Mesenchymal stem cells (MSCs) are promising cell candidates for cartilage regeneration. Furthermore, it is important to control the cell-matrix interactions that have a direct influence on cell functions. Providing an appropriate microenvironment for cell differentiation in response to exogenous stimuli is a critical step towards the clinical utilization of MSCs. In this study, hydrogels consisted of different proportions of alginates that were modified using gelatin, collagen type I and arginine-glycine-aspartic acid (RGD) and were evaluated regarding their effects on mesenchymal stem cells. The effect of applying hydrostatic pressure on MSCs encapsulated in collagen-modified alginate with and without chondrogenic medium was evaluated 7, 14 and 21 days after culture, which is a comprehensive evaluation of chondrogenesis in 3D hydrogels with mechanical and chemical stimulants. Alcian blue, safranin O and dimethyl methylene blue (DMMB) staining showed the chondrogenic phenotype of cells seeded in the collagen- and RGD-modified alginate hydrogels with the highest intensity after 21 days of culture. The results of real-time PCR for cartilage-specific extracellular matrix genes indicated the chondrogenic differentiation of MSCs in all hydrogels. Also, the synergic effects of chemical and mechanical stimuli are indicated. The highest expression levels of the studied genes were observed in the cells embedded in collagen-modified alginate by loading after 14 days of exposure to the chondrogenic medium. The effect of using IHP on encapsulated MSCs in modified alginate with collagen type I is equal or even higher than using TGF-beta on encapsulated cells. The results of immunohistochemical assessments also confirmed the real-time PCR data.

中文翻译：

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评估海藻酸盐修饰对细胞基质相互作用、机械转导和封装 MSC 的软骨形成的影响

间充质干细胞 (MSCs) 是软骨再生的有前途的细胞候选者。此外，重要的是控制对细胞功能有直接影响的细胞-基质相互作用。为响应外源刺激的细胞分化提供适当的微环境是实现 MSCs 临床应用的关键一步。在这项研究中，水凝胶由不同比例的海藻酸盐组成，使用明胶、I 型胶原蛋白和精氨酸-甘氨酸-天冬氨酸 (RGD) 进行修饰，并评估了它们对间充质干细胞的影响。在培养后 7、14 和 21 天，评估了对包裹在有和没有软骨形成培养基的胶原修饰海藻酸盐中的 MSC 施加静水压力的效果，这是对具有机械和化学刺激剂的 3D 水凝胶中软骨形成的综合评估。阿尔辛蓝、番红 O 和二甲基亚甲基蓝 (DMMB) 染色显示了在培养 21 天后强度最高的胶原蛋白和 RGD 修饰的海藻酸盐水凝胶中接种的细胞的软骨形成表型。软骨特异性细胞外基质基因的实时 PCR 结果表明所有水凝胶中的 MSCs 都具有软骨分化。此外，还指出了化学和机械刺激的协同作用。在暴露于软骨形成培养基 14 天后，通过加载嵌入胶原修饰海藻酸盐的细胞中观察到所研究基因的最高表达水平。在含有 I 型胶原蛋白的改性海藻酸盐中使用 IHP 对封装的 MSC 的效果与对封装的细胞使用 TGF-β 的效果相同甚至更高。免疫组织化学评估的结果也证实了实时 PCR 数据。