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Vahidi G, Boone C, Hoffman F, Heveran C. Aging decreases osteocyte peri-lacunar-canalicular system turnover in female C57BL/6JN mice. Bone 2024; 186:117163. [PMID: 38857854 PMCID: PMC11227388 DOI: 10.1016/j.bone.2024.117163] [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: 03/04/2024] [Revised: 06/06/2024] [Accepted: 06/07/2024] [Indexed: 06/12/2024]
Abstract
Osteocytes engage in bone resorption and mineralization surrounding their expansive lacunar-canalicular system (LCS) through peri-LCS turnover. However, fundamental questions persist about where, when, and how often osteocytes engage in peri-LCS turnover and how these processes change with aging. Furthermore, whether peri-LCS turnover is associated with natural variation in cortical tissue strain remains unexplored. To address these questions, we utilized confocal scanning microscopy, immunohistochemistry, and scanning electron microscopy to characterize osteocyte peri-LCS turnover in the cortical (mid-diaphysis) and cancellous (metaphysis) regions of femurs from young adult (5 mo) and early-old-age (22 mo) female C57BL/6JN mice. LCS bone mineralization was measured by the presence of perilacunar fluorochrome labels. LCS bone resorption was measured by immunohistochemical marker of bone resorption. The dynamics of peri-LCS turnover were estimated from serial fluorochrome labeling, where each mouse was administered two labels between 2 and 16 days before euthanasia. Osteocyte participation in mineralizing their surroundings is highly abundant in both cortical and cancellous bone of young adult mice but significantly decreases with aging. LCS bone resorption also decreases with aging. Aging has a greater impact on peri-LCS turnover dynamics in cancellous bone than in cortical bone. Lacunae with recent peri-LCS turnover are larger in both age groups. While peri-LCS turnover is associated with variation in tissue strain between cortical quadrants and intracortical location for 22 mo mice, these associations were not seen for 5 mo mice. The impact of aging on decreasing peri-LCS turnover may have significant implications for bone quality and mechanosensation.
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Affiliation(s)
- Ghazal Vahidi
- Department of Mechanical & Industrial Engineering, Montana State University, Bozeman, MT, USA
| | - Connor Boone
- Department of Mechanical & Industrial Engineering, Montana State University, Bozeman, MT, USA
| | - Fawn Hoffman
- Department of Biomedical Sciences, College of Idaho, Caldwell, ID, USA
| | - Chelsea Heveran
- Department of Mechanical & Industrial Engineering, Montana State University, Bozeman, MT, USA.
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2
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Moreno-Jiménez I, Heinig S, Heras U, Maichl DS, Strifler S, Leich E, Blouin S, Fratzl P, Fratzl-Zelman N, Jundt F, Cipitria A. 3D osteocyte lacunar morphometry of human bone biopsies with high resolution microCT: From monoclonal gammopathy to newly diagnosed multiple myeloma. Bone 2024:117236. [PMID: 39151745 DOI: 10.1016/j.bone.2024.117236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2024] [Revised: 07/26/2024] [Accepted: 08/13/2024] [Indexed: 08/19/2024]
Abstract
Osteocytes are mechanosensitive, bone-embedded cells which are connected via dendrites in a lacuno-canalicular network and regulate bone resorption and formation balance. Alterations in osteocyte lacunar volume, shape and density have been identified in conditions of aging, osteoporosis and osteolytic bone metastasis, indicating patterns of impaired bone remodeling, osteolysis and disease progression. Osteolytic bone disease is a hallmark of the hematologic malignancy multiple myeloma (MM), in which monoclonal plasma cells in the bone marrow disrupt the bone homeostasis and induce excessive resorption at local and distant sites. Qualitative and quantitative changes in the 3D osteocyte lacunar morphometry have not yet been evaluated in MM, nor in the precursor conditions monoclonal gammopathy of undetermined significance (MGUS) and smoldering multiple myeloma (SMM). In this study, we characterized the osteocyte lacunar morphology in trabecular bone of the iliac crest at the ultrastructural level using high resolution microCT in human bone biopsy samples of three MGUS, two SMM and six newly diagnosed MM. In MGUS, SMM and MM we found a trend for lower lacunar density and a shift towards larger lacunae with disease progression (higher 50 % cutoff of the lacunar volume cumulative distribution) in the small osteocyte lacunae 20-900 μm3 range compared to control samples. In the larger lacunae 900-3000 μm3 range, we detected significantly higher lacunar density and microporosity in the MM group compared to the MGUS/SMM group. Regarding the shape distribution, the MGUS/SMM group showed a trend for flatter, more elongated and anisotropic osteocyte lacunae compared to the control group. Altogether, our findings suggest that osteocytes in human MM bone disease undergo changes in their lacunae density, volume and shape, which could be an indicator for osteolysis and disease progression. Future studies are needed to understand whether alterations of the lacunae architecture affect the mechanoresponsiveness of osteocytes and ultimately bone adaptation and fracture resistance in MM and its precursors conditions.
