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Rahmati M, Haffner M, Lee MA, Leach JK, Saiz AM. The critical impact of traumatic muscle loss on fracture healing: Basic science and clinical aspects. J Orthop Res 2024; 42:249-258. [PMID: 37990953 DOI: 10.1002/jor.25746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 10/05/2023] [Accepted: 11/20/2023] [Indexed: 11/23/2023]
Abstract
Musculoskeletal trauma, specifically fractures, is a leading cause of patient morbidity and disability worldwide. In approximately 20% of cases with fracture and related traumatic muscle loss, bone healing is impaired leading to fracture nonunion. Over the past few years, several studies have demonstrated that bone and the surrounding muscle tissue interact not only anatomically and mechanically but also through biochemical pathways and mediators. Severe damage to the surrounding musculature at the fracture site causes an insufficiency in muscle-derived osteoprogenitor cells that are crucial for fracture healing. As an endocrine tissue, skeletal muscle produces many myokines that act on different bone cells, such as osteoblasts, osteoclasts, osteocytes, and mesenchymal stem cells. Investigating how muscle influences fracture healing at cellular, molecular, and hormonal levels provides translational therapeutic solutions to this clinical challenge. This review provides an overview about the contributions of surrounding muscle tissue in directing fracture healing. The focus of the review is on describing the interactions between bone and muscle in both healthy and fractured environments. We discuss current progress in identifying the bone-muscle molecular pathways and strategies to harness these pathways as cues for accelerating fracture healing. In addition, we review the existing challenges and research opportunities in the field.
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Affiliation(s)
- Maryam Rahmati
- Department of Orthopaedic Surgery, University of California, Davis, Sacramento, California, USA
| | - Max Haffner
- Department of Orthopaedic Surgery, University of California, Davis, Sacramento, California, USA
| | - Mark A Lee
- Department of Orthopaedic Surgery, University of California, Davis, Sacramento, California, USA
| | - Jonathan Kent Leach
- Department of Orthopaedic Surgery, University of California, Davis, Sacramento, California, USA
- Department of Biomedical Engineering, University of California, Davis, Davis, California, USA
| | - Augustine M Saiz
- Department of Orthopaedic Surgery, University of California, Davis, Sacramento, California, USA
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2
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Bacevich BM, Smith RDJ, Reihl AM, Mazzocca AD, Hutchinson ID. Advances with Platelet-Rich Plasma for Bone Healing. Biologics 2024; 18:29-59. [PMID: 38299120 PMCID: PMC10827634 DOI: 10.2147/btt.s290341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Accepted: 01/17/2024] [Indexed: 02/02/2024]
Abstract
Despite significant advances in the understanding and delivery of osteosynthesis, fracture non-union remains a challenging clinical problem in orthopaedic surgery. To bridge the gap, basic science characterization of fracture healing provides a platform to identify and target biological strategies to enhance fracture healing. Of immense interest, Platelet-rich plasma (PRP) is a point of care orthobiologic that has been extensively studied in bone and soft tissue healing given its relative ease of translation from the benchtop to the clinic. The aim of this narrative review is to describe and relate pre-clinical in-vitro and in-vivo findings to clinical observations investigating the efficacy of PRP to enhance bone healing for primary fracture management and non-union treatment. A particular emphasis is placed on the heterogeneity of PRP preparation techniques, composition, activation strategies, and delivery. In the context of existing data, the routine use of PRP to enhance primary fracture healing and non-union management cannot be supported. However, it is acknowledged that extensive heterogeneity of PRP treatments in clinical studies adds obscurity; ultimately, refinement (and consensus) of PRP treatments for specific clinical indications, including repetition studies are warranted.
