生物3D打印仿生支架促进肩袖损伤后的愈合

Bio-3D printed bionic scaffold promotes healing after rotator cuff injury

背景:大多数肩袖损伤发生于冈上肌腱,由于肌腱组织缺少血管以及肩袖复杂的解剖结构,临床治疗效果非常有限。组织工程技术和干细胞生物学的快速发展为提高肌腱修复质量带来了新的希望。目的:通过生物3D打印技术制备人脐带间充质干细胞/甲基丙烯酸酐化明胶复合支架,观察该支架修复肩袖损伤的效果。方法:(1)体外细胞实验:制备明胶微载体,将人脐带间充质干细胞接种于明胶微载体表面构建组织工程化干细胞。制备甲基丙烯酸酐化明胶水凝胶打印墨水,使用甲基丙烯酸酐化明胶水凝胶打印墨水重悬组织工程化干细胞,放入3D打印机的生物墨水容器中进行打印,蓝光照射固化5 min后即得人脐带间充质干细胞/甲基丙烯酸酐化明胶复合支架。通过死活染色、CCK-8实验检测支架内人脐带间充质干细胞的活性。(2)动物体内实验:采用随机区组设计方法将24只SD大鼠随机4组,每组6只:正常组不进行任何处理,肩袖损伤组、单纯支架组、细胞支架组建立冈上肌腱撕裂的肩袖损伤模型,单纯支架组、细胞支架组造模后分别将甲基丙烯酸酐化明胶支架、人脐带间充质干细胞/甲基丙烯酸酐化明胶复合支架植入肌腱损伤处。术后4周,分别进行大鼠行为学测试及肩袖冈上肌腱组织学病理组织形态观察。结果与结论:(1)体外细胞实验:死活染色结果显示,明胶微载体可减轻3D打印过程对人脐带间充质干细胞造成的损伤,随着培养时间的延长,支架内的人脐带间充质干细胞存活率升高;CCK-8实验结果显示,随着培养时间的延长,支架内的人脐带间充质干细胞活性无明显变化。(2)动物体内实验:行为学测试结果显示,相较于肩袖损伤组、单纯支架组,细胞支架组大鼠四肢运动功能明显改善;肩袖冈上肌腱苏木精-伊红与Masson染色结果显示,相较于肩袖损伤组、单纯支架组,细胞支架组肌纤维排列较规律,无明显的炎性细胞浸润,胶原容积百分比降低;免疫荧光染色结果显示,相较于肩袖损伤组、单纯支架组,细胞支架组肩袖冈上肌腱内白细胞介素6、肿瘤坏死因子α蛋白表达明显降低。(3)结果表明,生物3D打印的人脐带间充质干细胞/甲基丙烯酸酐化明胶复合支架可促进肩袖损伤组织修复再生。

BACKGROUND:Most rotator cuff injuries occur in the supraspinatus tendon.Clinical treatment of rotator cuff injuries is very limited due to the lack of blood vessels and the complex anatomical structure of the rotator cuff.The rapid development of tissue engineering technology and stem cell biology has brought new hope for improving the quality of tendon repair.OBJECTIVE:To prepare human umbilical cord mesenchymal stem cells/gelatin methacrylate composite scaffolds by bio-3D printing technology to observe the effect of this scaffold on repairing rotator cuff injury.METHODS:(1)In vitro cell assay:The gelatin microcarrier was prepared.The tissue engineered stem cells were constructed by inoculating human umbilical cord mesenchymal stem cells on the surface of gelatin microcarrier.Gelatin methacrylate hydrogel printing ink was prepared.Tissue engineered stem cells were re-suspended with gelatin methacrylate hydrogel printing ink and put into the bio-ink container of 3D printer for printing.Human umbilical cord mesenchymal stem cells/gelatin methacrylate composite scaffold was obtained after 5 minutes of blue light irradiation and curing.The activity of human umbilical cord mesenchymal stem cells in scaffolds was detected by dead/alive staining and CCK-8 assay.(2)In vivo animal experiments:A random block design method was used to randomly assign 24 SD rats to 4 groups with 6 rats in each group.No treatment was given in the normal group.The rotator cuff injury model of supratinatus tendon tear was established in the rotator cuff injury group,the simple scaffold group,and the cellular scaffold group.The gelatin methacrylate scaffold and human umbilical cord mesenchymal stem cell/gelatin methacrylatecomposite scaffold were implanted into the tendon injury after the model was made in the simple scaffold group and the cellular scaffold group,respectively.Four weeks after operation,behavioral tests and histopathological morphology observation of supraspinatus tendon of rotator cuff were performed.RESULTS AND CONCLUSION:(1)In vitro cellular assay:The dead/alive staining showed that gelatin microcarrier could reduce the damage of human umbilical cord mesenchymal stem cells caused by 3D printing process.With the extension of culture time,the survival rate of human umbilical cord mesenchymal stem cells increased in the scaffold.The results of CCK-8 assay showed that with the extension of culture time,the activity of human umbilical cord mesenchymal stem cells in the scaffold did not change significantly.(2)In vivo animal experiments:Behavioral test results showed that compared with rotator cuff injury group and simple scaffold group,cellular scaffold group significantly improved limb motor function.The results of hematoxylin-eosin and Masson staining of rotator cuff supraspinatus tendon showed that compared with rotator cuff injury group and simple scaffold group,the muscle fiber arrangement in the cellular scaffold group was more regular;there was no obvious inflammatory cell infiltration,and the percentage of collagen volume decreased.The results of immunofluorescence staining showed that the expression levels of interleukin 6 and tumor necrosis factorαin the rotator cuff supraspinatus tendon were significantly decreased in the cellular scaffold group compared with the rotator cuff injury group and the simple scaffold group.(3)The results showed that bio-3D-printed cell scaffolds encapsulating human umbilical cord mesenchymal stem cells/gelatin methacrylate could promote tissue repair and regeneration of rotator cuff injuries.