PMID- 35615640 OWN - NLM STAT- PubMed-not-MEDLINE LR - 20220716 IS - 2214-031X (Print) IS - 2214-0328 (Electronic) IS - 2214-031X (Linking) VI - 34 DP - 2022 May TI - MFG-E8 promotes tendon-bone healing by regualting macrophage efferocytosis and M2 polarization after anterior cruciate ligament reconstruction. PG - 11-21 LID - 10.1016/j.jot.2022.04.002 [doi] AB - BACKGROUND: Scar tissue formation at the tendon-bone interface caused by excessive inflammation leads to insufficient healing strength, while the phagocytic clearance of dying cells (efferocytosis) has profound consequences on macrophage polarisation and the inflammatory response. Modulating the inflammatory microenvironment may have satisfactory curative effects in patients with anterior cruciate ligament reconstruction (ACLR). METHODS: Bone marrow-derived macrophages (BMDMs) and polymorphonuclear leukocytes (PMNs) were harvested from bone marrow. The effects of milk fat globulin protein E8 (MFG-E8) on macrophage polarisation were compared with those of M1 and M2 macrophages induced by conventional methods. The BMDMs and apoptotic PMNs co-culture system was used to assess the efficiency of efferocytosis. The biological functions of MFG-E8 in tendon-bone healing by regulating macrophage efferocytosis and polarisation were further investigated using a rat ACLR model. RESULTS: BMDMs and PMNs were successfully isolated. Compared to conventional induction methods, MFG-E8 alone did not significantly induce macrophage M1 or M2 polarisation, but it could partially reverse the expression of inducible nitric oxide synthase (iNOS) in M1 macrophages. In vitro studies revealed that appropriate dosing of MFG-E8 could significantly promote the efficiency of macrophage efferocytosis and subsequently increase M2 polarisation. More importantly, significantly increased peri-tunnel new bone formation, tighter connected interface and better mechanical properties were observed after ACLR when treated with MFG-E8 in vivo. We further demonstrated that MFG-E8 remarkably facilitated the clearance of apoptotic cells and increased the number of M2 macrophages at the interface between the tendon graft and bone tunnel in the early postoperative stage. CONCLUSION: MFG-E8 promoted tendon-bone healing histologically and biomechanically, probably by the regulation of inflammatory processes via macrophage efferocytosis and M2 polarisation.The translational potential of this article: Regulation of macrophage efferocytosis and M2 polarization by MFG-E8 is expected to be a therapeutic strategy for promoting tendon-bone healing in patients undergoing ACLR. CI - (c) 2022 The Authors. FAU - Geng, Rui AU - Geng R AD - School of Medicine, Southeast University, No. 87 Dingjiaqiao road, 210009, Nanjing, Jiangsu Province, China. AD - Sports Medicine Center, Department of Orthopaedic Surgery, Zhongda Hospital Affiliated to Southeast University, No. 87 Dingjiaqiao road, 210009, Nanjing, Jiangsu Province, China. FAU - Lin, Yucheng AU - Lin Y AD - School of Medicine, Southeast University, No. 87 Dingjiaqiao road, 210009, Nanjing, Jiangsu Province, China. AD - Sports Medicine Center, Department of Orthopaedic Surgery, Zhongda Hospital Affiliated to Southeast University, No. 87 Dingjiaqiao road, 210009, Nanjing, Jiangsu Province, China. FAU - Ji, Mingliang AU - Ji M AD - School of Medicine, Southeast University, No. 87 Dingjiaqiao road, 210009, Nanjing, Jiangsu Province, China. AD - Sports Medicine Center, Department of Orthopaedic Surgery, Zhongda Hospital Affiliated to Southeast University, No. 87 Dingjiaqiao road, 210009, Nanjing, Jiangsu Province, China. FAU - Chang, Qing AU - Chang Q AD - School of Medicine, Southeast University, No. 87 Dingjiaqiao road, 210009, Nanjing, Jiangsu Province, China. AD - Sports Medicine Center, Department of Orthopaedic Surgery, Zhongda Hospital Affiliated to Southeast University, No. 87 Dingjiaqiao road, 210009, Nanjing, Jiangsu Province, China. FAU - Li, Zhuang AU - Li Z AD - School of Medicine, Southeast University, No. 87 Dingjiaqiao road, 210009, Nanjing, Jiangsu Province, China. AD - Sports Medicine Center, Department of Orthopaedic Surgery, Zhongda Hospital Affiliated to Southeast University, No. 87 Dingjiaqiao road, 210009, Nanjing, Jiangsu Province, China. FAU - Xu, Li AU - Xu L AD - School of Medicine, Southeast University, No. 87 Dingjiaqiao road, 210009, Nanjing, Jiangsu Province, China. AD - Sports Medicine Center, Department of Orthopaedic Surgery, Zhongda Hospital Affiliated to Southeast University, No. 87 Dingjiaqiao road, 210009, Nanjing, Jiangsu Province, China. FAU - Zhang, Weituo AU - Zhang W AD - School of Medicine, Southeast University, No. 87 Dingjiaqiao road, 210009, Nanjing, Jiangsu Province, China. AD - Sports Medicine Center, Department of Orthopaedic Surgery, Zhongda Hospital Affiliated to Southeast University, No. 87 Dingjiaqiao road, 210009, Nanjing, Jiangsu Province, China. FAU - Lu, Jun AU - Lu J AD - School of Medicine, Southeast University, No. 87 Dingjiaqiao road, 210009, Nanjing, Jiangsu Province, China. AD - Sports Medicine Center, Department of Orthopaedic Surgery, Zhongda Hospital Affiliated to Southeast University, No. 87 Dingjiaqiao road, 210009, Nanjing, Jiangsu Province, China. LA - eng PT - Journal Article DEP - 20220511 PL - Singapore TA - J Orthop Translat JT - Journal of orthopaedic translation JID - 101625127 PMC - PMC9109120 OTO - NOTNLM OT - Anterior cruciate ligament reconstruction OT - Efferocytosis OT - Macrophage polarization OT - Milk fat globulin protein E8 OT - Tendon-bone healing COIS- The authors have no conflicts of interest relevant to this article. EDAT- 2022/05/27 06:00 MHDA- 2022/05/27 06:01 PMCR- 2022/05/11 CRDT- 2022/05/26 02:29 PHST- 2022/01/12 00:00 [received] PHST- 2022/03/18 00:00 [revised] PHST- 2022/04/15 00:00 [accepted] PHST- 2022/05/26 02:29 [entrez] PHST- 2022/05/27 06:00 [pubmed] PHST- 2022/05/27 06:01 [medline] PHST- 2022/05/11 00:00 [pmc-release] AID - S2214-031X(22)00030-4 [pii] AID - 10.1016/j.jot.2022.04.002 [doi] PST - epublish SO - J Orthop Translat. 2022 May 11;34:11-21. doi: 10.1016/j.jot.2022.04.002. eCollection 2022 May.