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Affiliation(s)
- Blake M Bacevich
- Division of Sports Medicine, Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, Massachusetts General Brigham, Boston, MA, USA
| | - Richard David James Smith
- Division of Sports Medicine, Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, Massachusetts General Brigham, Boston, MA, USA
| | - Alec M Reihl
- Division of Sports Medicine, Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, Massachusetts General Brigham, Boston, MA, USA
| | - Augustus D Mazzocca
- Division of Sports Medicine, Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, Massachusetts General Brigham, Boston, MA, USA
- Medical Director, Division of Sports Medicine, Department of Orthopaedic Surgery, Massachusetts General Brigham, Boston, MA, USA
| | - Ian D Hutchinson
- Division of Sports Medicine, Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, Massachusetts General Brigham, Boston, MA, USA
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Wang Z, Yan B, Tang M, Jin D, Lai P. Tuberous sclerosis complex 1 targeted depletion in macrophages promotes osteogenesis by modulating secretion of Oncostatin M in the inflammatory stage of bone healing. Int Immunopharmacol 2023; 124:110895. [PMID: 37688912 DOI: 10.1016/j.intimp.2023.110895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 08/29/2023] [Accepted: 08/31/2023] [Indexed: 09/11/2023]
Abstract
In bone healing, earlier bone formation benefits bone repair. The first process of repair following bone injury involves the interaction between macrophage polarization and osteogenic activation of osteoblast linage cells, but the radical difference between the contributions of classically-activated M1 macrophages and alternatively-activated M2 macrophages to osteogenesis remains obscure. To test our hypothesis that M1 macrophages promote bone healing, we generated transgenic mice with myeloid lineage-specific TSC1 deletion (TSC1KO) to investigate the functional roles of M1 macrophages in the process of bone defect healing. We demonstrated that constitutive activation of mammalian target of rapamycin complex 1 (mTORC1) enhances M1 macrophage polarization during bone healing. By creating tibial bone defect as a model of bone repair in TSC1KO mice and their littermates, we surprisingly found osteogenic responses in the defective bone region of TSC1KO mice, where repair occurred by intramembranous ossification (IO) in the mice was promoted due to the enhanced M1-polarized macrophage polarization. We propose that Oncostatin M (OSM) secreted by M1-polarized macrophages but not M2 macrophages likely functions as a paracrine factor in this promoted repair process, as verified by the induction of osteoblastic differentiation and matrix mineralization. Interestingly, the expression level of the OSM receptor (OSMR) was continually upregulated in osteoblast linage cells with M1 medium. Additionally, OSMR activated the signaling transduction system of JAK/STAT/RUNX2 in MSCs, which in turn stimulates the recruitment of osteoblast lineage cells and activates IO. These results indicate that TSC1 targeted depletion in macrophages promotes bone healing by inducing secretion of OSM. This study highlights that regulation of M1 macrophage polarization is a novel basis for the improvement of bone regeneration and that regulation of macrophage polarization can be a potential therapeutic strategy to treat defects in the repair phase of bone healing.
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Affiliation(s)
- Zhenyu Wang
- Academy of Orthopedics Guangdong Province, Guangdong Provincial Key Laboratory of Bone and Joint Degeneration Diseases, The Third Affiliated Hospital, Southern Medical University, Guangzhou, 510630, China
| | - Bo Yan
- Academy of Orthopedics Guangdong Province, Guangdong Provincial Key Laboratory of Bone and Joint Degeneration Diseases, The Third Affiliated Hospital, Southern Medical University, Guangzhou, 510630, China
| | - Ming Tang
- Frazer Institute, Faculty of Medicine, The University of Queensland at the Translational Research Institute Australia, Brisbane, 999029, Australia
| | - Dadi Jin
- Academy of Orthopedics Guangdong Province, Guangdong Provincial Key Laboratory of Bone and Joint Degeneration Diseases, The Third Affiliated Hospital, Southern Medical University, Guangzhou, 510630, China.
| | - Pinglin Lai
- Academy of Orthopedics Guangdong Province, Guangdong Provincial Key Laboratory of Bone and Joint Degeneration Diseases, The Third Affiliated Hospital, Southern Medical University, Guangzhou, 510630, China.
