Pericyte signaling in the neurovascular unit.

Brain pericytes are intimately associated with capillary endothelial cells, separated only by basement membrane. Pericyte research has been hampered by absence of pericyte-specific immunochemical markers. The vast array of pericyte functions include contractility, immunologic, migratory, and angiogenic. Pericytes have stem cell potential, contribute to the integrity of the blood-brain barrier, and have a regulatory role for hemostasis in the brain. Improvement in pericyte identification is likely to lead to marked increase in appreciation of the role of pericytes in the neurovascular unit.