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Roberts BM, Geddis AV, Ciuciu A, Reynoso M, Mehta N, Varanoske AN, Kelley AM, Walker RJ, Munoz R, Kolb AL, Staab JS, Naimo MA, Tomlinson RE. Acetaminophen influences musculoskeletal signaling but not adaptations to endurance exercise training. FASEB J 2024; 38:e23586. [PMID: 38568858 DOI: 10.1096/fj.202302642r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 03/01/2024] [Accepted: 03/19/2024] [Indexed: 04/05/2024]
Abstract
Acetaminophen (ACE) is a widely used analgesic and antipyretic drug with various applications, from pain relief to fever reduction. Recent studies have reported equivocal effects of habitual ACE intake on exercise performance, muscle growth, and risks to bone health. Thus, this study aimed to assess the impact of a 6-week, low-dose ACE regimen on muscle and bone adaptations in exercising and non-exercising rats. Nine-week-old Wistar rats (n = 40) were randomized to an exercise or control (no exercise) condition with ACE or without (placebo). For the exercise condition, rats ran 5 days per week for 6 weeks at a 5% incline for 2 min at 15 cm/s, 2 min at 20 cm/s, and 26 min at 25 cm/s. A human equivalent dose of ACE was administered (379 mg/kg body weight) in drinking water and adjusted each week based on body weight. Food, water intake, and body weight were measured daily. At the beginning of week 6, animals in the exercise group completed a maximal treadmill test. At the end of week 6, rats were euthanized, and muscle cross-sectional area (CSA), fiber type, and signaling pathways were measured. Additionally, three-point bending and microcomputer tomography were measured in the femur. Follow-up experiments in human primary muscle cells were used to explore supra-physiological effects of ACE. Data were analyzed using a two-way ANOVA for treatment (ACE or placebo) and condition (exercise or non-exercise) for all animal outcomes. Data for cell culture experiments were analyzed via ANOVA. If omnibus significance was found in either ANOVA, a post hoc analysis was completed, and a Tukey's adjustment was used. ACE did not alter body weight, water intake, food intake, or treadmill performance (p > .05). There was a treatment-by-condition effect for Young's Modulus where placebo exercise was significantly lower than placebo control (p < .05). There was no treatment by condition effects for microCT measures, muscle CSA, fiber type, or mRNA expression. Phosphorylated-AMPK was significantly increased with exercise (p < .05) and this was attenuated with ACE treatment. Furthermore, phospho-4EBP1 was depressed in the exercise group compared to the control (p < .05) and increased in the ACE control and ACE exercise group compared to placebo exercise (p < .05). A low dose of ACE did not influence chronic musculoskeletal adaptations in exercising rodents but acutely attenuated AMPK phosphorylation and 4EBP1 dephosphorylation post-exercise.
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Affiliation(s)
- Brandon M Roberts
- Military Performance Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts, USA
| | - Alyssa V Geddis
- Military Performance Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts, USA
| | - Alexandra Ciuciu
- Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Marinaliz Reynoso
- Military Performance Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts, USA
| | - Nikhil Mehta
- Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Alyssa N Varanoske
- Military Performance Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts, USA
- Oak Ridge Institute for Science and Education, Belcamp, Maryland, USA
| | - Alyssa M Kelley
- Military Performance Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts, USA
| | - Raymond J Walker
- Military Performance Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts, USA
| | - Rigoberto Munoz
- Military Performance Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts, USA
| | - Alexander L Kolb
- Military Performance Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts, USA
| | - Jeffery S Staab
- Military Performance Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts, USA
| | - Marshall A Naimo
- Military Performance Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts, USA
| | - Ryan E Tomlinson
- Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
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2
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Collins JA, Kim CJ, Coleman A, Little A, Perez MM, Clarke EJ, Diekman B, Peffers MJ, Chubinskaya S, Tomlinson RE, Freeman TA, Loeser RF. Cartilage-specific Sirt6 deficiency represses IGF-1 and enhances osteoarthritis severity in mice. Ann Rheum Dis 2023; 82:1464-1473. [PMID: 37550003 PMCID: PMC10579179 DOI: 10.1136/ard-2023-224385] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 07/22/2023] [Indexed: 08/09/2023]
Abstract
OBJECTIVES Prior studies noted that chondrocyte SIRT6 activity is repressed in older chondrocytes rendering cells susceptible to catabolic signalling events implicated in osteoarthritis (OA). This study aimed to define the effect of Sirt6 deficiency on the development of post-traumatic and age-associated OA in mice. METHODS Male cartilage-specific Sirt6-deficient mice and Sirt6 intact controls underwent destabilisation of the medial meniscus (DMM) or sham surgery at 16 weeks of age and OA severity was analysed at 6 and 10 weeks postsurgery. Age-associated OA was assessed in mice aged 12 and 18 months of age. OA severity was analysed by micro-CT, histomorphometry and scoring of articular cartilage structure, toluidine blue staining and osteophyte formation. SIRT6-regulated pathways were analysed in human chondrocytes by RNA-sequencing, qRT-PCR and immunoblotting. RESULTS Sirt6-deficient mice displayed enhanced DMM-induced OA severity and accelerated age-associated OA when compared with controls, characterised by increased cartilage damage, osteophyte formation and subchondral bone sclerosis. In chondrocytes, RNA-sequencing revealed that SIRT6 depletion significantly repressed cartilage extracellular matrix (eg, COL2A1) and anabolic growth factor (eg, insulin-like growth factor-1 (IGF-1)) gene expression. Gain-of-function and loss-of-function studies in chondrocytes demonstrated that SIRT6 depletion attenuated, whereas adenoviral overexpression or MDL-800-induced SIRT6 activation promoted IGF-1 signalling by increasing Aktser473 phosphorylation. CONCLUSIONS SIRT6 deficiency increases post-traumatic and age-associated OA severity in vivo. SIRT6 profoundly regulated the pro-anabolic and pro-survival IGF-1/Akt signalling pathway and suggests that preserving the SIRT6/IGF-1/Akt axis may be necessary to protect cartilage from injury-associated or age-associated OA. Targeted therapies aimed at increasing SIRT6 function could represent a novel strategy to slow or stop OA.
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Affiliation(s)
- John A Collins
- Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
- Department of Medicine, Division of Rheumatology, Allergy and Immunology and the Thurston Arthritis Research Center, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - C James Kim
- Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Ashley Coleman
- Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Abreah Little
- Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Matheus M Perez
- Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Emily J Clarke
- Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, UK
| | - Brian Diekman
- Department of Medicine, Division of Rheumatology, Allergy and Immunology and the Thurston Arthritis Research Center, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Mandy J Peffers
- Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, UK
| | - Susanna Chubinskaya
- Department of Pediatrics, Rush University Medical Center, Chicago, Illinois, USA
| | - Ryan E Tomlinson
- Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Theresa A Freeman
- Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Richard F Loeser
- Department of Medicine, Division of Rheumatology, Allergy and Immunology and the Thurston Arthritis Research Center, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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3
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Rajpar I, Kumar G, Fortina P, Tomlinson RE. Toll-like receptor 4 signaling in osteoblasts is required for load-induced bone formation in mice. iScience 2023; 26:106304. [PMID: 36950122 PMCID: PMC10025993 DOI: 10.1016/j.isci.2023.106304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 01/06/2023] [Accepted: 02/24/2023] [Indexed: 03/06/2023] Open
Abstract
In mature bone, NGF is produced by osteoblasts following mechanical loading and signals through resident sensory nerves expressing its high affinity receptor, neurotrophic tyrosine kinase receptor type 1 (TrkA), to support bone formation. Here, we investigated whether osteoblastic expression of Toll-like receptor 4 (TLR4), a key receptor in the NF-κB signaling pathway, is required to initiate NGF-TrkA signaling required for load-induced bone formation. Although Tlr4 conditional knockout mice have normal skeletal mass and strength in adulthood, the loss of TLR4 signaling significantly reduced lamellar bone formation following loading. Inhibition of TLR4 signaling reduced Ngf expression in primary osteoblasts and RNA sequencing of bones from Tlr4 conditional knockout mice and wild-type littermates revealed dysregulated inflammatory signaling three days after osteogenic mechanical loading. In total, our study reveals an important role for osteoblastic TLR4 in the skeletal adaptation of bone to mechanical forces.
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Affiliation(s)
- Ibtesam Rajpar
- Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, PA, USA
| | - Gaurav Kumar
- Department of Cancer Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Paolo Fortina
- Department of Cancer Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Ryan E. Tomlinson
- Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, PA, USA
- Corresponding author
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Sedigh A, Ghelich P, Quint J, Mollocana-Lara EC, Samandari M, Tamayol A, Tomlinson RE. Approximating scaffold printability utilizing computational methods. Biofabrication 2023; 15:10.1088/1758-5090/acbbf0. [PMID: 36787632 PMCID: PMC10123880 DOI: 10.1088/1758-5090/acbbf0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 02/14/2023] [Indexed: 02/16/2023]
Abstract
Bioprinting facilitates the generation of complex, three-dimensional (3D), cell-based constructs for various applications. Although multiple bioprinting technologies have been developed, extrusion-based systems have become the dominant technology due to the diversity of materials (bioinks) that can be utilized, either individually or in combination. However, each bioink has unique material properties and extrusion characteristics that affect bioprinting utility, accuracy, and precision. Here, we have extended our previous work to achieve high precision (i.e. repeatability) and printability across samples by optimizing bioink-specific printing parameters. Specifically, we hypothesized that a fuzzy inference system (FIS) could be used as a computational method to address the imprecision in 3D bioprinting test data and uncover the optimal printing parameters for a specific bioink that result in high accuracy and precision. To test this hypothesis, we have implemented a FIS model consisting of four inputs (bioink concentration, printing flow rate, speed, and temperature) and two outputs to quantify the precision (scaffold bioprinted linewidth variance) and printability. We validate our use of the bioprinting precision index with both standard and normalized printability factors. Finally, we utilize optimized printing parameters to bioprint scaffolds containing up to 30 × 106cells ml-1with high printability and precision. In total, our results indicate that computational methods are a cost-efficient measure to improve the precision and robustness of extrusion 3D bioprinting.