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Karmakar R, Dey S, Alam A, Khandelwal M, Pati F, Rengan AK. Attributes of Nanomaterials and Nanotopographies for Improved Bone Tissue Engineering and Regeneration. ACS APPLIED BIO MATERIALS 2023; 6:4020-4041. [PMID: 37691480 DOI: 10.1021/acsabm.3c00549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Bone tissue engineering (BTE) is a multidisciplinary area that can solve the limitation of conventional grafting methods by developing viable and biocompatible bone replacements. The three essential components of BTE, i.e., Scaffold material and Cells and Growth factors altogether, facilitate support and guide for bone formation, differentiation of the bone tissues, and enhancement in the cellular activities and bone regeneration. However, there is a scarcity of the appropriate materials that can match the mechanical property as well as functional similarity to native tissue, considering the bone as hard tissue. In such scenarios, nanotechnology can be leveraged upon to achieve the desired aspects of BTE, and that is the key point of this review article. This review article examines the significant areas of nanotechnology research that have an impact on regeneration of bone: (a) scaffold with nanomaterials helps to enhance physicochemical interactions, biocompatibility, mechanical stability, and attachment; (b) nanoparticle-based approaches for delivering bioactive chemicals, growth factors, and genetic material. The article begins with the introduction of components and healing mechanisms of bone and the factors associated with them. The focus of this article is on the various nanotopographies that are now being used in scaffold formation, by describing how they are made, and how these nanotopographies affect the immune system and potential underlying mechanisms. The advantages of 4D bioprinting in BTE by using nanoink have also been mentioned. Additionally, we have investigated the importance of an in silico approach for finding the interaction between drugs and their related receptors, which can help to formulate suitable systems for delivery. This review emphasizes the role of nanoscale approach and how it helps to increase the efficacy of parameters of scaffold as well as drug delivery system for tissue engineering and bone regeneration.
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Affiliation(s)
- Rounik Karmakar
- Department of Biomedical Engineering, Indian Institute of Technology (IIT), Hyderabad, Kandi-502285, Sangareddy, Telangana, India
| | - Sreenath Dey
- Department of Biomedical Engineering, Indian Institute of Technology (IIT), Hyderabad, Kandi-502285, Sangareddy, Telangana, India
| | - Aszad Alam
- Department of Materials Science and Metallurgical Engineering, Indian Institute of Technology, Hyderabad, Kandi-502285, Sangareddy, Telangana, India
| | - Mudrika Khandelwal
- Department of Materials Science and Metallurgical Engineering, Indian Institute of Technology, Hyderabad, Kandi-502285, Sangareddy, Telangana, India
| | - Falguni Pati
- Department of Biomedical Engineering, Indian Institute of Technology (IIT), Hyderabad, Kandi-502285, Sangareddy, Telangana, India
| | - Aravind Kumar Rengan
- Department of Biomedical Engineering, Indian Institute of Technology (IIT), Hyderabad, Kandi-502285, Sangareddy, Telangana, India
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Wu X, Chen J, Sun W, Hart DA, Ackermann PW, Ahmed AS. Network proteomic analysis identifies inter-alpha-trypsin inhibitor heavy chain 4 during early human Achilles tendon healing as a prognostic biomarker of good long-term outcomes. Front Immunol 2023; 14:1191536. [PMID: 37483617 PMCID: PMC10358850 DOI: 10.3389/fimmu.2023.1191536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 06/16/2023] [Indexed: 07/25/2023] Open
Abstract
The suboptimal or protracted regeneration of injured connective tissues often results in significant dysfunction, pain, and functional disability. Despite the prevalence of the condition, few studies have been conducted which focused on biomarkers or key molecules involved in processes governing healing outcomes. To gain insight into injured connective tissue repair, and using the Achilles tendon as a model system, we utilized quantitative proteomic and weighted co-expression network analysis of tissues acquired from Achilles tendon rupture (ATR) patients with different outcomes at 1-year postoperatively. Two modules were detected to be associated with prognosis. The initial analysis identified inter-alpha-trypsin inhibitor heavy chain 4 (ITIH4) as a biomarker or hub protein positively associated with better healing outcomes. Additional analysis identified the beneficial role of ITIH4 in inflammation, cell viability, apoptosis, proliferation, wound healing, and for the synthesis of type I collagen in cultured fibroblasts. Functionally, the effects of ITIH4 were found to be mediated by peroxisome proliferator-activated receptor gamma (PPARγ) signaling pathways. Taken together, these findings suggest that ITIH4 plays an important role in processes of connective tissue repair and advocate for the potential of ITIH4 as a therapeutic target for injured connective tissue repair. Trial registration http://clinicaltrials.gov, identifiers NCT02318472, NCT01317160.
