The Role of Adult Stem Cells on Microvascular Tube Stabilization

In the recent years, different studies have established a link between adult mesenchymal stem cells (MSCs) and perivascular cells like pericytes that envelop the vascular tubes. This link was validated mainly through shared marker signatures and raised the hypothesis that all MSCs are pericytes. A controversy however remains on whether there are functions specific only for one of the cell types. In this communication, we report the specific role of pericytes in vascular tube stabilization that is not shared with MSCs. An experimental model was introduced for the induction of endothelial cell (EC) tubulogenesis after 24 hours of incubation on micropatterned polymer surfaces. Pericytes or MSCs were added separately to this system in order to evaluate their effect the tubular stabilization. In the absence of additional cells or in the presence only of MSCs the tubular structures were lost after 36h. Adding only pericytes however stabilized the EC vasculogenic tubes. Furthermore, only pericytes, but not MSCs, were able to migrate through a mimetic basement membrane and could interact with the ECs to stabilize the lumen structures. We thus suggest that pericytes have specific cell functions of potential major importance in vascular and bone tissue regeneration. Their use in tissue engineering will thus become critical.