Abstract
A novel category of microengineered laboratory models called "organs-on-chips" combines some of the best aspects of existing in vivo and in vitro models. The development of blood-brain barrier (BBB) organ-on-chip models has advanced, but there are still obstacles to overcome, which are outlined in this paper. Specialized endothelial cells create the BBB, which divides brain tissue from blood. It offers equilibrium for ideal neuronal activity and shields the brain from potentially hazardous blood-borne substances. Drug development and biological research both benefit from studying BBB function and malfunction. Real-time analysis of (human) cells in an artificial physiological microenvironment is made possible by microfluidic BBBs-on-chips, which, for instance, include tiny geometries, fluid flow, and sensors. The possibility for more accurate microenvironments and the investigation of organ-level functioning is already demonstrated by BBBs-on-chips examples in the literature. The current lack of consistent measurement of variables like barrier permeability and shear stress is a major obstacle in the field of BBB-on-chip development. This restricts the ability to compare the effectiveness of certain BBB-on-chip models directly to that of other models, both new and old. We make suggestions for more model characterisation standards and draw the conclusion that the quickly developing area of BBB-on-chip models has tremendous promise for additional research into BBB biology and medication development.