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Affiliation(s)
- Ashkan Sedigh
- Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, PA, United States of America
| | - Pejman Ghelich
- Department of Biomedical Engineering, University of Connecticut, Farmington, CT, United States of America
| | - Jacob Quint
- Department of Biomedical Engineering, University of Connecticut, Farmington, CT, United States of America
| | - Evelyn C Mollocana-Lara
- Department of Biomedical Engineering, University of Connecticut, Farmington, CT, United States of America
| | - Mohamadmahdi Samandari
- Department of Biomedical Engineering, University of Connecticut, Farmington, CT, United States of America
| | - Ali Tamayol
- Department of Biomedical Engineering, University of Connecticut, Farmington, CT, United States of America
| | - Ryan E Tomlinson
- Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, PA, United States of America
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5
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Wang ML, Rajpar I, Ruggiero NA, Fertala J, Steplewski A, Beredjiklian PK, Rivlin MR, Chen Y, Feldman GJ, Fertala A, Tomlinson RE. Circulating inflammatory cytokines alter transcriptional activity within fibrotic tissue of Dupuytren's disease patients. J Orthop Res 2022; 40:738-749. [PMID: 33913534 DOI: 10.1002/jor.25059] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 03/31/2021] [Accepted: 04/19/2021] [Indexed: 02/04/2023]
Abstract
Dupuytren's disease is a benign fibroproliferative disorder of the hand that results in disabling digital contractures that impair function and diminish the quality of life. The incidence of this disease has been correlated with chronic inflammatory states, but any direct association between inflammatory cytokines and Dupuytren's disease is not known. We hypothesized that advanced fibroproliferation is associated with increased levels of circulating inflammatory cytokines. Blood and fibrotic cord tissue were collected preoperatively from patients with severe contracture and control patients. Blood plasma concentrations of known inflammatory cytokines were evaluated using a multiplex immunoassay. Proteins from the cord tissue were analyzed by RNA sequencing and immunohistochemistry. Moreover, collagen-rich cords were analyzed using Fourier-transform infrared spectroscopy. The results indicate that patients exhibited significantly elevated circulating inflammatory cytokines, including tumor necrosis factor-α (TNF-α), interleukin (IL)-2, and IL-12p70, as compared with controls. Similarly, IL-4 and IL-13 were detected significantly more frequently in Dupuytren's disease as compared with control. RNA sequencing revealed 5311 differentially expressed genes and distinct clustering between diseased and control samples. In addition to increased expression of genes associated with fibroproliferation, we also observed upregulation of transcripts activated by inflammatory cytokines, including prolactin inducible protein and keratin intermediate filaments. IL-2, but not TNF-α, was detected in fibrotic cord tissue by immunohistochemistry. Finally, spectroscopic assays revealed a significant reduction of the collagen content and alterations of collagen cross-linking within the Dupuytren's disease tissues. In total, our results illustrate that patients with severe Dupuytren's disease exhibit substantially elevated circulating inflammatory cytokines that may drive fibroproliferation. Clinical Significance: The results from this study establish the basis for a specific cytokine profile that may be useful for diagnostic testing and therapeutic intervention in Dupuytren's disease.
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Affiliation(s)
- Mark L Wang
- Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
- Division of Hand Surgery, The Rothman Orthopaedic Institute, Philadelphia, Pennsylvania, USA
| | - Ibtesam Rajpar
- Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Nicholas A Ruggiero
- Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Jolanta Fertala
- Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Andrzej Steplewski
- Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Pedro K Beredjiklian
- Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
- Division of Hand Surgery, The Rothman Orthopaedic Institute, Philadelphia, Pennsylvania, USA
| | - Michael R Rivlin
- Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
- Division of Hand Surgery, The Rothman Orthopaedic Institute, Philadelphia, Pennsylvania, USA
| | - Yong Chen
- Department of Molecular and Cellular Biosciences, Rowan University, Glassboro, New Jersey, USA
| | - George J Feldman
- Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Andrzej Fertala
- Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Ryan E Tomlinson
- Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
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Rajpar I, Tomlinson RE. Function of peripheral nerves in the development and healing of tendon and bone. Semin Cell Dev Biol 2022; 123:48-56. [PMID: 33994302 PMCID: PMC8589913 DOI: 10.1016/j.semcdb.2021.05.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 04/30/2021] [Accepted: 05/02/2021] [Indexed: 01/03/2023]
Abstract
Although the functions of the peripheral nervous system in whole body homeostasis and sensation have been understood for many years, recent investigation has uncovered new roles for innervation in the musculoskeletal system. This review centers on advances regarding the function of nerves in the development and repair of two connected tissues: tendon and bone. Innervation in healthy tendons is generally confined to the tendon sheaths, and tendon-bone attachment units are typically aneural. In contrast to tendon, bone is an innervated and vascularized structure. Historically, the function of abundant peripheral nerves in bone has been limited to pain and some non-painful sensory perception in disease and injury. Indeed, much of our understanding of peripheral nerves in tendons, bones, and entheses is limited to the source and type of innervation in healthy and injured tissues. However, more recent studies have made important observations regarding the appearance, type, and innervation patterns of nerves during embryonic and postnatal development and in response to injury, which suggest a more expansive role for peripheral nerves in the formation of musculoskeletal tissues. Indeed, tendons and bones develop in a close spatiotemporal relationship in the embryonic mesoderm. Models of limb denervation have shed light on the importance of sensory innervation in bone and to a lesser extent, tendon development, and more recent work has unraveled key nerve signaling pathways. Furthermore, loss of sensory innervation also impairs healing of bone fractures and may contribute to chronic tendinopathy. However, more study is required to translate our knowledge of peripheral nerves to therapeutic strategies to combat bone and tendon diseases.
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Affiliation(s)
- Ibtesam Rajpar
- Department of Orthopedic Surgery, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA
| | - Ryan E Tomlinson
- Department of Orthopedic Surgery, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA.
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7
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Boneski PK, Madhu V, Tomlinson RE, Shapiro IM, van de Wetering K, Risbud MV. Abcc6 Null Mice—a Model for Mineralization Disorder PXE Shows Vertebral Osteopenia Without Enhanced Intervertebral Disc Calcification With Aging. Front Cell Dev Biol 2022; 10:823249. [PMID: 35186933 PMCID: PMC8850990 DOI: 10.3389/fcell.2022.823249] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2021] [Accepted: 01/03/2022] [Indexed: 12/12/2022] Open
Abstract
Chronic low back pain is a highly prevalent health condition intricately linked to intervertebral disc degeneration. One of the prominent features of disc degeneration that is commonly observed with aging is dystrophic calcification. ATP-binding cassette sub-family C member 6 (ABCC6), a presumed ATP efflux transporter, is a key regulator of systemic levels of the mineralization inhibitor pyrophosphate (PPi). Mutations in ABCC6 result in pseudoxanthoma elasticum (PXE), a progressive human metabolic disorder characterized by mineralization of the skin and elastic tissues. The implications of ABCC6 loss-of-function on pathological mineralization of structures in the spine, however, are unknown. Using the Abcc6−/− mouse model of PXE, we investigated age-dependent changes in the vertebral bone and intervertebral disc. Abcc6−/− mice exhibited diminished trabecular bone quality parameters at 7 months, which remained significantly lower than the wild-type mice at 18 months of age. Abcc6−/− vertebrae showed increased TRAP staining along with decreased TNAP staining, suggesting an enhanced bone resorption as well as decreased bone formation. Surprisingly, however, loss of ABCC6 resulted only in a mild, aging disc phenotype without evidence of dystrophic mineralization. Finally, we tested the utility of oral K3Citrate to treat the vertebral phenotype since it is shown to regulate hydroxyapatite mechanical behavior. The treatment resulted in inhibition of the osteoclastic response and an early improvement in mechanical properties of the bone underscoring the promise of potassium citrate as a therapeutic agent. Our data suggest that although ectopic mineralization is tightly regulated in the disc, loss of ABCC6 compromises vertebral bone quality and dysregulates osteoblast-osteoclast coupling.
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Affiliation(s)
- Paige K. Boneski
- Department of Orthopedic Surgery, Thomas Jefferson University, Philadelphia, PA, United States
| | - Vedavathi Madhu
- Department of Orthopedic Surgery, Thomas Jefferson University, Philadelphia, PA, United States
| | - Ryan E. Tomlinson
- Department of Orthopedic Surgery, Thomas Jefferson University, Philadelphia, PA, United States
| | - Irving M. Shapiro
- Department of Orthopedic Surgery, Thomas Jefferson University, Philadelphia, PA, United States
| | - Koen van de Wetering
- Department of Dermatology and Cutaneous Biology, Jefferson Institute of Molecular Medicine and PXE International Center of Excellence in Research and Clinical Care, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, United States
| | - Makarand V. Risbud
- Department of Orthopedic Surgery, Thomas Jefferson University, Philadelphia, PA, United States
- *Correspondence: Makarand V. Risbud,
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8
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Steplewski A, Fertala J, Tomlinson RE, Wang ML, Donahue A, Arnold WV, Rivlin M, Beredjiklian PK, Abboud JA, Namdari S, Fertala A. Mechanisms of reducing joint stiffness by blocking collagen fibrillogenesis in a rabbit model of posttraumatic arthrofibrosis. PLoS One 2021; 16:e0257147. [PMID: 34492074 PMCID: PMC8423260 DOI: 10.1371/journal.pone.0257147] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 08/24/2021] [Indexed: 02/06/2023] Open
Abstract
Posttraumatic fibrotic scarring is a significant medical problem that alters the proper functioning of injured tissues. Current methods to reduce posttraumatic fibrosis rely on anti-inflammatory and anti-proliferative agents with broad intracellular targets. As a result, their use is not fully effective and may cause unwanted side effects. Our group previously demonstrated that extracellular collagen fibrillogenesis is a valid and specific target to reduce collagen-rich scar buildup. Our previous studies showed that a rationally designed antibody that binds the C-terminal telopeptide of the α2(I) chain involved in the aggregation of collagen molecules limits fibril assembly in vitro and reduces scar formation in vivo. Here, we have utilized a clinically relevant arthrofibrosis model to study the broad mechanisms of the anti-scarring activity of this antibody. Moreover, we analyzed the effects of targeting collagen fibril formation on the quality of healed joint tissues, including the posterior capsule, patellar tendon, and subchondral bone. Our results show that blocking collagen fibrillogenesis not only reduces collagen content in the scar, but also accelerates the remodeling of healing tissues and changes the collagen fibrils’ cross-linking. In total, this study demonstrated that targeting collagen fibrillogenesis to limit arthrofibrosis affects neither the quality of healing of the joint tissues nor disturbs vital tissues and organs.
