Distinct Contributions of Astrocytes and Pericytes to Neuroinflammation Identified in a 3D Human Blood-Brain Barrier on a Chip

Abstract

Neurovascular inflammation is a major contributor to many neurological disorders, but modeling these processes in vitro has proven to be difficult. Here, we microengineered a three-dimensional (3D) model of the human blood-brain barrier (BBB) within a microfluidic chip by creating a cylindrical collagen gel containing a central hollow lumen inside a microchannel, culturing primary human brain microvascular endothelial cells on the gel’s inner surface, and flowing medium through the lumen. Studies were carried out with the engineered microvessel containing endothelium in the presence or absence of either primary human brain pericytes beneath the endothelium or primary human brain astrocytes within the surrounding collagen gel to explore the ability of this simplified model to identify distinct contributions of these supporting cells to the neuroinflammatory response. This human 3D BBB-on-a-chip exhibited barrier permeability similar to that observed in other in vitro BBB models created with non-human cells, and when stimulated with the inflammatory trigger, tumor necrosis factor-alpha (TNF-α), different secretion profiles for granulocyte colony-stimulating factor (G-CSF) and interleukin-6 (IL-6) were observed depending on the presence of astrocytes or pericytes. Importantly, the levels of these responses detected in the 3D BBB chip were significantly greater than when the same cells were co-cultured in static Transwell plates. Thus, as G-CSF and IL-6 have been reported to play important roles in neuroprotection and neuroactivation in vivo, this 3D BBB chip potentially offers a new method to study human neurovascular function and inflammation in vitro, and to identify physiological contributions of individual cell types.

Dynamic interactions ofPlasmodiumspp. with vascular endothelium

“…146 Coculture models of the human blood brain barrier including pericytes and astrocytes along with brain endothelial cells under continuous flow (1dyne/cm 2 ) have confirmed a long suspected role for both stromal populations in regulating BBB function. 147 Cocultures in this model showed a 2-fold increase in barrier integrity as measured by 3kDa dextran flux and 2-to 5-fold increase in responsiveness to TNF-a as measured by IL-6, IL-8 and G-CSF production compared with endothelial cells alone. 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.…”

Three-dimensional biomimetic vascular model reveals a RhoA, Rac1, and N -cadherin balance in mural cell–endothelial cell-regulated barrier function

“…A deeper understanding of human pathophysiology requires the development of robust on-chip systems that can recapitulate the structures, mechanics, and complex cell-cell interactions that occur in vivo (76)(77)(78)(79)(80)). Whereas we demonstrate herein the feasibility to capture these interactions in on-chip systems, a challenge in the future is to establish tissue-specific features of vascular beds such as low permeable brain vasculature (blood brain barrier) or high permeable liver sinusoids consisting of endothelial cells with fenestrae.…”

[O2–04–01]: Clearance of Beta‐amyloid Is Facilitated by Apolipoprotein E and Circulating High‐density Lipoproteins in Bioengineered Human Vessels

“…Considerable recent advances in tissue engineering technology have helped to develop microfluidic systems (i.e. 'organ on a chip') that recapitulate the 3D complexity of the BBB, primarily to produce small vessel structures like capillaries (Prabhakarpandian et al, 2013;Herland et al, 2016;Booth and Kim, 2012;Griep et al, 2013;Cho et al, 2015). However, as CAA preferentially forms in larger arteries, we aimed to produce 3D in vitro models of functional human vessels that retain the anatomical and functional properties of native human cerebral arteries.…”