Differential biomarker expression of blood and lymphatic vasculature in multi-organ-chips.

Since the blood and lymphatic endothelium regulates homeostasis and inflammation during health and disease, establishment of vascularized Organ-on-Chip platforms with blood and lymphatic endothelial cells (BEC/LEC) is a pre-requisite to further advance the field of tissue engineering. Here, we aimed to determine whether characteristics of BECs and LECs cultured under flow in a multi-organ-chip (MOC) are influenced by shear stress or inflammation. Dermis-derived primary BECs and LECs were used to endothelialize a MOC followed by culture for up to 14 days at lymphatic and blood flow rates. Under blood flow, both cell types changed morphology, aligned in flow direction, and showed close cell-cell contacts as in in vivo blood vasculature. Under lymphatic flow, neither BEC nor LEC aligned, and both showed a cobblestone-appearance with limited intercellular contacts similar to lymphatics. Cells retained their cell type-specific phenotype and cytokine secretion profiles. CCL21 expression in LECs was rescued by flow, but diminished again with TNFα exposure, together with the LEC-specific markers PROX1 and TFF3. Homeostatic cytokine secretion was higher in BECs, but the response to TNFα was more pronounced in LECs. Results indicate that BEC and LEC phenotype and cytokine secretion is mostly an intrinsic property with only morphology and CCL21 being influenced by flow.