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Affiliation(s)
- Xinjie Wu
- Division of Spine Surgery, Department of Orthopaedic Surgery, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, China
- Department of Molecular Medicine and Surgery, Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Junyu Chen
- Department of Molecular Medicine and Surgery, Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Wei Sun
- Department of Orthopedic Surgery, China-Japan Friendship Hospital, Beijing, China
| | - David A. Hart
- Department of Surgery, Faculty of Kinesiology and the McCaig Institute for Bone & Joint Health, University of Calgary, Calgary, AB, Canada
| | - Paul W. Ackermann
- Department of Molecular Medicine and Surgery, Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Aisha S. Ahmed
- Department of Molecular Medicine and Surgery, Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden
- Department of Physiology, University of Helsinki, Helsinki, Finland
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Ru X, Cai P, Tan M, Zheng L, Lu Z, Zhao J. Temporal transcriptome highlights the involvement of cytokine/JAK/STAT3 signaling pathway in the osteoinduction of BMSCs. J Orthop Surg Res 2023; 18:289. [PMID: 37038162 PMCID: PMC10088166 DOI: 10.1186/s13018-023-03767-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Accepted: 03/30/2023] [Indexed: 04/12/2023] Open
Abstract
BACKGROUND Mesenchymal stem cells (MSCs)-based therapy offers an effective strategy for bone regeneration to solve the clinical orthopedic problems. However, the transcriptional regulation of multiple transitional stages of continuous osteogenesis from MSCs has not been fully characterized. METHODS Bone marrow mesenchymal stem cells (BMSCs) stimulated with osteogenic induction media were utilized to construct the in vitro osteogenic differentiation model. BMSCs were harvested after induction for 0, 7, 14 and 21 days, respectively, to perform the mRNA-sequencing (mRNA-Seq). The transcription factor networks and common molecules during the osteogenesis were revealed by using the temporal transcriptome. Further verification was performed by the quantitative real-time polymerase chain reaction (qRT-PCR), immunofluorescence and Western blotting. RESULTS It showed that BMSCs could differentiate into osteogenic, and crucial regulator in the MAPK signaling pathway, the PPAR signaling pathway, the Toll-like receptor signaling and the Cytokine/JAK/STAT signaling pathway. PPI protein interaction analysis also suggested that three cytokines are involved in osteogenic differentiation as core genes, including leukemia inhibitory factor (LIF), interleukin-6 (IL6) and colony-stimulating factor 3 (CSF3). The osteogenic process was negatively affected by the inhibition of JAK/STAT3 signaling pathway. CONCLUSIONS This work might provide new insights in the crucial features of the transcriptional regulation during the osteogenesis, as well as offer important clues about the activity and regulation of the relatively long-activated Cytokine/JAK/STAT3 signaling pathway in osteoinduction of BMSCs.
