National Research Council of Canada, Ontario, Canada
The blood-brain barrier (BBB) is a crucial physiological interface that tightly regulates the exchange of substances between the bloodstream and the brain parenchyma. Accurate modeling of the BBB is essential for understanding its complex functions and developing novel therapeutic strategies for neurological diseases. Organ on chip technology has emerged as a promising tool for creating in vitro models that mimic the structural and functional aspects of the BBB vasculature. Moreover, BBB models in vitro are crucial tools to aid in the pre-clinical evaluation and selection of BBB-permeant biotherapeutics. We developed a 3D human BBB-on-Chip co-culture model using the SynVivo microfluidic platform (SynBBB) combining human iPSC derived brain endothelial cells (iBECs) and primary astrocytes and pericytes recapitulating the critical components of the BBB and neurovascular unit. We established perfusable iBEC lumens under physiological shear stress conditions that were accompanied by ECM remodeling and an increase in endothelial gene expression profiles inducing a more endothelial like phenotype as assessed by RNASeq. The iBECs formed tight barriers within the SynBBB chips, as assessed by restricted sodium fluorescein and dextran permeability and functional on-CHIP transendothelial electrical resistance values. Barrier tightening was increased under shear stress and astrocyte/pericyte co-cultures recapitulating a tightening response due to astrocytic cues. We benchmarked the iBEC BBB model with immortalized and primary brain endothelial cell sources in the SynBBB chips illustrating the utility of the platform across multiple BEC sources while also discriminating differences in barrier tightness. We deployed this BBB-on-Chip model to study antibody-triggered receptor mediated transcytosis by perfusing the endothelialized lumens with a well characterized single domain BBB-carrier FC5-Fc and non-crossing A20.1 control. To assess BBB permeability, we developed a highly sensitive WES-based immunoassay adaptable to small chip effluent volumes. We observed a significant increase in FC5-Fc transcytosis under physiological shear stress conditions compared to static cultures. We further deployed the SynBBB chips towards establishing a blood-brain-barrier tumor (BBTB) model in the pre-clinical assessment of glioblastoma- targeting EGFRvIII-CAR-T based immunotherapies. The BBTB model was able to discriminate cytotoxic efficacies of the different EGFR-CARs and provide a measure of potential alterations to BBB integrity. Collectively, these findings suggest that iBECs and SynBBB technology can recapitulate the physiological characteristics of the BBB in vivo and offer a more predictive platform for assessing antibody transcytosis across the BBB and deciphering the mechanisms of CAR-T–induced BBB disruption, accompanying toxicity and effector function on post-barrier target cells.