Human iPSC-derived brain endothelial microvessels in a multi-well format enable permeability screens of anti-inflammatory drugs

Optimizing drug candidates for blood-brain barrier (BBB) penetration in humans remains one of the key challenges and many devastating brain diseases including neurodegenerative diseases still do not have adequate treatments. So far, it has been difficult to establish state-of-the-art human stem cell derived in vitro models that mimic physiological barrier properties including a 3D microvasculature in a format that is scalable enough to screen drugs for BBB penetration in early drug development phases. To address this challenge, we established human induced pluripotent stem cell (iPSC)-derived brain endothelial microvessels in a standardized and scalable multi-well plate format. iPSC-derived brain microvascular endothelial cells (BMECs) were supplemented with primary cell conditioned media and grew to intact microvessels in 10 days of culturing. Produced microvessels show a typical BBB phenotype including endothelial protein expression, tight-junctions and polarized localization of efflux transporter. Microvessels exhibited physiological relevant trans-endothelial electrical resistance (TEER), were leak-tight for 10 kDa dextran-Alexa 647 and strongly limited the permeability of sodium fluorescein (NaF). Permeability tests with reference compounds confirmed the suitability of our model as platform to identify potential BBB penetrating anti-inflammatory drugs. In summary, the here presented brain microvessel platform recapitulates physiological properties and allows rapid screening of BBB permeable anti-inflammatory compounds that has been suggested as promising substances to cure so far untreatable neurodegenerative diseases.