Department of Orthopaedics, Nanjing Jinling Hospital, Affiliated Hospital of Medical School, Nanjing University, 305 Zhongshan East Road, Nanjing, 210002, China.
Department of Orthopaedics, Changzhou Traditional Chinese Medical Hospital, Changzhou hospital Affiliated to Nanjing University of Chinese Medicine, 25 North Heping Road, Changzhou, 213000, Jiangsu, China.
Sci Rep. 2024 Mar 4;14(1):5344. doi: 10.1038/s41598-024-55281-5.
Chronic rotator cuff injuries (CRCIs) still present a great challenge for orthopaedics surgeons. Many new therapeutic strategies are developed to facilitate repair and improve the healing process. However, there is no reliable animal model for chronic rotator cuff injury research. To present a new valuable rat model for future chronic rotator cuff injuries (CRCIs) repair studies, and describe the changes of CRCIs on the perspectives of histology, behavior and MRI. Sixty male Wistar rats were enrolled and underwent surgery of the left shoulder joint for persistent subacromial impingement. They were randomly divided into experimental group (n = 30, a 3D printed PEEK implant shuttled into the lower surface of the acromion) and sham operation group (n = 30, insert the same implant, but remove it immediately). Analyses of histology, behavior, MRI and inflammatory pain-related genes expression profiles were performed to evaluate the changes of CRCIs. After 2-weeks running, the rats in the experimental group exhibited compensatory gait patterns to protect the injured forelimb from loading after 2-weeks running. After 8-weeks running, the rats in the experimental group showed obvious CRCIs pathological changes: (1) acromion bone hyperplasia and thickening of the cortical bone; (2) supraspinatus muscle tendon of the humeral head: the bursal-side tendon was torn and layered with disordered structure, forming obvious gaps; the humeral-side tendon is partially broken, and has a neatly arranged collagen. Partial fat infiltration is found. The coronal T2-weighted images showed that abnormal tendon-to-bone junctions of the supraspinatus tendon. The signal intensity and continuity were destroyed with contracted tendon. At the nighttime, compared with the sham operation group, the expression level of IL-1β and COX-2 increased significantly (P = 0063, 0.0005) in the experimental group. The expression of COX-2 in experimental group is up-regulated about 1.5 times than that of daytime (P = 0.0011), but the expression of IL-1β, TNF-a, and NGF are all down-regulated (P = 0.0146, 0.0232, 0.0161). This novel rat model of chronic rotator cuff injuries has the similar characteristics with that of human shoulders. And it supplies a cost-effective, reliable animal model for advanced tissue engineered strategies and future therapeutic strategies.
慢性肩袖损伤（CRCIs）仍然是骨科医生面临的巨大挑战。许多新的治疗策略被开发出来以促进修复并改善愈合过程。然而，目前还没有可靠的动物模型用于慢性肩袖损伤研究。为了提出一种新的有价值的大鼠模型用于未来的慢性肩袖损伤（CRCIs）修复研究，并从组织学、行为和 MRI 角度描述 CRCIs 的变化。
将 60 只雄性 Wistar 大鼠纳入研究并接受左侧肩关节持续肩峰下撞击术。它们被随机分为实验组（n=30，将 3D 打印的 PEEK 植入物穿梭到肩峰的下表面）和假手术组（n=30，插入相同的植入物，但立即取出）。进行组织学、行为、MRI 和炎症性疼痛相关基因表达谱分析，以评估 CRCIs 的变化。
在 2 周跑步后，实验组的大鼠表现出代偿性的步态模式，以保护受伤的前肢免受负重。在 8 周跑步后，实验组的大鼠表现出明显的 CRCIs 病理变化：（1）肩峰骨增生和皮质骨增厚；（2）肱骨头的冈上肌腱：滑囊侧肌腱撕裂并分层结构紊乱，形成明显的间隙；肱骨侧肌腱部分断裂，胶原排列整齐。部分脂肪浸润。冠状位 T2 加权图像显示冈上肌腱的异常肌腱-骨交界处。信号强度和连续性被收缩的肌腱破坏。在夜间，与假手术组相比，实验组的 IL-1β 和 COX-2 的表达水平显著增加（P=0.0063，0.0005）。实验组 COX-2 的表达水平上调约 1.5 倍（P=0.0011），而 IL-1β、TNF-a 和 NGF 的表达均下调（P=0.0146，0.0232，0.0161）。
这种新型的慢性肩袖损伤大鼠模型具有与人肩部相似的特征。它为先进的组织工程策略和未来的治疗策略提供了一种具有成本效益、可靠的动物模型。
