(W1146) Selective vulnerability of cerebral vascular smooth muscle cells to NOTCH3 variants in an iPSC model of genetic small vessel disease CADASIL and a novel therapeutic target
Professor of Molecular Medicine The University of Manchester Manchester, England, United Kingdom
Abstract: NOTCH3 variants underlie CADASIL (cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy), the most common genetic small vessel disease (SVD) and a leading cause of vascular dementia. Despite its prevalence, CADASIL is often underdiagnosed due to its late-onset nature. Clinically, CADASIL is characterized by recurrent strokes, migraines with aura, mood disturbances, progressive cognitive decline, and ultimately vascular dementia. NOTCH3 is primarily expressed in vascular smooth muscle cells (VSMCs), but the molecular mechanisms remain poorly understood, leaving no specific or effective treatments available. Although CADASIL affects small vessels systemically, its clinical manifestations are predominantly brain specific. To investigate this brain-selective vulnerability, we developed human induced pluripotent stem cell (iPSC) models harbouring the NOTCH3-R153C and NOTCH3-C224Y variants. These iPSCs were differentiated into VSMCs through three developmental lineages: neuroectodermal (NE), lateral plate mesodermal (LPM), and paraxial mesodermal (PM), representing brain, cardiac, and peripheral VSMCs, respectively. Intriguingly, only NE-VSMCs from CADASIL iPSCs exhibited significant abnormalities, including increased proliferation and migration, decreased contractility, disorganized focal adhesion and actin cytoskeleton, and elevated cell death. These phenotypes were absent in LPM-VSMCs and PM-VSMCs, highlighting the heightened susceptibility of brain VSMCs to NOTCH3 variants. Further analysis of NE-VSMCs using RNA sequencing, qRT-PCR, and immunostaining revealed an upregulation of extracellular matrix (ECM)-related genes and a downregulation of contractile genes, indicating a phenotypic switch from contractile to synthetic states. RNA sequencing also identified dysfunction in a pathway, the manipulation of which successfully reversed the abnormal behavioural and functional changes in VSMCs, suggesting a promising drug target. Our findings provide critical insights into the brain-specific mechanisms of CADASIL and pave the way for the development of targeted therapies for this devastating condition.
Funding Source: The British Heart Foundation; National Centre for 3Rs in Research.
