A modular approach to create a neurovascular unit-on-a-chip

Abstract

In this work, we describe the fabrication and working of a modular microsystem that recapitulates the functions of the "Neurovascular Unit". The microdevice comprised a vertical stack of a poly(dimethylsiloxane) (PDMS) neural parenchymal chamber separated by a vascular channel via a microporous polycarbonate (PC) membrane. The neural chamber housed a mixture of neurons (~4%), astrocytes (~95%), and microglia (~1%). The vascular channel was lined with a layer of rat brain microvascular endothelial cell line (RBE4). Cellular components in the neural chamber and vascular channel showed viability (>90%). The neural cells fired inhibitory as well as excitatory potentials following 10 days of culture. The endothelial cells showed diluted-acetylated low density lipoprotein (dil-a-LDL) uptake, expressed von Willebrand factor (vWF) and zonula occludens (ZO-1) tight junctions, and showed decreased Alexafluor™-conjugated dextran leakage across their barriers significantly compared with controls (p < 0.05). When the vascular layer was stimulated with TNF-α for 6 h, about 75% of resident microglia and astrocytes on the neural side were activated significantly (p < 0.05 compared to controls) recapitulating tissue-mimetic responses resembling neuroinflammation. The impact of this microsystem lies in the fact that this biomimetic neurovascular platform might not only be harnessed for obtaining mechanistic insights for neurodegenerative disorders, but could also serve as a potential screening tool for central nervous system (CNS) therapeutics in toxicology and neuroinfectious diseases.

A versatile lab-on-a-chip tool for modeling biological barriers

“…Still, a comprehensive study on a human brain endothelial cell line in a microdevice, with a complex characterization of barrier properties including microscopy, has so far been missing. Previously, the rat cell line RBE4 was studied for a similar purpose [17,36]. Biochips modeling the vascular system also widely use peripheral endothelial cells [37][38][39][40].…”

Microfluidic Platforms for the Investigation of Intercellular Signalling Mechanisms

“…Additionally, signalling of the 'neurovascular unit', the functional module comprised of the neural parenchyma and blood-brain barrier, has been investigated by Achyuta and colleagues. [ 48 ] Their platform mimicked in-vivo conditions by vertically stacking a vascular channel on top of a neural parenchymal chamber, with a microporous polycarbonate membrane to separate the two chambers. Both the endothelial cell barriers of the vascular channel and the capacity of the neural cells to fi re action potentials were demonstrated to be functional.…”

Developmentally inspired human ‘organs on chips’

“…1A,B; Huh et al, 2010). Since this study was published, multi-channel design approaches have been used by multiple research groups to build microfluidic organ-chip models of the human lung small airway, skin, kidney, intestine, placenta, blood-retinal barrier, blood-brain barrier, neurovascular unit and neuromuscular unit, among others (Kim et al, 2012;Achyuta et al, 2013;Abaci et al, 2015;Benam et al, 2016a;Lee et al, 2016;Musah et al, 2017;Yeste et al, 2017;Wang et al, 2017;Workman et al, 2018;Kasendra et al, 2018;Sances et al, 2018; reviewed by Bhatia and Ingber, 2014).…”