potential interest for the vascular regenerative medicine. Altogether, our observations suggest that sex steroid combinations could induce in vivo improvement of neurodegenerative, traumatic and ischemic neurological disorders and vascular diseases via their effect on resident pluripotent vascular SMC, i.e., without a need of in vitro developed stem cells.