Introduction: Human embryonic stem cell-derived cardiomyocytes (hESCM) represent a promising tool for cell therapy. Their functional properties must be assessed. Methods: We characterized hES-CM at their early stage of development (15-40 days) with electrophysiological, RT-PCR and modelling tools. The hES-CM action potential (AP) was simulated on the basis of the Ten Tusscher model of human adult ventricular cell, modified to incorporate all the experimentally assessed modifications of ionic currents; in particular the hyperpolarization-activated funny current was introduced following a Hodgkin-Huxley formulation with a single activation gate. This led to an in silico cell showing a spontaneous beating activity. Electrotonic coupling with one or more fibroblasts, modelled both as having an ohmic ( ¨passive ¨ ) membrane resistance or considering time and voltage-dependent (¨active ¨ ) currents, was simulated. Results: the uncoupled hES-CM model well fitted our experimental data in terms of APD (experimental 228+/-11; simulation 231 ms), Vmax (4216+/- 611; 4778 mV/s) and beating frequency (36+/-6; 35 bpm). MDP (-47+/-7; -79 mV), APA (63+/-5; 92 mV) and diastolic depolarization rate (DDR) (22+/-5; 13 mV/s) were out of range. Electrotonic coupling was assessed: fibroblast membrane potential was more and more similar to the hES-CM when increasing the coupling conductance. Coupling the hES-CM with 1 and 2 fibroblasts caused an increment of DDR (+4, +5 mV/s respectively) and beating frequency (+3, +6 bpm) and a reduction of the AP peak (-0.4, -1.3 mV). While the correct AP features reproduced by the uncoupled model were preserved, coupling the hES-CM with 1 and 2 ¨active ¨ fibroblasts led to a better fit of DDR. Conclusions: these results suggest that our novel mathematical model can serve as a predictive approach to interpret and refine in-vitro experiments on hES-CM and that few coupled fibroblasts can significantly affect DDR while their influence on the AP amplitude is relatively small.
M. Paci, L. Sartiani, M. Jaconi, E. Cerbai, S. Severi (2010). Mathematical Modelling of Electrotonic Interaction between Stem Cell-Derived Cardiomyocytes and Fibroblasts.
Mathematical Modelling of Electrotonic Interaction between Stem Cell-Derived Cardiomyocytes and Fibroblasts
PACI, MICHELANGELO;SEVERI, STEFANO
2010
Abstract
Introduction: Human embryonic stem cell-derived cardiomyocytes (hESCM) represent a promising tool for cell therapy. Their functional properties must be assessed. Methods: We characterized hES-CM at their early stage of development (15-40 days) with electrophysiological, RT-PCR and modelling tools. The hES-CM action potential (AP) was simulated on the basis of the Ten Tusscher model of human adult ventricular cell, modified to incorporate all the experimentally assessed modifications of ionic currents; in particular the hyperpolarization-activated funny current was introduced following a Hodgkin-Huxley formulation with a single activation gate. This led to an in silico cell showing a spontaneous beating activity. Electrotonic coupling with one or more fibroblasts, modelled both as having an ohmic ( ¨passive ¨ ) membrane resistance or considering time and voltage-dependent (¨active ¨ ) currents, was simulated. Results: the uncoupled hES-CM model well fitted our experimental data in terms of APD (experimental 228+/-11; simulation 231 ms), Vmax (4216+/- 611; 4778 mV/s) and beating frequency (36+/-6; 35 bpm). MDP (-47+/-7; -79 mV), APA (63+/-5; 92 mV) and diastolic depolarization rate (DDR) (22+/-5; 13 mV/s) were out of range. Electrotonic coupling was assessed: fibroblast membrane potential was more and more similar to the hES-CM when increasing the coupling conductance. Coupling the hES-CM with 1 and 2 fibroblasts caused an increment of DDR (+4, +5 mV/s respectively) and beating frequency (+3, +6 bpm) and a reduction of the AP peak (-0.4, -1.3 mV). While the correct AP features reproduced by the uncoupled model were preserved, coupling the hES-CM with 1 and 2 ¨active ¨ fibroblasts led to a better fit of DDR. Conclusions: these results suggest that our novel mathematical model can serve as a predictive approach to interpret and refine in-vitro experiments on hES-CM and that few coupled fibroblasts can significantly affect DDR while their influence on the AP amplitude is relatively small.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
