Bioprinting of cellular aggregates, such as tissue spheroids or organoids, in complex three-dimensional (3D) arrangements has been a major obstacle for scaffold-free fabrication of tissues and organs. In this research, we unveiled a new approach to the bioprinting of tissue spheroids in a yield stress granular gel, which exhibited unprecedented capabilities in freeform positioning of spheroids in 3D. Due to its Herschel-Bulkley and self-healing properties as well as its biological inertness, the granular gel supported both the positioning and self-assembly of tissue spheroids. We studied the underlying physical mechanism of the approach to elucidate the interactions between the aspirated spheroids and the yield-stress of the gel during the transfer of spheroids from cell media to the gel. We demonstrate the application of the proposed approach in the realization of various freeform shapes and self-assembly of human mesenchymal stem cell spheroids for the construction of cartilage and bone tissues.

中文翻译：

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屈服应力凝胶中组织球体的抽吸辅助自由形式生物印刷

在复杂的三维（3D）排列中对细胞聚集体（例如组织球体或类器官）进行生物打印已成为无支架制造组织和器官的主要障碍。在这项研究中，我们揭示了一种在屈服应力颗粒状凝胶中生物球组织生物打印的新方法，该方法在3D球体的自由形式定位方面显示出前所未有的能力。由于其Herschel-Bulkley的特性和自我修复的特性以及其生物学惰性，这种颗粒状凝胶既支持组织球的定位又可以自我组装。我们研究了该方法的基本物理机制，以阐明从细胞培养基到细胞球体的球体转移过程中，抽吸的球体与凝胶的屈服应力之间的相互作用。