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Affiliation(s)
- Andrzej Steplewski
- Department of Orthopaedic Surgery, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
| | - Jolanta Fertala
- Department of Orthopaedic Surgery, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
| | - Ryan E. Tomlinson
- Department of Orthopaedic Surgery, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
| | - Mark L. Wang
- Department of Orthopaedic Surgery, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
- Rothman Institute of Orthopaedics, Thomas Jefferson University Hospital, Philadelphia, Pennsylvania, United States of America
| | - Allison Donahue
- College of Medicine, Drexel University, Philadelphia, Pennsylvania, United States of America
| | - William V. Arnold
- Department of Orthopaedic Surgery, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
- Rothman Institute of Orthopaedics, Thomas Jefferson University Hospital, Philadelphia, Pennsylvania, United States of America
| | - Michael Rivlin
- Department of Orthopaedic Surgery, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
- Rothman Institute of Orthopaedics, Thomas Jefferson University Hospital, Philadelphia, Pennsylvania, United States of America
| | - Pedro K. Beredjiklian
- Department of Orthopaedic Surgery, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
- Rothman Institute of Orthopaedics, Thomas Jefferson University Hospital, Philadelphia, Pennsylvania, United States of America
| | - Joseph A. Abboud
- Department of Orthopaedic Surgery, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
- Rothman Institute of Orthopaedics, Thomas Jefferson University Hospital, Philadelphia, Pennsylvania, United States of America
| | - Surena Namdari
- Department of Orthopaedic Surgery, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
- Rothman Institute of Orthopaedics, Thomas Jefferson University Hospital, Philadelphia, Pennsylvania, United States of America
| | - Andrzej Fertala
- Department of Orthopaedic Surgery, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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Abstract
3D bioprinting allows biocompatible materials and cells to be deposited in precise locations in three-dimensional space, enabling researchers to surpass the limitations of traditional 2D cell culture and to create innovative therapies. 3D bioprinting is one of the newest tools developed in the field of tissue engineering, which has traditionally utilized a paradigm revolving around scaffolds, cells, and signals. In this review, we discuss how new developments in each of these three research areas relates to bioprinting dental tissues - specifically teeth, periodontal ligament, and alveolar bone. Important considerations include how scaffold materials and geometry affect regeneration of dental tissues, the importance of using dental cells in these applications, and the role of signaling molecules for creating a clinically relevant bioengineered dental implant. We conclude with potential new directions for research that would allow the burgeoning field of regenerative dentistry to achieve its lofty goals.
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Affiliation(s)
- Devin Grace Morrison
- Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Ryan E Tomlinson
- Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
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10
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Fioravanti G, Hua PQ, Tomlinson RE. The TrkA agonist gambogic amide augments skeletal adaptation to mechanical loading. Bone 2021; 147:115908. [PMID: 33713848 PMCID: PMC8097708 DOI: 10.1016/j.bone.2021.115908] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 03/02/2021] [Accepted: 03/03/2021] [Indexed: 10/21/2022]
Abstract
The periosteal and endosteal surfaces of mature bone are densely innervated by sensory nerves expressing TrkA, the high-affinity receptor for nerve growth factor (NGF). In previous work, we demonstrated that administration of exogenous NGF significantly increased load-induced bone formation through the activation of Wnt signaling. However, the translational potential of NGF is limited by the induction of substantial mechanical and thermal hyperalgesia in mice and humans. Here, we tested the effect of gambogic amide (GA), a recently identified robust small molecule agonist for TrkA, on hyperalgesia and load-induced bone formation. Behavioral analysis was used to assess pain up to one week after axial forelimb compression. Contrary to our expectations, GA treatment was not associated with diminished use of the loaded forelimb or sensitivity to thermal stimulus. Furthermore, dynamic histomorphometry revealed a significant increase in relative periosteal bone formation rate as compared to vehicle treatment. Additionally, we found that GA treatment was associated with an increase in the number of osteoblasts per bone surface in loaded limbs as well as a significant increase in the fold change of Ngf, Wnt7b, and Axin2 mRNA expression as compared to vehicle (control). To test the effect of GA on osteoblasts directly, we cultured MC3T3-E1 cells for up to 21 days in osteogenic differentiation media containing NGF, GA, or vehicle (control). Media containing GA induced the significant upregulation of the osteoblastic differentiation markers Runx2, Bglap2, and Sp7 in a dose-dependent manner, whereas treatment with NGF was not associated with any significant increases in these markers. Furthermore, consistent with our in vivo findings, we observed that administration of 50 nM of GA upregulated expression of Ngf at both Day 3 and Day 7. However, cells treated with the highest dose of GA (500 nM) had significantly increased apoptosis and impaired cell proliferation. In conclusion, our study indicates GA may be useful for augmenting skeletal adaptation to mechanical forces without inducing hyperalgesia.
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Affiliation(s)
- Gabriella Fioravanti
- Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, PA, United States of America
| | - Phuong Q Hua
- Department of Biomedical Engineering, Drexel University, Philadelphia, PA, United States of America
| | - Ryan E Tomlinson
- Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, PA, United States of America.
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11
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Staab JS, Kolb AL, Tomlinson RE, Pajevic PD, Matheny RW, Hughes JM. Emerging evidence that adaptive bone formation inhibition by non-steroidal anti-inflammatory drugs increases stress fracture risk. Exp Biol Med (Maywood) 2021; 246:1104-1111. [PMID: 33641442 DOI: 10.1177/1535370221993098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
There is mounting evidence suggesting that the commonly used analgesics, non-steroidal anti-inflammatory drugs (NSAIDs), may inhibit new bone formation with physical training and increase risk of stress fractures in physically active populations. Stress fractures are thought to occur when bones are subjected to repetitive mechanical loading, which can lead to a cycle of tissue microdamage, repair, and continued mechanical loading until fracture. Adaptive bone formation, particularly on the periosteal surface of long bones, is a concurrent adaptive response of bone to heightened mechanical loading that can improve the fatigue resistance of the skeletal structure, and therefore may play a critical role in offsetting the risk of stress fracture. Reports from animal studies suggest that NSAID administration may suppress this important adaptive response to mechanical loading. These observations have implications for populations such as endurance athletes and military recruits who are at risk of stress fracture and whose use of NSAIDs is widespread. However, results from human trials evaluating exercise and bone adaptation with NSAID consumption have been less conclusive. In this review, we identify knowledge gaps that must be addressed to further support NSAID-related guidelines intended for at-risk populations and individuals.
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Affiliation(s)
- Jeffery S Staab
- Military Performance Division, United States Army Research Institute of Environmental Medicine, Natick, MA 01760, USA
| | - Alexander L Kolb
- Military Performance Division, United States Army Research Institute of Environmental Medicine, Natick, MA 01760, USA
| | - Ryan E Tomlinson
- Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | | | - Ronald W Matheny
- Military Operational Medicine Research Program, Fort Detrick, MD 21702, USA
| | - Julie M Hughes
- Military Performance Division, United States Army Research Institute of Environmental Medicine, Natick, MA 01760, USA
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12
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Szeri F, Lundkvist S, Donnelly S, Engelke UFH, Rhee K, Williams CJ, Sundberg JP, Wevers RA, Tomlinson RE, Jansen RS, van de Wetering K. The membrane protein ANKH is crucial for bone mechanical performance by mediating cellular export of citrate and ATP. PLoS Genet 2020; 16:e1008884. [PMID: 32639996 PMCID: PMC7371198 DOI: 10.1371/journal.pgen.1008884] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 07/20/2020] [Accepted: 05/25/2020] [Indexed: 01/23/2023] Open
Abstract
The membrane protein ANKH was known to prevent pathological mineralization of joints and was thought to export pyrophosphate (PPi) from cells. This did not explain, however, the presence of ANKH in tissues, such as brain, blood vessels and muscle. We now report that in cultured cells ANKH exports ATP, rather than PPi, and, unexpectedly, also citrate as a prominent metabolite. The extracellular ATP is rapidly converted into PPi, explaining the role of ANKH in preventing ankylosis. Mice lacking functional Ank (Ankank/ank mice) had plasma citrate concentrations that were 65% lower than those detected in wild type control animals. Consequently, citrate excretion via the urine was substantially reduced in Ankank/ank mice. Citrate was even undetectable in the urine of a human patient lacking functional ANKH. The hydroxyapatite of Ankank/ank mice contained dramatically reduced levels of both, citrate and PPi and displayed diminished strength. Our results show that ANKH is a critical contributor to extracellular citrate and PPi homeostasis and profoundly affects bone matrix composition and, consequently, bone quality.
