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Wu T, Bonnheim NB, Pendleton MM, Emerzian SR, Keaveny TM. Radiation-induced changes in load-sharing and structure-function behavior in murine lumbar vertebrae. Comput Methods Biomech Biomed Engin 2024; 27:1278-1286. [PMID: 37504955 DOI: 10.1080/10255842.2023.2239415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 07/12/2023] [Indexed: 07/29/2023]
Abstract
In this study, we used micro-CT-based finite element analysis to investigate the biomechanical effects of radiation on the microstructure and mechanical function of murine lumbar vertebrae. Specifically, we evaluated vertebral microstructure, whole-bone stiffness, and cortical-trabecular load sharing in the L5 vertebral body of mice exposed to ionizing radiation 11 days post exposure (5 Gy total dose; n = 13) and controls (n = 14). Our findings revealed the irradiated group exhibited reduced trabecular bone volume and microstructure (p < 0.001) compared to controls, while cortical bone volume remained unchanged (p = 0.91). Axially compressive loads in the irradiated group were diverted from the trabecular centrum and into the vertebral cortex, as evidenced by a higher cortical load-fraction (p = 0.02) and a higher proportion of cortical tissue at risk of initial failure (p < 0.01). Whole-bone stiffness was lower in the irradiated group compared to the controls, though the difference was small and non-significant (2045 ± 142 vs. 2185 ± 225 vs. N/mm, irradiated vs. control, p = 0.07). Additionally, the structure-function relationship between trabecular bone volume and trabecular load fraction differed between groups (p = 0.03), indicating a less biomechanically efficient trabecular network in the irradiated group. We conclude that radiation can decrease trabecular bone volume and result in a less biomechanically efficient trabecular structure, leading to increased reliance on the vertebral cortex to resist axially compressive loads. These findings offer biomechanical insight into the effects of radiation on structure-function behavior in murine lumbar vertebrae independent of possible tissue-level material effects.
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Affiliation(s)
- Tongge Wu
- Department of Mechanical Engineering, University of California, Berkeley, CA, USA
| | - Noah B Bonnheim
- Department of Orthopaedic Surgery, University of California, San Francisco, CA, USA
| | - Megan M Pendleton
- Department of Mechanical Engineering, University of California, Berkeley, CA, USA
| | - Shannon R Emerzian
- Department of Mechanical Engineering, University of California, Berkeley, CA, USA
| | - Tony M Keaveny
- Department of Mechanical Engineering, University of California, Berkeley, CA, USA
- Department of Bioengineering, University of California, Berkeley, CA, USA
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2
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Bhattacharyya ND, Kyaw W, McDonald MM, Dhenni R, Grootveld AK, Xiao Y, Chai R, Khoo WH, Danserau LC, Sergio CM, Timpson P, Lee WM, Croucher PI, Phan TG. Minimally invasive longitudinal intravital imaging of cellular dynamics in intact long bone. Nat Protoc 2023; 18:3856-3880. [PMID: 37857852 DOI: 10.1038/s41596-023-00894-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 07/28/2023] [Indexed: 10/21/2023]
Abstract
Intravital two-photon microscopy enables deep-tissue imaging at high temporospatial resolution in live animals. However, the endosteal bone compartment and underlying bone marrow pose unique challenges to optical imaging as light is absorbed, scattered and dispersed by thick mineralized bone matrix and the adipose-rich bone marrow. Early bone intravital imaging methods exploited gaps in the cranial sutures to bypass the need to penetrate through cortical bone. More recently, investigators have developed invasive methods to thin the cortical bone or implant imaging windows to image cellular dynamics in weight-bearing long bones. Here, we provide a step-by-step procedure for the preparation of animals for minimally invasive, nondestructive, longitudinal intravital imaging of the murine tibia. This method involves the use of mixed bone marrow radiation chimeras to unambiguously double-label osteoclasts and osteomorphs. The tibia is exposed by a simple skin incision and an imaging chamber constructed using thermoconductive T-putty. Imaging sessions up to 12 h long can be repeated over multiple timepoints to provide a longitudinal time window into the endosteal and marrow niches. The approach can be used to investigate cellular dynamics in bone remodeling, cancer cell life cycle and hematopoiesis, as well as long-lived humoral and cellular immunity. The procedure requires an hour to complete and is suitable for users with minimal prior expertise in small animal surgery.
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Affiliation(s)
- Nayan Deger Bhattacharyya
- Garvan Institute of Medical Research, Sydney, New South Wales, Australia
- St Vincent's Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, New South Wales, Australia
| | - Wunna Kyaw
- Garvan Institute of Medical Research, Sydney, New South Wales, Australia
- St Vincent's Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, New South Wales, Australia
| | - Michelle M McDonald
- Garvan Institute of Medical Research, Sydney, New South Wales, Australia
- St Vincent's Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, New South Wales, Australia
- School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
- Charles Perkins Centre, The University of Sydney, Sydney, New South Wales, Australia
| | - Rama Dhenni
- Garvan Institute of Medical Research, Sydney, New South Wales, Australia
- St Vincent's Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, New South Wales, Australia
| | - Abigail K Grootveld
- Garvan Institute of Medical Research, Sydney, New South Wales, Australia
- St Vincent's Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, New South Wales, Australia
| | - Ya Xiao
- Garvan Institute of Medical Research, Sydney, New South Wales, Australia
- St Vincent's Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, New South Wales, Australia
| | - Ryan Chai
- Garvan Institute of Medical Research, Sydney, New South Wales, Australia
- St Vincent's Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, New South Wales, Australia
| | - Weng Hua Khoo
- Garvan Institute of Medical Research, Sydney, New South Wales, Australia
- St Vincent's Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, New South Wales, Australia
| | - Linda C Danserau
- Garvan Institute of Medical Research, Sydney, New South Wales, Australia
- St Vincent's Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, New South Wales, Australia
- ACRF INCITe Centre for Intravital Imaging of Niches for Cancer Immune Therapy, Sydney, New South Wales, Australia
| | - C Marcelo Sergio
- Garvan Institute of Medical Research, Sydney, New South Wales, Australia
| | - Paul Timpson
- Garvan Institute of Medical Research, Sydney, New South Wales, Australia
- St Vincent's Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, New South Wales, Australia
- ACRF INCITe Centre for Intravital Imaging of Niches for Cancer Immune Therapy, Sydney, New South Wales, Australia
| | - Woei Ming Lee
- ACRF INCITe Centre for Intravital Imaging of Niches for Cancer Immune Therapy, Sydney, New South Wales, Australia
- John Curtin School of Medical Research, Australian National University, Canberra, New South Wales, Australia
| | - Peter I Croucher
- Garvan Institute of Medical Research, Sydney, New South Wales, Australia
- St Vincent's Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, New South Wales, Australia
- ACRF INCITe Centre for Intravital Imaging of Niches for Cancer Immune Therapy, Sydney, New South Wales, Australia
| | - Tri Giang Phan
- Garvan Institute of Medical Research, Sydney, New South Wales, Australia.
- St Vincent's Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, New South Wales, Australia.
- ACRF INCITe Centre for Intravital Imaging of Niches for Cancer Immune Therapy, Sydney, New South Wales, Australia.
