Modeling and Rescue of the Vascular Phenotype of Williams-Beuren Syndrome in Patient Induced Pluripotent Stem Cells

Abstract

Elastin haploinsufficiency in Williams-Beuren syndrome (WBS) leads to increased vascular smooth muscle cell (SMC) proliferation and stenoses. Our objective was to generate a human induced pluripotent stem (hiPS) cell model for in vitro assessment of the WBS phenotype and to test the ability of candidate agents to rescue the phenotype. hiPS cells were reprogrammed from skin fibroblasts of a WBS patient with aortic and pulmonary stenosis and healthy control BJ fibroblasts using four-factor retrovirus reprogramming and were differentiated into SMCs. Differentiated SMCs were treated with synthetic elastin-binding protein ligand 2 (EBPL2) (20 g/ml) or the antiproliferative drug rapamycin (100 nM) for 5 days. We generated four WBS induced pluripotent stem (iPS) cell lines that expressed pluripotency genes and differentiated into all three germ layers. Directed differentiation of BJ iPS cells yielded an 85%-92% pure SMC population that expressed differentiated SMC markers, were functionally contractile, and formed tube-like structures on three-dimensional gel assay. Unlike BJ iPS cells, WBS iPS cells generated immature SMCs that were highly proliferative, showed lower expression of differentiated SMC markers, reduced response to the vasoactive agonists, carbachol and endothelin-1, impaired vascular tube formation, and reduced calcium flux. EBPL2 partially rescued and rapamycin fully rescued the abnormal SMC phenotype by decreasing the smooth muscle proliferation rate and enhancing differentiation and tube formation. WBS iPS cellderived SMCs demonstrate an immature proliferative phenotype with reduced functional and contractile properties, thereby recapitulating the human disease phenotype. The ability of rapamycin to rescue the phenotype provides an attractive therapeutic candidate for patients with WBS and vascular stenoses. STEM CELLS TRANSLATIONAL MEDICINE 2013;2:2-15

Generation of functionally competent and durable engineered blood vessels from human induced pluripotent stem cells

“…Indeed, the hiPS cell-derived vascular precursor cells have been shown to be excellent models to study disease. For example, hiPS cell-derived vascular precursors have been used to derive blood-brain barrier type endothelial cells (ECs) in culture (14) or to study patientspecific EC and smooth muscle cell defects in a Hutchinson Gilford progeria model (15) and rescue the vascular phenotype of Williams-Beuren syndrome (16).…”

Fibulin-4 and fibulin-5 in elastogenesis and beyond: Insights from mouse and human studies

“…SVAS is caused by deletion in the elastin gene (ELN) and is characterized by hyperproliferation of SMCs and narrowing of the ascending aorta (Ge et al, 2012, Kinnear et al, 2013). A mouse model of SVAS was established by deleting the Eln gene in vivo, and primary Eln -null SMCs recapitulate human disease phenotypes (Li et al, 1998).…”

Induced pluripotent stem cells: at the heart of cardiovascular precision medicine

“…115 These pathological features were rescued by elastin recombinant protein, thus confirming elastin haploinsufficiency as the cause. Subsequently, hiPSC-SMCs derived from patients with WBS were found to have the same pathological features that were later confirmed by Kinnear et al 116 The use of hiPSC platform was a significant breakthrough, as hemizygous transgenic mouse models of WBS failed to exhibit supravalvular aortic stenosis. 117 Importantly, the authors found the drug rapamycin, an antiproliferative agent, to be effective at reversing the pathological phenotypes, demonstrating the potential use of this FDA-approved drug for the prevention of arterial stenosis following surgical correction.…”