The relationship between the mechanical forces associated with bowel movement and colonic mucosal physiology is understudied. This is partly due to the limited availability of physiologically relevant fecal models that can exert these mechanical stimuli in colon models in a simple-to-implement manner. In this report, we created a mucus-coated fecal surrogate that was magnetically propelled to produce a controllable sweeping mechanical stimulation on primary intestinal epithelial cell monolayers. The mucus layer was derived from purified porcine stomach mucins, which were first modified with reactive vinyl sulfone (VS) groups followed by reaction with a thiol crosslinker (PEG-4SH) via a Michael addition click reaction. Formation of mucus hydrogel network was achieved at the optimal mixing ratio at 2.5 % w/v mucin-VS and 0.5 % w/v PEG-4SH. The artificial mucus layer possessed similar properties as the native mucus in terms of its storage modulus (66 Pa) and barrier function (resistance to penetration by 1-μm microbeads). This soft, but mechanically resilient mucus layer was covalently linked to a stiff fecal hydrogel surrogate (based on agarose and magnetic particles, with a storage modulus of 4600 Pa). The covalent bonding between the mucus and agarose ensured its stability in the subsequent fecal sliding movement when tested at travel distances as long as 203 m. The mucus layer served as a lubricant and protected epithelial cells from the moving fecal surrogate over a 1 h time without cell damage. To demonstrate its utility, this mucus-coated fecal surrogate was used to mechanically stimulate a fully differentiated, primary colon epithelium, and the physiological stimulated response of mucin-2 (MUC2), interleukin-8 (IL-8) and serotonin (5HT) secretion was quantified. Compared with a static control, mechanical stimulation caused a significant increase in MUC2 secretion into luminal compartment (6.4 × ), a small but significant increase in IL-8 secretion (2.5 × and 3.5 × , at both luminal and basal compartments, respectively), and no detectable alteration in 5HT secretion. This mucus-coated fecal surrogate is expected to be useful in colon organ-on-chips and microphysiological systems to facilitate the investigation of feces-induced mechanical stimulation on intestinal physiology and pathology.

中文翻译：

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涂有粘液、磁力驱动的粪便替代品可模拟粪便对结肠上皮的剪切力


与排便相关的机械力和结肠粘膜生理学之间的关系尚未得到充分研究。这部分是由于生理相关粪便模型的可用性有限，这些模型可以以易于实施的方式在结肠模型中施加这些机械刺激。在本报告中，我们创建了一种涂有粘液的粪便替代物，它通过磁力推动对原代肠上皮细胞单层产生可控的扫频机械刺激。粘液层源自纯化的猪胃粘蛋白，首先用反应性乙烯基砜 (VS) 基团进行修饰，然后通过迈克尔加成点击反应与硫醇交联剂 (PEG-4SH) 进行反应。以 2.5% w/v mucin-VS 和 0.5% w/v PEG-4SH 的最佳混合比例实现了粘液水凝胶网络的形成。人造粘液层在储能模量 (66 Pa) 和屏障功能（抵抗 1 μm 微珠渗透）方面具有与天然粘液相似的特性。这种柔软但具有机械弹性的粘液层与坚硬的粪便水凝胶替代物（基于琼脂糖和磁性颗粒，储能模量为 4600 Pa）共价连接。在长达 203 m 的行程测试中，粘液和琼脂糖之间的共价键确保了其在随后的粪便滑动运动中的稳定性。粘液层充当润滑剂，在 1 小时内保护上皮细胞免受移动粪便替代物的影响，而不会造成细胞损伤。为了证明其实用性，这种粘液包被的粪便替代物被用来机械刺激完全分化的初级结肠上皮，以及粘蛋白-2 (MUC2)、白细胞介素-8 (IL-8) 和血清素 (5HT) 的生理刺激反应分泌量被量化。 与静态对照相比，机械刺激导致腔室中 MUC2 分泌显着增加 (6.4 ×)，IL-8 分泌小幅但显着增加 (腔室和基底室分别为 2.5 × 和 3.5 ×)， 5HT 分泌没有可检测到的变化。这种涂有粘液的粪便替代品预计可用于结肠器官芯片和微生理系统，以促进粪便诱导的机械刺激对肠道生理学和病理学的研究。