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Affiliation(s)
- Inés Moreno-Jiménez
- Max Planck Institute of Colloids and Interfaces, Department of Biomaterials, 14476 Potsdam, Germany.
| | - Sharen Heinig
- Max Planck Institute of Colloids and Interfaces, Department of Biomaterials, 14476 Potsdam, Germany
| | - Unai Heras
- Group of Bioengineering in Regeneration and Cancer, Biogipuzkoa Health Research Institute, 20014 San Sebastian, Spain; Department of Cell Biology and Histology, Faculty of Medicine and Nursing, University of the Basque Country UPV/EHU, 48940 Leioa, Spain
| | - Daniela Simone Maichl
- Department of Internal Medicine II, University Hospital Würzburg, 97080 Würzburg, Germany
| | - Susanne Strifler
- Department of Internal Medicine II, University Hospital Würzburg, 97080 Würzburg, Germany
| | - Ellen Leich
- Institute of Pathology, University of Würzburg, 97080 Würzburg, Germany; Comprehensive Cancer Center Mainfranken, 97080 Würzburg, Germany
| | - Stéphane Blouin
- Ludwig Boltzmann Institute of Osteology at the Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, Vienna, Austria
| | - Peter Fratzl
- Max Planck Institute of Colloids and Interfaces, Department of Biomaterials, 14476 Potsdam, Germany
| | - Nadja Fratzl-Zelman
- Ludwig Boltzmann Institute of Osteology at the Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, Vienna, Austria
| | - Franziska Jundt
- Department of Internal Medicine II, University Hospital Würzburg, 97080 Würzburg, Germany; Comprehensive Cancer Center Mainfranken, 97080 Würzburg, Germany.
| | - Amaia Cipitria
- Max Planck Institute of Colloids and Interfaces, Department of Biomaterials, 14476 Potsdam, Germany; Group of Bioengineering in Regeneration and Cancer, Biogipuzkoa Health Research Institute, 20014 San Sebastian, Spain; IKERBASQUE, Basque Foundation for Science, 48009 Bilbao, Spain.
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3
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Ajami S, Van den Dam Z, Hut J, Savery D, Chin M, Koudstaal M, Steacy M, Carriero A, Pitsillides A, Chang YM, Rau C, Marathe S, Dunaway D, Jeelani NUO, Schievano S, Pauws E, Borghi A. Cranial bone microarchitecture in a mouse model for syndromic craniosynostosis. J Anat 2024. [PMID: 39096036 DOI: 10.1111/joa.14121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Revised: 06/27/2024] [Accepted: 07/23/2024] [Indexed: 08/04/2024] Open
Abstract
Crouzon syndrome is a congenital craniofacial disorder caused by mutations in the Fibroblast Growth Factor Receptor 2 (FGFR2). It is characterized by the premature fusion of cranial sutures, leading to a brachycephalic head shape, and midfacial hypoplasia. The aim of this study was to investigate the effect of the FGFR2 mutation on the microarchitecture of cranial bones at different stages of postnatal skull development, using the FGFR2C342Y mouse model. Apart from craniosynostosis, this model shows cranial bone abnormalities. High-resolution synchrotron microtomography images of the frontal and parietal bone were acquired for both FGFR2C342Y/+ (Crouzon, heterozygous mutant) and FGFR2+/+ (control, wild-type) mice at five ages (postnatal days 1, 3, 7, 14 and 21, n = 6 each). Morphometric measurements were determined for cortical bone porosity: osteocyte lacunae and canals. General linear model to assess the effect of age, anatomical location and genotype was carried out for each morphometric measurement. Histological analysis was performed to validate the findings. In both groups (Crouzon and wild-type), statistical difference in bone volume fraction, average canal volume, lacunar number density, lacunar volume density and canal volume density was found at most age points, with the frontal bone generally showing higher porosity and fewer lacunae. Frontal bone showed differences between the Crouzon and wild-type groups in terms of lacunar morphometry (average lacunar volume, lacunar number density and lacunar volume density) with larger, less dense lacunae around the postnatal age of P7-P14. Histological analysis of bone showed marked differences in frontal bone only. These findings provide a better understanding of the pathogenesis of Crouzon syndrome and will contribute to computational models that predict postoperative changes with the aim to improve surgical outcome.
