Differentiation of human umbilical cord mesenchymal stem cells into germ-like cells in mouse seminiferous tubules.

Our previous study demonstrated that human umbilical cord mesenchymal stem cells (HUMSCs) were capable of differentiation into germ cells in vitro. To assess this potential in vivo, HUMSCs were microinjected into the lumen of seminiferous tubules of immunocompetent mice, which were treated with busulfan to destroy endogenous spermatogenesis. Bromodeoxyuridine labeling studies demonstrated that HUMSCs survived in the tubule for at least 120 days, exhibited a round cell shape typical of proliferating or differentiating germ cells, migrated to the basement of the tubule, where proliferating spermatogonia reside and returned to the luminal compartment, where differentiating spermatids and spermatozoa reside.