Graduate School of Biomedical Engineering, Tohoku University, 6-6-12 Aramaki-Aza Aoba, Aoba-Ku, Sendai, Miyagi, 980-8579, Japan.
Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-Ku, Sendai, Miyagi, 980-8577, Japan.
Sci Rep. 2024 Nov 20;14(1):28730. doi: 10.1038/s41598-024-79625-3.
Inflammatory microenvironments often become acidic (pH < 7.4) due to tissue oxygen deprivation and lactate release in glycolysis by activated immune cells. Although neutrophils are known to accumulate in such microenvironments, the effects of pH on their migration are not fully understood. Here, we first investigated the pH control around cultured cells with a microfluidic device, which was equipped with two gas channels above three parallel media channels. By supplying gas mixtures with predefined carbon dioxide (CO) concentrations to the gas channels, the gas exchange adjusted the dissolved CO and affected the chemical equilibrium of sodium hydrogen carbonate in the cell culture medium. A pH gradient from 8.3 to 6.8 was generated along the media channels when gas mixtures containing 1% and 50% CO were supplied to the left and right gas channels, respectively. Neutrophil-like differentiated human promyelocytic leukemia cells (HL-60) were then seeded to the fibronectin-coated media channels and their migratory behaviors were quantified while varying the pH. The cell migration became more active and faster under high pH than under low pH conditions. However, no directional migration along the pH gradient was detected during the three-hour observation. Thus, the microfluidic device is useful to elucidate pH-dependent cellular dynamics.
炎症微环境通常由于组织缺氧和激活的免疫细胞糖酵解过程中乳酸的释放而变得酸性（pH < 7.4）。尽管已知中性粒细胞会在这种微环境中聚集，但 pH 对其迁移的影响尚未完全阐明。在这里，我们首先使用配备有两个气体通道的微流控装置研究了培养细胞周围的 pH 控制，该装置具有三个平行的介质通道上方的两个气体通道。通过将具有预定二氧化碳 (CO) 浓度的气体混合物供应到气体通道中，气体交换调节了溶解的 CO 并影响了细胞培养基中碳酸氢钠的化学平衡。当将包含 1%和 50% CO 的气体混合物分别供应到左侧和右侧气体通道时，在介质通道中产生了从 8.3 到 6.8 的 pH 梯度。然后将类似于中性粒细胞的分化人早幼粒细胞白血病细胞 (HL-60) 播种到纤连蛋白包被的介质通道中，并在不同 pH 值下定量它们的迁移行为。与低 pH 条件相比，高 pH 条件下细胞迁移更加活跃和快速。然而，在三个小时的观察过程中，没有检测到沿着 pH 梯度的定向迁移。因此，微流控装置可用于阐明 pH 依赖性细胞动力学。
