Department of Bioengineering, Lehigh University, Bethlehem, PA, USA.
Department of Neuroscience, Imaging, and Clinical Science, University G. D'Annuzio, Chieti-Pescara, Italy.
Anal Chim Acta. 2021 Aug 15;1173:338678. doi: 10.1016/j.aca.2021.338678. Epub 2021 May 25.
Oxidative stress (OS) is one of the leading causes of cytotoxicity and is linked to many human physio-pathological conditions. In particular, myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) induced by OS is debilitating to quality of life, while no clear biological markers have been identified for diagnostic measures. Recently, impedance measurements of peripheral blood cells of ME/CFS patients have been shown as a promising approach to diagnose the disease. Inspired by this study and aiming to interrogate muscle cells directly, we investigated if broadband measurements of single muscle cells could differentiate normal and oxidatively stressed cell populations. We first optimized a protocol through HO treatment to introduce oxidative stress to cultured rat L6 skeletal muscle cells. The treated cells were further characterized through broadband impedance spectroscopy of single cells using a microfluidic lab-on-a-chip system. The resulting dielectric properties of cytoplasm permittivity and conductivity are electrically distinct from normally cultured cells. The reflection and transmission coefficients, ΔS11 and ΔS21, of the normal cells are tightly clustered and closely resemble those of the cell-free solution across the frequency range of 9 kHz to 9 GHz. On the other hand, dielectric properties of the oxidized cells have a wide distribution in the GHz range, deviating both in the positive and negative directions from the normally cultured cells. Simulation results guide our hypothesis that the dielectric differences could be linked to ion alterations, while calcium imaging directly supports the contribution of calcium flux to the observed deviation of S parameters. The unique electrical profile associated with oxidized cells in the GHz frequencies provide a framework for future development of technologies to diagnose oxidative-stress related diseases such as ME/CFS.
氧化应激（OS）是细胞毒性的主要原因之一，与许多人类生理病理状况有关。特别是，OS 引起的肌痛性脑脊髓炎/慢性疲劳综合征（ME/CFS）对生活质量造成损害，而目前尚无明确的生物标志物可用于诊断措施。最近，ME/CFS 患者外周血细胞的阻抗测量已被证明是一种有前途的诊断方法。受此研究启发，我们旨在直接检测肌肉细胞，如果能够对单个肌肉细胞进行宽带测量，是否可以区分正常细胞和氧化应激细胞群体。我们首先通过 HO 处理优化了一个方案，以向培养的大鼠 L6 骨骼肌细胞引入氧化应激。然后使用微流控片上实验室系统对单个细胞进行宽带阻抗谱测量，进一步对处理后的细胞进行特性分析。细胞质介电常数和电导率的介电特性与正常培养的细胞在电学上有明显区别。正常细胞的反射和传输系数ΔS11 和 ΔS21 在 9 kHz 至 9 GHz 的频率范围内紧密聚集，与无细胞溶液的相似。另一方面，氧化细胞的介电特性在 GHz 范围内分布广泛，在正方向和负方向都偏离正常培养的细胞。仿真结果验证了我们的假设，即介电差异可能与离子变化有关，而钙成像直接支持钙通量对观察到的 S 参数偏差的贡献。与氧化细胞相关的独特电特性在 GHz 频率范围内为未来开发用于诊断 ME/CFS 等与氧化应激相关疾病的技术提供了框架。
