La cardiomyopathie associée à la DMD est une atteinte pour laquelle il n’existe pas actuellement de traitement. Les cellules souches embryonnaires humaines (hES), par leurs propriétés d’autorenouvellement et de différenciation, sont envisagées comme outil thérapeutique. Pour une recherche sur l’implantation de cellules, il n’existait pas de modèle in vitro au long cours. Nous avons ainsi développé un modèle de culture organotypique de tranches de cœur dans lequel nous avons, plusieurs mois après transplantation, retrouvé les cellules hES greffées, différenciées en cardiomyocytes. Par ailleurs, nous avons optimisé la différenciation cardiaque pour améliorer le rendement en cardiomyocytes, en induisant la différenciation cardiaque et en cultivant les cellules hES en bioréacteur. Le modèle d’étude au long terme permettant le suivi des cellules greffées dérivées de cellules hES nous permettra de valider les premières étapes précédant les études in vivo dans des modèles pathologiques. / Cardiomyopathy associated with DMD is a frequent occurrence with no treatment. Human embryonic stem cells (hESC), because of their self-renew differentiation properties are the best candidates to cardiac cellular therapy. To investigate cells implantation, there was no long term in vitro model. Thus, we have developed an organotypic model of heart slices in which we have, several months after transplantation, found grafted hES cells with evidence of cardiac differentiation. In addition, we have optimised cardiac differentiation to improve cardiac yield, inducing cardiac differentiation and cultivating hES cells in bioreactors. During long term culture model allows the study of grafted hES cells, combines to hESC-derived cells in reasonable number and purity, will constitute validation of the first steps before in vivo studies in pathological models.

Aim: Isolated papillary muscles and enzymatically dissociated myocytes of guinea-pig hearts are routinely used for experimental cardiac research. The aim of our study is to investigate adult mammalian ventricular slices as an alternative preparation. Method: Vibratome cut ventricular slices (350 μm thick) were examined histologically and with 2-photon microscopy for fibre orientation. Intracellular action potentials were recorded with conventional glass microelectrodes, extracellular potentials were measured with tungsten platinum electrodes and multi-electrode arrays (MEA). Results: Dominant direction of fibre orientation was absent in vertical and horizontal transmural slices, but was longitudinal in tangential slices. Control action potential duration (APD90, 169.9 ± 4 ms) and drug effects on this parameter were similar to papillary muscles. The L-type Ca-channel blocker nifedipine shortened APD90 with a half maximal effective concentration (EC50) of 4.5 μM. The IKr blocker E4031 and neuroleptic drug risperidone prolonged APD90 with EC50 values of 31 nM and 0.67 μM, respectively. Mapping field potentials on multi-electrode arrays showed uniform spread of excitation with a mean conduction velocity of 0.47 m ⋅ s-1. Conclusion: Slices from adult mammalian hearts could become a useful routine model for electrophysiological and pharmacological research. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

Aim: Isolated papillary muscles and enzymatically dissociated myocytes of guinea-pig hearts are routinely used for experimental cardiac research. The aim of our study is to investigate adult mammalian ventricular slices as an alternative preparation. Method: Vibratome cut ventricular slices (350 μm thick) were examined histologically and with 2-photon microscopy for fibre orientation. Intracellular action potentials were recorded with conventional glass microelectrodes, extracellular potentials were measured with tungsten platinum electrodes and multi-electrode arrays (MEA). Results: Dominant direction of fibre orientation was absent in vertical and horizontal transmural slices, but was longitudinal in tangential slices. Control action potential duration (APD90, 169.9 ± 4 ms) and drug effects on this parameter were similar to papillary muscles. The L-type Ca-channel blocker nifedipine shortened APD90 with a half maximal effective concentration (EC50) of 4.5 μM. The IKr blocker E4031 and neuroleptic drug risperidone prolonged APD90 with EC50 values of 31 nM and 0.67 μM, respectively. Mapping field potentials on multi-electrode arrays showed uniform spread of excitation with a mean conduction velocity of 0.47 m ⋅ s-1. Conclusion: Slices from adult mammalian hearts could become a useful routine model for electrophysiological and pharmacological research. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.