Three-dimensional (3D) cultivation platforms allow the creation of cell models, which more closely resemble in vivo-like cell behavior. Therefore, 3D cell culture platforms have started to replace conventional two-dimensional (2D) cultivation techniques in many fields. Besides the advantages of 3D culture, there are also some challenges: cultivation in 3D often results in an inhomogeneous microenvironment and therefore unique cultivation conditions for each cell inside the construct. As a result, the analysis and precise control over the singular cell state is limited in 3D. In this work, we address these challenges by exploring ways to monitor oxygen concentrations in gelatin methacryloyl (GelMA) 3D hydrogel culture at the cellular level using hypoxia reporter cells and deep within the construct using a non-invasive optical oxygen sensing spot. We could show that the appearance of oxygen limitations is more prominent in softer GelMA-hydrogels, which enable better cell spreading. Beyond demonstrating novel or space-resolved techniques of visualizing oxygen availability in hydrogel constructs, we also describe a method to create a stable and controlled oxygen gradient throughout the construct using a 3D printed flow-through chamber.

中文翻译：

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明胶-甲基丙烯酰水凝胶 3D 细胞培养中氧可用性和天然和人工氧梯度产生的研究

三维 (3D) 培养平台允许创建细胞模型，这些模型更类似于体内样细胞行为。因此，3D 细胞培养平台开始在许多领域取代传统的二维 (2D) 培养技术。除了 3D 培养的优势外，还存在一些挑战：3D 培养通常会导致微环境不均匀，因此构建体中每个细胞的培养条件都不同。因此，对单个细胞状态的分析和精确控制在 3D 中受到限制。在这项工作中，我们通过探索使用缺氧报告细胞在细胞水平上监测明胶甲基丙烯酰 (GelMA) 3D 水凝胶培养物中氧浓度的方法和使用非侵入性光学氧传感点深入构建体来应对这些挑战。我们可以证明，氧气限制的出现在较软的 GelMA 水凝胶中更为突出，这使得细胞能够更好地扩散。除了展示可视化水凝胶结构中氧气可用性的新颖或空间分辨技术外，我们还描述了一种使用 3D 打印流通室在整个结构中创建稳定和受控的氧气梯度的方法。