Microfluidic strategies for the blood-brain barrier construction and assessment

With growing interest in neurological diseases, treatment of neurodegenerative diseases such as Alzheimer's disease is crucial. However, drug development for nervous system diseases is still limited due to its inadequate permeation across the blood-brain barrier (BBB). The inherent complexity of brain structures prevents potential drugs reaching the cerebral targets, thereby limiting their efficacy. The microfluidic blood-brain barrier (BBB) models, evolved from tissue engineering and microfabrication technology, represent a technological breakthrough to facilitate biomedical research and drug discovery by recapitulating the main structural and functional complexity of the human BBB in vitro. In this review, key parameters determining the physiologically related microfluidic BBB models are presented. The current techniques for evaluating the integrity of the in vitro BBB models are highlighted, including testing for the presence of tight junction proteins, measurement of trans-epithelial electric resistance (TEER) and permeability of specific substances. Future opportunities and perspectives for developing the microfluidic BBB models to accelerate neuroscience and pharmaceutical research are also discussed.