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Affiliation(s)
- Sara Ajami
- UCL Great Ormond Street Institute of Child Health, University College London, London, UK
- Craniofacial Unit, Great Ormond Street Hospital, London, UK
| | - Zoe Van den Dam
- UCL Great Ormond Street Institute of Child Health, University College London, London, UK
| | - Julia Hut
- UCL Great Ormond Street Institute of Child Health, University College London, London, UK
| | - Dawn Savery
- UCL Great Ormond Street Institute of Child Health, University College London, London, UK
| | - Milton Chin
- UCL Great Ormond Street Institute of Child Health, University College London, London, UK
- Oral and Maxillofacial Department, Erasmus MC, Rotterdam, The Netherlands
| | - Maarten Koudstaal
- Oral and Maxillofacial Department, Erasmus MC, Rotterdam, The Netherlands
| | - Miranda Steacy
- UCL Great Ormond Street Institute of Child Health, University College London, London, UK
| | - Alessandra Carriero
- Department of Biomedical Engineering, The City College of New York, New York, NY, USA
| | - Andrew Pitsillides
- Comparative Biomedical Sciences, The Royal Veterinary College, Royal College Street, London, UK
| | - Y-M Chang
- Comparative Biomedical Sciences, The Royal Veterinary College, Royal College Street, London, UK
| | - Christoph Rau
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK
| | | | - David Dunaway
- UCL Great Ormond Street Institute of Child Health, University College London, London, UK
- Craniofacial Unit, Great Ormond Street Hospital, London, UK
| | - Noor Ul Owase Jeelani
- UCL Great Ormond Street Institute of Child Health, University College London, London, UK
- Craniofacial Unit, Great Ormond Street Hospital, London, UK
| | - Silvia Schievano
- UCL Great Ormond Street Institute of Child Health, University College London, London, UK
- Craniofacial Unit, Great Ormond Street Hospital, London, UK
| | - Erwin Pauws
- UCL Great Ormond Street Institute of Child Health, University College London, London, UK
| | - Alessandro Borghi
- UCL Great Ormond Street Institute of Child Health, University College London, London, UK
- Craniofacial Unit, Great Ormond Street Hospital, London, UK
- Department of Engineering, Durham University, Durham, UK
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Vom Scheidt A, Krug J, Goggin P, Bakker AD, Busse B. 2D vs. 3D Evaluation of Osteocyte Lacunae - Methodological Approaches, Recommended Parameters, and Challenges: A Narrative Review by the European Calcified Tissue Society (ECTS). Curr Osteoporos Rep 2024; 22:396-415. [PMID: 38980532 PMCID: PMC11324773 DOI: 10.1007/s11914-024-00877-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 06/11/2024] [Indexed: 07/10/2024]
Abstract
PURPOSE OF REVIEW Quantification of the morphology of osteocyte lacunae has become a powerful tool to investigate bone metabolism, pathologies and aging. This review will provide a brief overview of 2D and 3D imaging methods for the determination of lacunar shape, orientation, density, and volume. Deviations between 2D-based and 3D-based lacunar volume estimations are often not sufficiently addressed and may give rise to contradictory findings. Thus, the systematic error arising from 2D-based estimations of lacunar volume will be discussed, and an alternative calculation proposed. Further, standardized morphological parameters and best practices for sampling and segmentation are suggested. RECENT FINDINGS We quantified the errors in reported estimation methods of lacunar volume based on 2D cross-sections, which increase with variations in lacunar orientation and histological cutting plane. The estimations of lacunar volume based on common practice in 2D imaging methods resulted in an underestimation of lacunar volume of up to 85% compared to actual lacunar volume in an artificial dataset. For a representative estimation of lacunar size and morphology based on 2D images, at least 400 lacunae should be assessed per sample.
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Affiliation(s)
- Annika Vom Scheidt
- Division of Macroscopic and Clinical Anatomy, Gottfried Schatz Research Center, Medical University of Graz, Auenbruggerplatz 25, Graz, 8036, Austria.
| | - Johannes Krug
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 55a, 22529, Hamburg, Germany
- Interdisciplinary Competence Center for Interface Research, University Medical Center Hamburg-Eppendorf, Butenfeld 34, 22529, Hamburg, Germany
| | - Patricia Goggin
- Biomedical Imaging Unit, Laboratory and Pathology Block, University of Southampton, Southampton General Hospital, Tremona Road, Southampton, SO16 6YD, UK
| | - Astrid Diana Bakker
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), Amsterdam Movement Sciences, University of Amsterdam and Vrije Universiteit Amsterdam, Gustav Mahlerlaan, Amsterdam, 3004, 1081 LA, The Netherlands
| | - Björn Busse
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 55a, 22529, Hamburg, Germany
- Interdisciplinary Competence Center for Interface Research, University Medical Center Hamburg-Eppendorf, Butenfeld 34, 22529, Hamburg, Germany
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5
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Silveira A, Greving I, Longo E, Scheel M, Weitkamp T, Fleck C, Shahar R, Zaslansky P. Deep learning to overcome Zernike phase-contrast nanoCT artifacts for automated micro-nano porosity segmentation in bone. JOURNAL OF SYNCHROTRON RADIATION 2024; 31:136-149. [PMID: 38095668 PMCID: PMC10833422 DOI: 10.1107/s1600577523009852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 11/13/2023] [Indexed: 01/09/2024]
Abstract
Bone material contains a hierarchical network of micro- and nano-cavities and channels, known as the lacuna-canalicular network (LCN), that is thought to play an important role in mechanobiology and turnover. The LCN comprises micrometer-sized lacunae, voids that house osteocytes, and submicrometer-sized canaliculi that connect bone cells. Characterization of this network in three dimensions is crucial for many bone studies. To quantify X-ray Zernike phase-contrast nanotomography data, deep learning is used to isolate and assess porosity in artifact-laden tomographies of zebrafish bones. A technical solution is proposed to overcome the halo and shade-off domains in order to reliably obtain the distribution and morphology of the LCN in the tomographic data. Convolutional neural network (CNN) models are utilized with increasing numbers of images, repeatedly validated by `error loss' and `accuracy' metrics. U-Net and Sensor3D CNN models were trained on data obtained from two different synchrotron Zernike phase-contrast transmission X-ray microscopes, the ANATOMIX beamline at SOLEIL (Paris, France) and the P05 beamline at PETRA III (Hamburg, Germany). The Sensor3D CNN model with a smaller batch size of 32 and a training data size of 70 images showed the best performance (accuracy 0.983 and error loss 0.032). The analysis procedures, validated by comparison with human-identified ground-truth images, correctly identified the voids within the bone matrix. This proposed approach may have further application to classify structures in volumetric images that contain non-linear artifacts that degrade image quality and hinder feature identification.
