The Molecular Constituents of the Blood–Brain Barrier

The blood–brain barrier (BBB) maintains the optimal microenvironment in the central nervous system (CNS) for proper brain function. The BBB comprises specialized CNS endothelial cells with fundamental molecular properties essential for the function and integrity of the BBB. The restrictive nature of the BBB hinders the delivery of therapeutics for many neurological disorders. In addition, recent evidence shows that BBB dysfunction can precede or hasten the progression of several neurological diseases. Despite the physiological significance of the BBB in health and disease, major discoveries of the molecular regulators of BBB formation and function have occurred only recently. This review highlights recent findings describing the molecular determinants and core cellular pathways that confer BBB properties on CNS endothelial cells.

TrendsThe BBB comprises CNS endothelial cells that display specialized molecular properties essential for BBB function and integrity.These molecular BBB properties are not intrinsic to CNS endothelial cells but have to be induced by the environment.The formation, function, and maintenance of the BBB require functional interaction between CNS endothelial cells and NVUs.Advances in gene profiling and cell-type purification methods have progressed the identification of the molecular mediators and core cellular pathways involved in BBB function and integrity.A comprehensive understanding of the key molecules and cellular pathways involved in BBB function would offer novel strategies for CNS therapeutics.