The stem cell niche at the perivascular space in human tissue plays a pivotal role in dictating the overall fate of stem cells living within. Mesenchymal stem cells (MSCs), in particular, experience mutable microenvironmental conditions, which induce specific metabolic profiles with effects on processes such as cell differentiation and dysregulation of the immunomodulatory funtion. Reports specifically focusing on the metabolic status of MSCs under the effect of pathophysiological stimuli; in terms of flow velocities, shear stresses or oxygen tension; do not reproducce the gradients in these field variables, arousing the need of more advanced models reproducing the metabolic niche. Organ on a chip technology offers the most advanced tools for stem cell niche modelling thus allowing for controlled dynamic culture conditions while profiling tunable oxygen tension gradients. However, current systems for live cell detection of metabolic activity inside microfluidic devices require the integration of microsensors which allow for extracellular measurments only, giving innacurate and indirect information about the metabolic state of cells. Here, we present a metabolic toolbox coupling a miniatuirzed in vitro system for human-MSCs (h-MSCs) dynamic culture, that mimics the in vivo scenario of the perivascular niche, with high-resolution imaging of intracellular metabolism. Using Fluorescence Lifetime Imaging Microscopy (FLIM) we were able to monitor the spatial metabolic machinery and correlate it with the measured cells oxygen uptake activity after tuning the oxygen tension decay along the fluidic chamber by in silico models prediction. Our platform allows for the generation of a metabolic profile in MSC mimicking the physiological niche in space and time, and its real-time monitoring representing a functional tool for modelling perivascular niches, relevant diseases and metabolic-related uptake of pharmaceuticals.

中文翻译：

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血管周围生境芯片上的间充质干细胞代谢的无细胞内标记检测

人组织中血管周围空间的干细胞生态位在决定生活在其中的干细胞的整体命运方面起着关键作用。间充质干细胞（MSC）尤其会经历可变的微环境条件，该条件会诱导特定的代谢谱，从而影响诸如细胞分化和免疫调节功能失调等过程。报告专门研究了在病理生理刺激作用下MSC的代谢状态；在流速，剪切应力或氧气张力方面；不能重现这些场变量的梯度，因此需要更高级的模型来重现代谢位。芯片上的器官技术为干细胞生态位建模提供了最先进的工具，因此可以控制动态培养条件，同时描绘出可调节的氧气张力梯度。但是，当前用于活细胞检测微流体装置内部代谢活性的系统需要集成微传感器，该传感器仅允许进行细胞外测量，从而提供有关细胞代谢状态的不准确和间接信息。在这里，我们介绍了一个代谢工具箱，该工具箱耦合了人类MSCs（h-MSCs）动态培养的微型体外系统，该模型模仿了血管周围生境的体内情况，并具有细胞内代谢的高分辨率成像。通过使用计算机模型预测调整了沿流体腔的氧张力衰减后，使用荧光寿命成像显微镜（FLIM），我们能够监测空间代谢机制并将其与测得的细胞的氧吸收活性相关联。我们的平台允许在MSC中生成时空分布图，模拟时空上的生理生态位，并且其实时监控代表了用于建模血管周围壁ni，相关疾病和代谢相关药物的功能性工具。