TGF-β1 derived from macrophages contributes to load-induced tendon-bone healing in the murine rotator cuff repair model by promoting chondrogenesis

Bone & Joint Research

article

Linfeng Wang¹  Shengcan Li¹  Han Xiao¹  Tao Zhang¹  Yuqian Liu¹  Jianzhong Hu²  Daqi Xu¹  Hongbin Lu¹ 

[1] Department of Sports Medicine, Xiangya Hospital, Central South University;Key Laboratory of Organ Injury, Aging and Regenerative Medicine of Hunan Province

关键词: Mechanical stimulation;    Tendon-bone healing;    Macrophage polarization;    Mesenchymal stem cell chondrogenesis;    Transforming growth factor-β1;    chondrogenesis;    Macrophage;    transforming growth factor-beta 1;    rotator cuff repair;    mesenchymal stem cells (MSCs);    enthesis;    tendons;    enzyme-linked immunosorbent assay;    Flow cytometry;    growth factor;   

DOI  :  10.1302/2046-3758.123.BJR-2022-0368.R1

学科分类：骨科学

来源: British Editorial Society Of Bone And Joint Surgery

【 摘 要 】

AimsIt has been established that mechanical stimulation benefits tendon-bone (T-B) healing, and macrophage phenotype can be regulated by mechanical cues; moreover, the interaction between macrophages and mesenchymal stem cells (MSCs) plays a fundamental role in tissue repair. This study aimed to investigate the role of macrophage-mediated MSC chondrogenesis in load-induced T-B healing in depth.MethodsC57BL/6 mice rotator cuff (RC) repair model was established to explore the effects of mechanical stimulation on macrophage polarization, transforming growth factor (TGF)-β1 generation, and MSC chondrogenesis within T-B enthesis by immunofluorescence and enzyme-linked immunosorbent assay (ELISA). Macrophage depletion was performed by clodronate liposomes, and T-B healing quality was evaluated by histology and biomechanics. In vitro, bone marrow-derived macrophages (BMDMs) were stretched with CELLOAD-300 load system and macrophage polarization was identified by flow cytometry and quantitative real-time polymerase chain reaction (qRT-PCR). MSC chondrogenic differentiation was measured by histochemical analysis and qRT-PCR. ELISA and qRT-PCR were performed to screen the candidate molecules that mediated the pro-chondrogenic function of mechanical stimulated BMDMs.ResultsMechanical stimulation promoted macrophage M2 polarization in vivo and in vitro. The conditioned media from mechanically stimulated BMDMs (MS-CM) enhanced MSC chondrogenic differentiation, and mechanically stimulated BMDMs generated more TGF-β1. Further, neutralizing TGF-β1 in MS-CM can attenuate its pro-chondrogenic effect. In vivo, mechanical stimulation promoted TGF-β1 generation, MSC chondrogenesis, and T-B healing, which were abolished following macrophage depletion.ConclusionMacrophages subjected to appropriate mechanical stimulation could polarize toward the M2 phenotype and secrete TGF-β1 to promote MSC chondrogenesis, which subsequently augments T-B healing.

【 授权许可】

CC BY-NC