Three-Dimensional Human Neurovascular Unit Modeling Reveals Cell-Specific Mechanisms of Traumatic Brain Injury.

Severe traumatic brain injury includes neurovascular unit (NVU) damage that is linked to the later development of neurodegenerative diseases. Cell-type-specific contributions and crosstalk between cells of the neurovascular unit following brain injury remain poorly defined in human cells. Here, we developed a three-dimensional (3D) human NVU model using silk-collagen scaffolds to examine cellular responses to controlled cortical impact (CCI). Using this platform, we show that CCI induced acute cell death in astrocytes, microglia, and endothelial cells but spared pericytes, which occurred independently of classical apoptotic or necroptotic pathways. Astrocytes and microglia were the primary sources of early bioactive IL-1β release, while endothelial junctional integrity was differentially regulated by support cells: astrocytes destabilized VE-cadherin, pericytes preserved barrier proteins, and microglia contributed to Claudin-5 loss in multicellular settings. Conditioned media experiments demonstrated that soluble factors from injured support cells alone were sufficient to disrupt endothelial junctional proteins (ZO-1 and Occludin) and induce inflammatory adhesion molecules (ICAM-1 and VCAM-1). Together, these findings define cell-type-specific injury responses and reveal how NVU interactions regulate vascular dysfunction after trauma, providing a human-based framework for understanding blood-brain barrier (BBB) disruption following traumatic brain injury (TBI).