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Affiliation(s)
- Andreia Silveira
- Department for Restorative, Preventive and Pediatric Dentistry, Charité-Universitaetsmedizin, Berlin, Germany
| | - Imke Greving
- Institute of Materials Physics, Helmholtz-Zentrum Hereon, Geesthacht, Germany
| | - Elena Longo
- Elettra – Sincrotrone Trieste SCpA, Basovizza, Trieste, Italy
| | | | | | - Claudia Fleck
- Fachgebiet Werkstofftechnik / Chair of Materials Science and Engineering, Institute of Materials Science and Technology, Faculty III Process Sciences, Technische Universität Berlin, Berlin, Germany
| | - Ron Shahar
- Koret School of Veterinary Medicine, The Robert H. Smith Faculty of Agriculture, Food and Environmental Sciences, Hebrew University of Jerusalem, Rehovot, Israel
| | - Paul Zaslansky
- Department for Restorative, Preventive and Pediatric Dentistry, Charité-Universitaetsmedizin, Berlin, Germany
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Liu Y, Pu X, Duan M, Chen C, Zhao Y, Zhang D, Xie J. Biomimetic Fibers Derived from an Equidistant Micropillar Platform Dictate Osteocyte Fate via Mechanoreception. NANO LETTERS 2023; 23:7950-7960. [PMID: 37418659 DOI: 10.1021/acs.nanolett.3c01739] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/09/2023]
Abstract
It is a big challenge to design a biomimetic physical microenvironment with greater similarity to in vivo tissue to observe real cell behaviors. We established a novel cell culture platform based on patterned equidistant micropillars with stiff and soft stiffnesses to mimic the changes that happened in the transition from normal to osteoporotic disease. We first demonstrated that the soft micropillar substrate decreased osteocyte synaptogenesis through synaptogyrin 1 and that this decrease was accompanied by impairment of cell mechanoperception and a decrease in cellular cytoskeletal rearrangement. We then found that the soft equidistant micropillar substrate reduced the osteocyte synaptogenesis mainly via the inactivation of Erk/MAPK signaling. We finally found that soft micropillar substrate-mediated synaptogenesis impacted the cell-to-cell communication and matrix mineralization of osteocytes. Taken together, this study provides evidence of cellular mechanical responses that are much more similar to those of real osteocytes at the bone tissue level.
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Affiliation(s)
- Yang Liu
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610044, China
| | - Xiaohua Pu
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610044, China
| | - Mengmeng Duan
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610044, China
| | - Cheng Chen
- College of Medical Informatics, Chongqing Medical University, Chongqing 400016, China
| | - Yanfang Zhao
- Department of Pediatric Dentistry, School of Dentistry, The University of Alabama at Birmingham, 1919 7th Ave. S, Birmingham, Alabama 35233, United States
| | - Demao Zhang
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610044, China
- Institute of Biomedical Engineering, West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu 610041, China
| | - Jing Xie
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610044, China
- National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610044, China
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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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Meslier QA, Shefelbine SJ. Using Finite Element Modeling in Bone Mechanoadaptation. Curr Osteoporos Rep 2023; 21:105-116. [PMID: 36808071 PMCID: PMC10105683 DOI: 10.1007/s11914-023-00776-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 01/18/2023] [Indexed: 02/21/2023]
Abstract
PURPOSE OF THE REVIEW Bone adapts structure and material properties in response to its mechanical environment, a process called mechanoadpatation. For the past 50 years, finite element modeling has been used to investigate the relationships between bone geometry, material properties, and mechanical loading conditions. This review examines how we use finite element modeling in the context of bone mechanoadpatation. RECENT FINDINGS Finite element models estimate complex mechanical stimuli at the tissue and cellular levels, help explain experimental results, and inform the design of loading protocols and prosthetics. FE modeling is a powerful tool to study bone adaptation as it complements experimental approaches. Before using FE models, researchers should determine whether simulation results will provide complementary information to experimental or clinical observations and should establish the level of complexity required. As imaging technics and computational capacity continue increasing, we expect FE models to help in designing treatments of bone pathologies that take advantage of mechanoadaptation of bone.
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Affiliation(s)
- Quentin A Meslier
- Department of Bioengineering, Northeastern University, 334 Snell, 360 Huntington Ave, Boston, MA, USA
| | - Sandra J Shefelbine
- Department of Bioengineering, Northeastern University, 334 Snell, 360 Huntington Ave, Boston, MA, USA.
- Department of Mechanical and Industrial Engineering, Northeastern University, 334 Snell, 360 Huntington Ave, Boston, MA, USA.
