A microfluidic chip recapitulating the human neurovascular unit with a functional blood-brain barrier for modeling gut-brain interactions

The blood-brain barrier (BBB) is essential for central nervous system homeostasis, but most current in vitro models lack structural and functional fidelity. We developed a physiologically relevant human neurovascular unit microfluidic chip (hNVU-on-a-chip) incorporating brain microvascular endothelial cells, astrocytes, and microglia to reconstruct a biomimetic BBB microenvironment. Barrier function was confirmed by low apparent permeability (Papp) and active P-glycoprotein (P-gp) efflux, with performance superior to Transwell models. Transcriptomic profiling revealed endothelial maturation with upregulated barrier and transport genes and downregulated proliferative pathways. Introducing gut microbial metabolites altered brain-side neurotransmitter metabolism, elevating biogenic amines and reducing precursors, consistent with enhanced turnover. Together, the hNVU-on-a-chip recapitulates BBB architecture and function, and provides a robust platform to investigate gut-brain axis interactions.