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Affiliation(s)
- Flora Szeri
- Department of Dermatology and Cutaneous Biology, Jefferson Institute of Molecular Medicine and PXE International Center of Excellence in Research and Clinical Care, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
| | - Stefan Lundkvist
- Department of Dermatology and Cutaneous Biology, Jefferson Institute of Molecular Medicine and PXE International Center of Excellence in Research and Clinical Care, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
| | - Sylvia Donnelly
- Department of Dermatology and Cutaneous Biology, Jefferson Institute of Molecular Medicine and PXE International Center of Excellence in Research and Clinical Care, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
| | - Udo F. H. Engelke
- Translational Metabolic Laboratory, Department Laboratory Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Kyu Rhee
- Division of Infectious Diseases, Department of Medicine, Weill Cornell Medicine, New York, New York, United States of America
| | - Charlene J. Williams
- Cooper Medical School of Rowan University, Camden, New Jersey, United States of America
| | - John P. Sundberg
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | - Ron A. Wevers
- Translational Metabolic Laboratory, Department Laboratory Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Ryan E. Tomlinson
- Department of Orthopedic Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
| | - Robert S. Jansen
- Division of Infectious Diseases, Department of Medicine, Weill Cornell Medicine, New York, New York, United States of America
| | - Koen van de Wetering
- Department of Dermatology and Cutaneous Biology, Jefferson Institute of Molecular Medicine and PXE International Center of Excellence in Research and Clinical Care, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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13
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Abou DS, Rittenbach A, Tomlinson RE, Finley PA, Tsui B, Simons BW, Jha AK, Ulmert D, Riddle RC, Thorek DLJ. Preclinical Single Photon Emission Computed Tomography of Alpha Particle-Emitting Radium-223. Cancer Biother Radiopharm 2020; 35:520-529. [PMID: 32182119 DOI: 10.1089/cbr.2019.3308] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Objective: Dose optimization and pharmacokinetic evaluation of α-particle emitting radium-223 dichloride (223RaCl2) by planar γ-camera or single photon emission computed tomography (SPECT) imaging are hampered by the low photon abundance and injected activities. In this study, we demonstrate SPECT of 223Ra using phantoms and small animal in vivo models. Methods: Line phantoms and mice bearing 223Ra were imaged using a dedicated small animal SPECT by detecting the low-energy photon emissions from 223Ra. Localization of the therapeutic agent was verified by whole-body and whole-limb autoradiography and its radiobiological effect confirmed by immunofluorescence. Results: A state-of-the-art commercial small animal SPECT system equipped with a highly sensitive collimator enables collection of sufficient counts for three-dimensional reconstruction at reasonable administered activities and acquisition times. Line sources of 223Ra in both air and in a water scattering phantom gave a line spread function with a full-width-at-half-maximum of 1.45 mm. Early and late-phase imaging of the pharmacokinetics of the radiopharmaceutical were captured. Uptake at sites of active bone remodeling was correlated with DNA damage from the α particle emissions. Conclusions: This work demonstrates the capability to noninvasively define the distribution of 223RaCl2, a recently approved α-particle-emitting radionuclide. This approach allows quantitative assessment of 223Ra distribution and may assist radiation-dose optimization strategies to improve therapeutic response and ultimately to enable personalized treatment planning.
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Affiliation(s)
- Diane S Abou
- Department of Radiology, Washington University School of Medicine, St. Louis, Missouri, USA.,Program in Quantitative Molecular Therapeutics, Washington University School of Medicine, St. Louis, Missouri, USA.,Radiology Cyclotron Facility, Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, Missouri, USA.,Oncologic Imaging Program, Siteman Cancer Center, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Andrew Rittenbach
- Information Sciences Institute, University of Southern California, Los Angeles, California, USA
| | - Ryan E Tomlinson
- Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Paige A Finley
- Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Benjamin Tsui
- Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Brian W Simons
- Center for Comparative Medicine, Baylor College of Medicine, Houston, Texas, USA
| | - Abhinav K Jha
- Department of Radiology, Washington University School of Medicine, St. Louis, Missouri, USA.,Department of Biomedical Engineering, Washington University, St. Louis, Missouri, USA
| | - David Ulmert
- Department of Molecular and Medical Pharmacology, University of California Los Angeles, Los Angeles, California, USA.,Division of Urological Research, Department of Clinical Sciences, Lünd University, Malmö, Sweden
| | - Ryan C Riddle
- Department of Orthopaedic Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Daniel L J Thorek
- Department of Radiology, Washington University School of Medicine, St. Louis, Missouri, USA.,Program in Quantitative Molecular Therapeutics, Washington University School of Medicine, St. Louis, Missouri, USA.,Oncologic Imaging Program, Siteman Cancer Center, Washington University School of Medicine, St. Louis, Missouri, USA.,Department of Biomedical Engineering, Washington University, St. Louis, Missouri, USA
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14
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Kushwaha P, Kim S, Foxa GE, Michalski MN, Williams BO, Tomlinson RE, Riddle RC. Frizzled-4 is required for normal bone acquisition despite compensation by Frizzled-8. J Cell Physiol 2020; 235:6673-6683. [PMID: 31985040 DOI: 10.1002/jcp.29563] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Accepted: 01/10/2020] [Indexed: 12/20/2022]
Abstract
The activation of the Wnt/β-catenin signaling pathway is critical for skeletal development but surprisingly little is known about the requirements for the specific frizzled (Fzd) receptors that recognize Wnt ligands. To define the contributions of individual Fzd proteins to osteoblast function, we profiled the expression of all 10 mammalian receptors during calvarial osteoblast differentiation. Expression of Fzd4 was highly upregulated during in vitro differentiation and therefore targeted for further study. Mice lacking Fzd4 in mature osteoblasts had normal cortical bone structure but reduced cortical tissue mineral density and also exhibited an impairment in the femoral trabecular bone acquisition that was secondary to a defect in the mineralization process. Consistent with this observation, matrix mineralization, markers of osteoblastic differentiation, and the ability of Wnt3a to stimulate the accumulation of β-catenin were reduced in cultures of calvarial osteoblasts deficient for Fzd4. Interestingly, Fzd4-deficient osteoblasts exhibited an increase in the expression of Fzd8 both in vitro and in vivo, which suggests that the two receptors may exhibit overlapping functions. Indeed, ablating a single Fzd8 allele in osteoblast-specific Fzd4 mutants produced a more severe effect on bone acquisition. Taken together, our data indicate that Fzd4 is required for normal bone development and mineralization despite compensation from Fzd8.
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Affiliation(s)
- Priyanka Kushwaha
- Department of Orthopaedic Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Soohyun Kim
- Department of Orthopaedic Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Gabrielle E Foxa
- Program for Skeletal Disease and Tumor Microenvironment and Center for Cancer and Cell Biology, Van Andel Research Institute, Grand Rapids, Michigan
| | - Megan N Michalski
- Program for Skeletal Disease and Tumor Microenvironment and Center for Cancer and Cell Biology, Van Andel Research Institute, Grand Rapids, Michigan
| | - Bart O Williams
- Program for Skeletal Disease and Tumor Microenvironment and Center for Cancer and Cell Biology, Van Andel Research Institute, Grand Rapids, Michigan
| | - Ryan E Tomlinson
- Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Ryan C Riddle
- Department of Orthopaedic Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland.,Research and Development Service, Baltimore Veterans Administration Medical Center, Baltimore, Maryland
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15
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Abstract
The skeleton is well-innervated, but only recently have the functions of this complex network in bone started to become known. Although our knowledge of skeletal sensory and sympathetic innervation is incomplete, including the specific locations and subtypes of nerves in bone, we are now able to reconcile early studies utilizing denervation models with recent work dissecting the molecular signaling between bone and nerve. In total, sensory innervation functions in bone much as it does elsewhere in the body-to sense and respond to stimuli, including mechanical loading. Similarly, sympathetic nerves regulate autonomic functions related to bone, including homeostatic remodeling and vascular tone. However, more study is required to translate our current knowledge of bone-nerve crosstalk to novel therapeutic strategies that can be effectively utilized to combat skeletal diseases, disorders of low bone mass, and age-related decreases in bone quality.
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Affiliation(s)
- Ryan E. Tomlinson
- Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, PA, United States
- *Correspondence: Ryan E. Tomlinson
| | - Blaine A. Christiansen
- Department of Orthopaedic Surgery, School of Medicine, University of California, Davis, Sacramento, CA, United States
| | - Adrienne A. Giannone
- Department of Anatomy, Physiology, and Cell Biology, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States
| | - Damian C. Genetos
- Department of Anatomy, Physiology, and Cell Biology, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States
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16
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Park J, Fertala A, Tomlinson RE. Naproxen impairs load-induced bone formation, reduces bone toughness, and diminishes woven bone formation following stress fracture in mice. Bone 2019; 124:22-32. [PMID: 30998998 DOI: 10.1016/j.bone.2019.04.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 04/01/2019] [Accepted: 04/14/2019] [Indexed: 01/17/2023]
Abstract
Debilitating stress fractures are surprisingly common in physically active individuals, including athletes, military recruits, and dancers. These individuals are overrepresented in the 30 million daily users of non-steroidal anti-inflammatory drugs (NSAIDs). We hypothesized that regular use of NSAIDs would predispose habitually loaded bones to stress fracture and delay the repair of these injuries. In this project, we used repetitive axial forelimb compression in mice as a model to test these hypotheses. First, adult mice were subjected to six bouts of forelimb compression over a period of two weeks, with aspirin, naproxen, or vehicle continuously administered through drinking water. Naproxen-treated mice had diminished load-induced bone formation as well as a significant loss in toughness in non-loaded bone, which were not observed in aspirin-treated mice. Furthermore, there were no differences in RANKL/OPG ratio or cortical bone parameters. Picrosirius red staining and second harmonic generation imaging revealed that alterations in bone collagen fibril size and organization were driving the loss of toughness in naproxen-treated mice. Separately, adult mice were subjected to an ulnar stress fracture generated by a single bout of fatigue loading, with NSAIDs provided 24 h before injury. Both aspirin-treated and naproxen-treated mice had normal forelimb use in the week after injury, whereas control mice favored the injured forelimb until day 7. However, woven bone volume was only significantly impaired by naproxen. Both NSAIDs were found to significantly inhibit Ptgs2 and Ngf expression following stress fracture, but only naproxen significantly affected serum PGE2 concentration. Overall, our results suggest that naproxen, but not aspirin, may increase the risk of stress fracture and extend the healing time of these injuries, warranting further clinical evaluation for patients at risk for fatigue injuries.
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Affiliation(s)
- Jino Park
- Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Andrzej Fertala
- Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Ryan E Tomlinson
- Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, PA 19107, USA.
