Abstract
Pericytes play critical roles in the development, maturation and remodeling of blood vessels, and in the central nervous system (CNS), evidence suggests that pericytes also regulate blood flow and form an integral part of the blood-brain barrier. The study of this important cell type has been hampered by the lack of any pericyte-specific marker and by the difficulty of culturing pericytes in adequate numbers to high purity. Here we present a novel yet simple approach to isolate and culture large numbers of pericytes from the mouse CNS that nevertheless leads to very pure pericyte cultures. In our method, vascular cells obtained from adult mice brains are cultured initially under conditions optimized for endothelial cells, but after two passages switched to a medium optimized for pericyte growth. After growing the cells for 1-2 additional passages we obtained a largely homogeneous population of cells that expressed the pericyte markers NG2, PDGFβ-receptor, and CD146, but were negative for markers of endothelial cells (CD31), microglia (Mac-1) and astrocytes (GFAP). Under these conditions, pericytes could be grown to high passage number, and were maintained highly pure and largely undifferentiated, as determined by antigen expression profile and low levels of α-SMA expression, a marker of pericyte differentiation. Furthermore, switching the cells from pericyte medium into DMEM containing 10% FBS promoted α-SMA expression, demonstrating that high passage pericytes could still differentiate. Thus, we provide an alternative approach to the culture of CNS pericytes that is easy to establish and provides large numbers of highly pure pericytes for extended periods of time. This system should provide others working in the pericyte field with a useful additional tool to study the behavior of this fascinating cell type.