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Affiliation(s)
- Xiao Ru
- Guangxi Engineering Center in Biomedical Material for Tissue and Organ Regeneration, Guangxi Medical University, Nanning, 530021, China
- Collaborative Innovation Centre of Regenerative Medicine and Medical BioResource Development and Application Co-Constructed by the Province and Ministry, Guangxi Medical University, Nanning, 530021, China
| | - Peian Cai
- Guangxi Engineering Center in Biomedical Material for Tissue and Organ Regeneration, Guangxi Medical University, Nanning, 530021, China
- Collaborative Innovation Centre of Regenerative Medicine and Medical BioResource Development and Application Co-Constructed by the Province and Ministry, Guangxi Medical University, Nanning, 530021, China
| | - Manli Tan
- Guangxi Engineering Center in Biomedical Material for Tissue and Organ Regeneration, Guangxi Medical University, Nanning, 530021, China.
- Collaborative Innovation Centre of Regenerative Medicine and Medical BioResource Development and Application Co-Constructed by the Province and Ministry, Guangxi Medical University, Nanning, 530021, China.
- Life Science Institute, Guangxi Medical University, Nanning, 530021, China.
| | - Li Zheng
- Guangxi Engineering Center in Biomedical Material for Tissue and Organ Regeneration, Guangxi Medical University, Nanning, 530021, China.
- Collaborative Innovation Centre of Regenerative Medicine and Medical BioResource Development and Application Co-Constructed by the Province and Ministry, Guangxi Medical University, Nanning, 530021, China.
- Life Science Institute, Guangxi Medical University, Nanning, 530021, China.
| | - Zhenhui Lu
- Guangxi Engineering Center in Biomedical Material for Tissue and Organ Regeneration, Guangxi Medical University, Nanning, 530021, China.
- Collaborative Innovation Centre of Regenerative Medicine and Medical BioResource Development and Application Co-Constructed by the Province and Ministry, Guangxi Medical University, Nanning, 530021, China.
- Life Science Institute, Guangxi Medical University, Nanning, 530021, China.
| | - Jinmin Zhao
- Guangxi Engineering Center in Biomedical Material for Tissue and Organ Regeneration, Guangxi Medical University, Nanning, 530021, China
- Collaborative Innovation Centre of Regenerative Medicine and Medical BioResource Development and Application Co-Constructed by the Province and Ministry, Guangxi Medical University, Nanning, 530021, China
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Wu S, Ma J, Liu J, Liu C, Ni S, Dai T, Wang Y, Weng Y, Zhao H, Zhou D, Zhao X. Immunomodulation of Telmisartan-Loaded PCL/PVP Scaffolds on Macrophages Promotes Endogenous Bone Regeneration. ACS APPLIED MATERIALS & INTERFACES 2022; 14:15942-15955. [PMID: 35353482 DOI: 10.1021/acsami.1c24748] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Biomaterial-immune system interactions play an important role in postimplantation osseointegration to retain the functionality of healthy and intact bones. Therefore, appropriate osteoimmunomodulation of implants has been considered and validated as an efficient strategy to alleviate inflammation and enhance new bone formation. Here, we fabricated a nanostructured PCL/PVP (polycaprolactone/polyvinylpyrrolidone) electrospinning scaffold for cell adhesion, tissue ingrowth, and bone defect padding. In addition, telmisartan, an angiotensin 2 receptor blocker with distinct immune bioactivity, was doped into PCL-/PVP-electrospun scaffolds at different proportions [1% (TPP-1), 5% (TPP-5), and 10% (TPP-10)] to investigate its immunomodulatory effects and osteoinductivity/conductivity. Telmisartan-loaded scaffolds displayed in vitro anti-inflammatory bioactivity on lipopolysaccharide-induced M1 macrophages by polarizing them to an M2-like phenotype and exhibited pro-osteogenic properties on bone marrow-derived mesenchymal stem cells (BMSCs). Histological analysis and micro-CT results of a rat skull defect model also showed that the telmisartan-loaded scaffolds induced a higher M2/M1 ratio, less inflammatory infiltration, and better bone regenerative patterns. Furthermore, activation of the BMP2 (bone morphogenetic protein-2)-Smad signaling pathway was found to be dominant in telmisartan-loaded scaffold-mediated macrophage-BMSC interactions. These findings indicate that telmisartan incorporation with PCL/PVP nanofibrous scaffolds is a potential therapeutic strategy for promoting bone healing by modulating M1 macrophages to a more M2 phenotype at early stages of postimplantation.
