In Vitro Blood–Brain Barrier Studies

The blood–brain barrier (BBB) is an important anatomical structure required for maintaining homeostasis between vasculature and the brain. The regular function of the BBB is required for the exchange of biomolecules, maintenance of the ion balance, delivery of nutrients, and avoidance of the transport of toxic molecules. The difficulty for molecules to pass the BBB is a serious obstacle in the development of CNS targeting drugs. It is also challenging to estimate the permeability of molecules across the BBB in a fast, repeatable, and cost-effective manner. To determine the potential of small molecules to cross the BBB, a variety of techniques and models, spanning from artificial membranes, cell cultures, and animal models have been used as prediction tools in drug discovery. In vitro models are useful and simple tools that may be used to complement and precede animal and human investigations. They are suitable for preliminary research and for testing the interaction between this critical barrier and potential drug candidates (toxicity, permeability, interaction with efflux transporters). This chapter aims to provide a complete overview on the existing in vitro BBB models along with their applications in drug discovery and disease modeling.