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3
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Emerzian SR, Wu T, Vaidya R, Tang SY, Abergel RJ, Keaveny TM. Relative Effects of Radiation-Induced Changes in Bone Mass, Structure, and Tissue Material on Vertebral Strength in a Rat Model. J Bone Miner Res 2023; 38:1032-1042. [PMID: 37191221 PMCID: PMC10524463 DOI: 10.1002/jbmr.4828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 04/06/2023] [Accepted: 05/07/2023] [Indexed: 05/17/2023]
Abstract
The observed increased risk of fracture after cancer radiation therapy is presumably due to a radiation-induced reduction in whole-bone strength. However, the mechanisms for impaired strength remain unclear, as the increased fracture risk is not fully explained by changes in bone mass. To provide insight, a small animal model was used to determine how much of this whole-bone weakening effect for the spine is attributable to changes in bone mass, structure, and material properties of the bone tissue and their relative effects. Further, because women have a greater risk of fracture after radiation therapy than men, we investigated if sex had a significant influence on bone's response to irradiation. Fractionated in vivo irradiation (10 × 3 Gy) or sham irradiation (0 Gy) was administered daily to the lumbar spine in twenty-seven 17-week-old Sprague-Dawley rats (n = 6-7/sex/group). Twelve weeks after final treatment, animals were euthanized, and lumbar vertebrae (L4 and L5 ) were isolated. Using a combination of biomechanical testing, micro-CT-based finite element analysis, and statistical regression analysis, we separated out the effect of mass, structural, and tissue material changes on vertebral strength. Compared with the sham group (mean ± SD strength = 420 ± 88 N), the mean strength of the irradiated group was lower by 28% (117 N/420 N, p < 0.0001). Overall, the response of treatment did not differ with sex. By combining results from both general linear regression and finite element analyses, we calculated that mean changes in bone mass, structure, and material properties of the bone tissue accounted for 56% (66 N/117 N), 20% (23 N/117 N), and 24% (28 N/117 N), respectively, of the overall change in strength. As such, these results provide insight into why an elevated clinical fracture risk for patients undergoing radiation therapy is not well explained by changes in bone mass alone. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Shannon R. Emerzian
- Department of Mechanical Engineering, University of
California, Berkeley, California, USA
| | - Tongge Wu
- Department of Mechanical Engineering, University of
California, Berkeley, California, USA
| | - Rachana Vaidya
- Department of Orthopaedic Surgery, Washington University,
St. Louis, Missouri, USA
| | - Simon Y. Tang
- Department of Orthopaedic Surgery, Washington University,
St. Louis, Missouri, USA
- Department of Biomedical Engineering, Washington
University, St. Louis, Missouri, USA
- Department of Material Science & Mechanical
Engineering, Washington University, St. Louis, Missouri, USA
| | - Rebecca J. Abergel
- Department of Nuclear Engineering, University of
California, Berkeley, California, USA
| | - Tony M. Keaveny
- Department of Mechanical Engineering, University of
California, Berkeley, California, USA
- Department of Bioengineering, University of California,
Berkeley, California, USA
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4
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Buccino F, Zagra L, Longo E, D'Amico L, Banfi G, Berto F, Tromba G, Vergani LM. Osteoporosis and Covid-19: Detected similarities in bone lacunar-level alterations via combined AI and advanced synchrotron testing. MATERIALS & DESIGN 2023; 231:112087. [PMID: 37323219 PMCID: PMC10257887 DOI: 10.1016/j.matdes.2023.112087] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 05/03/2023] [Accepted: 06/09/2023] [Indexed: 06/17/2023]
Abstract
While advanced imaging strategies have improved the diagnosis of bone-related pathologies, early signs of bone alterations remain difficult to detect. The Covid-19 pandemic has brought attention to the need for a better understanding of bone micro-scale toughening and weakening phenomena. This study used an artificial intelligence-based tool to automatically investigate and validate four clinical hypotheses by examining osteocyte lacunae on a large scale with synchrotron image-guided failure assessment. The findings indicate that trabecular bone features exhibit intrinsic variability related to external loading, micro-scale bone characteristics affect fracture initiation and propagation, osteoporosis signs can be detected at the micro-scale through changes in osteocyte lacunar features, and Covid-19 worsens micro-scale porosities in a statistically significant manner similar to the osteoporotic condition. Incorporating these findings with existing clinical and diagnostic tools could prevent micro-scale damages from progressing into critical fractures.
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Affiliation(s)
- Federica Buccino
- Department of Mechanical Engineering, Politecnico di Milano, 20156, Italy
| | - Luigi Zagra
- I.R.C.C.S Ospedale Galeazzi - Sant'Ambrogio, Milano 20157, Italy
| | - Elena Longo
- Elettra-Sincrotrone Trieste SCpA, Basovizza, Trieste 34149, Italy
| | - Lorenzo D'Amico
- Elettra-Sincrotrone Trieste SCpA, Basovizza, Trieste 34149, Italy
| | - Giuseppe Banfi
- I.R.C.C.S Ospedale Galeazzi - Sant'Ambrogio, Milano 20157, Italy
| | - Filippo Berto
- Università La Sapienza, Rome 00185, Italy
- NTNU, Norway
| | - Giuliana Tromba
- Elettra-Sincrotrone Trieste SCpA, Basovizza, Trieste 34149, Italy
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5
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Crocker DB, Hoffman I, Carter JL, Akkus O, Rimnac CM. Fatigue crack propagation and fracture toughness of cortical bone are radiation dose-dependent. J Orthop Res 2023; 41:823-833. [PMID: 35949192 PMCID: PMC9911555 DOI: 10.1002/jor.25424] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 07/08/2022] [Accepted: 08/09/2022] [Indexed: 02/04/2023]
Abstract
Cortical bone allograft sterilized with a standard γ-radiation dose of 25-35kGy has demonstrated reduced static and cyclic fracture resistance compared with unirradiated bone. To mitigate radiation damage, we recently observed a dose-dependent response of high-cycle fatigue behavior of human cortical bone from 0 to 25 kGy, with lower doses exhibiting logarithmically longer fatigue lives. The objectives of this study were as follows: (1) to determine whether fracture toughness, work-to-fracture, and fatigue crack propagation resistance of human cortical bone are also radiation dose-dependent, and (2) to determine the associations of radiation dose and a Raman biomarker for collagen disorder with fracture properties. Compact tension specimens were machined from two donor femoral pairs and allocated to four treatment groups: 0 (unirradiated control), 10, 17.5, and 25 kGy. Fracture toughness specimens were monotonically loaded to failure and the critical stress intensity factor (KC ) was determined. Work-to-fracture was calculated from the load versus displacement integral up to fracture. Fatigue crack propagation specimens were cyclically loaded under constant room-temperature irrigation and fatigue crack growth rate (da/dN) and cyclic stress intensity (∆K) were calculated. Fracture toughness, work-to-fracture, and fatigue crack propagation resistance decreased 18%, 33%, and 15-fold from 0 to 25 kGy, respectively (p < 0.05). Radiation dose was more predictive of fracture properties than collagen disorder. These findings support that quasi-static and fatigue fracture properties of cortical bone are radiation dose-dependent within this dose range. The structural alterations arising from irradiation that cause these losses in fracture resistance remain to be elucidated.
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Affiliation(s)
- Dylan B. Crocker
- Department of Mechanical and Aerospace Engineering, Case Western Reserve University, Cleveland, OH
| | - Isaac Hoffman
- Department of Materials Science and Engineering, Case Western Reserve University, Cleveland, OH
| | - Jennifer L.W. Carter
- Department of Materials Science and Engineering, Case Western Reserve University, Cleveland, OH
| | - Ozan Akkus
- Department of Mechanical and Aerospace Engineering, Case Western Reserve University, Cleveland, OH
- Department of Orthopaedic Surgery, Case Western Reserve University, Cleveland, OH
| | - Clare M. Rimnac
- Department of Mechanical and Aerospace Engineering, Case Western Reserve University, Cleveland, OH
- Department of Orthopaedic Surgery, Case Western Reserve University, Cleveland, OH
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6
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Sauer K, Zizak I, Forien JB, Rack A, Scoppola E, Zaslansky P. Primary radiation damage in bone evolves via collagen destruction by photoelectrons and secondary emission self-absorption. Nat Commun 2022; 13:7829. [PMID: 36539409 PMCID: PMC9768145 DOI: 10.1038/s41467-022-34247-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 10/18/2022] [Indexed: 12/24/2022] Open
Abstract
X-rays are invaluable for imaging and sterilization of bones, yet the resulting ionization and primary radiation damage mechanisms are poorly understood. Here we monitor in-situ collagen backbone degradation in dry bones using second-harmonic-generation and X-ray diffraction. Collagen breaks down by cascades of photon-electron excitations, enhanced by the presence of mineral nanoparticles. We observe protein disintegration with increasing exposure, detected as residual strain relaxation in pre-stressed apatite nanocrystals. Damage rapidly grows from the onset of irradiation, suggesting that there is no minimal 'safe' dose that bone collagen can sustain. Ionization of calcium and phosphorous in the nanocrystals yields fluorescence and high energy electrons giving rise to structural damage that spreads beyond regions directly illuminated by the incident radiation. Our findings highlight photoelectrons as major agents of damage to bone collagen with implications to all situations where bones are irradiated by hard X-rays and in particular for small-beam mineralized collagen fiber investigations.