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Yang KG, Goff E, Cheng KL, Kuhn GA, Wang Y, Cheng JCY, Qiu Y, Müller R, Lee WYW. Abnormal morphological features of osteocyte lacunae in adolescent idiopathic scoliosis: A large-scale assessment by ultra-high-resolution micro-computed tomography. Bone 2023; 166:116594. [PMID: 36341948 DOI: 10.1016/j.bone.2022.116594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 10/10/2022] [Accepted: 10/13/2022] [Indexed: 11/18/2022]
Abstract
AIM Abnormal osteocyte lacunar morphology in adolescent idiopathic scoliosis (AIS) has been reported while the results were limited by the number of osteocyte lacunae being quantified. The present study aimed to validate previous findings through (a) comparing morphological features of osteocyte lacunae between AIS patients and controls in spine and ilium using a large-scale assessment, and (b) investigating whether there is an association between the acquired morphological features of osteocyte lacunae and disease severity in AIS. METHOD Trabecular bone tissue of the facet joint of human vertebrae on both concave and convex sides at the apex of the scoliotic curve were collected from 4 AIS and 5 congenital scoliosis (CS) patients, and also at the same anatomic site from 3 non-scoliosis (NS) subjects intraoperatively. Trabecular bone tissue from ilium was obtained from 12 AIS vs 9 NS subjects during surgery. Osteocyte lacunae were assessed using ultra-high-resolution micro-computed tomography. Clinical information such as age, body mass index (BMI) and radiological Cobb angle of the major curve were collected. RESULTS There was no significant difference between density of osteocyte lacuna and bone volume fraction (BV/TV) between groups. A total of 230,076 and 78,758 osteocyte lacunae from facet joints of apical vertebra of scoliotic curve and iliac bone were included in the analysis, respectively. In facet joint bone biopsies, lacunar stretch (Lc.St) was higher, and lacunar equancy (Lc.Eq), lacunar oblateness (Lc.Ob), and lacunar sphericity (Lc.Sr) were lower in AIS and CS groups when compared with NS group. CA side was associated with higher Lc.St when compared with CX side. In iliac bone biopsies, Lc.Ob was higher and lacunar surface area (Lc.S) was lower in AIS group than NS group. Median values of Lc.St, Lc.Eq and Lc.Sr were significantly associated with radiological Cobb angle with adjustment for age and BMI (R-squared: 0.576, 0.558 and 0.543, respectively). CONCLUSIONS This large-scale assessment of osteocyte lacunae confirms that AIS osteocyte lacunae are more oblate in iliac bone that is less influenced by asymmetric loading of the deformed spine than the vertebrae. Shape of osteocyte lacunae in iliac bone is associated with radiological Cobb angle of the major curve in AIS patients, suggesting the likelihood of systemic abnormal osteocyte morphology in AIS. Osteocyte lacunae from concave side of scoliotic curves were more stretched in both AIS and CS groups, which is likely secondary to asymmetric mechanical loading.
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Affiliation(s)
- Kenneth Guangpu Yang
- SH Ho Scoliosis Research Laboratory, Joint Scoliosis Research Centre of the Chinese University of Hong Kong and Nanjing University Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong, Hong Kong, China; Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Elliott Goff
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
| | - Ka-Lo Cheng
- SH Ho Scoliosis Research Laboratory, Joint Scoliosis Research Centre of the Chinese University of Hong Kong and Nanjing University Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong, Hong Kong, China
| | - Gisela A Kuhn
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
| | - Yujia Wang
- SH Ho Scoliosis Research Laboratory, Joint Scoliosis Research Centre of the Chinese University of Hong Kong and Nanjing University Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong, Hong Kong, China; Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Jack Chun-Yiu Cheng
- SH Ho Scoliosis Research Laboratory, Joint Scoliosis Research Centre of the Chinese University of Hong Kong and Nanjing University Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong, Hong Kong, China
| | - Yong Qiu
- SH Ho Scoliosis Research Laboratory, Joint Scoliosis Research Centre of the Chinese University of Hong Kong and Nanjing University Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong, Hong Kong, China; Spine Surgery, Nanjing Drum Tower Hospital, Nanjing University, Nanjing, China
| | - Ralph Müller
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland.
| | - Wayne Yuk-Wai Lee
- SH Ho Scoliosis Research Laboratory, Joint Scoliosis Research Centre of the Chinese University of Hong Kong and Nanjing University Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong, Hong Kong, China; Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong, China.
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10
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Buccino F, Aiazzi I, Casto A, Liu B, Sbarra MC, Ziarelli G, Banfi G, Vergani LM. The synergy of synchrotron imaging and convolutional neural networks towards the detection of human micro-scale bone architecture and damage. J Mech Behav Biomed Mater 2023; 137:105576. [PMID: 36413863 DOI: 10.1016/j.jmbbm.2022.105576] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 06/20/2022] [Accepted: 11/15/2022] [Indexed: 11/19/2022]
Abstract
The growing health and economic burden of bone fractures, their intricate multiscale features and the existing knowledge gaps in the comprehension of micro-scale bone damage occurrence make fracture diagnosis a challenging issue. In this scenario, deep-learning and artificial intelligence embody the new frontier of healthcare system, by overcoming the subjectivity of clinicians in the analysis of medical images. However, the preliminary attempts in exploiting the power of machine learning algorithms such as neural networks are still limited to bone macro-scale, while there is an evident lack in their application to smaller scales, where damage starts nucleating. Currently, speculations at the micro-scale are only feasible with the aid of high-resolution imaging techniques, that are particularly time consuming in terms of output images analysis. In this context, this works aims at combining the visualization of the micro-crack propagation mechanism with the promising application of convolutional neural networks. The implemented artificial intelligence tool is based for the first time on a large number of human synchrotron images coming from healthy and osteoporotic femoral heads tested under micro-compression. The designed convolutional neural networks are able to automatically detect lacunae and micro-cracks at different compression levels with high accuracy levels; indeed, with the baseline setup, networks achieve more than 0.99 level of accuracy for both cracks and lacunae, and more than 0.87 of the meanIoU adopted as validation metric. This approach is particularly encouraging for the development of powerful recognition system to comprehend bone micro-damage initiation and propagation, paving the way to the application of machine learning studies to bone micromechanics. This could be additionally crucial for future patient specific micro-scale observations to be related to the clinical practice.
