Laboratory for Living Systems Engineering, Department of Biomedical Engineering, USC Viterbi School of Engineering, University of Southern California, Los Angeles, CA 90089, USA.
Ming Hsieh Department of Electrical Engineering, USC Viterbi School of Engineering, University of Southern California, Los Angeles, CA 90089, USA.
Lab Chip. 2021 Feb 23;21(4):674-687. doi: 10.1039/d0lc00948b.
Controlled electrical stimulation is essential for evaluating the physiology of cardiac tissues engineered in heart-on-a-chip devices. However, existing stimulation techniques, such as external platinum electrodes or opaque microelectrode arrays patterned on glass substrates, have limited throughput, reproducibility, or compatibility with other desirable features of heart-on-a-chip systems, such as the use of tunable culture substrates, imaging accessibility, or enclosure in a microfluidic device. In this study, indium tin oxide (ITO), a conductive, semi-transparent, and biocompatible material, was deposited onto glass and polydimethylsiloxane (PDMS)-coated coverslips as parallel or point stimulation electrodes using laser-cut tape masks. ITO caused substrate discoloration but did not prevent brightfield imaging. ITO-patterned substrates were microcontact printed with arrayed lines of fibronectin and seeded with neonatal rat ventricular myocytes, which assembled into aligned cardiac tissues. ITO deposited as parallel or point electrodes was connected to an external stimulator and used to successfully stimulate micropatterned cardiac tissues to generate calcium transients or propagating calcium waves, respectively. ITO electrodes were also integrated into the cantilever-based muscular thin film (MTF) assay to stimulate and quantify the contraction of micropatterned cardiac tissues. To demonstrate the potential for multiple ITO electrodes to be integrated into larger, multiplexed systems, two sets of ITO electrodes were deposited onto a single substrate and used to stimulate the contraction of distinct micropatterned cardiac tissues independently. Collectively, these approaches for integrating ITO electrodes into heart-on-a-chip devices are relatively facile, modular, and scalable and could have diverse applications in microphysiological systems of excitable tissues.
电刺激控制对于评估在芯片心脏器件中构建的心肌组织的生理学功能至关重要。然而，现有的刺激技术，如外部铂电极或在玻璃基底上形成的不透明微电极阵列，其通量、重现性或与芯片心脏系统的其他理想特性（如可调谐培养基底、成像可达性或微流控设备封装）的兼容性有限。在这项研究中，使用激光切割胶带掩模，将导电、半透明且生物相容的材料铟锡氧化物 (ITO) 沉积到玻璃和聚二甲基硅氧烷 (PDMS) 涂层盖玻片上，作为平行或点状刺激电极。ITO 会导致基底变色，但不影响明场成像。ITO 图案化基底通过微接触印刷阵列线的纤维连接蛋白并接种新生大鼠心室肌细胞，这些细胞组装成排列整齐的心肌组织。将 ITO 沉积为平行或点状电极与外部刺激器连接，并成功地用于刺激微图案化心肌组织，分别产生钙瞬变或传播的钙波。ITO 电极也被集成到基于悬臂梁的肌薄型（MTF）检测中，以刺激和量化微图案化心肌组织的收缩。为了证明将多个 ITO 电极集成到更大的、复用系统中的潜力，将两套 ITO 电极沉积到单个基底上，并分别用于独立刺激不同微图案化心肌组织的收缩。总的来说，这些将 ITO 电极集成到芯片心脏器件中的方法相对简单、模块化且可扩展，并且可能在可兴奋组织的微生理系统中有多种应用。
