Human-induced pluripotent stem cell-derived cardiomyocytes exhibit temporal changes in phenotype

Abstract

Human-induced pluripotent stem cell-derived cardiomyocytes (hiPS-CMs) have been recently derived and are used for basic research, cardiotoxicity assessment, and phenotypic screening. However, the hiPS-CM phenotype is dependent on their derivation, age, and culture conditions, and there is disagreement as to what constitutes a functional hiPS-CM. The aim of the present study is to characterize the temporal changes in hiPS-CM phenotype by examining five determinants of cardiomyocyte function: gene expression, ion channel functionality, calcium cycling, metabolic activity, and responsiveness to cardioactive compounds. Based on both gene expression and electrophysiological properties, at day 30 of differentiation, hiPS-CMs are immature cells that, with time in culture, progressively develop a more mature phenotype without signs of dedifferentiation. This phenotype is characterized by adult-like gene expression patterns, action potentials exhibiting ventricular atrial and nodal properties, coordinated calcium cycling and beating, suggesting the formation of a functional syncytium. Pharmacological responses to pathological (endothelin-1), physiological (IGF-1), and autonomic (isoproterenol) stimuli similar to those characteristic of isolated adult cardiac myocytes are present in maturing hiPS-CMs. In addition, thyroid hormone treatment of hiPS-CMs attenuated the fetal gene expression in favor of a more adult-like pattern. Overall, hiPS-CMs progressively acquire functionality when maintained in culture for a prolonged period of time. The description of this evolving phenotype helps to identify optimal use of hiPS-CMs for a range of research applications.

Action Potential Characterization of Human Induced Pluripotent Stem Cell–Derived Cardiomyocytes Using Automated Patch-Clamp Technology

“…Color images available online at www.liebertpub.com/adt we have shown that whole-cell recordings with high GO seal resistances can be obtained reproducibly with the CytoPatch 2 equipment, and that cardiac AP can be induced and recorded, offering comparable results with those obtained in manual patch-clamp studies. 22,[28][29][30] In particular it is possible to characterize and quantify cell fractions in terms of the quantitative features of the AP, that is, to distinguish between atrial, nodal, and ventricular types of AP, and to determine the yield of successful recordings. In this respect, it was encouraging for us to find proportions of ventricular, atrial, and nodal CMs, according to AP morphology, [30][31][32][33] as well as quantitative AP parameters, 28,30-36 similar to those reported in previous electrophysiology studies on stem-cell-derived CM preparations.…”

Human Induced Pluripotent Stem Cell–Derived Cardiomyocytes

“…15, 52 By contrast, although the I Ca,T current has been found in a subset of cells, its properties have not defined. 55 …”

Human engineered heart tissue as a model system for drug testing

“…nodal CM[10]. These differences in ion channel expression between sam-205 ples from human ventricles and hiPSC-CM argue again for a mixed pop-206 ulation of ventricular, atrial and nodal-like CM after differentiation.…”