Mathematical modelling of the action potential of human embryonic stem cell derived cardiomyocytes (original) (raw)
Related papers
Simulation of developmental changes in action potentials with ventricular cell models
Systems and synthetic biology, 2007
During cardiomyocyte development, early embryonic ventricular cells show spontaneous activity that disappears at a later stage. Dramatic changes in action potential are mediated by developmental changes in individual ionic currents. Hence, reconstruction of the individual ionic currents into an integrated mathematical model would lead to a better understanding of cardiomyocyte development. To simulate the action potential of the rodent ventricular cell at three representative developmental stages, quantitative changes in the ionic currents, pumps, exchangers, and sarcoplasmic reticulum (SR) Ca(2+) kinetics were represented as relative activities, which were multiplied by conductance or conversion factors for individual ionic systems. The simulated action potential of the early embryonic ventricular cell model exhibited spontaneous activity, which ceased in the simulated action potential of the late embryonic and neonatal ventricular cell models. The simulations with our models were ...
Mechanism of spontaneous excitability in human embryonic stem cell derived cardiomyocytes
The Journal of Physiology, 2004
Human embryonic stem cell-derived cardiomyocytes (hES-CMs) are thought to recapitulate the embryonic development of heart cells. Given the exciting potential of hES-CMs as replacement tissue in diseased hearts, we investigated the pharmacological sensitivity and ionic current of mid-stage hES-CMs (20-35 days post plating). A high-resolution microelectrode array was used to assess conduction in multicellular preparations of hES-CMs in spontaneously contracting embryoid bodies (EBs). TTX (10 µM) dramatically slowed conduction velocity from 5.1 to 3.2 cm s −1 while 100 µM TTX caused complete cessation of spontaneous electrical activity in all EBs studied. In contrast, the Ca 2+ channel blockers nifedipine or diltiazem (1 µM) had a negligible effect on conduction. These results suggested a prominent Na + channel current, and therefore we patch-clamped isolated cells to record Na + current and action potentials (APs). We found for isolated hES-CMs a prominent Na + current (244 ± 42 pA pF −1 at 0 mV; n = 19), and a hyperpolarization-activated current (HCN), but no inward rectifier K + current. In cell clusters, 3 µM TTX induced longer AP interpulse intervals and 10 µM TTX caused cessation of spontaneous APs. In contrast nifedipine (Ca 2+ channel block) and 2 mM Cs + (HCN complete block) induced shorter AP interpulse intervals. In single cells, APs stimulated by current pulses had a maximum upstroke velocity (dV /dt max ) of 118 ± 14 V s −1 in control conditions; in contrast, partial block of Na + current significantly reduced stimulated dV /dt max (38 ± 15 V s −1 ). RT-PCR revealed Na V 1.5, Ca V 1.2, and HCN-2 expression but we could not detect Kir2.1. We conclude that hES-CMs at mid-range development express prominent Na + current. The absence of background K + current creates conditions for spontaneous activity that is sensitive to TTX in the same range of partial block of Na V 1.5; thus, the Na V 1.5 Na + channel is important for initiating spontaneous excitability in hES-derived heart cells.
Annals of Biomedical Engineering, 2013
The clear importance of human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CMs) as an in-vitro model highlights the relevance of studying these cells and their function also in-silico. Moreover, the phenotypical differences between the hiPSC-CM and adult myocyte action potentials (APs) call for understanding of how hiPSC-CMs are maturing towards adult myocytes. Using recently published experimental data, we developed two computational models of the hiPSC-CM AP, distinguishing between the ventricular-like and atrial-like phenotypes, emerging during the differentiation process of hiPSC-CMs. Also, we used the computational approach to quantitatively assess the role of ionic mechanisms which are likely responsible for the not completely mature phenotype of hiPSC-CMs. Our models reproduce the typical hiPSC-CM ventricular-like and atriallike spontaneous APs and the response to prototypical current blockers, namely tetrodotoxine, nifedipine, E4041 and 3R4S-Chromanol 293B. Moreover, simulations using our ventricular-like model suggest that the interplay of immature I Na , I f and I K1 currents has a fundamental role in the hiPSC-CM spontaneous beating whereas a negative shift in I CaL activation causes the observed long lasting AP. In conclusion, this work provides two novel tools useful in investigating the electrophysiological features of hiPSC-CMs, whose importance is growing fast as in-vitro models for pharmacological studies.
2010
Human embryonic stem cell-derived cardiomyocytes (hES-CMs) represent a promising tool for cell therapy and drug screening. We developed a hES-CM mathematical model based on data acquired with electrophysiological and RT-PCR techniques. Coupling with modelled fibroblasts was assessed too. hES-CM model reproduced satisfactorily most of the action potential (AP) features. Coupling with fibroblasts shows an increment of slope of diastolic depolarization and beating frequency and reduction of the AP peak. These results suggest that our novel mathematical model can serve as a predictive approach to interpret and refine in-vitro experiments on hES-CMs.
