An iPSC-derived vascular model of Marfan syndrome identifies key mediators of smooth muscle cell death

Abstract

Marfan syndrome (MFS) is a heritable connective tissue disorder caused by mutations in FBN1, which encodes the extracellular matrix protein fibrillin-1. To investigate the pathogenesis of aortic aneurysms in MFS, we generated a vascular model derived from human induced pluripotent stem cells (MFS-hiPSCs). Our MFS-hiPSC-derived smooth muscle cells (SMCs) recapitulated the pathology seen in Marfan aortas, including defects in fibrillin-1 accumulation, extracellular matrix degradation, transforming growth factor-β (TGF-β) signaling, contraction and apoptosis; abnormalities were corrected by CRISPR-based editing of the FBN1 mutation. TGF-β inhibition rescued abnormalities in fibrillin-1 accumulation and matrix metalloproteinase expression. However, only the noncanonical p38 pathway regulated SMC apoptosis, a pathological mechanism also governed by Krüppel-like factor 4 (KLF4). This model has enabled us to dissect the molecular mechanisms of MFS, identify novel targets for treatment (such as p38 and KLF4) and provided an innovative human platform for the testing of new drugs.

Differentiation and Application of Induced Pluripotent Stem Cell–Derived Vascular Smooth Muscle Cells

“…93 The authors of this study recapitulated various aspects of the disease, including irregular fibrillin-1 deposition, and in doing so, identified several important downstream targets, including KLF4 and p38. Moreover, they restored fibrillin-1, TGF-β, and abnormal matrix metalloproteinase levels by correcting for the missense mutation in the fibrillin-1 gene using CRISPR-Cas9 system, providing strong evidence for the use of gene editing as a therapeutic tool.…”

TGF-β (Transforming Growth Factor-β) Signaling Protects the Thoracic and Abdominal Aorta From Angiotensin II-Induced Pathology by Distinct Mechanisms

“…Surprisingly, 2G7 did not reduce serum total TGF-β2 activity (Figure XB in the online-only Data Supplement; P=0.9). We then tested whether 2G7 or another putative “pan-neutralizing anti-TGF-β antibody” 1D11 (also widely used in aortopathy research) 12, 22–24 could neutralize all 3 TGF-β isoforms in vitro. Both 2G7 and 1D11 neutralized TGF-β1 and TGF-β3; whereas, neither antibody had any activity against TGF-β2 (Figure XD – XF in the online-only Data Supplement).…”

Application of induced pluripotent stem cells to model smooth muscle cell function in vascular diseases

“…However, their SMC from different lineages appeared to be phenotypically and functionally indistinguishable, although origin-specific responses to certain cytokines and extracellular matrix (ECM) remodeling proteins were observed. Nevertheless, their subsequent study demonstrated that SMC derived from iPSC of Marfan syndrome patients showed distinct origin-specific disease phenotype [20]. SMC derived from neuroectoderm lineage displayed a more severe form of fibrillin abnormality and increased TGFβ1 activation than that derived from other lineages.…”

“…Moreover, there is a need for investigating the exact molecular mechanism of TGFβ signaling pathway in TAA progression, as studies have generated controversies as to the effect of TGFβ activation on aneurysm formation in general, where some reported that the effect appears to be temporally dependent on the degree of TAA progression [20]. Recently, Granata et al generated iPSC from dermal fibroblasts of patients with MFS [20].…”

“…Recently, Granata et al generated iPSC from dermal fibroblasts of patients with MFS [20]. SMC differentiated from these MFS iPSC showed that losartan could restore only certain downstream pathways of TGFβ signaling, in particular the matrix metalloproteinase expression level and ECM (fibrillin) organization, to normal conditions.…”