Injectable hydrogels are attractive biomaterials for cell delivery in tissue engineering. However, the in vivo viability of transplanted cells remains limited. Typically, macroporous structures constructed in hydrogels are utilized to enhance oxygen and nutrients diffusion for cell survival and to promote integration between the material and host tissue. A new gas-foaming method to generate pores was proposed by directly adding Mg particles into cell-laden hydrogel solutions, taking advantage of the H2 gas formed during the degradation of Mg. The optimization design of the size and amount of Mg particles added into the hydrogels was investigated. Improved cell viability and proliferation were demonstrated in the group with Mg particles. Additionally, Mg2+ ions generated during Mg degradation facilitated the osteogenic differentiation of stem cells encapsulated in hydrogels. Extensive vascularized bone regeneration in the femoral defects of rats revealed that the use of Mg particles as the foaming agent is feasible, endowing injectable hydrogels with optimized porosity and enhanced bioactivity, and providing a new strategy for future designs of porous hydrogels in tissue engineering.

中文翻译：

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基于镁颗粒降解的原位气体发泡：一种制备可注射大孔水凝胶的新颖方法。

可注射的水凝胶是用于组织工程中细胞递送的有吸引力的生物材料。但是，移植细胞的体内生存能力仍然受到限制。通常，利用在水凝胶中构建的大孔结构来增强氧气和营养物质的扩散，以促进细胞存活并促进材料与宿主组织之间的整合。通过利用将Mg降解过程中形成的H2气体直接添加到充满细胞的水凝胶溶液中，将Mg颗粒直接添加到泡沫中，提出了一种新的产生气泡的气体发泡方法。研究了添加到水凝胶中的Mg颗粒的大小和数量的优化设计。在含镁颗粒的组中证明了提高的细胞活力和增殖。此外，在Mg降解过程中产生的Mg2 +离子促进了封装在水凝胶中的干细胞的成骨分化。在大鼠股骨缺损中广泛的血管化骨再生表明，使用镁颗粒作为发泡剂是可行的，赋予可注射的水凝胶以最佳的孔隙率和增强的生物活性，并为组织工程中多孔水凝胶的未来设计提供了新的策略。