Young-Jae Nam, MD, PhD
Assistant Professor of Medicine
A fundamental, but unsolved problem in heart diseases is irreversible loss of cardiomyocytes that is replaced by fibrotic scar in response to injury. Therefore, to convert cardiac fibroblasts, the most abundant cell type in the heart, into cardiomyocytes after injury is a particularly attractive heart repair strategy. Over the last several years, we have made several important contributions toward this goal: 1) in vitro reprogramming of adult mouse fibroblasts into beating cardiomyocytes by forced expression of four cardiogenic transcription factors (Nature 2012; 485: 599-604), 2) developing in vivo reprogramming strategy targeting activated cardiac fibroblasts after myocardial infarction which improved heart function and reduced scar formation infarction (Nature 2012; 485: 599-604, Nature Medicine 2013;19: 413-415), 3) identifying the optimal combination of factors that is necessary and sufficient to induce a contractile phenotype in adult human fibroblasts (PNAS 2013;110(14):5588-5593), and 4) defining the cardiomyocyte subtype-specific properties of reprogrammed cells (Development 2014;141(22):4267-78). Based on these progresses, the new research direction in my lab is to understand cardiac fate specification during de novo cardiomyocyte generation and thus to develop entirely new cardiomyocyte induction strategies targeting individual subtypes of cardiomyocytes including atrial, ventricular, and pacemaker cardiomyocytes by direct reprogramming of fibroblasts and directed cardiac differentiation of pluripotent stem cells.