Abstract
BackgroundCardiac cell lines and primary cells are widely used in cardiovascular research. Despite increasing number of publications using these models, comparative characterization of these cell lines has not been performed, therefore, their limitations are undetermined. We aimed to compare cardiac cell lines to primary cardiomyocytes and to mature cardiac tissues in a systematic manner. Methods and resultsCardiac cell lines (H9C2, AC16, HL-1) were differentiated with widely used protocols. Left ventricular tissue, neonatal primary cardiomyocytes, and human induced pluripotent stem cell-derived cardiomyocytes served as reference tissue or cells. RNA expression of cardiac markers (e.g. Tnnt2, Ryr2) was markedly lower in cell lines compared to references. Differentiation induced increase in cardiac- and decrease in embryonic markers however, the overall transcriptomic profile and annotation to relevant biological processes showed consistently less pronounced cardiac phenotype in all cell lines in comparison to the corresponding references. Immunocytochemistry confirmed low expressions of structural protein sarcomeric alpha-actinin, troponin I and caveolin-3 in cell lines. Susceptibility of cell lines to sI/R injury in terms of viability as well as mitochondrial polarization differed from the primary cells irrespective of their degree of differentiation. ConclusionExpression patterns of cardiomyocyte markers and whole transcriptomic profile, as well as response to sI/R, and to hypertrophic stimuli indicate low-to-moderate similarity of cell lines to primary cells/cardiac tissues regardless their differentiation. Low resemblance of cell lines to mature adult cardiac tissue limits their potential use. Low translational value should be taken into account while choosing a particular cell line to model cardiomyocytes.
Highlights
The number of publications on pathologies of cardiac cells including myocardial infarction, heart failure or cardiomyopathies are increasing, since these conditions are the leading cause of death in developed countries
In cells with human origin, i.e., AC16 and hiPSC-CMs, mRNA expression of elements of the contractile machinery and ryanodine receptor-1 and 2 showed a 50% to 8-fold decrease as compared to the expression levels observed in healthy adult cardiac samples
Expression of tran scription factors Nkx2.5, Gata4, Gata6 and Nr2f2 in hiPSC-CMs was comparable to the expression level in left ventricular samples, AC16 cells showed a significantly different expression pattern, which was influenced by differentiation only in case of Nr2f2 (Fig. 3A)
Summary
The number of publications on pathologies of cardiac cells including myocardial infarction, heart failure or cardiomyopathies are increasing, since these conditions are the leading cause of death in developed countries. Isolated murine adult and neonatal primary cardiomyocytes have been the most widely used models to study cardiac biology in vitro, but their use is somewhat limited due to the limited lifespan in culture, the need for high number of animals and the limited possibilities of genetic manipulations [1]. Despite increasing number of publications using these models, comparative characterization of these cell lines has not been per formed, their limitations are undetermined. Differentiation induced increase in cardiac- and decrease in embryonic markers the overall transcriptomic profile and annotation to relevant biological processes showed consistently less pronounced cardiac phenotype in all cell lines in comparison to the corresponding references. Conclusion: Expression patterns of cardiomyocyte markers and whole transcriptomic profile, as well as response to sI/R, and to hypertrophic stimuli indicate low-to-moderate similarity of cell lines to primary cells/cardiac
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