Global transcriptional profiles of beating clusters derived from human induced pluripotent stem cells and embryonic stem cells are highly similar

<p>Abstract</p> <p>Background</p> <p>Functional and molecular integrity of cardiomyocytes (CMs) derived from induced pluripotent stem (iPS) cells is essential for their use in tissue repair, disease modelling and drug screening. In this study we compared global transcriptomes of beating clusters (BCs) microdissected from differentiating human iPS cells and embryonic stem (ES) cells.</p> <p>Results</p> <p>Hierarchical clustering and principal component analysis revealed that iPS-BCs and ES-BCs cluster together, are similarly enriched for cardiospecific genes and differ in expression of only 1.9% of present transcripts. Similarly, sarcomeric organization, electrophysiological properties and calcium handling of iPS-CMs were indistinguishable from those of ES-CMs. Gene ontology analysis revealed that among 204 genes that were upregulated in iPS-BCs vs ES-BCs the processes related to extracellular matrix, cell adhesion and tissue development were overrepresented. Interestingly, 47 of 106 genes that were upregulated in undifferentiated iPS vs ES cells remained enriched in iPS-BCs vs ES-BCs. Most of these genes were found to be highly expressed in fibroblasts used for reprogramming and 34% overlapped with the recently reported iPS cell-enriched genes.</p> <p>Conclusions</p> <p>These data suggest that iPS-BCs are transcriptionally highly similar to ES-BCs. However, iPS-BCs appear to share some somatic cell signature with undifferentiated iPS cells. Thus, iPS-BCs may not be perfectly identical to ES-BCs. These minor differences in the expression profiles may occur due to differential cellular composition of iPS-BCs and ES-BCs, due to retention of some genetic profile of somatic cells in differentiated iPS cell-derivatives, or both.</p

Macromarketing Pedagogy:Empowering Students to Achieve a Sustainable World

The United Nation's Sustainable Development Goals (SDGs) are challenging the world to work towards a more sustainable future. Its 17 goals are ambitious, requiring concerted and system-based efforts driven by critical and socially aware thinking. However, marketing education is largely falling short of teaching students to think that way. Given macromarketing's unique perspective on the interactions among markets, marketing, and society, macromarketers are poised to contribute to marketing pedagogy and to commit students to realizing the SDGs. This article first looks back at the previous 40 years of macromarketing pedagogy, before offering contemporary approaches to teaching macromarketing through four illustrative case studies found in an online repository called Pedagogy Place. It then looks forward, setting an aspiring vision for macro-oriented classrooms in the coming years

Modulation of L-type Calcium Current by Intracellular Magnesium in Differentiating Cardiomyocytes Derived from Induced Pluripotent Stem Cells

Intracellular Mg2+, which is implicated in arrhythmogenesis and transient cardiac ischemia, inhibits L-type Ca2+ calcium channel current (I-CaL) of adult cardiomyocytes (CMs). We take the advantage of an in vitro model of CMs based on induced pluripotent stem cells to investigate the effects of intracellular Mg2+ on the phosphorylation or dephosphorylation processes of L-type Ca2+ channels (LTCCs) at early and late stages of cardiac cell differentiation. Using the whole-cell patch-clamp technique, we demonstrate that increasing intracellular Mg2+ concentration [Mg2+](i) from 0.2 to 5mM markedly reduced the peak of I-CaL density, showing less effect on both the activation and inactivation properties in the late differentiation stage (LDS) of CMs more so than in the early differentiation stage (EDS). Increasing the [Mg2+](i) from 0.2 to 2mM in the presence of cAMP-dependent protein kinase A significantly decreased I-CaL in LDS (70%) and in EDS (36%) CMs. In addition, the effect of forskolin was greatly attenuated in the presence of 2mM [Mg2+](i) in LDS but not in EDS CMs. The effect of forskolin was enhanced in the presence of ATP-gamma-S in LDS CMs compared with EDS CMs. The exposure of both EDS and LDS CMs to 2mM [Mg2+](i) considerably reduced the effects of iso-butylmethylxanthine (IBMX) and okadaic acid on I-CaL. Our results provide evidence for differential regulation of LTCCs activities by cytosolic Mg2+ concentration in developing cardiac cells and confirm that Mg2+ acts under conditions that favor opening of the LTCCs caused by channel phosphorylation

The Effect of Antiarrhythmic Drugs on the Beat Rate Variability of Human Embryonic and Human Induced Pluripotent Stem Cell Derived Cardiomyocytes

