Abstract
In native conditions, cardiac cells must continuously comply with diverse stimuli necessitating a perpetual adaptation. Polydimethylsiloxane (PDMS) is commonly used in cell culture to study cellular response to changes in the mechanical environment. The aim of this study was to evaluate the impact of using PDMS substrates on the properties of spontaneous activity of cardiomyocyte monolayer cultures. We compared PDMS to the gold standard normally used in culture: a glass substrate. Although mean frequency of spontaneous activity remained unaltered, incidence of reentrant activity was significantly higher in samples cultured on glass compared to PDMS substrates. Higher spatial and temporal instability of the spontaneous rate activation was found when cardiomyocytes were cultured on PDMS, and correlated with decreased connexin-43 and increased CaV3.1 and HCN2 mRNA levels. Compared to cultures on glass, cultures on PDMS were associated with the strongest response to isoproterenol and acetylcholine. These results reveal the importance of carefully selecting the culture substrate for studies involving mechanical stimulation, especially for tissue engineering or pharmacological high-throughput screening of cardiac tissue analog.
Highlights
Cardiomyocytes are central to the electromechanical properties of the heart
The effect of substrate stiffness on spontaneous activity was first evaluated by videomicroscopy
We hypothesized that culturing on such elastomeric substrates affects the spontaneous activity of cultured neonatal rat ventricular cardiomyocyte (NRVM) monolayers, based on published studies illustrating the effect of the substrate properties on cardiomyocyte shape [41, 66, 67], calcium transient morphology [21], and spontaneous frequency of contraction [35, 68]
Summary
Cardiomyocytes are central to the electromechanical properties of the heart. Cardiac tissue can exhibit sensitivity to arrhythmias, which are complex spatiotemporal electrical activities. Dynamic electrical behaviors of cardiac tissue include normal propagation from pacemaker sites [1, 2], stable rotating spiral waves [3], unstable spiral waves that break up during propagation [4], and bursts of activity often associated with the initiation and termination of spiral waves [5]. Cardiomyocytes are electrically excitable; some exhibit spontaneous activity. Substrate-Dependent Instability of Spontaneous Activity in Monolayers heartandstroke.com/site/c.ikIQLcMWJtE/b.2796497/ k.BF8B/Home.htm] The authors would like to gratefully acknowledge the Réseau ThéCell [http://www.reseauthecell.qc.ca] B., J.E.D.) for his support during the realisation of this study
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