The intestinal environment is unique because it supports the intestinal epithelial cells under a normal oxygen environment and the microbiota under an anoxic environment. Due to importance of understanding the interactions between the epithelium and the microbiota, there is a strong need for developing representative and simple experimental models. Current approaches do not capture the dual-oxygen environment, require external anaerobic chambers, or are complex. Another major limitation is that in the solutions that can mimic the dual-oxygen environment, the oxygenation level of the epithelial cells is not known, raising the question whether the cells are hypoxic. We report standalone microfluidic devices that form a dual-oxygen environment without the use of an external anaerobic chamber or oxygen scavengers to coculture intestinal epithelial and bacterial cells. By changing the thickness of the device cover, the oxygen tension in the chamber could be modulated. We verified the oxygen levels using several tests: microscale oxygen sensitive sensors incorporated within the devices, hypoxic immunostaining of Caco-2 cells, and genetically encoded bacteria. Collectively, these methods monitored oxygen concentrations in devices more comprehensively than previous reports and allowed for control of oxygen tension to match the requirements of both intestinal cells and anaerobic bacteria. Our experimental model is supported by the mathematical model that considers diffusion of oxygen into the top chamber and the cellular oxygen consumption rate. This allowed us to experimentally determine the oxygen consumption rate of the epithelial cells more precisely.

中文翻译：

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一种新型的独立微流控装置，用于局部控制肠道细菌相互作用的氧张力。

肠道环境是独特的，因为它在正常氧气环境下支持肠道上皮细胞，而在缺氧环境下则支持微生物群。由于了解上皮细胞与微生物群之间相互作用的重要性，因此非常需要开发具有代表性的简单实验模型。当前的方法不能捕获双氧环境，需要外部厌氧室，或者很复杂。另一个主要局限性在于，在可以模拟双氧环境的溶液中，上皮细胞的氧合水平尚不清楚，这引发了细胞是否缺氧的问题。我们报告独立的微流控设备，形成双氧环境，而无需使用外部厌氧室或除氧剂来共培养肠上皮和细菌细胞。通过改变设备盖的厚度，可以调节腔室中的氧气张力。我们使用几种测试验证了氧气水平：设备中内置的微型氧气敏感传感器，Caco-2细胞的低氧免疫染色以及遗传编码的细菌。总体而言，这些方法比以前的报告更全面地监测设备中的氧气浓度，并允许控制氧气张力以匹配肠细胞和厌氧细菌的需求。我们的实验模型得到了数学模型的支持，该数学模型考虑了氧气向顶室的扩散和细胞耗氧率。这使我们能够通过实验更精确地确定上皮细胞的耗氧率。