| Abstract | Background: The blood-brain barrier (BBB) is the most important biological barrier between the blood circulation and the central nervous system (CNS), it functions as a physical barrier and plays a major role as a transport and metabolic barrier. In vitro models of the human BBB are highly desirable for drug development and studies of neurovascular pathology. Human induced pluripotent stem cell (iPSC) derived brain endotheli-al-like cells (iBECs) have demonstrated a substantial advantage over primary and immortalized brain endothelial cells for BBB modeling.
Methods: We developed a 3D BBB-on-Chip co-culture model using the SynVivo-BBB channel microfluidic technology to model critical com-ponents of the BBB. We established iBEC microvessel lumens under physiological in vivo shear stress conditions (5 dynes/cm2) in the apical channel of the chips, while human primary astrocytes and pericytes were cultured on the basolateral side separated by a porous 1μm membrane. We deployed this BBB-on-Chip model to study antibody-triggered receptor mediated transcytosis by perfusing the iBEC lumens with a well characterized single domain BBB-carrier FC5-Fc and non-crossing A20.1 control. Leveraging Wes (ProteinSimple), we established protocols for on-CHIP BBB permeability quantification, using anti-Fc and anti-His antibodies, in small sample volumes extracted from the microfluidic channels.
Results: Astrocyte, pericyte and endothelial cell co-cultures, coupled with in vivo hemodynamic shear stress, enhanced tight junction formation by increased membrane expression of ZO-1 and decreased sodium fluorescein permeability across the iBEC monolayer. We observed similar FC5-Fc transcytosis under 3D static conditions compared to conventional 2D transwell assays; however, a significant increase in FC5-Fc transcytosis was observed under physiological shear stress conditions. Similar BBB crossing of FC5-Fc was observed in in vivo brain exposure experiments.
Limitations: This study is limited due to the small volume in the chips. Highly sensitive analytics coupled with small volume size can be used to study the transport mechanism and kinetics.
Conclusions: These findings suggest that 3D BBB-on-CHIP technology can recapitulate the physiological characteristics of the BBB in vivo and offer a more predictive platform for assessing antibody transcytosis across the BBB. |
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