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17
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Cavinatto L, Hinckel BB, Tomlinson RE, Gupta S, Farr J, Bartolozzi AR. The Role of Bone Marrow Aspirate Concentrate for the Treatment of Focal Chondral Lesions of the Knee: A Systematic Review and Critical Analysis of Animal and Clinical Studies. Arthroscopy 2019; 35:1860-1877. [PMID: 30871903 DOI: 10.1016/j.arthro.2018.11.073] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 11/08/2018] [Accepted: 11/22/2018] [Indexed: 02/02/2023]
Abstract
PURPOSE To summarize currently available data regarding the use of bone marrow aspirate concentrate (BMAC) for the treatment of focal chondral lesions of the knee in experimental animal models and human clinical studies. METHODS A systematic review searching for the terms "(bone marrow)" AND "(aspirate OR concentrate)" AND "(cartilage OR chondral OR osteochondral)" was performed in the databases PubMed, Cochrane Central Register of Controlled Trials, and Google Scholar regarding the use of BMAC for the treatment of focal chondral lesions of the knee. The inclusion criteria were animal and clinical studies published in English that used autologous BMAC to treat focal chondral defects of the knee. We excluded studies that evaluated nonconcentrated preparations of bone marrow aspirate or preparations that were culture expanded. RESULTS A total of 23 studies were included: 10 studies performed in animal models and 13 human clinical studies. Animal studies showed inconsistent outcomes regarding the efficacy of BMAC for the treatment of chondral or osteochondral lesions, assessed by gross morphology, second-look arthroscopy, magnetic resonance imaging, histology, immunohistochemistry, mechanical testing, and micro-tomography. Chondral defect filling was achieved with fibrocartilage or "hyaline-like" cartilage. Cells present in BMAC did not meet the criteria to be characterized as mesenchymal stem cells according to the International Society for Cell Therapy because freshly isolated cells failed to show tri-lineage differentiation. Overall, all clinical studies, independent of the study group or level of evidence, reported improved clinical outcomes and higher macroscopic, magnetic resonance imaging, and histology scores. Comparative trials favored BMAC over microfracture and reported equivalent outcomes between BMAC and matrix-induced autologous chondrocyte implantation. However, clinical studies were scant and showed low scientific rigor, poor methodologic quality, and low levels of evidence on average. CONCLUSIONS Although clinical success in short-term and midterm applications has been suggested for the application of BMAC for the restoration of cartilage defects in lesions of the knee, current study designs are generally of low scientific rigor. In addition, clinical applications of this technology in animal model investigations have shown inconsistent outcomes. Thus, clinicians should apply this technology cautiously. LEVEL OF EVIDENCE Level IV, systematic review of Level II, III, and IV evidence studies.
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Affiliation(s)
| | | | | | - Sunny Gupta
- Jefferson 3B Orthopaedics, Philadelphia, Pennsylvania, U.S.A
| | - Jack Farr
- Cartilage Restoration Center, OrthoIndy, Greenwood, Indiana, U.S.A
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18
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Ziegler SG, Ferreira CR, MacFarlane EG, Riddle RC, Tomlinson RE, Chew EY, Martin L, Ma CT, Sergienko E, Pinkerton AB, Millán JL, Gahl WA, Dietz HC. Ectopic calcification in pseudoxanthoma elasticum responds to inhibition of tissue-nonspecific alkaline phosphatase. Sci Transl Med 2018; 9:9/393/eaal1669. [PMID: 28592560 DOI: 10.1126/scitranslmed.aal1669] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 01/10/2017] [Accepted: 04/25/2017] [Indexed: 12/26/2022]
Abstract
Biallelic mutations in ABCC6 cause pseudoxanthoma elasticum (PXE), a disease characterized by calcification in the skin, eyes, and blood vessels. The function of ATP-binding cassette C6 (ABCC6) and the pathogenesis of PXE remain unclear. We used mouse models and patient fibroblasts to demonstrate genetic interaction and shared biochemical and cellular mechanisms underlying ectopic calcification in PXE and related disorders caused by defined perturbations in extracellular adenosine 5'-triphosphate catabolism. Under osteogenic culture conditions, ABCC6 mutant cells calcified, suggesting a provoked cell-autonomous defect. Using a conditional Abcc6 knockout mouse model, we excluded the prevailing pathogenic hypothesis that singularly invokes failure of hepatic secretion of an endocrine inhibitor of calcification. Instead, deficiency of Abcc6 in both local and distant cells was necessary to achieve the early onset and penetrant ectopic calcification observed upon constitutive gene targeting. ABCC6 mutant cells additionally had increased expression and activity of tissue-nonspecific alkaline phosphatase (TNAP), an enzyme that degrades pyrophosphate, a major inhibitor of calcification. A selective and orally bioavailable TNAP inhibitor prevented calcification in ABCC6 mutant cells in vitro and attenuated both the development and progression of calcification in Abcc6-/- mice in vivo, without the deleterious effects on bone associated with other proposed treatment strategies.
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Affiliation(s)
- Shira G Ziegler
- Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
| | - Carlos R Ferreira
- Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20814, USA
| | - Elena Gallo MacFarlane
- Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Ryan C Riddle
- Department of Orthopaedic Surgery, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.,Baltimore Veterans Administrations Medical Center, Baltimore, MD 21201, USA
| | - Ryan E Tomlinson
- Department of Orthopaedic Surgery, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Emily Y Chew
- National Eye Institute, National Institutes of Health, Bethesda, MD 20814, USA
| | - Ludovic Martin
- PXE Reference Center and MitoVasc Institute, Angers University Hospital, Angers, France
| | - Chen-Ting Ma
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | - Eduard Sergienko
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | | | - José Luis Millán
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | - William A Gahl
- Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20814, USA
| | - Harry C Dietz
- Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA. .,Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
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19
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Kim SP, Frey JL, Li Z, Kushwaha P, Zoch ML, Tomlinson RE, Da H, Aja S, Noh HL, Kim JK, Hussain MA, Thorek DLJ, Wolfgang MJ, Riddle RC. Sclerostin influences body composition by regulating catabolic and anabolic metabolism in adipocytes. Proc Natl Acad Sci U S A 2017; 114:E11238-E11247. [PMID: 29229807 PMCID: PMC5748171 DOI: 10.1073/pnas.1707876115] [Citation(s) in RCA: 102] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Sclerostin has traditionally been thought of as a local inhibitor of bone acquisition that antagonizes the profound osteoanabolic capacity of activated Wnt/β-catenin signaling, but serum sclerostin levels in humans exhibit a correlation with impairments in several metabolic parameters. These data, together with the increased production of sclerostin in mouse models of type 2 diabetes, suggest an endocrine function. To determine whether sclerostin contributes to the coordination of whole-body metabolism, we examined body composition, glucose homeostasis, and fatty acid metabolism in Sost-/- mice as well as mice that overproduce sclerostin as a result of adeno-associated virus expression from the liver. Here, we show that in addition to dramatic increases in bone volume, Sost-/- mice exhibit a reduction in adipose tissue accumulation in association with increased insulin sensitivity. Sclerostin overproduction results in the opposite metabolic phenotype due to adipocyte hypertrophy. Additionally, Sost-/- mice and those administered a sclerostin-neutralizing antibody are resistant to obesogenic diet-induced disturbances in metabolism. This effect appears to be the result of sclerostin's effects on Wnt signaling and metabolism in white adipose tissue. Since adipocytes do not produce sclerostin, these findings suggest an unexplored endocrine function for sclerostin that facilitates communication between the skeleton and adipose tissue.
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Affiliation(s)
- Soohyun P Kim
- Department of Orthopaedic Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Julie L Frey
- Department of Orthopaedic Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Zhu Li
- Department of Orthopaedic Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Priyanka Kushwaha
- Department of Orthopaedic Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Meredith L Zoch
- Department of Orthopaedic Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Ryan E Tomlinson
- Department of Orthopaedic Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Hao Da
- Department of Orthopaedic Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Susan Aja
- Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
- Center for Metabolism and Obesity Research, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Hye Lim Noh
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01655
| | - Jason K Kim
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01655
- Department of Medicine, Division of Endocrinology and Metabolism, University of Massachusetts Medical School, Worcester, MA 01655
- Department of Medicine, Division of Diabetes, University of Massachusetts Medical School, Worcester, MA 01655
| | - Mehboob A Hussain
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
- Department of Pediatrics, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Daniel L J Thorek
- Division of Nuclear Medicine and Molecular Imaging, Department of Radiology and Radiologic Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
- Cancer Molecular and Functional Imaging Program, Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Michael J Wolfgang
- Center for Metabolism and Obesity Research, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Ryan C Riddle
- Department of Orthopaedic Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD 21205;
- Baltimore Veterans Administration Medical Center, Baltimore, MD 21201
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20
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Buo AM, Tomlinson RE, Eidelman ER, Chason M, Stains JP. Connexin43 and Runx2 Interact to Affect Cortical Bone Geometry, Skeletal Development, and Osteoblast and Osteoclast Function. J Bone Miner Res 2017; 32:1727-1738. [PMID: 28419546 PMCID: PMC5550348 DOI: 10.1002/jbmr.3152] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 03/30/2017] [Accepted: 04/10/2017] [Indexed: 12/30/2022]
Abstract
The coupling of osteoblasts and osteocytes by connexin43 (Cx43) gap junctions permits the sharing of second messengers that coordinate bone cell function and cortical bone acquisition. However, details of how Cx43 converts shared second messengers into signals that converge onto essential osteogenic processes are incomplete. Here, we use in vitro and in vivo methods to show that Cx43 and Runx2 functionally interact to regulate osteoblast gene expression and proliferation, ultimately affecting cortical bone properties. Using compound hemizygous mice for the Gja1 (Cx43) and Runx2 genes, we observed a skeletal phenotype not visible in wild-type or singly hemizygous animals. Cortical bone analysis by micro-computed tomography (μCT) revealed that 8-week-old male, compound Gja1+/- Runx2+/- mice have a marked increase in cross-sectional area, endosteal and periosteal bone perimeter, and an increase in porosity compared to controls. These compound Gja1+/- Runx2+/- mice closely approximate the cortical bone phenotypes seen in osteoblast-specific Gja1-conditional knockout models. Furthermore, μCT analysis of skulls revealed an altered interparietal bone geometry in compound hemizygotes. Consistent with this finding, Alizarin red/Alcian blue staining of 2-day-old Gja1+/- Runx2+/- neonates showed a hypomorphic interparietal bone, an exacerbation of the open fontanelles, and a further reduction in the hypoplastic clavicles compared to Runx2+/- neonates. Expression of osteoblast genes, including osteocalcin, osterix, periostin, and Hsp47, was markedly reduced in tibial RNA extracts from compound hemizygous mice, and osteoblasts from compound hemizygous mice exhibited increased proliferative capacity. Further, the reduced osteocalcin expression and hyperproliferative nature of osteoblasts from Cx43 deficient mice was rescued by Runx2 expression. In summary, these findings provide evidence that Cx43 and Runx2 functionally intersect in vivo to regulate cortical bone properties and affect osteoblast differentiation and proliferation, and likely contributes to aspects of the skeletal phenotype of Cx43 conditional knockout mice. © 2017 American Society for Bone and Mineral Research.
