Advances of Blood-brain Barrier Model In Vitro

The special structural unit on the brain's capillaries supplies oxygen and nutrients to the brain, while at the same time forming a restrictive barrier called blood-brain barrier (BBB). The structural unit is mainly composed of a single layer of brain microvascular endothelial cells, surrounding by endothelial cells, as well as the neurons, microglia, and astrocytes, are involved in the formation of the blood-brain barrier. The blood-brain barrier is a selective permeation barrier, most of the central nervous system drug candidates have poor permeability in the blood-brain barrier. The disadvantages of drug screening experiments in laboratory animals are high cost, long cycle, and low accuracy. Besides, directly test in the human body is unethical. But establishing a reliable model of extracorporeal blood-brain barrier can simplify the experimental process, shorten the test period, and make the experimental results easier to determine. Therefore, the establishment of an in vitro BBB model can greatly accelerate the development of central nervous system drugs. The models that have been studied can be divided into three categories: single culture, co-culture, and triple culture. These models range from simple to complex, and more similar to blood-brain barrier in vivo. This article reviews the current blood-brain barrier model, and we expect it can provide new ideas for the design of in vitro BBB models in the future.