Learn from Your Elders: Developmental Biology Lessons to Guide Maturation of Stem Cell-Derived Cardiomyocytes

Abstract

Human pluripotent stem cells (hPSCs) offer a multifaceted platform to study cardiac developmental biology, understand disease mechanisms, and develop novel therapies. Remarkable progress over the last two decades has led to methods to obtain highly pure hPSC-derived cardiomyocytes (hPSC-CMs) with reasonable ease and scalability. Nevertheless, a major bottleneck for the translational application of hPSC-CMs is their immature phenotype, resembling that of early fetal cardiomyocytes. Overall, bona fide maturation of hPSC-CMs represents one of the most significant goals facing the field today. Developmental biology studies have been pivotal in understanding the mechanisms to differentiate hPSC-CMs. Similarly, evaluation of developmental cues such as electrical and mechanical activities or neurohormonal and metabolic stimulations revealed the importance of these pathways in cardiomyocyte physiological maturation. Those signals cooperate and dictate the size and the performance of the developing heart. Likewise, this orchestra of stimuli is important in promoting hPSC-CM maturation, as demonstrated by current in vitro maturation approaches. Different shades of adult-like phenotype are achieved by prolonging the time in culture, electromechanical stimulation, patterned substrates, microRNA manipulation, neurohormonal or metabolic stimulation, and generation of human-engineered heart tissue (hEHT). However, mirroring this extremely dynamic environment is challenging, and reproducibility and scalability of these approaches represent the major obstacles for an efficient production of mature hPSC-CMs. For this reason, understanding the pattern behind the mechanisms elicited during the late gestational and early postnatal stages not only will provide new insights into postnatal development but also potentially offer new scalable and efficient approaches to mature hPSC-CMs.

Cardiomyocyte maturation: advances in knowledge and implications for regenerative medicine

“…The adult cardiomyocyte in vivo has a large, anisotropic, rod-like shape that is approximately 150 μm in length, 20 μm in width, 15 μm in height and 40,000 μm 3 in volume 20 . By contrast, cultured hPSC-CMs range from circular cells with diameters of 5-10 μm and heights of ~5 μm at the start of spontaneous beating, to oblong cells measuring 30 μm in length, 10 μm in width and 2,000 μm 3 in volume after prolonged culture 21 . Adult cardiomyocyte morphology not only provides the structural framework of the cell but also directly establishes other critical functional properties of the cell such as electrophysiology and contractility.…”

“…Moreover, unlike studies of cell-lineage determination, we cannot rely on lessons from developmental biology to guide the maturation of hPSC-CMs (Box 1). Our knowledge of cardiac development at late gestation is limited 2,3 and stems principally from studies in animal models. Although a few pioneering studies on human late prenatal or early postnatal heart growth have been performed [4][5][6] , much of what we know about human heart maturation is formed on the basis of findings in vitro and in adult hearts.…”

Sustained Activation of AMPK Enhances Differentiation of Human iPSC-Derived Cardiomyocytes via Sirtuin Activation

“…Recent studies revealed the importance of metabolic pathways in cardiomyocyte maturation ( Horikoshi et al., 2019 ; Hu et al., 2018 ; Marchiano et al., 2019 ; Yang et al., 2019 ). AMPK is a master regulator of metabolism, yet its role during differentiation of iPSC-derived cardiomyocytes is not defined.…”

Retinoic acid promotes metabolic maturation of human Embryonic Stem Cell-derived Cardiomyocytes

“…As a single molecule, RA couldn't be expected to substantially induce hPSC-CM maturation like fully-developed cardiomyocytes isolated from adult heart, but it is an indispensable part of the orchestra. With the enrichment of the orchestra by different stimuli, including electromechanical stimulation, patterned biomaterials, developmental signal manipulation, metabolic stimulation and so on, fully mature cardiomyocytes might be obtained from hPSCs in the future 9 , 10 , 63 , 64 .…”