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Affiliation(s)
- Katrein Sauer
- grid.6363.00000 0001 2218 4662Charité – Universitätsmedizin Berlin, Department for Operative, Preventive and Pediatric Dentistry, Aßmannshauser Straße 4-6, 14197 Berlin, Germany
| | - Ivo Zizak
- grid.424048.e0000 0001 1090 3682Helmholtz-Zentrum Berlin, Department for Structure and Dynamics of Energy Materials (SE-ASD), Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - Jean-Baptiste Forien
- grid.250008.f0000 0001 2160 9702Lawrence Livermore National Laboratory, Materials Science Division, 7000 East Ave, Livermore, CA 94550 USA
| | - Alexander Rack
- grid.5398.70000 0004 0641 6373ESRF - The European Synchrotron, Structure of Materials Group - ID19, CS 40220, F-38043, Grenoble, Cedex 9 France
| | - Ernesto Scoppola
- grid.461615.10000 0000 8925 2562Max Planck Institute of Colloids and Interfaces, Department of Biomaterials, Am Mühlenberg 1, 14476 Potsdam, Brandenburg Germany
| | - Paul Zaslansky
- grid.6363.00000 0001 2218 4662Charité – Universitätsmedizin Berlin, Department for Operative, Preventive and Pediatric Dentistry, Aßmannshauser Straße 4-6, 14197 Berlin, Germany
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7
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Lacombe J, Zenhausern F. Effect of mechanical forces on cellular response to radiation. Radiother Oncol 2022; 176:187-198. [PMID: 36228760 DOI: 10.1016/j.radonc.2022.10.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 08/08/2022] [Accepted: 10/05/2022] [Indexed: 12/14/2022]
Abstract
While the cellular interactions and biochemical signaling has been investigated for long and showed to play a major role in the cell's fate, it is now also evident that mechanical forces continuously applied to the cells in their microenvironment are as important for tissue homeostasis. Mechanical cues are emerging as key regulators of cellular drug response and we aimed to demonstrate in this review that such effects should also be considered vital for the cellular response to radiation. In order to explore the mechanobiology of the radiation response, we reviewed the main mechanoreceptors and transducers, including integrin-mediated adhesion, YAP/TAZ pathways, Wnt/β-catenin signaling, ion channels and G protein-coupled receptors and showed their implication in the modulation of cellular radiosensitivity. We then discussed the current studies that investigated a direct effect of mechanical stress, including extracellular matrix stiffness, shear stress and mechanical strain, on radiation response of cancer and normal cells and showed through preliminary results that such stress effectively can alter cell response after irradiation. However, we also highlighted the limitations of these studies and emphasized some of the contradictory data, demonstrating that the effect of mechanical cues could involve complex interactions and potential crosstalk with numerous cellular processes also affected by irradiation. Overall, mechanical forces alter radiation response and although additional studies are required to deeply understand the underlying mechanisms, these effects should not be neglected in radiation research as they could reveal new fundamental knowledge for predicting radiosensitivity or understanding resistance to radiotherapy.
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Affiliation(s)
- Jerome Lacombe
- Center for Applied NanoBioscience and Medicine, College of Medicine Phoenix, University of Arizona, 475 North 5th Street, Phoenix, AZ 85004, USA; Department of Basic Medical Sciences, College of Medicine Phoenix, University of Arizona, 425 N 5th St, Phoenix, AZ 85004, USA.
| | - Frederic Zenhausern
- Center for Applied NanoBioscience and Medicine, College of Medicine Phoenix, University of Arizona, 475 North 5th Street, Phoenix, AZ 85004, USA; Department of Basic Medical Sciences, College of Medicine Phoenix, University of Arizona, 425 N 5th St, Phoenix, AZ 85004, USA; Department of Biomedical Engineering, College of Engineering, University of Arizona, 1127 E. James E. Rogers Way, Tucson, AZ 85721, USA.
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8
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Ina J, Vakharia A, Akkus O, Rimnac CM. The High-cycle Fatigue Life of Cortical Bone Allografts Is Radiation Sterilization Dose-dependent: An In Vitro Study. Clin Orthop Relat Res 2022; 480:1208-1219. [PMID: 35175232 PMCID: PMC9263473 DOI: 10.1097/corr.0000000000002146] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 01/28/2022] [Indexed: 01/31/2023]
Abstract
BACKGROUND Structural cortical bone allografts are a reasonable treatment option for patients with large cortical bone defects caused by trauma, tumors, or complications of arthroplasty. Although structural cortical bone allografts provide the benefit of an osteoconductive material, they are susceptible to fatigue failure (fracture) and carry a risk of disease transmission. Radiation-sterilization at the recommended dose of 25 kGy decreases the risk of disease transmission. However, previous studies demonstrated that radiation sterilization at this dose can negatively impact the high cycle-fatigue life of cortical bone. Although the effects of higher doses of radiation on cortical bone allografts are well described, the effects of lower doses of radiation on a high-cycle fatigue life of cortical bone are poorly understood. QUESTIONS/PURPOSES (1) Does the cycle-fatigue life of human cortical allograft bone vary with gamma radiation dose levels of 0 (control), 10 kGy, 17.5 kGy, and 25 kGy? (2) What differences in Raman spectral biomarkers are observed following varying doses of gamma radiation exposure? METHODS The high-cycle fatigue behavior of human cortical bone specimens was examined at different radiation sterilization doses under physiologic stress levels (35 MPa) and in a 37° C phosphate-buffered saline bath using a custom-designed rotating-bending fatigue device. Six human femora from three donors were obtained for this study (two male, 63 and 61 years old, respectively, and one female, 48 years old). Test specimens were allocated among four treatment groups (0 kGy [control], 10 kGy, 17.5 kGy, and 25 kGy) based on donor and anatomic location of harvest site (both length and cross-sectional quadrant of femoral diaphysis) to ensure equal variation (n = 13 per group). Specimens underwent high-cycle fatigue testing to failure. The number of cycles to failure was recorded. Raman spectroscopy (a noninvasive vibrational spectroscopy used to qualitatively assess bone quality) was used to detect whether any changes in Raman spectral biomarkers occurred after varying doses of gamma radiation exposure. RESULTS There was a decrease in the log-transformed mean high-cycle fatigue life in specimens irradiated at 25 kGy (5.39 ± 0.32) compared with all other groups (0 kGy: 6.20 ± 0.50; 10k Gy: 6.35 ± 0.79; 17.5 kGy: 6.01 ± 0.53; p = 0.001). Specimens irradiated at 25 kGy were also more likely to exhibit a more brittle fracture surface pattern than specimens with more ductile fracture surface patterns irradiated at 0 kGy, 10 kGy, and 17.5 kGy (p = 0.04). The Raman biomarker for the ratio of the relative amount of disordered collagen to ordered collagen showed a decrease at the 10 kGy radiation level from 1.522 ± 0.025 preirradiation to 1.489 ± 0.024 postirradiation (p = 0.01); no other detectable changes in Raman biomarkers were observed. CONCLUSION The high-cycle fatigue life of cortical bone undergoes a nonlinear, dose-dependent decrease with an increase in gamma radiation sterilization in a clinically relevant dose range (0-25 kGy). Importantly, a notable drop-off in the high-cycle fatigue life of cortical bone appeared to occur between 17.5 kGy and 25 kGy, correlating to a sixfold decrease in mean cycles to failure. We speculate that the decrease in the Raman biomarker for disordered collagen at 10 kGy with no loss in high-cycle fatigue life may be caused by an increased amount of nonenzymatic crosslinking of the collagen backbone relative to collagen chain-scission (whereas the benefits of crosslinking may be outweighed by excess scission of the collagen backbone at higher radiation doses), but future studies will need to ascertain whether this in fact is the case. CLINICAL RELEVANCE Radiation sterilization at the industry standard of 25 kGy has a substantial negative impact on the high-cycle fatigue life of cortical bone. Given these findings, it is possible to provide a meaningful increase in the high-cycle fatigue life and improve the overall functional lifetime of cortical bone allografts by lowering the radiation-sterilization dose below 25 kGy. Future work on radiation-sterilization methods at these clinically relevant doses is warranted to aid in preserving the high cycle fatigue life of cortical bone allografts while maintaining sterility.
