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 remains one of the key challenges in drug discovery to finally target brain disorders including neurodegenerative diseases which do not have adequate treatments so far. It has been difficult to establish state-of-the-art stem cell derived in vitro models that mimic physiological barrier properties including a 3D microvasculature in a format that is scalable to screen drugs for BBB penetration. 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 microvessels in 10 days. Produced microvessels show typical BBB 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. The here presented 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.

Screening of a neuronal cell model of tau pathology for therapeutic compounds.

We have developed a cell-based phenotypic automated high-content screening approach for N2a cells expressing the pro-aggregant repeat domain of tau protein (tauRDΔK), which allows analysis of a chemogenomic library of 1649 compounds for their effect on the inhibition or stimulation of intracellular tau aggregation. We identified several inhibitors and stimulators of aggregation and achieved a screening reproducibility >85% for all data. We identified 18 potential inhibitors (= 1.1% of the library) and 10 stimulators (= 0.6% of the library) of tau aggregation in this cell model of tau pathology. The results provide insights into the regulation of cellular tau aggregation and the pathways involved in this process (e.g., involving signaling via p38 mitogen-activated protein kinase, histone deacetylases, vascular endothelial growth factor, rho/ROCK). For example, inhibitors of protein kinases (e.g., p38) can reduce tau aggregation, whereas inhibitors of deacetylases (histone deacetylases) can enhance aggregation. These observations are compatible with reports that phosphorylated or acetylated tau promotes pathology.