Recreating blood-brain barrier physiology and structure on chip: A novel neurovascular microfluidic bioreactor

Abstract

The blood-brain barrier (BBB) is a critical structure that serves as the gatekeeper between the central nervous system and the rest of the body. It is the responsibility of the BBB to facilitate the entry of required nutrients into the brain and to exclude potentially harmful compounds; however, this complex structure has remained difficult to model faithfully in vitro. Accurate in vitro models are necessary for understanding how the BBB forms and functions, as well as for evaluating drug and toxin penetration across the barrier. Many previous models have failed to support all the cell types involved in the BBB formation and/or lacked the flow-created shear forces needed for mature tight junction formation. To address these issues and to help establish a more faithful in vitro model of the BBB, we have designed and fabricated a microfluidic device that is comprised of both a vascular chamber and a brain chamber separated by a porous membrane. This design allows for cell-to-cell communication between endothelial cells, astrocytes, and pericytes and independent perfusion of both compartments separated by the membrane. This NeuroVascular Unit (NVU) represents approximately one-millionth of the human brain, and hence, has sufficient cell mass to support a breadth of analytical measurements. The NVU has been validated with both fluorescein isothiocyanate (FITC)-dextran diffusion and transendothelial electrical resistance. The NVU has enabled in vitro modeling of the BBB using all human cell types and sampling effluent from both sides of the barrier.

Dynamic interactions ofPlasmodiumspp. with vascular endothelium

“…Neurons have also been integrated into microfluidic chips containing endothelial cells, astrocytes and pericytes, which results in a 5-fold decrease in 10kDa dextran flux in comparison to endothelial cells alone. 148 Moreover, these coculture systems allow for the examination of neuronal calcium signaling. 149 Similarly, 3D cultures of lung epithelial cells, fibroblasts and endothelial cells to recapitulate the features of the small airways including barrier function and ciliary movement on epithelial cells have been used to assess the effects of drugs on leukocyte recruitment in inflammatory lung diseases and their mechanism of action.…”

“…154 Histidine can be converted by histidine-L-decarboxylase to histamine which is elevated in severe malaria 155 and is a well described barrier disrupting agent acting through the G-protein coupled receptor H1 leading to subsequent RhoA/ROCK-dependent actin contraction. 156 Extracellular glutamate can also increase BBB permeability in vitro 148 and in vivo through the GPCR mGluR pathways. 157 In a mouse model of CM with the murine parasite P. berghei, CNS levels of glutamate are found to be increased while glutamine is decreased at the onset of neurologic dysfunction.…”

An integrative microfluidically supported in vitro model of an endothelial barrier combined with cortical spheroids simulates effects of neuroinflammation in neocortex development

“…30 An important feature of the hCMEC/D3 cell line used in our study, however, is the formation of a physiological barrier already in the absence of glia cells or astrocytes. 8,31 We therefore omitted inclusion of additional cell types in the endothelial layer.…”

Towards personalized computational oncology: from spatial models of tumour spheroids, to organoids, to tissues

“…These microphysiological systems are capable of maintaining live cultures for weeks and even months and can replicate complex organ environments, including 3D multicellular organ structures, nutrient supply and waste removal, oxygenation states, interstitial flows and a variety of microenvironmental gradients [163,165]. These systems are composed of individually addressable micro-compartments to permit precise regulation of a specific organ layer or tissue area and individualized tissue perfusion [166,167]. As such, they hold promise as attractive platforms for future drug development.…”