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Affiliation(s)
- Jason Ina
- Department of Orthopaedic Surgery, University Hospitals Cleveland Medical Center, Cleveland, OH, USA
| | - Ajit Vakharia
- Department of Orthopaedic Surgery, University Hospitals Cleveland Medical Center, Cleveland, OH, USA
| | - Ozan Akkus
- Department of Orthopaedic Surgery, University Hospitals Cleveland Medical Center, Cleveland, OH, USA
- Department of Mechanical and Aerospace Engineering, Case Western Reserve University, Cleveland, OH, USA
| | - Clare M. Rimnac
- Department of Orthopaedic Surgery, University Hospitals Cleveland Medical Center, Cleveland, OH, USA
- Department of Mechanical and Aerospace Engineering, Case Western Reserve University, Cleveland, OH, USA
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9
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Padala SR, Kashyap B, Dekker H, Mikkonen JJW, Palander A, Bravenboer N, Kullaa AM. Irradiation affects the structural, cellular and molecular components of jawbones. Int J Radiat Biol 2021; 98:136-147. [PMID: 34855558 DOI: 10.1080/09553002.2022.2013568] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
PURPOSE Emerging evidence shows that changes in the bone and its microenvironment following radiotherapy are associated with either an inhibition or a state of low bone formation. Ionizing radiation is damaging to the jawbone as it increases the complication rate due to the development of hypovascular, hypocellular, and hypoxic tissue. This review summarizes and correlates the current knowledge on the effects of irradiation on the bone with an emphasis on jawbone, as these have been a less extensively studied area. CONCLUSIONS The stringent regulation of bone formation and bone resorption can be influenced by radiation, causing detrimental effects at structural, cellular, vascular, and molecular levels. It is also associated with a high risk of damage to surrounding healthy tissues and an increased risk of fracture. Technological advances and research on animal models as well as a few human bone tissue studies have provided novel insights into the ways in which bone can be affected by high, low and sublethal dose of radiation. The influence of radiation on bone metabolism, cellular properties, vascularity, collagen, and other factors like inflammation, reactive oxygen species are discussed.
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Affiliation(s)
- Sridhar Reddy Padala
- Institute of Dentistry, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland
| | - Bina Kashyap
- Institute of Dentistry, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland
| | - Hannah Dekker
- Amsterdam University Medical Centers, Academic Centre for Dentistry Amsterdam (ACTA), Department of Oral and Maxillofacial Surgery/Oral Pathology, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Jopi J W Mikkonen
- Institute of Dentistry, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland
| | - Anni Palander
- Institute of Dentistry, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland
| | - Nathalie Bravenboer
- Amsterdam UMC, Department of Clinical Chemistry, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands.,Department of Internal Medicine, Division of Endocrinology and Center for Bone Quality, Leiden University Medical Center, Leiden, The Netherlands
| | - Arja M Kullaa
- Institute of Dentistry, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland
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10
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Graf-Alexiou L, Qiu Y, Aalto D, Westover L. An Investigation of the Effect of Irradiation on the Biomechanical Properties of Fibular Grafts. J Oral Maxillofac Surg 2021; 80:784.e1-784.e5. [PMID: 34942151 DOI: 10.1016/j.joms.2021.11.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 11/05/2021] [Accepted: 11/23/2021] [Indexed: 10/19/2022]
Abstract
PURPOSE Irradiation of fibular grafts for jaw reconstruction following mandibulectomy can be associated with increased graft failure and implant instability. The objective of this study is to investigate the effect of isolated irradiation on the biomechanical properties of ex-vivo porcine fibula grafts. It was hypothesized that the isolated irradiation (without biological response) will not significantly influence the biomechanical properties of the fibular grafts. METHODS Forty porcine fibular grafts (n = 20 irradiated and n = 20 nonirradiated) were obtained. The irradiated group was subjected to a single dose of 60 Gy of irradiation with cesium 137. Both groups underwent 3-point bending tests with cyclic loading for 1500 cycles (50 to 500 N at 2 Hz) followed by push to failure. Rate of damage (mm/s), stiffness (N/mm), modulus of elasticity (MPa), maximum load (N), maximum displacement (mm), and maximum stress (MPa) were compared between the 2 groups using independent t tests (P < .05). RESULTS No significant differences were found between the irradiated and nonirradiated groups for any of the biomechanical parameters (all P values > 0.05). CONCLUSIONS The results of this study support our hypothesis that even high levels of isolated irradiation do not significantly affect the biomechanical properties of fibular bone grafts. This work allows us to exclude acute structural changes in the bone due to irradiation as a possible factor leading to bone/implant instability following jaw reconstruction with fibular grafts. Further studies need to be conducted to better understand the range of factors that may lead to implant instability, including the biological response after radiation therapy.
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Affiliation(s)
- Lucas Graf-Alexiou
- Student, Department of Mechanical Engineering, University of Alberta, Edmonton, Canada
| | - Yuelin Qiu
- Student, Department of Civil Engineering, University of Alberta, Edmonton, Canada
| | - Daniel Aalto
- Assistant Professor, Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, Canada; Assistant Professor, Institute for Reconstructive Sciences in Medicine (iRSM), Edmonton, Canada
| | - Lindsey Westover
- Student, Department of Mechanical Engineering, University of Alberta, Edmonton, Canada.
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11
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Pendleton MM, Emerzian SR, Sadoughi S, Li A, Liu JW, Tang SY, O'Connell GD, Sibonga JD, Alwood JS, Keaveny TM. Relations Between Bone Quantity, Microarchitecture, and Collagen Cross-links on Mechanics Following In Vivo Irradiation in Mice. JBMR Plus 2021; 5:e10545. [PMID: 34761148 PMCID: PMC8567491 DOI: 10.1002/jbm4.10545] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Accepted: 08/20/2021] [Indexed: 01/22/2023] Open
Abstract
Humans are exposed to ionizing radiation via spaceflight or cancer radiotherapy, and exposure from radiotherapy is known to increase risk of skeletal fractures. Although irradiation can reduce trabecular bone mass, alter trabecular microarchitecture, and increase collagen cross‐linking, the relative contributions of these effects to any loss of mechanical integrity remain unclear. To provide insight, while addressing both the monotonic strength and cyclic‐loading fatigue life, we conducted total‐body, acute, gamma‐irradiation experiments on skeletally mature (17‐week‐old) C57BL/6J male mice (n = 84). Mice were administered doses of either 0 Gy (sham), 1 Gy (motivated by cumulative exposures from a Mars mission), or 5 Gy (motivated by clinical therapy regimens) with retrieval of the lumbar vertebrae at either a short‐term (11‐day) or long‐term (12‐week) time point after exposure. Micro‐computed tomography was used to assess trabecular and cortical quantity and architecture, biochemical composition assays were used to assess collagen quality, and mechanical testing was performed to evaluate vertebral compressive strength and fatigue life. At 11 days post‐exposure, 5 Gy irradiation significantly reduced trabecular mass (p < 0.001), altered microarchitecture (eg, connectivity density p < 0.001), and increased collagen cross‐links (p < 0.001). Despite these changes, vertebral strength (p = 0.745) and fatigue life (p = 0.332) remained unaltered. At 12 weeks after 5 Gy exposure, the trends in trabecular bone persisted; in addition, regardless of irradiation, cortical thickness (p < 0.01) and fatigue life (p < 0.01) decreased. These results demonstrate that the highly significant effects of 5 Gy total‐body irradiation on the trabecular bone morphology and collagen cross‐links did not translate into detectable effects on vertebral mechanics. The only mechanical deficits observed were associated with aging. Together, these vertebral results suggest that for spaceflight, irradiation alone will likely not alter failure properties, and for radiotherapy, more investigations that include post‐exposure time as a positive control and testing of both failure modalities are needed to determine the cause of increased fracture risk. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research. This article has been contributed to by US Government employees and their work is in the public domain in the USA.
