Biomaterials & Biomimetics Laboratory, School of Life Sciences, Central University of Gujarat, Gandhinagar, India.
Biomed Mater. 2020 Apr 8;15(3):035011. doi: 10.1088/1748-605X/ab772e.
The development of clinical applications has led to a perpetual increase in the demand for mesenchymal stem cells (MSCs). However, the ex vivo expansion of MSCs while maintaining their stemness and differentiation potential remains an immense challenge. MSCs require high cell density for their intercellular communication and specific physico-chemical cues from the surrounding environment for spheroid formation in order to maintain their stemness. Inadequacy of the traditional in vitro cell culture method (tissue culture plastic surface) to fulfill any of these special requirements is responsible for inducing the loss of stem cell properties of the MSCs over time. In this study, we propose that glucosaminoglycan (GAG) mimicking ultrafine nanofibers could support the spheroid culture for in vitro human MSC expansion. The geometrical and biochemical properties of nanofibers provide biomimicking cues to MSCs, as well as enhance cell-cell interactions and stimulate spheroid formation in MSCs, which subsequently result in increased cell proliferation, enhanced expression of stem cell markers and maintenance of their multilineage differentiation potential. Furthermore, close monitoring of the behavior of MSCs on nanofibers serves as the key to understand their mode of action in niche formation. Interestingly, GAG mimicking substrate stimulated MSCs for long-distance intercellular communication via 'tunneling tubes', their subsequent migration and niche formation. These kinds of cellular interactions over long distances have rarely been observed in MSCs to provide better insight for future studies on MSC niche. Furthermore, PCL-CHT nanofibers were observed to be as conducive to use as tissue culture polystyrene for stem cell expansion. Overall, these polymeric nanofibers provide a more relevant, convenient and more suitable substrate than the conventional monolayer culture for in vitro MSC expansion.
临床应用的发展导致对间充质干细胞（MSCs）的需求不断增加。然而，在保持其干细胞特性和分化潜能的情况下，体外扩增 MSC 仍然是一个巨大的挑战。MSCs 之间的细胞通讯需要高细胞密度，并且需要来自周围环境的特定物理化学线索来形成球体，以维持其干细胞特性。传统的体外细胞培养方法（组织培养塑料表面）无法满足这些特殊要求中的任何一个，这是导致 MSC 的干细胞特性随时间丧失的原因。在这项研究中，我们提出，糖胺聚糖（GAG）模拟超细微纤维可以支持球体培养，用于体外人 MSC 的扩增。纳米纤维的几何和生化特性为 MSC 提供了仿生线索，增强了细胞-细胞相互作用，并刺激 MSC 形成球体，从而导致细胞增殖增加、干细胞标志物表达增强，并维持其多系分化潜能。此外，密切监测 MSC 在纳米纤维上的行为是了解其在龛形成中的作用模式的关键。有趣的是，GAG 模拟底物通过“隧道”刺激 MSC 进行长距离细胞间通讯，随后它们迁移并形成龛。这种长距离的细胞相互作用在 MSC 中很少观察到，为未来对 MSC 龛的研究提供了更好的见解。此外，还观察到 PCL-CHT 纳米纤维与组织培养聚苯乙烯一样有利于干细胞的扩增。总的来说，这些聚合物纳米纤维为体外 MSC 扩增提供了比传统单层培养更相关、更方便、更合适的基质。
