Development, maintenance and disruption of the blood-brain barrier

The blood-brain barrier (BBB) has a key role in maintaining brain homeostasis and, thus, brain function. This Review outlines recent advances in understanding the development and maintenance of the BBB and the contribution of BBB disruption to various neurological diseases. It also discusses how such insights might be used to design new therapeutic strategies for BBB repair. The interface between the blood circulation and the neural tissue features unique characteristics that are encompassed by the term 'blood-brain barrier' (BBB). The main functions of this barrier, namely maintenance of brain homeostasis, regulation of influx and efflux transport, and protection from harm, are determined by its specialized multicellular structure. Every constituent cell type makes an indispensable contribution to the BBB's integrity. But if one member of the BBB fails, and as a result the barrier breaks down, there can be dramatic consequences and neuroinflammation and neurodegeneration can occur. In this Review, we highlight recently gained mechanistic insights into the development and maintenance of the BBB. We then discuss how BBB disruption can cause or contribute to neurological disease. Finally, we examine how this knowledge can be used to explore new possibilities for BBB repair.