3D Culture and Characterization of Blood-Brain Barrier Endothelial Cells in a New Microfluidic Platform

Abstract Background: The blood-brain barrier (BBB) protects the central nervous system (CNS) from harmful substances in the peripheral blood stream and ensures brain homeostasis by regulating the transport of nutrients and metabolites. It also prevents many pharmaceutical drugs from reaching their target site and dysfunctions of the BBB are often associated with CNS diseases. In order to provide a new in vitro platform that allows the investigation of barrier characteristics of the BBB and drug transport under physiological and pathological conditions, the TransBBB system was developed. The microfluidic chip consists of ten parallel culture chambers, each allowing the cultivation of endothelial cells on a physiological matrix under perfusion.Methods: Porcine brain capillary endothelial cells (PBCECs) were cultivated on the surface of a hydrogel matrix resulting in a barrier which separates the culture chambers into two compartments. A protocol was established in order to obtain a tight cell layer under perfusion and the effect of different perfusion volumes on BBB formation was investigated. The barrier was then characterized in terms of cell viability, barrier integrity and expression of tight junction proteins.Results: PBCECs formed a tight cell layer on the hydrogel surface preventing FITC dextran from permeating the cellular barrier. The presence of ZO-1 at the cell borders was shown indicating a functional BBB. The perfusion experiments suggested a critical role of medium volume for cell layer integrity under perfusion conditions.Conclusions: The TransBBB chip presented here provides a promising, scalable microfluidic platform for the investigation of cellular barriers which can be integrated seamlessly into existing cell culture and drug testing workflows.