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Affiliation(s)
- Atum M Buo
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Ryan E Tomlinson
- Department of Orthopedic Surgery, Johns Hopkins University, Baltimore, MD, USA
| | - Eric R Eidelman
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Max Chason
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Joseph P Stains
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, USA
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21
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Goh BC, Singhal V, Herrera AJ, Tomlinson RE, Kim S, Faugere MC, Germain-Lee EL, Clemens TL, Lee SJ, DiGirolamo DJ. Activin receptor type 2A (ACVR2A) functions directly in osteoblasts as a negative regulator of bone mass. J Biol Chem 2017; 292:13809-13822. [PMID: 28659341 DOI: 10.1074/jbc.m117.782128] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Revised: 06/27/2017] [Indexed: 02/06/2023] Open
Abstract
Bone and skeletal muscle mass are highly correlated in mammals, suggesting the existence of common anabolic signaling networks that coordinate the development of these two anatomically adjacent tissues. The activin signaling pathway is an attractive candidate to fulfill such a role. Here, we generated mice with conditional deletion of activin receptor (ACVR) type 2A, ACVR2B, or both, in osteoblasts, to determine the contribution of activin receptor signaling in regulating bone mass. Immunohistochemistry localized ACVR2A and ACVR2B to osteoblasts and osteocytes. Primary osteoblasts expressed activin signaling components, including ACVR2A, ACVR2B, and ACVR1B (ALK4) and demonstrated increased levels of phosphorylated Smad2/3 upon exposure to activin ligands. Osteoblasts lacking ACVR2B did not show significant changes in vitro However, osteoblasts deficient in ACVR2A exhibited enhanced differentiation indicated by alkaline phosphatase activity, mineral deposition, and transcriptional expression of osterix, osteocalcin, and dentin matrix acidic phosphoprotein 1. To investigate activin signaling in osteoblasts in vivo, we analyzed the skeletal phenotypes of mice lacking these receptors in osteoblasts and osteocytes (osteocalcin-Cre). Similar to the lack of effect in vitro, ACVR2B-deficient mice demonstrated no significant change in any bone parameter. By contrast, mice lacking ACVR2A had significantly increased femoral trabecular bone volume at 6 weeks of age. Moreover, mutant mice lacking both ACVR2A and ACVR2B demonstrated sustained increases in trabecular bone volume, similar to those in ACVR2A single mutants, at 6 and 12 weeks of age. Taken together, these results indicate that activin receptor signaling, predominantly through ACVR2A, directly and negatively regulates bone mass in osteoblasts.
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Affiliation(s)
- Brian C Goh
- From the Departments of Orthopaedic Surgery and
| | | | | | | | - Soohyun Kim
- From the Departments of Orthopaedic Surgery and
| | - Marie-Claude Faugere
- the Albert B. Chandler Medical Center, University of Kentucky, Lexington, Kentucky 40536
| | - Emily L Germain-Lee
- the Department of Pediatrics, University of Connecticut School of Medicine/UConn Health, Farmington, Connecticut 06030.,the Division of Pediatric Endocrinology, Connecticut Children's Medical Center, Hartford, Connecticut 06106, and
| | - Thomas L Clemens
- From the Departments of Orthopaedic Surgery and.,the Veterans Administration Medical Center, Baltimore, Maryland 21201
| | - Se-Jin Lee
- Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287
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22
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Moorer MC, Hebert C, Tomlinson RE, Iyer SR, Chason M, Stains JP. Defective signaling, osteoblastogenesis and bone remodeling in a mouse model of connexin 43 C-terminal truncation. J Cell Sci 2017; 130:531-540. [PMID: 28049723 PMCID: PMC5312734 DOI: 10.1242/jcs.197285] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 11/28/2016] [Indexed: 01/29/2023] Open
Abstract
In skeletal tissue, loss or mutation of the gap junction protein connexin 43 (Cx43, also known as GJA1) in cells of the osteoblast lineage leads to a profound cortical bone phenotype and defective tissue remodeling. There is mounting evidence in bone cells that the C-terminus (CT) of Cx43 is a docking platform for signaling effectors and is required for efficient downstream signaling. Here, we examined this function, using a mouse model of Cx43 CT-truncation (Gja1 K258Stop). Relative to Gja1+/- controls, male Gja1-/K258Stop mice have a cortical bone phenotype that is remarkably similar to those reported for deletion of the entire Cx43 gene in osteoblasts. Furthermore, we show that the Cx43 CT binds several signaling proteins that are required for optimal osteoblast function, including PKCδ, ERK1 and ERK2 (ERK1/2, also known as MAPK3 and MAPK1, respectively) and β-catenin. Deletion of the Cx43 CT domain affects these signaling cascades, impacting osteoblast proliferation, differentiation, and collagen processing and organization. These data imply that, at least in bone, Cx43 gap junctions not only exchange signals, but also recruit the appropriate effector molecules to the Cx43 CT in order to efficiently activate signaling cascades that affect cell function and bone acquisition.
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Affiliation(s)
- Megan C Moorer
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Carla Hebert
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Ryan E Tomlinson
- Department of Orthopaedic Surgery, Johns Hopkins University, Baltimore, MD 21287, USA
| | - Shama R Iyer
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Max Chason
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Joseph P Stains
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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23
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Tomlinson RE, Li Z, Zhang Q, Goh BC, Li Z, Thorek DLJ, Rajbhandari L, Brushart TM, Minichiello L, Zhou F, Venkatesan A, Clemens TL. NGF-TrkA Signaling by Sensory Nerves Coordinates the Vascularization and Ossification of Developing Endochondral Bone. Cell Rep 2016; 16:2723-2735. [PMID: 27568565 DOI: 10.1016/j.celrep.2016.08.002] [Citation(s) in RCA: 106] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Revised: 06/13/2016] [Accepted: 07/31/2016] [Indexed: 12/16/2022] Open
Abstract
Developing tissues dictate the amount and type of innervation they require by secreting neurotrophins, which promote neuronal survival by activating distinct tyrosine kinase receptors. Here, we show that nerve growth factor (NGF) signaling through neurotrophic tyrosine kinase receptor type 1 (TrkA) directs innervation of the developing mouse femur to promote vascularization and osteoprogenitor lineage progression. At the start of primary ossification, TrkA-positive axons were observed at perichondrial bone surfaces, coincident with NGF expression in cells adjacent to centers of incipient ossification. Inactivation of TrkA signaling during embryogenesis in TrkA(F592A) mice impaired innervation, delayed vascular invasion of the primary and secondary ossification centers, decreased numbers of Osx-expressing osteoprogenitors, and decreased femoral length and volume. These same phenotypic abnormalities were observed in mice following tamoxifen-induced disruption of NGF in Col2-expressing perichondrial osteochondral progenitors. We conclude that NGF serves as a skeletal neurotrophin to promote sensory innervation of developing long bones, a process critical for normal primary and secondary ossification.
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Affiliation(s)
- Ryan E Tomlinson
- Department of Orthopaedic Surgery, Johns Hopkins University, Baltimore, MD 21287, USA
| | - Zhi Li
- Department of Orthopaedic Surgery, Johns Hopkins University, Baltimore, MD 21287, USA
| | - Qian Zhang
- Department of Orthopaedic Surgery, Johns Hopkins University, Baltimore, MD 21287, USA
| | - Brian C Goh
- Department of Orthopaedic Surgery, Johns Hopkins University, Baltimore, MD 21287, USA
| | - Zhu Li
- Department of Orthopaedic Surgery, Johns Hopkins University, Baltimore, MD 21287, USA
| | - Daniel L J Thorek
- Department of Radiology and Radiological Sciences, Johns Hopkins University, Baltimore, MD 21287, USA; Department of Oncology, Johns Hopkins University, Baltimore, MD 21287, USA
| | | | - Thomas M Brushart
- Department of Orthopaedic Surgery, Johns Hopkins University, Baltimore, MD 21287, USA
| | | | - Fengquan Zhou
- Department of Orthopaedic Surgery, Johns Hopkins University, Baltimore, MD 21287, USA
| | - Arun Venkatesan
- Department of Neurology, Johns Hopkins University, Baltimore, MD 21287, USA
| | - Thomas L Clemens
- Department of Orthopaedic Surgery, Johns Hopkins University, Baltimore, MD 21287, USA; Baltimore Veterans Administration Medical Center, Baltimore, MD 21201, USA.
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24
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Zhang Q, Doucet M, Tomlinson RE, Han X, Quarles LD, Collins MT, Clemens TL. The hypoxia-inducible factor-1α activates ectopic production of fibroblast growth factor 23 in tumor-induced osteomalacia. Bone Res 2016; 4:16011. [PMID: 27468359 PMCID: PMC4948305 DOI: 10.1038/boneres.2016.11] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Accepted: 05/04/2016] [Indexed: 12/27/2022] Open
Abstract
Tumor-induced osteomalacia (TIO) is a rare paraneoplastic syndrome in which ectopic production of fibroblast growth factor 23 (FGF23) by non-malignant mesenchymal tumors causes phosphate wasting and bone fractures. Recent studies have implicated the hypoxia-inducible factor-1α (HIF-1α) in other phosphate wasting disorders caused by elevated FGF23, including X-linked hypophosphatemic rickets and autosomal dominant hypophosphatemia. Here we provide evidence that HIF-1α mediates aberrant FGF23 in TIO by transcriptionally activating its promoter. Immunohistochemical studies in phosphaturic mesenchymal tumors resected from patients with documented TIO showed that HIF-1α and FGF23 were co-localized in spindle-shaped cells adjacent to blood vessels. Cultured tumor tissue produced high levels of intact FGF23 and demonstrated increased expression of HIF-1α protein. Transfection of MC3T3-E1 and Saos-2 cells with a HIF-1α expression construct induced the activity of a FGF23 reporter construct. Prior treatment of tumor organ cultures with HIF-1α inhibitors decreased HIF-1α and FGF23 protein accumulation and inhibited HIF-1α-induced luciferase reporter activity in transfected cells. Chromatin immunoprecipitation assays confirmed binding to a HIF-1α consensus sequence within the proximal FGF23 promoter, which was eliminated by treatment with a HIF-1α inhibitor. These results show for the first time that HIF-1α is a direct transcriptional activator of FGF23 and suggest that upregulation of HIF-1α activity in TIO contributes to the aberrant FGF23 production in these patients.