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Affiliation(s)
- Federica Buccino
- Department of Mechanical Engineering, Politecnico di Milano, Italy
| | - Irene Aiazzi
- Department of Mechanical Engineering, Politecnico di Milano, Italy
| | - Alessandro Casto
- Department of Mechanical Engineering, Politecnico di Milano, Italy
| | - Bingqi Liu
- Department of Mechanical Engineering, Politecnico di Milano, Italy
| | | | - Giovanni Ziarelli
- Department of Mathematical Engineering, Politecnico di Milano, Italy
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11
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Qian W, Schmidt R, Turner JA, Bare SP, Lappe JM, Recker RR, Akhter MP. A pilot study on the nanoscale properties of bone tissue near lacunae in fracturing women. Bone Rep 2022; 17:101604. [PMID: 35874169 PMCID: PMC9304727 DOI: 10.1016/j.bonr.2022.101604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 07/09/2022] [Accepted: 07/12/2022] [Indexed: 11/17/2022] Open
Abstract
The goal of this study is to investigate the causes of osteoporosis-related skeletal fragility in postmenopausal women. We hypothesize that bone fragility in these individuals is largely due to mineral, and/or intrinsic material properties in the osteocyte lacunar/peri-lacunar regions of bone tissue. Innovative measurements with nanoscale resolution, including scanning electron microscope (SEM), an atomic force microscope that is integrated with infrared spectroscopy (AFM-IR), and nanoindentation, were used to characterize osteocyte lacunar and peri-lacunar properties in bone biopsies from fracturing (Cases) and matched (Age, BMD), non-fracturing (Controls) postmenopausal healthy women. In the peri-lacunar space, the nanoindentation results show that the modulus and hardness of the Controls are lower than the Cases. The AFM-IR results conclusively show that the mineral matrix, maturity (peak) (except in outer/far regions in Controls) were greater in Controls than in Cases. Furthermore, these results indicate that while mineral-to-matrix area ratio tend to be greater, the mineral maturity and crystallinity peak ratio "near" lacunae is greater than at regions "far" or more distance from lacunae in the Controls only. Due to the heterogeneity of bone structure, additional measurements are needed to provide more convincing evidence of altered lacunar characteristics and changes in the peri-lacunar bone as mechanisms related to postmenopausal women and fragility. Such findings would motivate new osteocyte-targeted treatments to reduce fragility fracture risks in these groups.
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Affiliation(s)
- Wen Qian
- Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588-0526, United States of America
| | - Roman Schmidt
- Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588-0526, United States of America
| | - Joseph A. Turner
- Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588-0526, United States of America
| | - Sue P. Bare
- Osteoporosis Research Center, Creighton University School of Medicine, Omaha, NE 68178, United States of America
| | - Joan M. Lappe
- Osteoporosis Research Center, Creighton University School of Medicine, Omaha, NE 68178, United States of America
| | - Robert R. Recker
- Osteoporosis Research Center, Creighton University School of Medicine, Omaha, NE 68178, United States of America
| | - Mohammed P. Akhter
- Osteoporosis Research Center, Creighton University School of Medicine, Omaha, NE 68178, United States of America
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12
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Soldati E, Roseren F, Guenoun D, Mancini L, Catelli E, Prati S, Sciutto G, Vicente J, Iotti S, Bendahan D, Malucelli E, Pithioux M. Multiscale Femoral Neck Imaging and Multimodal Trabeculae Quality Characterization in an Osteoporotic Bone Sample. MATERIALS (BASEL, SWITZERLAND) 2022; 15:8048. [PMID: 36431532 PMCID: PMC9694313 DOI: 10.3390/ma15228048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 11/05/2022] [Accepted: 11/09/2022] [Indexed: 06/16/2023]
Abstract
Although multiple structural, mechanical, and molecular factors are definitely involved in osteoporosis, the assessment of subregional bone mineral density remains the most commonly used diagnostic index. In this study, we characterized bone quality in the femoral neck of one osteoporotic patients as compared to an age-matched control subject, and so used a multiscale and multimodal approach including X-ray computed microtomography at different spatial resolutions (pixel size: 51.0, 4.95 and 0.9 µm), microindentation and Fourier transform infrared spectroscopy. Our results showed abnormalities in the osteocytes lacunae volume (358.08 ± 165.00 for the osteoporotic sample vs. 287.10 ± 160.00 for the control), whereas a statistical difference was found neither for shape nor for density. The osteoporotic femoral head and great trochanter reported reduced elastic modulus (Es) and hardness (H) compared to the control reference (−48% (p < 0.0001) and −34% (p < 0.0001), respectively for Es and H in the femoral head and −29% (p < 0.01) and −22% (p < 0.05), respectively for Es and H in the great trochanter), whereas the corresponding values in the femoral neck were in the same range. The spectral analysis could distinguish neither subregional differences in the osteoporotic sample nor between the osteoporotic and healthy samples. Although, infrared spectroscopic measurements were comparable among subregions, and so regardless of the bone osteoporotic status, the trabecular mechanical properties were comparable only in the femoral neck. These results illustrate that bone remodeling in osteoporosis is a non-uniform process with different rates in different bone anatomical regions, hence showing the interest of a clear analysis of the bone microarchitecture in the case of patients’ osteoporotic evaluation.
