Biomaterials. 2021;266

        微球，也被称作微载体，近年来在组织工程和3D生物打印中被广泛应用于细胞的大规模培养。据报道，同平面培养体系相比，经由微载体进行扩增的间充质干细胞提高了成骨基因的表达水平，进而有助于后续在体内的分化潜能。对于转化医学，认识以微球为基础的特性与细胞反应之间的联系至关重要。在细胞扩增过程和再生治疗领域，调控微球的表面特性来引导细胞在3D培养体系中的分化，将有机会将细胞递送系统从一个被动的机械支持系统转变为一个功能化的要素。

来自英国诺丁汉大学的团队通过制备具有不同表面拓扑形貌的聚乳酸微球（光滑、凹陷、多角），进而探究其对间充质干细胞分化的影响。在体外利用间充质干细胞进行同的成骨相关基因，蛋白和矿化物质的测定，同时利用大鼠桡骨临界骨缺损进行体内试验。研究发现，细胞黏附在不同拓扑表面微球经由多种整合素蛋白进行介导。间充质干细胞在表面凹陷和光滑微球上表现出了不同的代谢水平。在体内实验中，不同的3D表面同样也呈现出了不同的组织学特点。

Microparticles, also known as microcarriers, have gained significance as building blocks for tissue engineering strategies, in bioinks for three-dimensional (3D) bioprinting and for large-scale expansion of anchorage-dependent cells. Microcarrier-expanded mesenchymal stem cells have been reported to show increased osteogenic gene expression and improved subsequent differentiation potential in vivo compared to planar cultures. Understanding the correlation between microparticle-based cues and associated cellular responses is critical to achieve predictable outputs for translational applications. Tailoring surface properties of microparticles to direct differentiation in 3D pro vides the opportunity to transform cell delivery systems from passive mechanical supports to functional components of cell expansion processes and regenerative therapies.

Microparticles with different topological surfaces (smooth, dimpled and angular) were developed by a team from Nottingham University, UK. To test the capability of topographical designs on microparticles to induce osteogenesis, a range of viability and osteo-specific gene, protein and mineralization assays were performed using primary human mesenchymal stem cells (hMSCs) in vitro, and within non-healing murine radial bone defects in vivo. As showed in the study, cell adhesion is mediated by different integrins on varied topographical designs. Altered metabolic profiles of hMSCs were observed on dimpled versus smooth microparticles. Varying histological features were also observed in vivo by different 3D surface topographies.

 

doi: 10.1016/j.biomaterials.2020.120450

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