Microphysiological Uremia Model Reveals Biophysical Potentiators of Vascular Dysfunction.

Cardiovascular disease is a leading cause of mortality in individuals with chronic kidney disease (CKD), with hypertension being a major contributor to both kidney damage and increased cardiovascular risk. Despite the established link between CKD and cardiovascular disease, the role of uremic toxins in monocyte-endothelial interactions under hypertensive conditions remains underexplored. Here, a 3D microfluidic model is developed to examine the effects of indoxyl sulfate on monocyte adhesion and extravasation across engineered microvessels embedded in hydrogels with different densities under controlled luminal pressure. Elevated pressure alone in absence of indoxyl sulfate significantly enhanced monocyte adhesion and extravasation, regardless of matrix density, while matrix density regulated adhesion and transmigration in the uremic environment. ICAM-1 is identified as a key driver of THP-1 monocyte adhesion to the endothelium. Additionally, denser hydrogels primed monocytes toward a pro-inflammatory phenotype with reduced phagocytic capacity, while softer hydrogels induced an anti-inflammatory-like phenotype with enhanced phagocytosis. However, the uremic environment reduced phagocytosis and shifted cells toward a pro-inflammatory-like state, irrespective of matrix density. This approach has the potential to dissect multiple factors that contribute to elevated cardiovascular risks in CKD patients and improve the understanding of mechanisms involved in monocyte dynamics in CKD-related cardiovascular disease.