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Affiliation(s)
- Megan M Pendleton
- Department of Mechanical Engineering University of California Berkeley CA USA
| | - Shannon R Emerzian
- Department of Mechanical Engineering University of California Berkeley CA USA
| | - Saghi Sadoughi
- Department of Mechanical Engineering University of California Berkeley CA USA
| | - Alfred Li
- Endocrine Research Unit University of California and Veteran Affairs Medical Center San Francisco CA USA
| | - Jennifer W Liu
- Department of Orthopaedic Surgery Washington University St. Louis MO USA
| | - Simon Y Tang
- Department of Orthopaedic Surgery Washington University St. Louis MO USA.,Department of Biomedical Engineering Washington University St. Louis MO USA.,Department of Mechanical Engineering and Materials Science Washington University St. Louis MO USA
| | - Grace D O'Connell
- Department of Mechanical Engineering University of California Berkeley CA USA.,Department of Orthopaedic Surgery University of California San Francisco CA USA
| | - Jean D Sibonga
- Biomedical Research and Environmental Sciences Division NASA Johnson Space Center Houston TX USA
| | - Joshua S Alwood
- Space Biosciences Division NASA Ames Research Center Moffett Field CA USA
| | - Tony M Keaveny
- Department of Mechanical Engineering University of California Berkeley CA USA.,Department of Bioengineering University of California Berkeley CA USA
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12
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Tuieng RJ, Cartmell SH, Kirwan CC, Sherratt MJ. The Effects of Ionising and Non-Ionising Electromagnetic Radiation on Extracellular Matrix Proteins. Cells 2021; 10:3041. [PMID: 34831262 PMCID: PMC8616186 DOI: 10.3390/cells10113041] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 10/28/2021] [Accepted: 10/30/2021] [Indexed: 02/07/2023] Open
Abstract
Exposure to sub-lethal doses of ionising and non-ionising electromagnetic radiation can impact human health and well-being as a consequence of, for example, the side effects of radiotherapy (therapeutic X-ray exposure) and accelerated skin ageing (chronic exposure to ultraviolet radiation: UVR). Whilst attention has focused primarily on the interaction of electromagnetic radiation with cells and cellular components, radiation-induced damage to long-lived extracellular matrix (ECM) proteins has the potential to profoundly affect tissue structure, composition and function. This review focuses on the current understanding of the biological effects of ionising and non-ionising radiation on the ECM of breast stroma and skin dermis, respectively. Although there is some experimental evidence for radiation-induced damage to ECM proteins, compared with the well-characterised impact of radiation exposure on cell biology, the structural, functional, and ultimately clinical consequences of ECM irradiation remain poorly defined.
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Affiliation(s)
- Ren Jie Tuieng
- Division of Cell Matrix Biology & Regenerative Medicine, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, UK;
| | - Sarah H. Cartmell
- Department of Materials, School of Natural Sciences, Faculty of Science and Engineering and The Henry Royce Institute, Royce Hub Building, University of Manchester, Manchester M13 9PL, UK;
| | - Cliona C. Kirwan
- Division of Cancer Sciences and Manchester Breast Centre, Oglesby Cancer Research Building, Manchester Cancer Research Centre, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M20 4BX, UK;
| | - Michael J. Sherratt
- Division of Cell Matrix Biology & Regenerative Medicine and Manchester Breast Centre, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, UK
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13
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Waletzko-Hellwig J, Pohl C, Riese J, Schlosser M, Dau M, Engel N, Springer A, Bader R. Effect of High Hydrostatic Pressure on Human Trabecular Bone Regarding Cell Death and Matrix Integrity. Front Bioeng Biotechnol 2021; 9:730266. [PMID: 34458245 PMCID: PMC8387795 DOI: 10.3389/fbioe.2021.730266] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 08/02/2021] [Indexed: 11/13/2022] Open
Abstract
The reconstruction of critical size bone defects is still clinically challenging. Even though the transplantation of autologous bone is used as gold standard, this therapy is accompanied by donor site morbidities as well as tissue limitations. The alternatively used allografts, which are devitalized due to thermal, chemical or physical processing, often lose their matrix integrity and have diminished biomechanical properties. High Hydrostatic Pressure (HHP) may represent a gentle alternative to already existing methods since HHP treated human osteoblasts undergo cell death and HHP treated bone cylinders maintain their mechanical properties. The aim of this study was to determine the biological effects caused by HHP treatment regarding protein/matrix integrity and type of cell death in trabecular bone cylinders. Therefore, different pressure protocols (250 and 300 MPa for 10, 20 and 30 min) and end point analysis such as quantification of DNA-fragmentation, gene expression, SDS-PAGE, FESEM analysis and histological staining were performed. While both protein and matrix integrity was preserved, molecular biological methods showed an apoptotic differentiation of cell death for lower pressures and shorter applications (250 MPa for 10 and 20 min) and necrotic differentiation for higher pressures and longer applications (300 MPa for 30 min). This study serves as a basis for further investigation as it shows that HHP successfully devitalizes trabecular bone cylinders.
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Affiliation(s)
- Janine Waletzko-Hellwig
- Department of Oral, Maxillofacial and Plastic Surgery, Rostock University Medical Center, Rostock, Germany
| | - Christopher Pohl
- Department of General Surgery, Visceral, Thoracic and Vascular Surgery, University Medical Center Greifswald, Greifswald, Germany
| | - Janik Riese
- Department of General Surgery, Visceral, Thoracic and Vascular Surgery, University Medical Center Greifswald, Greifswald, Germany
| | - Michael Schlosser
- Department of General Surgery, Visceral, Thoracic and Vascular Surgery, University Medical Center Greifswald, Greifswald, Germany
| | - Michael Dau
- Department of Oral, Maxillofacial and Plastic Surgery, Rostock University Medical Center, Rostock, Germany
| | - Nadja Engel
- Department of Oral, Maxillofacial and Plastic Surgery, Rostock University Medical Center, Rostock, Germany
| | - Armin Springer
- Medical Biology and Electron Microscopy Center, Rostock University Medical Center, Rostock, Germany
| | - Rainer Bader
- Biomechanics and Implant Technology Research Laboratory, Department of Orthopedics, Rostock University Medical Center, Rostock, Germany
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14
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Pierantoni M, Silva Barreto I, Hammerman M, Verhoeven L, Törnquist E, Novak V, Mokso R, Eliasson P, Isaksson H. A quality optimization approach to image Achilles tendon microstructure by phase-contrast enhanced synchrotron micro-tomography. Sci Rep 2021; 11:17313. [PMID: 34453067 PMCID: PMC8397765 DOI: 10.1038/s41598-021-96589-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 08/06/2021] [Indexed: 12/19/2022] Open
Abstract
Achilles tendons are mechanosensitive, and their complex hierarchical structure is in part the result of the mechanical stimulation conveyed by the muscles. To fully understand how their microstructure responds to mechanical loading a non-invasive approach for 3D high resolution imaging suitable for soft tissue is required. Here we propose a protocol that can capture the complex 3D organization of the Achilles tendon microstructure, using phase-contrast enhanced synchrotron micro-tomography (SR-PhC-μCT). We investigate the effects that sample preparation and imaging conditions have on the resulting image quality, by considering four types of sample preparations and two imaging setups (sub-micrometric and micrometric final pixel sizes). The image quality is assessed using four quantitative parameters. The results show that for studying tendon collagen fibers, conventional invasive sample preparations such as fixation and embedding are not necessary or advantageous. Instead, fresh frozen samples result in high-quality images that capture the complex 3D organization of tendon fibers in conditions as close as possible to natural. The comprehensive nature of this innovative study by SR-PhC-μCT breaks ground for future studies of soft complex biological tissue in 3D with high resolution in close to natural conditions, which could be further used for in situ characterization of how soft tissue responds to mechanical stimuli on a microscopic level.
