Blood-Brain Barrier: Structure, Function, and Implications for Disease and Therapy

The Blood-Brain Barrier (BBB) is a crucial physiological feature that protects the Central Nervous System (CNS) from potentially harmful substances in the bloodstream while maintaining a stable environment necessary for proper neural function. This selective permeability barrier is formed by specialized endothelial cells, tight junctions, and a supportive network of astrocytes and pericytes. The BBB’s role in regulating the passage of ions, molecules, and cells between the blood and brain is essential for maintaining homeostasis and protecting the brain from toxins, pathogens, and fluctuations in blood composition. However, this protective barrier also poses significant challenges for the delivery of therapeutic agents to the brain, particularly in the context of neurological diseases such as brain cancer, Alzheimer’s disease, and multiple sclerosis. This article provides a comprehensive overview of the structure and function of the BBB, its role in neurological health and disease, and current and emerging strategies for overcoming its limitations in drug delivery.