Short-Term Interaction with Endothelial Cells Enhances Angiogenic Activity of Growth-Arrested Mesenchymal Stromal Cells In Vitro and In Ovo.

We compared angiogenic effects of conditioned medium from mesenchymal stromal cell (MSC) monoculture and co-culture of MSC with endothelial cells (EC). Conditioned medium from 24-h EC-MSC co-cultures significantly stimulated the proliferation and migration of EC in monoculture and growth of the vascular network of the chorioallantoic membrane of the quail embryo in ovo in comparison with the conditioned medium from MSC monoculture. Conditioned medium from the co-culture contained increased levels of angiogenic factors (FGF-2, MCP-1, PDGF-AB/BB, IL-6, IL-8, etc.), which could explain the revealed effects. We hypothesized that a similar mechanism of EC-mediated enhancement of functional activity of MSC could be involved in reparative angiogenesis in the target tissues in vivo.