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Affiliation(s)
- Maria Pierantoni
- Department of Biomedical Engineering, Lund University, Box 118, 221 00, Lund, Sweden.
| | | | - Malin Hammerman
- Department of Biomedical Engineering, Lund University, Box 118, 221 00, Lund, Sweden
- Department of Biomedical and Clinical Sciences, Linköping University, 581 83, Linköping, Sweden
| | - Lissa Verhoeven
- Department of Biomedical Engineering, Lund University, Box 118, 221 00, Lund, Sweden
| | - Elin Törnquist
- Department of Biomedical Engineering, Lund University, Box 118, 221 00, Lund, Sweden
| | - Vladimir Novak
- Swiss Light Source, Paul Scherrer Institute, 5232, Villigen, Switzerland
| | - Rajmund Mokso
- Swiss Light Source, Paul Scherrer Institute, 5232, Villigen, Switzerland
- Division of Solid Mechanics, Lund University, Box 118, 221 00, Lund, Sweden
| | - Pernilla Eliasson
- Department of Biomedical and Clinical Sciences, Linköping University, 581 83, Linköping, Sweden
| | - Hanna Isaksson
- Department of Biomedical Engineering, Lund University, Box 118, 221 00, Lund, Sweden
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15
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Kim H, Pyo H, Park HC, Lim DH, Yu JI, Park W, Ahn YC, Choi DH, Oh D, Noh JM, Cho WK, Yoo GS, Jung SH, Kim ES, Lee SH, Park SJ, Lee CS. Clinical and dosimetric risk factors for vertebral compression fracture after single-fraction stereotactic body radiation therapy for spine metastases. J Bone Oncol 2021; 28:100368. [PMID: 34026479 PMCID: PMC8131921 DOI: 10.1016/j.jbo.2021.100368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 04/23/2021] [Accepted: 04/27/2021] [Indexed: 10/31/2022] Open
Abstract
Objectives This analysis was performed to evaluate the incidence of vertebral compression fracture (VCF) and determine the contributing factors for VCF in patients undergoing single-fraction stereotactic body radiotherapy (SBRT) for spinal bone metastases (SBM). Methods A retrospective review of medical records was conducted for patients undergoing SBRT for SBM at our institution between January 2010 and December 2018. Patients who had undergone neither pre-SBRT surgical excision nor post-SBRT prophylactic fixation were included. The effects of clinical and dosimetric parameters were analyzed with respect to VCF risk. The following dosimietric parameters of the planning target volume (PTV) were calculated: mean/minimum/maximum dose, radiation dose to 10-90% volume, and irradiated volume receiving more than 10-25 Gy (PTV_V10 - 25 Gy). Results Among 163 patients (179 vertebrae), 21 (12.8%) experienced VCF. The 1-year and 2-year VCF rates were 12.1% and 13.2%, respectively. Among dosimetric parameters, PTV_V15 Gy was the most significant for VCF prediction. In a univariate analysis, breast or prostate primary, no vertebral body collapse, and PTV_V15 Gy ≤42 cm3 were significantly associated with a lower incidence rate of VCF. In a multivariate analysis, PTV_V15 Gy was the only significant factor for VCF risk. The 1-year VCF rate was 3.8% in patients with PTV_V15 Gy ≤42 cm3, while it was 22.1% in those with PTV_V15 Gy > 42 cm3 (p < 0.01). Conclusions SBRT-related VCF was found in 12% of patients in our institution. The PTV_V15 Gy is a significant factor for VCF prediction.
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Affiliation(s)
- Haeyoung Kim
- Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Hongryull Pyo
- Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Hee Chul Park
- Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Do Hoon Lim
- Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Jeong Il Yu
- Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Won Park
- Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Yong Chan Ahn
- Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Doo Ho Choi
- Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Dongryul Oh
- Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Jae Myoung Noh
- Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Won Kyung Cho
- Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Gyu Sang Yoo
- Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Sang Hoon Jung
- Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Eun-Sang Kim
- Department of Neurosurgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Sun-Ho Lee
- Department of Neurosurgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Se-Jun Park
- Department of Orthopedic Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Chong-Suh Lee
- Department of Orthopedic Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
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16
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Gomes AD, de Oliveira AAR, Houmard M, Nunes EHM. Gamma sterilization of collagen/hydroxyapatite composites: Validation and radiation effects. Appl Radiat Isot 2021; 174:109758. [PMID: 33962117 DOI: 10.1016/j.apradiso.2021.109758] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 02/06/2021] [Accepted: 04/26/2021] [Indexed: 11/30/2022]
Abstract
In this work, gamma sterilization was validated, and the impact of this sterilization process on collagen/hydroxyapatite (Col/HAp) composites was investigated. It has been already recognized that the improper sterilization of healthcare products may lead to infection and mortality/morbidity issues in patients. Gamma sterilization has emerged as a promising sterilization method because it shows advantages such as low cost, a small increase in temperature of irradiated materials, and no production of toxic residues. Moreover, gamma rays can reach the products even when contained in sealed packages. The dose of gamma radiation applied in this study ranged from 17.5 to 50 kGy. The studied samples were examined by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TG), and differential scanning calorimetry (DSC). No apparent effect of gamma radiation on HAp was observed even when doses as high as 50 kGy were applied. On the other hand, Col was greatly affected by gamma radiation, displaying cross-linking and degradation after sterilization. These structural changes may alter Col's properties, which could, in turn, impact its medical use. As a consequence, it is strongly recommended that the irradiation dose used to sterilize the Col/HAp composites shall be kept as low as possible to mitigate the structural changes induced in Col. It was noticed that a radiation dose of 17.5 kGy was sufficient to sterilize the examined samples because a sterility assurance level (SAL) below 10-6 was detected. Although dramatic structural changes were observed in Col when this dose was applied, the sterilized samples showed no toxicity to human mesenchymal stem cells. Based on these results, we established a VDMax of 17.5 kGy for Col/HAp-based healthcare products.
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Affiliation(s)
- Anderson D Gomes
- JHS Biomaterials, Rua Ouro Branco 345, Novo Alvorada, Sabará, Minas Gerais, CEP, 34650-120, Brazil; Universidade Federal de Minas Gerais, Escola de Engenharia, Departamento de Engenharia Metalúrgica e de Materiais, Bloco 2, Sala 2233, Avenida Presidente Antônio Carlos 6627, Pampulha, Belo Horizonte, Minas Gerais, CEP, 31270-901, Brazil.
| | - Agda A R de Oliveira
- JHS Biomaterials, Rua Ouro Branco 345, Novo Alvorada, Sabará, Minas Gerais, CEP, 34650-120, Brazil
| | - Manuel Houmard
- Universidade Federal de Minas Gerais, Escola de Engenharia, Departamento de Engenharia Química, Bloco 2, Sala 5212, Avenida Presidente Antônio Carlos 6627, Pampulha, Belo Horizonte, Minas Gerais, CEP, 31270-901, Brazil
| | - Eduardo H M Nunes
- Universidade Federal de Minas Gerais, Escola de Engenharia, Departamento de Engenharia Metalúrgica e de Materiais, Bloco 2, Sala 2233, Avenida Presidente Antônio Carlos 6627, Pampulha, Belo Horizonte, Minas Gerais, CEP, 31270-901, Brazil.
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17
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Bartlow CM, Mann KA, Damron TA, Oest ME. Altered mechanical behavior of demineralized bone following therapeutic radiation. J Orthop Res 2021; 39:750-760. [PMID: 32965711 PMCID: PMC8212945 DOI: 10.1002/jor.24868] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 07/15/2020] [Accepted: 09/21/2020] [Indexed: 02/04/2023]
Abstract
Post-radiotherapy (RTx) bone fragility fractures are a late-onset complication occurring in bone within or underlying the radiation field. These fractures are difficult to predict, as patients do not present with local osteopenia. Using a murine hindlimb RTx model, we previously documented decreased mineralized bone strength and fracture toughness, but alterations in material properties of the organic bone matrix are largely unknown. In this study, 4 days of fractionated hindlimb irradiation (4 × 5 Gy) or Sham irradiation was administered in a mouse model (BALB/cJ, end points: 0, 4, 8, and 12 weeks, n = 15/group/end point). Following demineralization, the viscoelastic stress relaxation, and monotonic tensile mechanical properties of tibiae were determined. Irradiated tibiae demonstrated an immediate (day after last radiation fraction) and sustained (4, 8, 12 weeks) increase in stress relaxation compared to the Sham group, with a 4.4% decrease in equilibrium stress (p < .017). While tensile strength was not different between groups, irradiated tibiae had a lower elastic modulus (-5%, p = .027) and energy to failure (-12.2%, p = .012) with monotonic loading. Gel electrophoresis showed that therapeutic irradiation (4 × 5 Gy) does not result in collagen fragmentation, while irradiation at a common sterilization dose (25 kGy) extensively fragmented collagen. These results suggest that altered collagen mechanical behavior has a role in postirradiation bone fragility, but this can occur without detectable collagen fragmentation. Statement of Clinical Significance: Therapeutic irradiation alters bone organic matrix mechanics and which contribute to diminished fatigue strength, but this does not occur via collagen fragmentation.
