Selective vulnerability of cerebral vasculature to NOTCH3 variants in small vessel disease and rescue by phosphodiesterase-5 inhibitor

NOTCH3 variants cause CADASIL the most common genetic form of small vessel disease (SVD) and vascular dementia (VaD) and increase the stroke and SVD/VaD risk. CADASIL is a systemic vasculopathy but predominantly manifests in the brain. The molecular mechanisms of CADASIL remain largely unclear with no specific available treatments. NOTCH3 is primarily expressed in vascular smooth muscle cells (VSMCs). Using human induced pluripotent stem cell (iPSC) models and developmental lineage-specific VSMC differentiation, we revealed a selective vulnerability of cerebral but not peripheral VSMC mimics to NOTCH3 variants. Transcriptomic, protein and functional analyses demonstrated a switching of CADASIL iPSC-VSMCs from a contractile to a synthetic phenotype, accompanied with extensive extracellular matrix accumulation and impairment of cell adhesion leading to anoikis. Importantly, we describe an endothelial independent nitric oxide signalling in VSMCs which was dysregulated in the CADASIL iPSC-VSMCs, and posphodiesterase-5 (PDE5) inhibition successfully rescued the abnormal VSMC function, suggesting a novel therapeutic strategy. Our findings offer new mechanistic insights into brain specific phenotype in NOTCH3-associated SVD/VaD and support patient-specific iPSCs to be a valuable model for identifying targeted treatment for NOTCH3-associated SVD/VaD.