The Blood–Brain Barrier: An Introduction to Its Structure and Function

Abstract

The blood-brain barrier (BBB) formed by the brains microvascular system is impermeable for most therapeutically used compounds and overcoming this barrier remains to be one of the big challenges in modern medicine. It is composed of highly specialized endothelial cells, which are surrounded by pericytes and a basal membrane. Together with nearby astrocytes and neurons they constitute the so-called neurovascular unit, which restricts substance transfer from blood to brain and vice versa and maintains the cerebral ion homeostasis. Chapters of this book describe the discovery of the BBB, its evolutionary development as well as the cellular and molecular mechanisms, which underlay its structure and function in health and disease. The organization of tight junctional complexes or specific transport processes at the BBB will be addressed as well as methods to investigate BBB function in vitro and in vivo. Changes in the barrier function under several diseases conditions such as stroke or inflammation will be discussed as well as approaches to overcome the barrier by colloidal carriers or ultrasound.

Liposomal-Based Formulations: A Path from Basic Research to Temozolomide Delivery Inside Glioblastoma Tissue

“…For instance, orally administered liposomes are very sensitive to gastrointestinal conditions, i.e., gastric acid, bile salts, and lipases [34], while the intravenous delivery of liposomes is associated with serum protein adsorption, which results in liposome removal by RES, mainly in the liver [35]. When brain is the target of liposomal drug delivery systems, the situation becomes more challenging due to the BBB, formed by the brain microvascular system [36], which separates the bloodstream from the CNS, as well as the P-glycoprotein, the most important efflux transporter associated to the failure of various therapies applied to treat CNS diseases [37]. In addition, nanosized liposomes (<100 nm) tend to attract each other to reduce their surface tension, which causes loss of payload or unwanted mixing [38,39].…”