Zhu Jun, Shao Jiahua, Chen Yi, Zhao Guangyi, Li Lexiang, Fu Qiwei, Qian Qirong, Zhou Qi, Ding Zheru, Zhou Yiqin
Department of Orthopedics, Shanghai Changzheng Hospital, Naval Medical University, Shanghai 200003, China.
Department of Pathology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15260, USA.
Stem Cells Int. 2021 Mar 26;2021:6640424. doi: 10.1155/2021/6640424. eCollection 2021.
Rotator cuff injury healing is problematic because the tendon-bone junction often forms cicatricial tissues, rather than fibrocartilage, which leads to mechanical impairment and is prone to redamage. Kartogenin (KGN) is a newly discovered small molecule compound which can induce cartilage formation through chondrogenesis of endogenous mesenchymal stem cells.
In this study, we used KGN with fibrin glue (FG) to repair the rotator cuff injury by promoting the formation of fibrocartilage at the tendon to bone interface. Firstly, we assessed the release rate of KGN from the FG-KGN complex and then created a rabbit rotator cuff tendon graft-bone tunnel model. The rabbits received saline, FG-KGN, or FG injections onto the tendon to bone interface after injury. Shoulder tissues were harvested at 6 and 12 weeks, and the sections were stained with HE and Safranin O/Fast green. The samples were assessed by histologic evaluation and biomechanical testing. Synovial mesenchymal stem cells derived from the synovial tissue around the rotator cuff were harvested for western blotting and qRT-PCR analysis.
KGN was released rapidly from the FG-KGN complex during first 4 hrs and followed by a slow release until 7 days. The tendon graft-bone interface in the control (saline) group and the FG group was filled with scar tissue, rather than cartilage-like tissue, and only a small number of chondrocytes were found at the adjacent bone surface. In the FG-KGN group, the tendon to bone interface was fully integrated and populated by chondrocytes with proteoglycan deposition, indicating the formation of fibrocartilage-like tissues. At 12 weeks, the maximum tensile strength of the FG-KGN group was significantly higher than that of the FG and control groups ( < 0.01). The RNA expression levels of tendinous genes such as Tenascin C and the chondrogenic gene Sox-9 were substantially elevated in SMSCs treated with the FG-KGN complex compared to the other two groups.
These results indicated that fibrin glue is an effective carrier for KGN, allowing for the sustained release of KGN. The FG-KGN complex could effectively promote the regeneration and formation of fibrocartilage tissue of the tendon-bone interface in the rabbit rotator cuff tendon graft-bone tunnel model.
肩袖损伤的愈合存在问题，因为肌腱 - 骨连接处常形成瘢痕组织而非纤维软骨，这会导致机械功能受损且易于再次损伤。卡托金（KGN）是一种新发现的小分子化合物，它可通过内源性间充质干细胞的软骨形成诱导软骨生成。
在本研究中，我们使用KGN与纤维蛋白胶（FG）通过促进肌腱 - 骨界面处纤维软骨的形成来修复肩袖损伤。首先，我们评估了KGN从FG - KGN复合物中的释放速率，然后建立了兔肩袖肌腱移植 - 骨隧道模型。损伤后，给兔子在肌腱 - 骨界面注射生理盐水、FG - KGN或FG。在6周和12周时采集肩部组织，切片用苏木精 - 伊红（HE）和番红O/固绿染色。通过组织学评估和生物力学测试对样本进行评估。收集肩袖周围滑膜组织来源的滑膜间充质干细胞用于蛋白质印迹和定量逆转录 - 聚合酶链反应（qRT - PCR）分析。
在最初4小时内，KGN从FG - KGN复合物中快速释放，随后缓慢释放直至7天。对照组（生理盐水）和FG组的肌腱移植 - 骨界面充满瘢痕组织而非软骨样组织，且仅在相邻骨表面发现少量软骨细胞。在FG - KGN组中，肌腱 - 骨界面完全整合，有软骨细胞且有蛋白聚糖沉积，表明形成了纤维软骨样组织。在12周时，FG - KGN组的最大拉伸强度显著高于FG组和对照组（<0.01）。与其他两组相比，用FG - KGN复合物处理的滑膜间充质干细胞中肌腱相关基因如腱生蛋白C和软骨生成基因Sox - 9的RNA表达水平显著升高。
这些结果表明纤维蛋白胶是KGN的有效载体，可使KGN持续释放。在兔肩袖肌腱移植 - 骨隧道模型中，FG - KGN复合物可有效促进肌腱 - 骨界面纤维软骨组织的再生和形成。
