Immune cells and inflammatory mediators cause endothelial dysfunction in a vascular microphysiological system

Functional assessment of endothelium serves as an important indicator of vascular health and is compromised in vascular disorders including hypertension, atherosclerosis, and preeclampsia. Endothelial dysfunction in these cases is linked to dysregulation of the immune system involving both changes to immune cells and increased secretion of inflammatory cytokines. Herein, we utilize a well-established microfluidic device to generate a 3-dimensional vascular microphysiological system (MPS) consisting of a tubular blood vessel lined with human umbilical vein endothelial cells (HUVECs) to evaluate endothelial function measured via endothelial permeability and Ca²⁺ signaling. We evaluated the effect of a mixture of factors associated with inflammation and cardiovascular disease (TNFα, VEGF-A, IL-6 at 10 ng ml^-1 each) on vascular MPS and inferred that inflammatory mediators contribute to endothelial dysfunction by disrupting the endothelial barrier over a 48 hour treatment and by diminishing coordinated Ca²⁺ activity over a 1 hour treatment. We also evaluated the effect of peripheral blood mononuclear cells (PBMCs) on endothelial permeability and Ca²⁺ signaling in the HUVEC MPS. HUVECs were co-cultured with PBMCs either directly wherein PBMCs passed through the lumen or indirectly with PBMCs embedded in the supporting collagen hydrogel. We revealed that phytohemagglutinin (PHA)-M activated PBMCs cause endothelial dysfunction in MPS both through increased permeability and decreased coordinated Ca²⁺ activity compared to non-activated PBMCs. Our MPS has potential applications in modeling cardiovascular disorders and screening for potential treatments using measures of endothelial function.