Marfan Syndrome (MFS), one of the most common heritable connective tissue disorders, affects 1 in 5,000 individuals and has destructive manifestations in multiple organ systems; notably the cardiovascular system. MFS is an autosomal dominant disease caused by a genetic mutation in the Fibrillin-1 gene leading to aberrant TGF? signaling, and frequently results in aortic aneurysm, dissection, and death. Interestingly, the associated degeneration within the aortic vessel wall almost always occurs in the aortic root or ascending aorta and not in the descending or abdominal aorta; while this putatively reflects regional differences in hemodynamic stress, antihypertensive treatment alone is not effective in managing aortic aneurysm in MFS. Alternatively, it is also the case that aortic smooth muscle cells (ASMCs), which predominate the vasoactive medial layer of the vessel wall, have heterogeneous subtypes stemming from distinct developmental germ-layers based on their anatomical location; Neuroectoderm (NE) origin gives rise to ascending ASMCs and Paraxial mesoderm (PM) origin gives rise to descending ASMCs. This project will use origin-specific ASMCs differentiated from induced pluripotent stem cells (iPSCs) from patients with MFS and healthy controls to test a novel hypothesis that developmental origin causes location-specific abnormalities in ASMCs associated with medial degeneration in MFS. Additionally, it will explore for biomarkers of presymptomatic congenital defects in Marfan Syndrome to identify novel targets for prophylactic therapeutic intervention. These studies will characterize phenotypic differences in human ASMC subtypes at the cellular and tissue level with stem-cell culturing and vascular tissue engineering techniques. Using state-of-the-art core facilities we will also conduct transcriptomic and proteomic analysis on these cellular and tissue models to cultivate a rich biological profile for bioinformatic analysis. Furthermore, we will develop a bioinformatics pipeline to elucidate novel prophylactic targets inherently responsible for ascending aortic MFS-induced medial degeneration, using our uniquely combined phenotypic, transcriptomic, and proteomic results as input. Lastly, based on our bioinformatic outputs we will test our intervention on our human iPSC-based in vitro models and compare to treatment with Losartan, a commonly used anti-hypertensive drug that also exhibits unique anti-remodeling properties and has shown promise for managing the symptoms of MFS in animals and in patients. The training plan for this fellowship will focus on technical skills, experimental design and critical analysis, critique of published scientific data, and presentation skills. It will be achieved by regular mentor meetings, journal clubs, conference presentations, bi- annual committee meetings, and advanced coursework. The majority of training will occur in the Costa Lab at the Cardiovascular Research Center at ISMMS, a highly active and collaborative environment with available mentors and students aligned with my research topics and career goals. Additional training will occur in the Ramirez Lab with senior researchers in Marfan Syndrome and biochemical investigation techniques.
This research proposes a bioengineering approach for investigating new human induced pluripotent stem cell (hiPSC)-based cellular and 3D tissue models of Marfan Syndrome (MFS), a rare connective tissue disorder that frequently causes aortic aneurysm and dissection specifically in the ascending aorta. Our findings will elucidate mechanobiological differences in aortic smooth muscle cells of distinct embryologic origin, and their underlying mechanisms of response to mechanical stimuli. This will help improve our understanding of aneurysm localization in MFS, and guide more effective therapies for MFS patients in the future.