Markers for human brain pericytes and smooth muscle cells

Brain pericytes and vascular smooth muscle cells (vSMCs) are a critical component of the neurovascular unit and are important in regulating cerebral blood flow and blood-brain barrier integrity. Identification of subtypes of mural cells in tissue and in vitro is important to any study of their function, therefore we identified distinct mural cell morphologies in neurologically normal post-mortem human brain. Further, the distribution of mural cell markers platelet-derived growth factor receptor-beta (PDGFR beta), alpha-smooth muscle actin (alpha SMA), CD13, neural/glial antigen-2 (NG2), CD146 and desmin was examined. We determined that PDGFR beta, NG2, CD13, and CD146 were expressed in capillary-associated pericytes. NG2, and CD13 were also present on vSMCs in large vessels, however abundant CD146 and desmin staining was also detected in vSMCs on large vessels, co-labelling with alpha SMA. To determine whether cultures recapitulated observations from tissue, primary human brain pericytes derived from neurologically normal autopsies were analysed for the presence of pericyte markers by immunocytochemistry, western blotting and qPCR. The proteins observed in brain pericytes in tissue (PDGFR beta, alpha SMA, desmin, CD146, CD13, and NG2) were present in vitro, validating a panel of proteins that can be used to label brain pericytes and vSMCs in tissue and in vitro. Finally, we showed that the proteins CD146 and desmin that are expressed on large vessels in situ, are also selective markers of a smooth muscle cell phenotype in vitro.