by Ryan Mateja, PhD
The blood-brain barrier (BBB) is a highly selective semipermeable membrane that plays a fundamental role in protecting and maintaining homeostasis of the brain. It is mainly composed of densely packed endothelial cells connected by tight junctions which protect the brain from invading pathogens and neurotoxic molecules while simultaneously ensuring the brain gets adequate nutrients.
While being highly complex and selective is instrumental to the protection provided by the BBB, it also creates a challenge to neuroscientists trying to discover and create therapeutic agents to treat central nervous system (CNS) pathologies. Because of this, CNS medicines have a high risk of failure and as a result disorders of the CNS represent one of the largest areas of unsatisfied medical needs.1
In the USA, the cost of discovery and development of new compounds can total $100 million dollars to reach phase I clinical trials and $1 billion dollars to bring your product to the patient. Despite this high cost, 95-97% of brain-directed pharmaceuticals never make it to the consumer since most are incapable of crossing the BBB in vivo.2