Science Advances.The blood-brain barrier consists of a blood vessel lining of endothelial cells that keeps foreign molecules from escaping from the blood vessels and entering the brain fluid where they could affect neurons and other brain cells.
The barrier is highly selective about the non-native molecules it allows into the brain, and that includes therapeutic substances.While small molecule or macromolecule drugs have the potential to treat brain tumors, infections, neurogenerative disorders, and stroke, the presence of the blood-brain barrier makes it difficult for doctors to administer such therapies.Scientists have attempted various workarounds, and none have proven sufficiently safe or effective.