Modeling Defective Epigenetic Inheritance in Vascular Aging Using Hutchinson-Gilford Progeria Syndrome Vascular Smooth Muscle Cells

Abstract

Cardiovascular disease (CVD) is the leading cause of death due to its prevalence in tandem with the propensity of atherosclerosis to worsen and cause myocardial infarction and stroke. The greatest risk factor for CVD development is age. The multifactorial etiology of atherosclerosis has made CVD difficult to model and consequently little is known about CVD onset and progression. Hutchinson-Gilford Progeria Syndrome (HGPS) is a severe human premature aging disorder caused by a mutation in Lamin A that leads to the accumulation of an aberrant Lamin A protein termed progerin. Patients who harbour this mutation develop atherosclerosis and die from myocardial infarction or stroke at an average age of 13 years old. Autopsies reveal deterioration of vascular smooth muscle cells (VSMCs) in HGPS patients, underlining a strong connection between VSMC loss and predisposition to CVD development. The major aim of this thesis was to model normative vascular aging and disease using HGPS induced pluripotent stem cell (iPSC)-derived VSMCs and monitor the onset of defective epigenetic inheritance in vitro. My results indicate reprogramming of patient fibroblasts to restores a normal nuclear phenotype. Patient derived iPSC lines generated from fibroblasts are nearly indistinguishable from healthy controls in terms of pluripotency, nuclear membrane integrity, as well as transcriptional and epigenetic profiles. However, differentiation of HGPS iPSCs to generate HGPS VSMCs recapitulates many aspects of normative vascular aging exemplified by increased ROS, DNA damage and transcriptomic aberrations. Furthermore, using a multi-omic approach including RNA-sequencing, and accelerated native isolation of protein on nascent DNA, HGPS VSMCs demonstrate loss of histone acetylation due to defective MOF abundance that contributed to impaired engagement with DNA damage repair pathway. This dissertation provides insights on the mechanisms that drive the epigenetic and transcriptomic changes in HGPS vasculature, illuminating druggable pathways that may also drive CVD in the general population.