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Affiliation(s)
- Siyu Wu
- The Affiliated Changzhou No. 2 People's Hospital of Nanjing Medical University, Changzhou 213164, China
- Dalian Medical University, Dalian 116044, China
| | - Jiayi Ma
- The Affiliated Changzhou No. 2 People's Hospital of Nanjing Medical University, Changzhou 213164, China
- Dalian Medical University, Dalian 116044, China
| | - Jun Liu
- The Affiliated Changzhou No. 2 People's Hospital of Nanjing Medical University, Changzhou 213164, China
- Dalian Medical University, Dalian 116044, China
| | - Chun Liu
- The Affiliated Changzhou No. 2 People's Hospital of Nanjing Medical University, Changzhou 213164, China
| | - Su Ni
- The Affiliated Changzhou No. 2 People's Hospital of Nanjing Medical University, Changzhou 213164, China
| | - Ting Dai
- The Affiliated Changzhou No. 2 People's Hospital of Nanjing Medical University, Changzhou 213164, China
| | - Yan Wang
- The Affiliated Changzhou No. 2 People's Hospital of Nanjing Medical University, Changzhou 213164, China
| | - Yiping Weng
- The Affiliated Changzhou No. 2 People's Hospital of Nanjing Medical University, Changzhou 213164, China
| | - Hongbin Zhao
- The Affiliated Changzhou No. 2 People's Hospital of Nanjing Medical University, Changzhou 213164, China
| | - Dong Zhou
- The Affiliated Changzhou No. 2 People's Hospital of Nanjing Medical University, Changzhou 213164, China
| | - Xiubo Zhao
- School of Pharmacy, Changzhou University, Changzhou 213164, China
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield S1 3JD, U.K
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Hixon KR, Miller AN. Animal models of impaired long bone healing and tissue engineering- and cell-based in vivo interventions. J Orthop Res 2022; 40:767-778. [PMID: 35072292 DOI: 10.1002/jor.25277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 12/05/2021] [Accepted: 01/16/2022] [Indexed: 02/04/2023]
Abstract
Bone healing after injury typically follows a systematic process and occurs spontaneously under appropriate physiological conditions. However, impaired long bone healing is still quite common and may require surgical intervention. Various complications can result in different forms of impaired bone healing including nonunion, critical-size defects, or stress fractures. While a nonunion may occur due to impaired biological signaling and/or mechanical instability, a critical-size defect exhibits extensive bone loss that will not spontaneously heal. Comparatively, a stress fracture occurs from repetitive forces and results in a non-healing crack or break in the bone. Clinical standards of treatment vary between these bone defects due to their pathological differences. The use of appropriate animal models for modeling healing defects is critical to improve current treatment methods and develop novel rescue therapies. This review provides an overview of these clinical bone healing impairments and current animal models available to study the defects in vivo. The techniques used to create these models are compared, along with the outcomes, to clarify limitations and future objectives. Finally, rescue techniques focused on tissue engineering and cell-based therapies currently applied in animal models are specifically discussed to analyze their ability to initiate healing at the defect site, providing information regarding potential future therapies. In summary, this review focuses on the current animal models of nonunion, critical-size defects, and stress fractures, as well as interventions that have been tested in vivo to provide an overview of the clinical potential and future directions for improving bone healing.
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Affiliation(s)
- Katherine R Hixon
- Department of Orthopaedic Surgery, Washington University, St. Louis, Missouri, USA.,Thayer School of Engineering, Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire, USA
| | - Anna N Miller
- Department of Orthopaedic Surgery, Washington University, St. Louis, Missouri, USA
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