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Affiliation(s)
- Christopher M. Bartlow
- Department of Orthopedic Surgery State University of New York Upstate Medical University Syracuse New York USA
| | - Kenneth A. Mann
- Department of Orthopedic Surgery State University of New York Upstate Medical University Syracuse New York USA
| | - Timothy A. Damron
- Department of Orthopedic Surgery State University of New York Upstate Medical University Syracuse New York USA
| | - Megan E. Oest
- Department of Orthopedic Surgery State University of New York Upstate Medical University Syracuse New York USA
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18
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Shimizu T, Demura S, Kato S, Shinmura K, Yokogawa N, Yonezawa N, Oku N, Kitagawa R, Handa M, Annen R, Nojima T, Murakami H, Tsuchiya H. Radiation Disrupts the Protective Function of the Spinal Meninges in a Mouse Model of Tumor-induced Spinal Cord Compression. Clin Orthop Relat Res 2021; 479:163-176. [PMID: 32858719 PMCID: PMC7899484 DOI: 10.1097/corr.0000000000001449] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 07/16/2020] [Indexed: 01/31/2023]
Abstract
BACKGROUND Recent advances in multidisciplinary treatments for various cancers have extended the survival period of patients with spinal metastases. Radiotherapy has been widely used to treat spinal metastases; nevertheless, long-term survivors sometimes undergo more surgical intervention after radiotherapy because of local tumor relapse. Generally, intradural invasion of a spinal tumor seldom occurs because the dura mater serves as a tissue barrier against tumor infiltration. However, after radiation exposure, some spinal tumors invade the dura mater, resulting in leptomeningeal dissemination, intraoperative dural injury, or postoperative local recurrence. The mechanisms of how radiation might affect the dura have not been well-studied. QUESTIONS/PURPOSES To investigate how radiation affects the spinal meninges, we asked: (1) What is the effect of irradiation on the meningeal barrier's ability to protect against carcinoma infiltration? (2) What is the effect of irradiation on the meningeal barrier's ability to protect against sarcoma infiltration? (3) What is the effect of irradiation on dural microstructure observed by scanning electron microscopy (SEM)? (4) What is the effect of irradiation on dural microstructure observed by transmission electron microscopy (TEM)? METHODS Eighty-four 10-week-old female ddY mice were randomly divided into eight groups: mouse mammary tumor (MMT) implantation 6 weeks after 0-Gy irradiation (nonirradiation) (n = 11), MMT implantation 6 weeks after 20-Gy irradiation (n = 10), MMT implantation 12 weeks after nonirradiation (n = 10), MMT implantation 12 weeks after 20-Gy irradiation (n = 11), mouse osteosarcoma (LM8) implantation 6 weeks after nonirradiation (n = 11), LM8 implantation 6 weeks after 20-Gy irradiation (n = 11), LM8 implantation 12 weeks after nonirradiation (n = 10), and LM8 implantation 12 weeks after 20-Gy irradiation (n = 10); female mice were used for a mammary tumor metastasis model and ddY mice, a closed-colony mice with genetic diversity, were selected to represent interhuman diversity. Mice in each group underwent surgery to generate a tumor-induced spinal cord compression model at either 6 weeks or 12 weeks after irradiation to assess changes in the meningeal barrier's ability to protect against tumor infiltration. During surgery, the mice were implanted with MMT (representative of a carcinoma) or LM8 tumor. When the mice became paraplegic because of spinal cord compression by the growing implanted tumor, they were euthanized and evaluated histologically. Four mice died from anesthesia and 10 mice per group were euthanized (MMT-implanted groups: MMT implantation occurred 6 weeks after nonirradiation [n = 10], 6 weeks after irradiation [n = 10], 12 weeks after nonirradiation [n = 10], and 12 weeks after irradiation [n = 10]; LM8-implanted groups: LM8 implantation performed 6 weeks after nonirradiation [n = 10], 6 weeks after irradiation [n = 10], 12 weeks after nonirradiation [n = 10], and 12 weeks after irradiation [n = 10]); 80 mice were evaluated. The spines of the euthanized mice were harvested; hematoxylin and eosin staining and Masson's trichrome staining slides were prepared for histologic assessment of each specimen. In the histologic assessment, intradural invasion of the implanted tumor was graded in each group by three observers blinded to the type of tumor, presence of irradiation, and the timing of the surgery. Grade 0 was defined as no intradural invasion with intact dura mater, Grade 1 was defined as intradural invasion with linear dural continuity, and Grade 2 was defined as intradural invasion with disruption of the dural continuity. Additionally, we euthanized 12 mice for a microstructural analysis of dura mater changes by two observers blinded to the presence of irradiation. Six mice (three mice in the 12 weeks after nonirradiation group and three mice in the 12 weeks after 20-Gy irradiation group) were quantitatively analyzed for defects on the dural surface with SEM. The other six mice (three mice in the 12 weeks after nonirradiation group and three mice in the 12 weeks after 20-Gy irradiation group) were analyzed for layer structure of collagen fibers constituting dura mater by TEM. In the SEM assessment, the number and size of defects on the dural surface on images (200 μm × 300 μm) at low magnification (× 2680) were evaluated. A total of 12 images (two per mouse) were evaluated for this assessment. The days from surgery to paraplegia were compared between each of the tumor groups using the Kruskal-Wallis test. The scores of intradural tumor invasion grades and the number of defects on dural surface per SEM image were compared between irradiation group and nonirradiation group using the Mann-Whitney U test. Interobserver reliabilities of assessing intradural tumor invasion grades and the number of dural defects on the dural surface were analyzed using Fleiss'κ coefficient. P values < 0.05 were considered statistically significant. RESULTS There was no difference in the median (range) time to paraplegia among the MMT implantation 6 weeks after nonirradiation group, the 6 weeks after irradiation group, the 12 weeks after nonirradiation group, and the 12 weeks after irradiation group (16 days [14 to 17] versus 14 days [12 to 18] versus 16 days [14 to 17] versus 14 days [12 to 15]; χ2 = 4.7; p = 0.19). There was also no difference in the intradural invasion score between the MMT implantation 6 weeks after irradiation group and the 6 weeks after nonirradiation group (8 of 10 Grade 0 and 2 of 10 Grade 1 versus 10 of 10 Grade 0; p = 0.17). On the other hand, there was a higher intradural invasion score in the MMT implantation 12 weeks after irradiation group than the 12 weeks after nonirradiation group (5 of 10 Grade 0, 3 of 10 Grade 1 and 2 of 10 Grade 2 versus 10 of 10 Grade 0; p = 0.02). Interobserver reliability of assessing intradural tumor invasion grades in the MMT-implanted group was 0.94. There was no difference in the median (range) time to paraplegia among in the LM8 implantation 6 weeks after nonirradiation group, the 6 weeks after irradiation group, the 12 weeks after nonirradiation group, and the 12 weeks after irradiation group (12 days [9 to 13] versus 10 days [8 to 13] versus 11 days [8 to 13] versus 9 days [6 to 12]; χ2 = 2.4; p = 0.50). There was also no difference in the intradural invasion score between the LM8 implantation 6 weeks after irradiation group and the 6 weeks after nonirradiation group (7 of 10 Grade 0, 1 of 10 Grade 1 and 2 of 10 Grade 2 versus 8 of 10 Grade 0 and 2 of 10 Grade 1; p = 0.51), whereas there was a higher intradural invasion score in the LM8 implantation 12 weeks after irradiation group than the 12 weeks after nonirradiation group (3 of 10 Grade 0, 3 of 10 Grade 1 and 4 of 10 Grade 2 versus 8 of 10 Grade 0 and 2 of 10 Grade 1; p = 0.04). Interobserver reliability of assessing intradural tumor invasion grades in the LM8-implanted group was 0.93. In the microstructural analysis of the dura mater using SEM, irradiated mice had small defects on the dural surface at low magnification and degeneration of collagen fibers at high magnification. The median (range) number of defects on the dural surface per image in the irradiated mice was larger than that of nonirradiated mice (2 [1 to 3] versus 0; difference of medians, 2/image; p = 0.002) and the median size of defects was 60 μm (30 to 80). Interobserver reliability of assessing number of defects on the dural surface was 1.00. TEM revealed that nonirradiated mice demonstrated well-organized, multilayer structures, while irradiated mice demonstrated irregularly layered structures at low magnification. At high magnification, well-ordered cross-sections of collagen fibers were observed in the nonirradiated mice. However, disordered alignment of collagen fibers was observed in irradiated mice. CONCLUSION Intradural tumor invasion and disruptions of the dural microstructure were observed in the meninges of mice after irradiation, indicating radiation-induced disruption of the meningeal barrier. CLINICAL RELEVANCE We conclude that in this form of delivery, radiation is associated with disruption of the dural meningeal barrier, indicating a need to consider methods to avoid or limit Postradiation tumor relapse and spinal cord compression when treating spinal metastases so that patients do not experience intradural tumor invasion. Surgeons should be aware of the potential for intradural tumor invasion when they perform post-irradiation spinal surgery to minimize the risks for intraoperative dural injury and spinal cord injury. Further research in patients with irradiated spinal metastases is necessary to confirm that the same findings are observed in humans and to seek irradiation methods that prevent or minimize the disruption of meningeal barrier function.