Embryonic stem cell (ESC) derived tissue is a promising tool to be used in different clinical, preclinical and also scientific settings, for example as in vivo biological pacemaker, preclinical drug safety screening tool or ultimately as part of a cell replacement therapy. However, before ESC derived tissue can be used routinely for these purposes in humans, further studies are needed. In this context, the aims of the present study were to examine the effect of antiarrhythmic drugs on human ESC (hESC) und human induced pluripotent stem cell (hiPSC) derived cardiomyocytes by analyzing the beat rate variability (BRV), which can be considered as the in vitro equivalent of the heart rate variability (HRV) in vivo. Short-term recordings of extracellular field potentials of spontaneously beating cardiomyocytes derived from hESCs and hiPSCs were made using Microelectrode Arrays (MEA). The effect of Flecainide, Ivabradine and Metoprolol was tested. The offline analysis of the BRV was mainly focused on time domain methods. Additionally a non-linear analysis method was used. The evaluation of the Poincare-Plots of the measurements without pharmacological intervention revealed that the vast majority of the scatter plots have a similar, ellipsoid shape. Flecainide and Ivabradine influenced BRV parameters significantly, whereas Metoprolol did not alter the BRV markedly. We detected remarkable similarities between the BRV of hESC and hiPSC derived cardiomyocytes in vitro and the HRV in vivo. The effect of antiarrhythmic drugs on spontaneously beating cardiomyocytes derived from hESC and hiPSC was generally consistent with clinical experiences and also with our previous study based on murine ESC derived cardiomyocytes. In conclusion, our study points out the great potential of hESC and hiPSC derived tissue to be used routinely for many different applications in medicine and science

Modeling genetic cardiac channelopathies using induced pluripotent stem cells - Status quo from an electrophysiological perspective

Long QT syndrome (LQTS), Brugada syndrome (BrS), and catecholaminergic polymorphic ventricular tachycardia (CPVT) are genetic diseases of the heart caused by mutations in specific cardiac ion channels and are characterized by paroxysmal arrhythmias, which can deteriorate into ventricular fibrillation. In LQTS3 and BrS different mutations in the SCN5A gene lead to a gain-or a loss-of-function of the voltage-gated sodium channel Nav1.5, respectively. Although sharing the same gene mutation, these syndromes are characterized by different clinical manifestations and functional perturbations and in some cases even present an overlapping clinical phenotype. Several studies have shown that Na(+ )current abnormalities in LQTS3 and BrS can also cause Ca2+-signaling aberrancies in cardiomyocytes (CMs). Abnormal Ca2+ homeostasis is also the main feature of CPVT which is mostly caused by heterozygous mutations in the RyR2 gene. Large numbers of disease-causing mutations were identified in RyR2 and SCN5A but it is not clear how different variants in the SCN5A gene produce different clinical syndromes and if in CPVT Ca2+ abnormalities and drug sensitivities vary depending on the mutation site in the RyR2. These questions can now be addressed by using patient-specific in vitro models of these diseases based on induced pluripotent stem cells (iPSCs). In this review, we summarize different insights gained from these models with a focus on electrophysiological perturbations caused by different ion channel mutations and discuss how will this knowledge help develop better stratification and more efficient personalized therapies for these patients

The influence of melatonin on the heart rhythm - An in vitro simulation with murine embryonic stem cell derived cardiomyocytes

Background: In healthy individuals, a major factor influencing the heart rate variability (HRV) is the circadian rhythm. The role of melatonin as an essential component of the circadian rhythm in the adult human organism and the beneficial effects of a treatment with melatonin during the fetal period is well described. Toxic effects of melatonin are discussed less frequently. Since pharmacological studies cannot be carried out on pregnant women, the establishment of an equivalent in vitro model is important. We therefore tested whether melatonin can influence the beat rate variability (BRV) of spontaneously beating cardiomyocytes derived from murine embryonic stem cells (mESCs) and whether melatonin exhibits toxic effects in this in vitro model. Methods: Microelectrode Arrays recorded extracellular field potentials of spontaneously beating cardiomyocytes. Melatonin was applied in a concentration range from 10(-11) M to 10(-5) M. The analysis of the BRV focused on time domain methods. Results: In line with clinical observations, melatonin decreased the beating frequency and increased the BRV. The effect of melatonin up to a concentration of 10(-)(6) M was reversible, whereas the application of higher concentrations induced an irreversible effect. Conclusion: The study underlines the potential of this in vitro model to help explore the development of circadian rhythms and their modulation by melatonin in the embryonic phase. The results imply that melatonin influences the heart rhythm as early as during the embryonic heart development. Furthermore, the results indicate a potentially toxic effect of melatonin that has not been described in detail before