Slow conduction in mixed cultured strands of primary ventricular cells and stem cell-derived cardiomyocytes

Abstract

Modern concepts for the treatment of myocardial diseases focus on novel cell therapeutic strategies involving stem cell-derived cardiomyocytes (SCMs). However, functional integration of SCMs requires similar electrophysiological properties as primary cardiomyocytes (PCMs) and the ability to establish intercellular connections with host myocytes in order to contribute to the electrical and mechanical activity of the heart. The aim of this project was to investigate the properties of cardiac conduction in a co-culture approach using SCMs and PCMs in cultured cell strands. Murine embryonic SCMs were pooled with fetal ventricular cells and seeded in predefined proportions on microelectrode arrays to form patterned strands of mixed cells. Conduction velocity (CV) was measured during steady state pacing. SCM excitability was estimated from action potentials measured in single cells using the patch clamp technique. Experiments were complemented with computer simulations of conduction using a detailed model of cellular architecture in mixed cell strands. CV was significantly lower in strands composed purely of SCMs (5.5 ± 1.5 cm/s, n = 11) as compared to PCMs (34.9 ± 2.9 cm/s, n = 21) at similar refractoriness (100% SCMs: 122 ± 25 ms, n = 9; 100% PCMs: 139 ± 67 ms, n = 14). In mixed strands combining both cell types, CV was higher than in pure SCMs strands, but always lower than in 100% PCM strands. Computer simulations demonstrated that both intercellular coupling and electrical excitability limit CV. These data provide evidence that in cultures of murine ventricular cardiomyocytes, SCMs cannot restore CV to control levels resulting in slow conduction, which may lead to reentry circuits and arrhythmias.

The K219T-Lamin mutation induces conduction defects through epigenetic inhibition of SCN5A in human cardiac laminopathy

“…Along this line, conduction velocities (CVs) were significantly decreased in confluent strands of K219T-CMs. As expected, most likely because of the fetal-like maturation stage of CMs differentiated from iPSCs 34 , CVs in CNTR multicellular strands (~100 mm/s) were found to be slower than the physiological CVs of neonatal CMs cultured on the same strands (~450 mm/s) or on anisotropic intact myocardial tissue (~600 mm/s); nonetheless, CVs recorded in our experiments were faster than those reported by others in multicellular preparations of stem cell-derived CMs (~50 mm/s) 33,57 . These differences are most likely due to different cellular excitabilities, the particular electrical coupling among the cells and the patterned geometry used for culturing confluent cells.…”

AAV-mediated expression of NFAT decoy oligonucleotides protects from cardiac hypertrophy and heart failure

“…Primary neonatal rat cardiomyocytes (NRVCMs) were isolated according to previously established protocols [ 22 ]. Experiments were executed under the guidelines from Directive 2010/63/EU of the European Parliament on the protection of animals used for scientific purposes with approval of the local authorities in Kiel (permission number 1085).…”

Substrate Stiffness Influences Structural and Functional Remodeling in Induced Pluripotent Stem Cell-Derived Cardiomyocytes

“…For functional integration of engineered myocardium in diseased adult hearts, adequate propagation of excitation across the cardiac tissue and graft is essential for coordinated impulse propagation. Slow and irregular electrical signal transmission in embryonic (ESC-) and iPSC-CMs caused by weak intercellular coupling poses a high risk for the development of a conduction barrier and arising arrhythmias (Shiba et al, 2012;Kucera et al, 2015;Sottas et al, 2018). In our experimental approach, we tested the hypothesis that growth surfaces with different stiffnesses affect cell-cell communication in iPSC-CMs by influencing the expression pattern of Cx43.…”

“…Since the expression pattern of Cx43 is not localized at specific end poles of the cell as known from adult cardiomyocytes, electrical signal propagation is not directed but diffuse and heterogeneous across the cell layer. In addition, reduced clustering of Cx43 results in significantly slower conduction velocity compared to native cardiomyocytes (Kucera et al, 2015;Marcu et al, 2015;Jiang et al, 2018;Sottas et al, 2018;Karbassi et al, 2020).…”