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Affiliation(s)
- Takaki Shimizu
- T. Shimizu, S. Demura, S. Kato, K. Shinmura, N. Yokogawa, N. Yonezawa, N. Oku, R. Kitagawa, M. Handa, R. Annen, T. Nojima, H. Tsuchiya, Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan
- H. Murakami, Department of Orthopaedic Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Satoru Demura
- T. Shimizu, S. Demura, S. Kato, K. Shinmura, N. Yokogawa, N. Yonezawa, N. Oku, R. Kitagawa, M. Handa, R. Annen, T. Nojima, H. Tsuchiya, Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan
- H. Murakami, Department of Orthopaedic Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Satoshi Kato
- T. Shimizu, S. Demura, S. Kato, K. Shinmura, N. Yokogawa, N. Yonezawa, N. Oku, R. Kitagawa, M. Handa, R. Annen, T. Nojima, H. Tsuchiya, Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan
- H. Murakami, Department of Orthopaedic Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Kazuya Shinmura
- T. Shimizu, S. Demura, S. Kato, K. Shinmura, N. Yokogawa, N. Yonezawa, N. Oku, R. Kitagawa, M. Handa, R. Annen, T. Nojima, H. Tsuchiya, Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan
- H. Murakami, Department of Orthopaedic Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Noriaki Yokogawa
- T. Shimizu, S. Demura, S. Kato, K. Shinmura, N. Yokogawa, N. Yonezawa, N. Oku, R. Kitagawa, M. Handa, R. Annen, T. Nojima, H. Tsuchiya, Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan
- H. Murakami, Department of Orthopaedic Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Noritaka Yonezawa
- T. Shimizu, S. Demura, S. Kato, K. Shinmura, N. Yokogawa, N. Yonezawa, N. Oku, R. Kitagawa, M. Handa, R. Annen, T. Nojima, H. Tsuchiya, Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan
- H. Murakami, Department of Orthopaedic Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Norihiro Oku
- T. Shimizu, S. Demura, S. Kato, K. Shinmura, N. Yokogawa, N. Yonezawa, N. Oku, R. Kitagawa, M. Handa, R. Annen, T. Nojima, H. Tsuchiya, Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan
- H. Murakami, Department of Orthopaedic Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Ryo Kitagawa
- T. Shimizu, S. Demura, S. Kato, K. Shinmura, N. Yokogawa, N. Yonezawa, N. Oku, R. Kitagawa, M. Handa, R. Annen, T. Nojima, H. Tsuchiya, Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan
- H. Murakami, Department of Orthopaedic Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Makoto Handa
- T. Shimizu, S. Demura, S. Kato, K. Shinmura, N. Yokogawa, N. Yonezawa, N. Oku, R. Kitagawa, M. Handa, R. Annen, T. Nojima, H. Tsuchiya, Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan
- H. Murakami, Department of Orthopaedic Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Ryohei Annen
- T. Shimizu, S. Demura, S. Kato, K. Shinmura, N. Yokogawa, N. Yonezawa, N. Oku, R. Kitagawa, M. Handa, R. Annen, T. Nojima, H. Tsuchiya, Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan
- H. Murakami, Department of Orthopaedic Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Takayuki Nojima
- T. Shimizu, S. Demura, S. Kato, K. Shinmura, N. Yokogawa, N. Yonezawa, N. Oku, R. Kitagawa, M. Handa, R. Annen, T. Nojima, H. Tsuchiya, Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan
- H. Murakami, Department of Orthopaedic Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Hideki Murakami
- T. Shimizu, S. Demura, S. Kato, K. Shinmura, N. Yokogawa, N. Yonezawa, N. Oku, R. Kitagawa, M. Handa, R. Annen, T. Nojima, H. Tsuchiya, Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan
- H. Murakami, Department of Orthopaedic Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Hiroyuki Tsuchiya
- T. Shimizu, S. Demura, S. Kato, K. Shinmura, N. Yokogawa, N. Yonezawa, N. Oku, R. Kitagawa, M. Handa, R. Annen, T. Nojima, H. Tsuchiya, Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan
- H. Murakami, Department of Orthopaedic Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
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Scheuren AC, Kuhn GA, Müller R. Effects of long-term in vivo micro-CT imaging on hallmarks of osteopenia and frailty in aging mice. PLoS One 2020; 15:e0239534. [PMID: 32966306 PMCID: PMC7511008 DOI: 10.1371/journal.pone.0239534] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 09/08/2020] [Indexed: 11/26/2022] Open
Abstract
In vivo micro-CT has already been used to monitor microstructural changes of bone in mice of different ages and in models of age-related diseases such as osteoporosis. However, as aging is accompanied by frailty and subsequent increased sensitivity to external stimuli such as handling and anesthesia, the extent to which longitudinal imaging can be applied in aging studies remains unclear. Consequently, the potential of monitoring individual mice during the entire aging process-from healthy to frail status-has not yet been exploited. In this study, we assessed the effects of long-term in vivo micro-CT imaging-consisting of 11 imaging sessions over 20 weeks-on hallmarks of aging both on a local (i.e., static and dynamic bone morphometry) and systemic (i.e., frailty index (FI) and body weight) level at various stages of the aging process. Furthermore, using a premature aging model (PolgA(D257A/D257A)), we assessed whether these effects differ between genotypes. The 6th caudal vertebrae of 4 groups of mice (PolgA(D257A/D257A) and PolgA(+/+)) were monitored by in vivo micro-CT every 2 weeks. One group was subjected to 11 scans between weeks 20 and 40 of age, whereas the other groups were subjected to 5 scans between weeks 26-34, 32-40 and 40-46, respectively. The long-term monitoring approach showed small but significant changes in the static bone morphometric parameters compared to the other groups. However, no interaction effect between groups and genotype was found, suggesting that PolgA mutation does not render bone more or less susceptible to long-term micro-CT imaging. The differences between groups observed in the static morphometric parameters were less pronounced in the dynamic morphometric parameters. Moreover, the body weight and FI were not affected by more frequent imaging sessions. Finally, we observed that longitudinal designs including baseline measurements at young adult age are more powerful at detecting effects of in vivo micro-CT imaging on hallmarks of aging than cross-sectional comparisons between multiple groups of aged mice subjected to fewer imaging sessions.
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Affiliation(s)
| | - Gisela A. Kuhn
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
| | - Ralph Müller
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
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