Lineage-Specific Induced Pluripotent Stem Cell-Derived Smooth Muscle Cell Modeling Predicts Integrin Alpha-V Antagonism Reduces Aortic Root Aneurysm Formation in Marfan Syndrome Mice

Background: To delineate the effects of Integrin αv signaling in Marfan syndrome (MFS) and examine the potential efficacy of Integrin αv blockade as a therapeutic strategy for MFS aneurysms.

Methods: Induced pluripotent stem cells were differentiated into aortic smooth muscle cells (SMCs) of the second heart field (SHF) and neural crest lineages, enabling in vitro modeling of thoracic aortic aneurysm in MFS. Fbn1^C1039G/+ MFS mice treated with Integrin αv antagonist (GLPG0187) confirmed the pathological role of Integrin αv on aneurysm formation.

Results: Induced pluripotent stem cell-derived MFS SHF SMCs overexpress Integrin αv relative to MFS neural crest and healthy control SHF cells. Furthermore, downstream targets of Integrin αv (FAK [focal adhesion kinase]/Akt^Thr308/mTORC1 [mechanistic target of rapamycin complex 1]) were activated, especially in MFS SHF. Treatment GLPG0187 reduced p-FAK/p-Akt^Thr308/mTORC1 activity in MFS SHF back to control SHF levels. Functionally, MFS SHF SMCs had increased proliferation and migration compared to MFS neural crest and control SMCs, which was then inhibited by GLPG0187 treatment. In the Fbn1^C1039G/+ MFS mouse model, Integrin αv, p-Akt^Thr308, and downstream targets of mTORC1 proteins were elevated in the aortic root/ascending segment compared to littermate wild-type control. Mice treated with GLPG0187 (age 6-14 weeks) resulted in reduced aneurysm growth, elastin fragmentation, and normalization of the FAK/Akt^Thr308/mTORC1 pathway. GLPG0187 treatment reduced the amount and severity of SMC modulation assessed by single-cell RNA sequencing.

Conclusions: The Integrin αv-FAK-Akt^Thr308 signaling pathway is activated in induced pluripotent stem cell SMCs from MFS patients, specifically from the SHF lineage. Mechanistically, this signaling pathway promotes SMC proliferation and migration in vitro. As biological proof of concept, GLPG0187 treatment slowed aneurysm growth and p-Akt^Thr308 signaling in Fbn1^C1039G/+ mice. Integrin αv blockade via GLPG0187 may be a promising therapeutic approach to inhibit MFS aneurysmal growth.

Marfan syndrome; aneurysm; mutation; proteomic; uncertainty.