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Affiliation(s)
- Enrico Soldati
- Aix Marseille University, CNRS, IUSTI, 13453 Marseille, France
- Aix Marseille University, CNRS, CRMBM, 13385 Marseille, France
- Aix Marseille University, CNRS, ISM, 13288 Marseille, France
| | - Flavy Roseren
- Aix Marseille University, CNRS, ISM, 13288 Marseille, France
| | - Daphne Guenoun
- Aix Marseille University, CNRS, ISM, 13288 Marseille, France
- Aix Marseille University, APHM, CNRS, ISM, Sainte Marguerite Hospital, Institute for Locomotion, Department of Radiology, 13274 Marseille, France
| | - Lucia Mancini
- Elettra-Sincrotrone Trieste S.C.p.A, SS 14–km 1535 in Area Science Park, Basovizza, 34149 Trieste, Italy
- Slovenian National Building and Civil Engineering Institute, Dimičeva ulica 12, 1000 Ljubljana, Slovenia
| | - Emilio Catelli
- University of Bologna, Department of Chemistry “G. Ciamician”, Ravenna Campus, Via Guaccimanni, 42, 48121 Ravenna, Italy
| | - Silvia Prati
- University of Bologna, Department of Chemistry “G. Ciamician”, Ravenna Campus, Via Guaccimanni, 42, 48121 Ravenna, Italy
| | - Giorgia Sciutto
- University of Bologna, Department of Chemistry “G. Ciamician”, Ravenna Campus, Via Guaccimanni, 42, 48121 Ravenna, Italy
| | - Jerome Vicente
- Aix Marseille University, CNRS, IUSTI, 13453 Marseille, France
| | - Stefano Iotti
- Università di Bologna, Department of Pharmacy and Biotechnology (FaBit), Via Zamboni 33, 40126 Bologna, Italy
- National Institute of Biostructures and Biosystems, Viale delle Medaglie d’Oro 305, 00136 Roma, Italy
| | - David Bendahan
- Aix Marseille University, CNRS, CRMBM, 13385 Marseille, France
| | - Emil Malucelli
- Università di Bologna, Department of Pharmacy and Biotechnology (FaBit), Via Zamboni 33, 40126 Bologna, Italy
| | - Martine Pithioux
- Aix Marseille University, CNRS, ISM, 13288 Marseille, France
- Aix Marseille University, APHM, CNRS, ISM, Sainte-Marguerite Hospital, Institute for Locomotion, Department of Orthopaedics and Traumatology, 13274 Marseille, France
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13
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Allison H, O'Sullivan L, McNamara L. Temporal changes in cortical microporosity during estrogen deficiency associated with perilacunar resorption and osteocyte apoptosis: A pilot study. Bone Rep 2022; 16:101590. [PMID: 35663377 PMCID: PMC9156983 DOI: 10.1016/j.bonr.2022.101590] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 05/13/2022] [Accepted: 05/14/2022] [Indexed: 02/07/2023] Open
Abstract
Osteocytes can actively regulate bone microporosity, through either perilacunar resorption or micropetrosis following apoptosis. Osteocyte apoptosis is more prevalent in estrogen deficiency and changes in the lacunar-canalicular network of osteocytes have been reported. Temporal changes in bone mineralisation and osteocytes cellular strains occur, which might be associated with osteocyte-driven microporosity changes, although time dependant changes in bone microporosity are not yet fully understood. In this pilot study we conducted micro-CT analysis, backscatter electron imaging and histological analysis of femoral cortical bone form an ovariectomized rat model of osteoporosis to investigate whether estrogen deficiency causes temporal changes in lacunar and vascular porosity. We also assessed MMP14 expression, lacunar occupancy and mineral infilling, as indicators of perilacunar resorption and micropetrosis. We report temporal changes in cortical microporosity in estrogen deficiency. Specifically, canalicular and vascular porosity initially increased (4 weeks post-OVX), coinciding with the period of rapid bone loss, whereas in the longer term (14 weeks post-OVX) lacunar and canalicular diameter decreased. Interestingly, these changes coincided with an increased prevalence of empty lacunae and osteocyte lacunae were observed to be more circular with a mineralised border around the lacunar space. In addition we report an increase in MMP14+ osteocytes, which also suggests active matrix degradation by these cells. Together these results provide an insight into the temporal changes in cortical microporosity during estrogen deficiency and suggest the likelihood of occurrence of both perilacunar resorption and osteocyte apoptosis leading to micropetrosis. We propose that microporosity changes arise due to processes driven by distinct populations of osteocytes, which are either actively resorbing their matrix or have undergone apoptosis and are infilling lacunae by micropetrosis.