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Affiliation(s)
- Qian Zhang
- Department of Orthopaedic Surgery, Johns Hopkins University , Baltimore, MD, USA
| | - Michele Doucet
- Department of Orthopaedic Surgery, Johns Hopkins University , Baltimore, MD, USA
| | - Ryan E Tomlinson
- Department of Orthopaedic Surgery, Johns Hopkins University , Baltimore, MD, USA
| | - Xiaobin Han
- Department of Medicine, University of Tennessee Health Science Center , Memphis, TN, USA
| | - L Darryl Quarles
- Department of Medicine, University of Tennessee Health Science Center , Memphis, TN, USA
| | - Michael T Collins
- Skeletal Clinical Studies Unit, Craniofacial and Skeletal Diseases Branch, National Institutes of Health , Bethesda, MD, USA
| | - Thomas L Clemens
- Department of Orthopaedic Surgery, Johns Hopkins University, Baltimore, MD, USA; Baltimore Veterans Administration Medical Center, Baltimore, MD, USA
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25
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Dewan AK, Tomlinson RE, Mitchell S, Goh BC, Yung RM, Kumar S, Tan EW, Faugere MC, Dietz HC, Clemens TL, Sponseller PD. Dysregulated TGF-β signaling alters bone microstructure in a mouse model of Loeys-Dietz syndrome. J Orthop Res 2015; 33:1447-54. [PMID: 26173585 DOI: 10.1002/jor.22920] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Accepted: 04/07/2015] [Indexed: 02/04/2023]
Abstract
Loeys-Dietz syndrome (LDS) is a connective tissue disorder characterized by vascular and skeletal abnormalities resembling Marfan syndrome, including a predisposition for pathologic fracture. LDS is caused by heterozygous mutations in the genes encoding transforming growth factor-β (TGF-β) type 1 and type 2 receptors. In this study, we characterized the skeletal phenotype of mice carrying a mutation in the TGF-β type 2 receptor associated with severe LDS in humans. Cortical bone in LDS mice showed significantly reduced tissue area, bone area, and cortical thickness with increased eccentricity. However, no significant differences in trabecular bone volume were observed. Dynamic histomorphometry performed in calcein-labeled mice showed decreased mineral apposition rates in cortical and trabecular bone with normal numbers of osteoblasts and osteoclasts. Mechanical testing of femurs by three-point bending revealed reduced femoral strength and fracture resistance. In vitro, osteoblasts from LDS mice demonstrated increased mineralization with enhanced expression of osteoblast differentiation markers compared with control cells. These changes were associated with impaired TGF-β1-induced Smad2 and Erk1/2 phosphorylation and upregulated TGF-β1 ligand mRNA expression, compatible with G357W as a loss-of-function mutation in the TGF-β type 2 receptor. Paradoxically, phosphorylated Smad2/3 in cortical osteocytes measured by immunohistochemistry was increased relative to controls, possibly suggesting the cross-activation of TGF-β-related receptors. The skeletal phenotype observed in the LDS mouse closely resembles the principal structural features of bone in humans with LDS and establishes this mouse as a valid in vivo model for further investigation of TGF-β receptor signaling in bone.
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Affiliation(s)
- Ashvin K Dewan
- Department of Orthopaedic Surgery, The Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Ryan E Tomlinson
- Department of Orthopaedic Surgery, The Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Stuart Mitchell
- Department of Orthopaedic Surgery, The Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Brian C Goh
- Department of Orthopaedic Surgery, The Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Rachel M Yung
- Department of Orthopaedic Surgery, The Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Sarvesh Kumar
- Department of Orthopaedic Surgery, The Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Eric W Tan
- Department of Orthopaedic Surgery, The Johns Hopkins University School of Medicine, Baltimore, Maryland
| | | | - Harry C Dietz
- McKusick-Nathans Institute of Genetic Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland.,Howard Hughes Medical Institute, The Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Thomas L Clemens
- Department of Orthopaedic Surgery, The Johns Hopkins University School of Medicine, Baltimore, Maryland.,Baltimore Veterans Administration Medical Center, Baltimore, Maryland
| | - Paul D Sponseller
- Department of Orthopaedic Surgery, The Johns Hopkins University School of Medicine, Baltimore, Maryland
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26
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Abstract
HIF-1 is a transcription factor typically associated with angiogenic gene transcription under hypoxic conditions. In this study, mice with HIF-1α deleted in the osteoblast lineage (ΔHIF-1α) were subjected to damaging or non-damaging mechanical loading known to produce woven or lamellar bone, respectively, at the ulnar diaphysis. By microCT, ΔHIF-1α mice produced significantly less woven bone than wild type (WT) mice 7days after damaging loading. This decrease in woven bone volume and extent was accompanied by a significant decrease in vascularity measured by immunohistochemistry against vWF. Additionally, osteocytes, rather than osteoblasts, appear to be the main bone cell expressing HIF-1α following damaging loading. In contrast, 10days after non-damaging mechanical loading, dynamic histomorphometry measurements demonstrated no impairment in loading-induced lamellar bone formation in ΔHIF-1α mice. In fact, both non-loaded and loaded ulnae from ΔHIF-1α mice had increased bone formation compared with WT ulnae. When comparing the relative increase in periosteal bone formation in loaded vs. non-loaded ulnae, it was not different between ΔHIF-1α mice and controls. There were no significant differences observed between WT and ΔHIF-1α mice in endosteal bone formation parameters. The increases in periosteal lamellar bone formation in ΔHIF-1α mice are attributed to non-angiogenic effects of the knockout. In conclusion, these results demonstrate that HIF-1α is a pro-osteogenic factor for woven bone formation after damaging loading, but an anti-osteogenic factor for lamellar bone formation under basal conditions and after non-damaging loading.
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Affiliation(s)
- Ryan E Tomlinson
- Departments of Orthopaedic Surgery and Biomedical Engineering, Musculoskeletal Research Center, Washington University in St. Louis, 425 S. Euclid Avenue, St. Louis, MO 63110, USA.
| | - Matthew J Silva
- Departments of Orthopaedic Surgery and Biomedical Engineering, Musculoskeletal Research Center, Washington University in St. Louis, 425 S. Euclid Avenue, St. Louis, MO 63110, USA.
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27
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Tomlinson RE, Schmieder AH, Quirk JD, Lanza GM, Silva MJ. Antagonizing the αv β3 integrin inhibits angiogenesis and impairs woven but not lamellar bone formation induced by mechanical loading. J Bone Miner Res 2014; 29:1970-80. [PMID: 24644077 PMCID: PMC4323187 DOI: 10.1002/jbmr.2223] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Revised: 02/25/2014] [Accepted: 02/27/2014] [Indexed: 12/26/2022]
Abstract
Angiogenesis and osteogenesis are critically linked, although the role of angiogenesis is not well understood in osteogenic mechanical loading. In this study, either damaging or non-damaging cyclic axial compression was used to generate woven bone formation (WBF) or lamellar bone formation (LBF), respectively, at the mid-diaphysis of the adult rat forelimb. αv β3 integrin-targeted nanoparticles or vehicle was injected intravenously after mechanical loading. β3 integrin subunit expression on vasculature was maximal 7 days after damaging mechanical loading, but was still robustly expressed 14 days after loading. Accordingly, targeted nanoparticle delivery in WBF-loaded limbs was increased compared with non-loaded limbs. Vascularity was dramatically increased after WBF loading (+700% on day 14) and modestly increased after LBF loading (+50% on day 14). This increase in vascularity was inhibited by nanoparticle treatment in both WBF- and LBF-loaded limbs at days 7 and 14 after loading. Decreased vascularity led to diminished woven, but not lamellar, bone formation. Decreased woven bone formation resulted in impaired structural properties of the skeletal repair, particularly in post-yield behavior. These results demonstrate that αv β3 integrin-mediated angiogenesis is critical for recovering fracture resistance after bone injury but is not required for bone modeling after modest mechanical strain. © 2014 American Society for Bone and Mineral Research.
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Affiliation(s)
- Ryan E Tomlinson
- Department of Orthopaedic Surgery, Musculoskeletal Research Center, Washington University in St. Louis, St. Louis, MO, USA; Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA
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Abstract
Bone is a highly vascularized tissue, although this aspect of bone is often overlooked. In this article, the importance of blood flow in bone repair and regeneration will be reviewed. First, the skeletal vascular anatomy, with an emphasis on long bones, the distinct mechanisms for vascularizing bone tissue, and methods for remodeling existing vasculature are discussed. Next, techniques for quantifying bone blood flow are briefly summarized. Finally, the body of experimental work that demonstrates the role of bone blood flow in fracture healing, distraction osteogenesis, osteoporosis, disuse osteopenia, and bone grafting is examined. These results illustrate that adequate bone blood flow is an important clinical consideration, particularly during bone regeneration and in at-risk patient groups.
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Affiliation(s)
- Ryan E Tomlinson
- Department of Orthopaedic Surgery, Washington University in St. Louis , Saint Louis, MO, USA ; Musculoskeletal Research Center, Washington University in St. Louis , Saint Louis, MO, USA
| | - Matthew J Silva
- Department of Orthopaedic Surgery, Washington University in St. Louis , Saint Louis, MO, USA ; Musculoskeletal Research Center, Washington University in St. Louis , Saint Louis, MO, USA
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29
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Tomlinson RE, Shoghi KI, Silva MJ. Nitric oxide-mediated vasodilation increases blood flow during the early stages of stress fracture healing. J Appl Physiol (1985) 2013; 116:416-24. [PMID: 24356518 DOI: 10.1152/japplphysiol.00957.2013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Despite the strong connection between angiogenesis and osteogenesis in skeletal repair conditions such as fracture and distraction osteogenesis, little is known about the vascular requirements for bone formation after repetitive mechanical loading. Here, established protocols of damaging (stress fracture) and nondamaging (physiological) forelimb loading in the adult rat were used to stimulate either woven or lamellar bone formation, respectively. Positron emission tomography was used to evaluate blood flow and fluoride kinetics at the site of bone formation. In the group that received damaging mechanical loading leading to woven bone formation (WBF), (15)O water (blood) flow rate was significantly increased on day 0 and remained elevated 14 days after loading, whereas (18)F fluoride uptake peaked 7 days after loading. In the group that received nondamaging mechanical loading leading to lamellar bone formation (LBF), (15)O water and (18)F fluoride flow rates in loaded limbs were not significantly different from nonloaded limbs at any time point. The early increase in blood flow rate after WBF loading was associated with local vasodilation. In addition, Nos2 expression in mast cells was increased in WBF-, but not LBF-, loaded limbs. The nitric oxide (NO) synthase inhibitor N(ω)-nitro-l-arginine methyl ester was used to suppress NO generation, resulting in significant decreases in early blood flow rate and bone formation after WBF loading. These results demonstrate that NO-mediated vasodilation is a key feature of the normal response to stress fracture and precedes woven bone formation. Therefore, patients with impaired vascular function may heal stress fractures more slowly than expected.
