Abstract 440: A Lamin A/C Haploinsufficiency Model of Cardiomyopathy Using Patient-Specific iPSC Derived Cardiomyocytes Demonstrates Impaired Contractility

Abstract

Background: Lamin A/C (LMNA) mutations are the second most common cause of familial dilated cardiomyopathy (DCM). LMNA encodes nuclear lamins which are intermediate filaments of the inner nuclear membrane. Patients with LMNA DCM present with early signs of arrhythmias and often display a rapid deterioration in cardiac function. Previous induced pluripotent derived stem cell (iPSC) modeling of cardiac laminopathy did not demonstrate defects in cardiomyocyte (CM) contractility nor provide evidence of arrhythmogenesis. Developing a robust human model that recapitulates disease manifestations of LMNA cardiomyopathy is a critical step for understanding CM-intrinsic defects contributing to disease pathogenesis. Purpose: As such, our lab hypothesized that iPSC-CMs derived from a laminopathy patient would recapitulate the contractile dysfunction of the disease if studied in monolayer using flexible matrigel substrate. Methods: Patients with symptomology indicative of LMNA DCM were recruited for clinical testing. Peripheral blood mononuclear cells were isolated and reprogrammed into iPSCs. CMs were generated using a chemical differentiation method and then subjected to molecular and functional assessment. Cardioexcyte96 based detection of impedance was utilized for analysis of contractility of iPSC-CMs in a monolayer. Results/Conclusions: We identified a large pedigree with DCM in which affected individuals had a putatively pathogenic mutation within LMNA. Western blot analyses demonstrated that lamin A/C can be detected in iPSC-CMs with reduced expression in mutant cells. Mutant iPSC-CMs in a monolayer demonstrate both increased time for contraction (+55.1 msec P<.0001) and relaxation (+44.8 msec P<.0001) compared to control. Our results are the first to provide evidence for contractile dysfunction in an iPSC-CM model of cardiac laminopathy. In addition, this work highlights the utility of impedance based measurement of contractility as a robust outcome that can be applied to high throughput discovery of therapeutic interventions in this disease model.