Placental mesenchymal stromal cells derived from blood vessels or avascular tissues: what is the better choice to support endothelial cell function?

Mesenchymal stromal cells (MSCs) are promising tools for therapeutic revascularization of ischemic tissues and for support of vessel formation in engineered tissue constructs. Recently, we could show that avascular-derived MSCs from placental amnion release soluble factors that exhibit survival-enhancing effects on endothelial cells (ECs). We hypothesize that MSCs derived from placental blood vessels might have even more potent angiogenic effects. Therefore, we isolated and characterized MSCs from placental chorionic blood vessels (bv-MSCs) and tested their angiogenic potential in comparison to amnion-derived avascular MSCs (av-MSCs). bv-MSCs express a very similar surface marker profile compared with av-MSCs and could be differentiated toward the adipogenic and osteogenic lineages. bv-MSCs exert immunosuppressive properties on peripheral blood mononuclear cells, suggesting that they are suitable for cell transplantation settings. Conditioned medium (Cdm) from av-MSCs and bv-MSCs significantly enhanced EC viability, whereas only Cdm from bv-MSCs significantly increased EC migration and network formation (Matrigel assay). Angiogenesis array analysis of av- and bv-MSC-Cdm revealed a similar secretion pattern of angiogenic factors, including angiogenin, interleukins-6 and -8, and tissue inhibitors of matrix metalloproteinase-1 and 2. Enzyme-linked immunosorbent assay analysis showed that, in contrast to av-MSCs, bv-MSCs secreted vascular endothelial growth factor. In direct coculture with bv-MSCs, ECs showed a significantly increased formation of vessel-like structures compared with av-MSCs. With regard to therapeutic treatment, bv-MSCs and particularly their Cdm might be valuable to stimulate angiogenesis especially in ischemic tissues. av-MSCs and their Cdm could be beneficial in conditions when it is required to promote the survival and stabilization of blood vessels without the risk of unmeant angiogenesis.