EXPRESS: Post-stenotic hemodynamics in intracranial atherosclerosis are associated with endothelial activation and pro-thrombotic signaling.

BACKGROUND: Intracranial atherosclerotic disease (ICAD) is a leading cause of ischemic stroke, yet how post-stenotic cerebral hemodynamics regulate endothelial phenotype remains poorly defined. We tested whether focal post-stenotic low wall shear stress (WSS) in patient-specific middle cerebral artery (MCA) stenoses associates with endothelial proliferation and pro-thrombotic activation. METHODS: CTA-derived geometries from SAMMPRIS participants were reconstructed for computational fluid dynamics (CFD) analysis (n=33 paired MCAs). A subset of stenotic and contralateral control models was 3D-printed, endothelialized with Human Umbilical Vein Endothelial Cells (HUVECs), and perfused under physiologic flow (n=8 pairs). Anatomically matched regions were analyzed for proliferation (Ki-67), biglycan (BGN), cell morphology, and pro-thrombotic mediators (LPCAT2, PAI1) using confocal imaging and automated segmentation. RESULTS: Stenotic MCAs exhibited significantly greater post-stenotic low-WSS area ratios than paired controls (p<0.0001). Distal low-WSS area correlated with increased proliferation (r=0.688, p=0.013) and BGN expression (r=0.580, p=0.046), confirmed by bootstrapping (p<0.001). Low-WSS regions demonstrated reduced cell area (0.85-fold, p=0.0013) and elevated LPCAT2 (1.34-fold) and PAI1 (1.41-fold) expression (both p<0.0001), which inversely correlated with particle-flow linearity (p≤0.031). CONCLUSIONS: Patient-specific cerebral stenoses generate focal low-WSS environments that can induce endothelial proliferation and pro-thrombotic signaling, supporting a mechanistic link between intracranial hemodynamics and endothelial dysfunction in ICAD.