Collagen is a promising material for tissue engineering, but the poor mechanical properties of collagen hydrogels, which tend to cause contraction under the action of cellular activity, make its application challengeable. In this study, the amino group of type I collagen (Col I) was modified with methacrylic anhydride (MA) and the photo-crosslinkable methacrylate anhydride modified type I collagen (CM) with three different degrees of substitution (DS) was prepared. The physical properties of CM and Col I hydrogels were tested, including micromorphology, mechanical properties and degradation properties. The results showed that the storage modulus and degradation rate of hydrogels could be adjusted by changing the DS of CM. In vitro, chondrocytes were seeded into these four groups of hydrogels and subjected to fluorescein diacetate/propidium iodide (FDA/PI) staining, cell counting kit-8 (CCK-8) test, histological staining and cartilage-related gene expression analysis. In vivo, these hydrogels encapsulating chondrocytes were implanted subcutaneously into nude mice, then histological staining and sulfated glycosaminoglycan (sGAG)/DNA assays were performed. The results demonstrated that contraction of hydrogels affected behaviors of chondrocytes, and CM hydrogels with suitable DS could resist contraction of hydrogels and promote the secretion of cartilage-specific matrix in vitro and in vivo.

中文翻译：

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胶原水凝胶通过限制细胞/水凝胶结构的收缩对软骨细胞行为的影响

胶原蛋白是一种很有前途的组织工程材料，但胶原蛋白水凝胶的力学性能较差，在细胞活动的作用下容易引起收缩，使其应用​​面临挑战。本研究以甲基丙烯酸酐（MA）对Ⅰ型胶原（Col I）的氨基进行修饰，制备了具有三种不同取代度（DS）的可光交联甲基丙烯酸酐改性Ⅰ型胶原（CM）。测试了 CM 和 Col I 水凝胶的物理性能，包括微形态、机械性能和降解性能。结果表明，可以通过改变CM的DS来调节水凝胶的储能模量和降解速率。体外，将软骨细胞接种到这四组水凝胶中，并进行荧光素二乙酸盐/碘化丙啶（FDA/PI）染色、细胞计数试剂盒8（CCK-8）测试、组织学染色和软骨相关基因表达分析。在体内，将这些包封软骨细胞的水凝胶皮下植入裸鼠体内，然后进行组织学染色和硫酸化糖胺聚糖 (sGAG)/DNA 测定。结果表明，水凝胶的收缩会影响软骨细胞的行为，而具有合适DS的CM水凝胶可以在体外和体内抵抗水凝胶的收缩并促进软骨特异性基质的分泌。将这些包裹软骨细胞的水凝胶植入裸鼠皮下，然后进行组织学染色和硫酸化糖胺聚糖 (sGAG)/DNA 测定。结果表明，水凝胶的收缩会影响软骨细胞的行为，而具有合适DS的CM水凝胶可以在体外和体内抵抗水凝胶的收缩并促进软骨特异性基质的分泌。将这些包裹软骨细胞的水凝胶植入裸鼠皮下，然后进行组织学染色和硫酸化糖胺聚糖 (sGAG)/DNA 测定。结果表明，水凝胶的收缩会影响软骨细胞的行为，而具有合适DS的CM水凝胶可以在体外和体内抵抗水凝胶的收缩并促进软骨特异性基质的分泌。