Abstract P1031: A Novel Transcription Factor Combination For Direct Reprogramming To A Spontaneously Contracting Human Cardiomyocyte-Like State

Abstract

The reprogramming of somatic cells to a spontaneously contracting cardiomyocyte-like state using defined transcription factors has proven successful in mouse fibroblasts, but has been less successful with human cells, limiting the potential clinical applicability of this technology in regenerative medicine. We hypothesized that this issue is due to a lack of cross-species concordance between the required transcription factor combinations. Despite a decade of research, direct myocardial reprogramming still relies on overexpression of reprogramming factors first identified in mice: GATA4, MEF2C, TBX5. Using the Mogrify algorithm, we identified new candidate transcription factor combinations to induce cell conversion between human fibroblasts and cardiomyocytes. We developed an automated, high-throughput method for screening transcription factors, small molecules, and growth factors utilizing acoustic liquid handling and high-content kinetic imaging cytometry. Using this high-throughput platform we identified the combination of MYOCD, SMAD6, and TBX20 (MST) that can produce 40% TNNT2+MYH6+ cells in just 6 days and consistently produce spontaneous cardiomyocyte-like calcium transients and spontaneous contraction at just 25 days. These findings indicate that human cardiac direct reprogramming is feasible at similar levels to that achieved in the mouse and represents a step forward towards the possible clinical application of this direct cardiacreprogramming approach.