A biomimetic microphysiological system predicts the impact of sepsis therapeutics on neutrophil-endothelial dynamics.

Current preclinical models fail to capture human neutrophil-endothelial interactions central to sepsis, contributing to repeated failure of candidate therapeutics in clinical trials. Here, we present a biomimetic microphysiological system (bMPS) integrating primary human endothelial cells, human neutrophils and controlled chemoattractant gradients under physiological flow in a microvascular network. This platform enables real-time visualization of neutrophil adhesion and transmigration, along with quantitative analysis of endothelial barrier integrity. We demonstrate chemoattractant-dependent differential neutrophil recruitment to host-derived IL-8 and bacterial-derived fMLP and differential responses to two different therapeutics: the PAF receptor antagonist BN-52021 reduces recruitment in response to IL-8 but not to fMLP, whereas the PKC-δ inhibitor suppresses adhesion, transmigration, and NET formation to both IL-8 and fMLP. Confocal imaging and quantitative analysis demonstrate that Cytomix-induced endothelial barrier disruption in primary human lung microvascular endothelial cells (HLMVECs) is significantly ameliorated by BN-52021 and the PKC-δ inhibitor-restoring VE-cadherin integrity and reducing intercellular gaps. This bMPS provides a predictive, human-relevant platform for function-focused sepsis drug screening.