Frontiers in physiology, 2017
Human induced pluripotent stem cell derived cardiomyocytes (iPSC-CMs) have applications in disease modeling, cell therapy, drug screening and personalized medicine. Computational models can be used to interpret experimental findings in iPSC-CMs, provide mechanistic insights, and translate these findings to adult cardiomyocyte (CM) electrophysiology. However, different cell lines display different expression of ion channels, pumps and receptors, and show differences in electrophysiology. In this exploratory study, we use a mathematical model based on iPSC-CMs from Cellular Dynamic International (CDI, iCell), and compare its predictions to novel experimental recordings made with the Axiogenesis Cor.4U line. We show that tailoring this model to the specific cell line, even using limited data and a relatively simple approach, leads to improved predictions of baseline behavior and response to drugs. This demonstrates the need and the feasibility to tailor models to individual cell lines,...
Biophysical Journal, 2009
The International Stem Cell Initiative characterized 59 human embryonic stem cell lines from 17 laboratories worldwide. Despite diverse genotypes and different techniques used for derivation and maintenance, all lines exhibited similar expression patterns for several markers of human embryonic stem cells. They expressed the glycolipid antigens SSEA3 and SSEA4, the keratan sulfate antigens TRA-1-60, TRA-1-81, GCTM2 and GCT343, and the protein antigens CD9, Thy1 (also known as CD90), tissue-nonspecific alkaline phosphatase and class 1 HLA, as well as the strongly developmentally regulated genes NANOG, POU5F1 (formerly known as OCT4), TDGF1, DNMT3B, GABRB3 and GDF3. Nevertheless, the lines were not identical: differences in expression of several lineage markers were evident, and several imprinted genes showed generally similar allelespecific expression patterns, but some gene-dependent variation was observed. Also, some female lines expressed readily detectable levels of XIST whereas others did not. No significant contamination of the lines with mycoplasma, bacteria or cytopathic viruses was detected.
Outwards currents in embryonic stem cell-derived cardiomyocytes
Pflügers Archiv, 2000
The aim of the present study was to investigate the expression and functional role of outwards currents during the early stages of cardiomyogenesis. The predominant repolarizing current in early-stage, embryonic stem (ES) cell-derived cardiomyocytes was a 4aminopyridine (4-AP) sensitive [concentration for halfmaximal inhibition (IC 50) 1.7 mM], transient outward current (I to) with a current density of 10.3±2.1 pA/pF (n=72). We observed two additional, rapidly activating, outwardly rectifying current components, I K,sus and I res , in early-and late-stage cardiomyocytes. These currents were characterized by slow and no inactivation, respectively, during the depolarizing voltage step. I K,sus was detected in about 25% of cells investigated and displayed 4-AP hypersensitivity (IC 50 29 µM), whereas I res was found in all cells of both differentiation stages and was 4-AP insensitive. In contrast to early-stage cells, I res formed the larger portion of the aggregate, whole-cell current in late-stage, ES cell-derived cardiomyocytes. The current densities of all three current components increased during development, however, the most prominent increase was observed for I res from 3.6±0.8 pA/pF (n=72) to 8±1.1 pA/pF (n=35). In current-clamp recordings in early-stage, spontaneously contracting cardiomyocytes, 4-AP depolarized the cells, lengthened the action potential duration (APD) and increased the action potential frequency. In late-stage cells 4-AP had no effect on action potential frequency. We conclude that in early-stage cardiomyocytes I to plays an important role in controlling electrical activity.
British Journal of Pharmacology
Two new technologies hold the promise to revolutionize cardiac safety and drug development: in vitro experiments on human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) and in silico human adult ventricular cardiomyocyte (hAdultV-CM) models. Their combination was recently proposed as a potential replacement for the present hERG-based QT study in safety pharmacology assessment. Here, we systematically compare in silico the effects of selective ionic current block on hiPSC-CM and hAdultV-CM action potentials (APs), to identify similarities/differences and to illustrate the potential of computational models as supportive tools for evaluating new in vitro technologies.
Mathematical Model of Mouse Embryonic Cardiomyocyte Excitation-Contraction Coupling
The Journal of General Physiology, 2008
Excitation–contraction (E–C) coupling is the mechanism that connects the electrical excitation with cardiomyocyte contraction. Embryonic cardiomyocytes are not only capable of generating action potential (AP)-induced Ca2+signals and contractions (E–C coupling), but they also can induce spontaneous pacemaking activity. The spontaneous activity originates from spontaneous Ca2+releases from the sarcoplasmic reticulum (SR), which trigger APs via the Na+/Ca2+exchanger (NCX). In the AP-driven mode, an external stimulus triggers an AP and activates voltage-activated Ca2+intrusion to the cell. These complex and unique features of the embryonic cardiomyocyte pacemaking and E–C coupling have never been assessed with mathematical modeling. Here, we suggest a novel mathematical model explaining how both of these mechanisms can coexist in the same embryonic cardiomyocytes. In addition to experimentally characterized ion currents, the model includes novel heterogeneous cytosolic Ca2+dynamics and ...
Successes and failures in modeling heart cell electrophysiology
Mathematical models of the electrical activity of the heart using equations for protein ion channels and other transporters began with the Noble 1962 model. These models then developed over a period of about 50 years. Cell types in all regions have been modeled and now are available for download from the CellML website (www.cellml.org). Simulation is a necessary tool of analysis in attempting to understand biological complexity. We often learn as much from the failures as from the successes of mathe-matical models. It is the iterative interaction between experiment and simulation that is important.