Low-concentration gelatin methacryloyl (GelMA) hydrogels have been found to be promising cell-laden bioinks with excellent cell viability. Herein, we report a strategy that accurately deposits cell-containing bioinks at 5% (w/v) GelMA using extrusion three-dimensional (3D) bioprinting technology by utilizing its photo-crosslinkable and thermosensitive properties without the need for any sacrificial materials. During the 3D printing process, regular, smooth microfibers were formed without any discontinuity of extrusion or clogging, and photo-crosslinking was then used to stabilize the printed GelMA structure. After printing, the scaffolds were cultured in a chondrogenic medium to evaluate their significant roles in directing the behaviors of bone mesenchymal stem cells (BMSCs). Evidence of chondrogenic differentiation was demonstrated by Alcian blue staining and immunofluorescence (Col2a1) as well as the expression of chondrogenic genes. Finally, after platelet-rich plasma treatment, the in vivo effects of the BMSCs on cartilage regeneration on the thigh muscles of female nude mice were measured by using immunohistochemical techniques. The results showed that with this strategy, GelMA bioink displays excellent printability and a high cell survival rate. In vitro and in vivo, the cell-laden scaffold successfully regenerated mature cartilage via a cartilage-specific extracellular matrix, which seems to be suitable for cartilage regeneration and repair.

中文翻译：

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明胶甲基丙烯酰胺设计的组织软骨的低温三维打印。

低浓度的明胶甲基丙烯酰（GelMA）水凝胶已被发现是充满希望的具有出色细胞活力的充满细胞的生物墨水。本文中，我们报告了一种策略，该方法利用挤出的三维（3D）生物打印技术利用其光可交联和热敏特性，而无需任何牺牲材料，即可准确地将含细胞的生物墨水以5％（w / v）的GelMA沉积。在3D打印过程中，形成规则，光滑的微纤维而不会出现挤出或堵塞的任何不连续现象，然后使用光交联来稳定打印的GelMA结构。打印后，将支架在软骨形成培养基中进行培养，以评估其在指导骨髓间充质干细胞（BMSC）行为中的重要作用。软骨形成分化的证据通过阿尔辛蓝染色和免疫荧光（Col2a1）以及软骨形成基因的表达得到证明。最后，经过富含血小板的血浆处理后，使用免疫组织化学技术测量了BMSCs对雌性裸鼠大腿肌肉软骨再生的体内作用。结果表明，采用这种策略，GelMA生物墨水具有出色的可印刷性和较高的细胞存活率。在体外和体内，载有细胞的支架通过特定于软骨的细胞外基质成功地再生了成熟的软骨，这似乎适用于软骨的再生和修复。