Explant Outgrowth, Propagation and Characterization of Human Pericytes

P>Objective: Pericytes are critical cellular components of the microvasculature that play a major role in vascular development and pathologies, yet their study has been hindered by lack of a standardized method for their isolation and growth. Here we report a method for culturing human pericytes from a readily available tissue source, placenta, and provide a thorough characterization of resultant cell populations. Methods: We developed an optimized protocol for obtaining pericytes by outgrowth from microvessel fragments recovered after enzymatic digestion of human placental tissue. We characterized outgrowth populations by immunostaining, by gene expression analysis, and by functional evaluation of cells implanted in vivo. Results: Our approach yields human pericytes that may be serially expanded in culture and that uniformly express the cellular markers NG2, CD90, CD146, alpha-SMA, and PDGFR-beta, but lack markers of smooth muscle cells, endothelial cells, and leukocytes. When co-implanted with human endothelial cells into C.B-17 SCID/bg mice, human pericytes invest and stabilize developing human endothelial cell-lined microvessels. Conclusions: We conclude that our method for culturing pericytes from human placenta results in the expansion of functional pericytes that may be used to study a variety of questions related to vascular biology.