Blood brain barrier-on-a-chip to model neurological diseases

The blood-brain barrier (BBB) is a vital and unique multi-dimensional selective barrier that helps maintain brain homeostasis. BBB is a complex and dynamic structure responsible for regulating the transport of ions and molecules. BBB contains several transporter proteins and tight junctions (TJs) that control the passage of nutrients, while protecting the brain from hazardous toxins and pathogens. Neurological diseases are the primary cause of disability and are considered the second-largest cause of death. BBB dysfunction reduce blood flow and will also permit the entry of toxic substances, and microbial agents in to the brain. This impairment of BBB has been associated with various neurodegenerative diseases. In vitro models that can provide an accurate and deep understanding of neurological disease progression and drug discovery are excellent options.Advancement in microfluidic in vitro models opened new opportunities to study human cell behaviour relative to physiological importance.The limitation of both static transwell and conventional in vitro models was addressed by developing a microfluidic BBB. The microfluidic system showed a close resemblance to the BBB in vivo. The neuronal transport processes and neurogenesis mechanism was well understood with simple neuronal networks. More complex three-dimensional models with multiple cell types, such as Organ on-chip systems, enabled a new platform for a better understanding of the disease and mimicking the physiological conditions. The structure of the blood-brain barrier, conventional models used to model BBB, recent developments in the BBB model using microfluidic technology and the relevance of microfluidic technology in neurological disease modeling is portrayed through this review.