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Affiliation(s)
- Ryan E Tomlinson
- Department of Orthopaedic Surgery, Washington University in St. Louis, St. Louis, Missouri
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30
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Matheny JB, Slyfield CR, Tkachenko EV, Lin I, Ehlert KM, Tomlinson RE, Wilson DL, Hernandez CJ. Anti-resorptive agents reduce the size of resorption cavities: a three-dimensional dynamic bone histomorphometry study. Bone 2013; 57:277-83. [PMID: 23988275 PMCID: PMC3818704 DOI: 10.1016/j.bone.2013.08.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Revised: 07/26/2013] [Accepted: 08/20/2013] [Indexed: 12/11/2022]
Abstract
Alterations in resorption cavities and bone remodeling events during anti-resorptive treatment are believed to contribute to reductions in fracture risk. Here, we examine changes in the size of individual remodeling events associated with treatment with a selective estrogen receptor modulator (raloxifene) or a bisphosphonate (risedronate). Adult female rats (6months of age) were submitted to ovariectomy (n=17) or sham surgery (SHAM, n=5). One month after surgery, the ovariectomized animals were separated into three groups: untreated (OVX, n=5), raloxifene treated (OVX+Ral, n=6) and risedronate treated (OVX+Ris, n=6). At 10months of age, the lumbar vertebrae were submitted to three-dimensional dynamic bone histomorphometry to examine the size (depth, breadth and volume) of individual resorption cavities and formation events. Maximum resorption cavity depth did not differ between the SHAM (23.66±1.87μm, mean±SD) and OVX (22.88±3.69μm) groups but was smaller in the OVX+Ral (14.96±2.30μm) and OVX+Ris (14.94±2.70μm) groups (p<0.01). Anti-resorptive treatment was associated with reductions in the surface area of resorption cavities and the volume occupied by each resorption cavity (p<0.01 each). The surface area and volume of individual formation events (double-labeled events) in the OVX+Ris group were reduced as compared to other groups (p<0.02). Raloxifene treated animals showed similar amounts of bone remodeling (ES/BS and dLS/BS) compared to sham-operated controls but smaller cavity size (depth, breadth and volume). The current study shows that anti-resorptive agents influence the size of resorption cavities and individual remodeling events and that the effect of anti-resorptives on individual remodeling events may not always be directly related to the degree of suppression of bone remodeling.
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Affiliation(s)
- J B Matheny
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, USA; Department of Biomedical Engineering, Cornell University, Ithaca, NY, USA
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31
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Tomlinson RE, McKenzie JA, Schmieder AH, Wohl GR, Lanza GM, Silva MJ. Angiogenesis is required for stress fracture healing in rats. Bone 2013; 52:212-9. [PMID: 23044046 PMCID: PMC3513671 DOI: 10.1016/j.bone.2012.09.035] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Revised: 09/25/2012] [Accepted: 09/28/2012] [Indexed: 12/12/2022]
Abstract
Although angiogenesis and osteogenesis are critically linked, the importance of angiogenesis for stress fracture healing is unknown. In this study, mechanical loading was used to create a non-displaced stress fracture in the adult rat forelimb. Fumagillin, an anti-angiogenic agent, was used as the water soluble analogue TNP-470 (25mg/kg) as well as incorporated into lipid-encapsulated α(v)β(3) integrin targeted nanoparticles (0.25mg/kg). In the first experiment, TNP-470 was administered daily for 5 days following mechanical loading, and changes in gene expression, vascularity, and woven bone formation were quantified. Although no changes in vascularity were detected 3 days after loading, treatment-related downregulation of angiogenic (Pecam1) and osteogenic (Bsp, Osx) genes was observed at this early time point. On day 7, microCT imaging of loaded limbs revealed diminished woven bone formation in treated limbs compared to vehicle treated limbs. In the second experiment, α(v)β(3) integrin targeted fumagillin nanoparticles were administered as before, albeit with a 100-fold lower dose, and changes in vascularity and woven bone formation were determined. There were no treatment-related changes in vessel count or volume 3 days after loading, although fewer angiogenic (CD105 positive) blood vessels were present in treated limbs compared to vehicle treated limbs. This result manifested on day 7 as a reduction in total vascularity, as measured by histology (vessel count) and microCT (vessel volume). Similar to the first experiment, treated limbs had diminished woven bone formation on day 7 compared to vehicle treated limbs. These results indicate that angiogenesis is required for stress fracture healing, and may have implications for inducing rapid repair of stress fractures.
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Affiliation(s)
- Ryan E. Tomlinson
- Department of Orthopaedic Surgery, Washington University in St. Louis, Saint Louis, MO, USA
- Department of Biomedical Engineering, Washington University in St. Louis, Saint Louis, MO, USA
| | - Jennifer A. McKenzie
- Department of Orthopaedic Surgery, Washington University in St. Louis, Saint Louis, MO, USA
| | - Anne H. Schmieder
- Department of Medicine, Division of Cardiology, Washington University in St. Louis, Saint Louis, MO, USA
| | - Gregory R. Wohl
- Department of Orthopaedic Surgery, Washington University in St. Louis, Saint Louis, MO, USA
| | - Gregory M. Lanza
- Department of Biomedical Engineering, Washington University in St. Louis, Saint Louis, MO, USA
- Department of Medicine, Division of Cardiology, Washington University in St. Louis, Saint Louis, MO, USA
| | - Matthew J. Silva
- Department of Orthopaedic Surgery, Washington University in St. Louis, Saint Louis, MO, USA
- Department of Biomedical Engineering, Washington University in St. Louis, Saint Louis, MO, USA
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32
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Slyfield CR, Niemeyer KE, Tkachenko EV, Tomlinson RE, Steyer GG, Patthanacharoenphon CG, Kazakia GJ, Wilson DL, Hernandez CJ. Three-dimensional surface texture visualization of bone tissue through epifluorescence-based serial block face imaging. J Microsc 2009; 236:52-9. [PMID: 19772536 DOI: 10.1111/j.1365-2818.2009.03204.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Serial block face imaging is a microscopy technique in which the top of a specimen is cut or ground away and a mosaic of images is collected of the newly revealed cross-section. Images collected from each slice are then digitally stacked to achieve 3D images. The development of fully automated image acquisition devices has made serial block face imaging more attractive by greatly reducing labour requirements. The technique is particularly attractive for studies of biological activity within cancellous bone as it has the capability of achieving direct, automated measures of biological and morphological traits and their associations with one another. When used with fluorescence microscopy, serial block face imaging has the potential to achieve 3D images of tissue as well as fluorescent markers of biological activity. Epifluorescence-based serial block face imaging presents a number of unique challenges for visualizing bone specimens due to noise generated by sub-surface signal and local variations in tissue autofluorescence. Here we present techniques for processing serial block face images of trabecular bone using a combination of non-uniform illumination correction, precise tiling of the mosaic in each cross-section, cross-section alignment for vertical stacking, removal of sub-surface signal and segmentation. The resulting techniques allow examination of bone surface texture that will enable 3D quantitative measures of biological processes in cancellous bone biopsies.
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Affiliation(s)
- C R Slyfield
- Musculoskeletal Mechanics and Materials Laboratory, Department of Mechanical and Aerospace Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
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33
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Tkachenko EV, Slyfield CR, Tomlinson RE, Daggett JR, Wilson DL, Hernandez CJ. Voxel size and measures of individual resorption cavities in three-dimensional images of cancellous bone. Bone 2009; 45:487-92. [PMID: 19482097 PMCID: PMC2728288 DOI: 10.1016/j.bone.2009.05.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2009] [Revised: 05/19/2009] [Accepted: 05/21/2009] [Indexed: 01/09/2023]
Abstract
Cavities formed by osteoclasts on the surface of cancellous bone during bone remodeling (resorption cavities) are believed to act as stress risers and impair cancellous bone strength and stiffness. Although resorption cavities are readily detected as eroded surfaces in histology sections, identification of resorption cavities in three-dimensional images of cancellous bone has been rare. Here we use sub-micrometer resolution images of rat lumbar vertebral cancellous bone obtained through serial milling (n=5) to determine how measures of the number and surface area of resorption cavities are influenced by image resolution. Three-dimensional images of a 1 mm cube of cancellous bone were collected at 0.7x0.7x5.0 microm/voxel using fluorescence based serial milling and uniformly coarsened to four other resolutions ranging from 1.4x1.4x5.0 to 11.2x11.2x10 microm/voxel. Cavities were identified in the three-dimensional image as an indentation on the cancellous bone surface and were confirmed as eroded surfaces by viewing two-dimensional cross-sections (mimicking histology techniques). The number of cavities observed in the 0.7x0.7x5.0 microm/voxel images (22.0+/-1.43, mean+/-SD) was not significantly different from that in the 1.4x1.4x5.0 microm/voxel images (19.2+/-2.59) and an average of 79% of the cavities observed at both of these resolutions were coincident. However, at lower resolutions, cavity detection was confounded by low sensitivity (<20%) and high false positive rates (>40%). Our results demonstrate that when image voxel size exceeds 1.4x1.4x5.0 microm/voxel identification of resorption cavities by bone surface morphology is highly inaccurate. Experimental and computational studies of resorption cavities in three-dimensional images of cancellous bone may therefore require images to be collected at resolutions of 1.4 microm/pixel in-plane or better to ensure consistent identification of resorption cavities.
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Affiliation(s)
- Evgeniy V Tkachenko
- Musculoskeletal Mechanics and Materials Laboratory, Department of Mechanical and Aerospace Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
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