An Overview of the Blood-Brain Barrier

Abstract

The blood-brain barrier (BBB) is a highly specialized structure formed by a tight monolayer of brain endothelial cells, which maintain bloodstream cells, neurotoxic compounds, and microorganims outside of the central nervous system (CNS). This barrier has also the ability to orchestrate the flow of some solutes from in and out of the brain. In addition, the BBB constitutes a key component of the neurovascular unit (NVU). The NVU is a functional unit composed of a complex cellular system formed by neurons, interneurons, astrocytic endfeet, microglia, oligodendrocytes, basal lamina covered with smooth muscular cells and pericytes, endothelial cells and extracellular matrix, and circulating blood components. The NVU unit reacts in response to physiological stimuli facilitating the activity-dependent regulation of vascular permeability, regulating the cerebral blood flow, and activating the neuroimmune response to maintain CNS homeostasis. Thus, the NVU facilitates the cross talk between the CNS and the periphery through the BBB. The BBB is organized to prevent undesirable substances from entering the brain while allowing access to necessary compounds. In consequence of its structure, the BBB is an impediment for drug delivery into the CNS and experimental protocols are being investigated to selectively modulate the BBB for delivery of therapeutic drugs to treat neurological diseases. As a consequence of pathological changes experienced in neurological diseases such as Alzheimer’s disease, meningitis, multiple sclerosis, malaria, Parkinson’s disease, stroke, and septic encephalopathy, the BBB loses some of its properties that contribute to exacerbate disease progression. Understanding the mechanisms operating at the BBB level may help to decrease the development of neurological diseases and improve the design of new strategies that may facilitate the delivery of therapeutics drugs. The BBB Methods and Protocols book is focused on experimental research with relevant models to study the physiology, biochemistry, and molecular biology of the BBB. This book may present a greater relevance to understand several important questions in the field of neurosciences.