Isolation and in vitro characterization of human dermal microvascular pericytes

Pericytes cover the abluminal surface of capillaries and venules and are thought to play an important role in microvascular regulation and pathology. The purpose of this study was to isolate and characterize human dermal microvascular pericytes (HDMPC), a minor cell type in the skin but a relatively easily obtainable human source of tissue. We developed and compared two procedures that differed in the preselection method. Isolation of dermal microvessel fragments from neonatal foreskins by trypsin digestion was followed by mechanical release of subepidermal tissue, collagenase treatment, and sieving through 100- and 30-microm meshes. After subcultivation, pericytes were preselected either by isolation of outgrowing capillary fragments or by 3G5-coupled magnetic beads. Pericytes were selected finally by cultivation of single cells in endothelial cell-conditioned media. Cultured HDMPC were seen to be large and well spread with irregular edges and prominent stress fibers. They lack contact inhibition, are positive for 3G5 antigen, alpha-smooth muscle actin, and vimentin, and are negative for the endothelial cell marker CD31, diI-acetylated low-density lipoprotein uptake, cytokeratin 5, 6, and 18, and S100 protein. Using both preselection methods, we could establish purified cell cultures of HDMPC. The results of these studies represent the first report of HDMPC isolation.