Dr. Li Dak Sum-Yip Yio Chin Center for Stem Cells and Regenerative Medicine and Department of Orthopedic Surgery of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China; Key Laboratory of Tissue Engineering and Regenerative Medicine of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, China; Department of Sports Medicine, Zhejiang University School of Medicine, Hangzhou, China; China Orthopedic Regenerative Medicine Group (CORMed), Hangzhou, China.
Guangxi Collaborative Innovation Center for Biomedicine, Guangxi Medical University, Nanning, China.
Biomaterials. 2022 Jan;280:121238. doi: 10.1016/j.biomaterials.2021.121238. Epub 2021 Nov 5.
Three dimensional (3D) microenvironments more accurately replicate native microenvironments for stem cell maintenance and function compared with two dimensional (2D) microenvironments. However, the molecular mechanisms by which 3D microenvironments regulate stem cell function remain largely unexplored at the single-cell level. Here, using a single-cell analysis and functional analysis, we found not all cell-subpopulations respond to 3D microenvironments based on a systematically 3D gelatin microcarrier culture system we developed for the expansion and function maintenance of hTSPCs. 3D microenvironments alter the cell-subpopulation distribution of human tendon stem/progenitor cells (hTSPCs) by improving the proportion of ICAM1+ITGB8+ and FGF7+CYGB+ subpopulations. We also revealed the activated FGF7 signaling in the two subpopulations is responsible for the enhanced tenogenesis of hTSPCs through cell-cell interactions. The hTSPCs cultured in 3D niche with a specific cell-subpopulation structure exhibited superior stem-cell characteristics and functions both in vitro and in vivo. Together, our study demonstrates that 3D microenvironments can regulate stem-cell function by modulating the critical cell subpopulation and identifies FGF7 as a novel regulator for tenogenic differentiation and tendon regeneration.
与二维（2D）微环境相比，三维（3D）微环境更能准确地模拟干细胞维持和功能的天然微环境。然而，3D 微环境调节干细胞功能的分子机制在单细胞水平上仍在很大程度上未被探索。在这里，我们使用单细胞分析和功能分析发现，并非所有细胞亚群都对我们开发的用于扩增和维持 hTSPC 功能的系统 3D 明胶微载体培养系统做出反应。3D 微环境通过提高 ICAM1+ITGB8+和 FGF7+CYGB+亚群的比例来改变人肌腱干/祖细胞（hTSPC）的细胞亚群分布。我们还揭示了两个亚群中激活的 FGF7 信号通过细胞-细胞相互作用负责增强 hTSPC 的肌腱形成。在具有特定细胞亚群结构的 3D 生态位中培养的 hTSPCs 表现出优异的干细胞特性和功能，无论是在体外还是体内。总之，我们的研究表明，3D 微环境可以通过调节关键的细胞亚群来调节干细胞功能，并确定 FGF7 是一种新的肌腱形成和肌腱再生的分化调节剂。
