Spatiotemporal Stability of Neonatal Rat Cardiomyocyte Monolayers Spontaneous Activity Is Dependent on the Culture Substrate

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.在生理原生微环境中，心肌细胞必须持续响应各类刺激，以实现持续性的适应性调整。聚二甲基硅氧烷（Polydimethylsiloxane, PDMS）是细胞培养领域中常用于研究细胞对机械环境变化响应的材料。本研究旨在评估PDMS基底对单层心肌细胞培养物自发放电活动特性的影响，并将其与细胞培养的金标准——玻璃基底进行对比。尽管自发放电的平均频率未发生显著变化，但相较于PDMS基底，玻璃基底上培养的样本其折返活动发生率显著更高。当心肌细胞在PDMS基底上培养时，其自发放电激活的空间与时间不稳定性更高，且该现象与连接蛋白43（connexin-43）表达下调、CaV3.1及HCN2的mRNA水平上调显著相关。相较于玻璃基底上的细胞培养物，PDMS基底上的培养物对异丙肾上腺素与乙酰胆碱的响应更为强烈。上述研究结果表明，在涉及机械刺激的研究中，尤其是组织工程或心肌组织类似物的药物高通量筛选研究，谨慎选择培养基底具有重要意义。