Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL), as the most common hereditary stroke syndrome caused by NOTCH3 mutation, represents a valuable model to explore the pathogenesis of vascular dementia (VaD) and genetic small vessel diseases (SVDs). To date, several cell and animal models have been developed for CADASIL, but none of them could effectively recapitulate the brain phenotype of this condition. Induced pluripotent stem cells (iPSCs) provide the opportunity to model CADASIL from patients with the ability to retain the genetic background of the patient especially the NOTCH3 mutation. Currently three studies established iPSC-derived CADASIL models have focussed on vascular mural cells (vMCs) and vascular endothelial cells (vECs). Investigations suggest defect may exist in the neurovascular interactions in CADASIL, which rely on the communications between the neurovascular unit (NVU) cells including vMCs, brain microvascular endothelial cells (BMECs), astrocytes and neurons. However, previous models have never stressed this condition and the underlying mechanisms. This thesis demonstrates the development of an in vitro iPSCs model of CADASIL using NVU cell types differentiated from three control and two CADASIL (Arg153Cys and Cys224Tyr) iPSC lines. The data in this thesis shows that vMCs, BMECs, astrocytes and neurons can be generated from iPSCs and these NVU cells can mimic blood brain barrier (BBB) in CADASIL when co-culturing on the Transwell settings. Using the trans-endothelial electrical resistance (TEER) measurement assay, we demonstrated that the BMECs barrier function was obviously promoted by co-culturing with vMCs, astrocytes or neurons. This in vitro BBB model revealed barrier function defect in CADASIL BMECs that could not be restored by co-culturing with other NVU cells. Moreover, it was observed in the Transwell co-culturing system that CADASIL vMCs failed to support BMECs barrier function. Altogether the data presented in this thesis has shown BMECs defect and vMCs dysfunction in CADASIL BBB. Understanding the molecular mechanisms of this condition is vital in identification of therapeutic targets and developing future treatments. The established iPSC- BBB model for CADASIL represents a valuable platform that could be further applied to understand neurovascular interactions in CADASIL pathology as well as other genetic SVDs.