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Key Words
- BMDD, Bone mineral density distribution
- BSEM
- BSEM, Backscattered scanning electron microscopy
- BV, Bone volume
- Dm, Diameter
- Estrogen deficiency
- Lacunar
- Lc, Lacunar
- MMP, Matrix metalloproteases
- Micro-CT, Micro computed tomography
- Microporosity
- OVX, Ovariectomized
- PLR, Perilacunar resorption
- Sp, spacing
- TRAP, Tartrate-resistant acid phosphatase
- TV, Total volume
- Tb, Trabecular
- Th, Thickness
- V Ca, Vascular canal
- Vascular canals
- micro-CT
- με, Microstrain (ε ×10−6)
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Affiliation(s)
- H. Allison
- Mechanobiology and Medical Devices Research Group (MMDRG), Centre for Biomechanics Research (BioMEC), Biomedical Engineering, College of Science and Engineering, National University of Ireland Galway, Ireland
| | - L.M. O'Sullivan
- Mechanobiology and Medical Devices Research Group (MMDRG), Centre for Biomechanics Research (BioMEC), Biomedical Engineering, College of Science and Engineering, National University of Ireland Galway, Ireland
| | - L.M. McNamara
- Mechanobiology and Medical Devices Research Group (MMDRG), Centre for Biomechanics Research (BioMEC), Biomedical Engineering, College of Science and Engineering, National University of Ireland Galway, Ireland
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14
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von Kroge S, Stürznickel J, Bechler U, Stockhausen KE, Eissele J, Hubert J, Amling M, Beil FT, Busse B, Rolvien T. Impaired bone quality in the superolateral femoral neck occurs independent of hip geometry and bone mineral density. Acta Biomater 2022; 141:233-243. [PMID: 34999261 DOI: 10.1016/j.actbio.2022.01.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 12/30/2021] [Accepted: 01/03/2022] [Indexed: 11/01/2022]
Abstract
Skeletal adaptation is substantially influenced by mechanical loads. Osteocytes and their lacuno-canalicular network have been identified as a key player in load sensation and bone quality regulation. In the femoral neck, one of the most common fracture sites, a complex loading pattern with lower habitual loading in the superolateral neck and higher compressive stresses in the inferomedial neck is present. Variations in the femoral neck-shaft angle (NSA), i.e., coxa vara or coxa valga, provide the opportunity to examine the influence of loading patterns on bone quality. We obtained femoral neck specimens of 28 osteoarthritic human subjects with coxa vara, coxa norma and coxa valga during total hip arthroplasty. Bone mineral density (BMD) was assessed preoperatively by dual energy X-ray absorptiometry (DXA). Cortical and trabecular microstructure and three-dimensional osteocyte lacunar characteristics were assessed in the superolateral and inferomedial neck using ex vivo high resolution micro-computed tomography. Additionally, BMD distribution and osteocyte lacunar characteristics were analyzed by quantitative backscattered electron imaging (qBEI). All groups presented thicker inferomedial than superolateral cortices. Furthermore, the superolateral site exhibited a lower osteocyte lacunar density along with lower lacunar sphericity than the inferomedial site, independent of NSA. Importantly, BMD and corresponding T-scores correlated with microstructural parameters at the inferomedial but not superolateral neck. In conclusion, we provide micromorphological evidence for fracture vulnerability of the superolateral neck, which is independent of NSA and BMD. The presented bone qualitative data provide an explanation why DXA may be insufficient to predict a substantial proportion of femoral neck fractures. STATEMENT OF SIGNIFICANCE: The femoral neck, one of the most common fracture sites, is subject to a complex loading pattern. Site-specific differences (i.e., superolateral vs. inferomedial) in bone quality influence fracture risk, but it is unclear how this relates to hip geometry and bone mineral density (BMD) measurements in vivo. Here, we examine femoral neck specimens using a variety of high-resolution imaging techniques and demonstrate impaired bone quality in the superolateral compared to the inferomedial neck. Specifically, we found impaired cortical and trabecular microarchitecture, mineralization, and osteocyte properties, regardless of neck-shaft angle. Since BMD correlated with bone quality of the inferomedial but not the superolateral neck, our results illustrate why bone densitometry may not predict a substantial proportion of femoral neck fractures.
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15
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Shin KS, Men S, Wong A, Cobb-Bruno C, Chen EY, Fu D. Quantitative Chemical Imaging of Bone Tissue for Intraoperative and Diagnostic Applications. Anal Chem 2022; 94:3791-3799. [PMID: 35188370 PMCID: PMC8944199 DOI: 10.1021/acs.analchem.1c04354] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Bone is difficult to image using traditional histopathological methods, leading to challenges in intraoperative pathological evaluation that is critical in guiding surgical treatment, particularly in orthopedic oncology. In this study, we demonstrate that a multimodal quantitative imaging approach that combines stimulated Raman scattering (SRS) microscopy, two-photon fluorescence (TPF) microscopy, and second-harmonic generation (SHG) microscopy can provide useful diagnostic information regarding intact bone tissue fragments from surgical excision or biopsy specimens. We imaged bone samples from 17 patient cases and performed quantitative chemical and morphological analyses of both mineral and organic components of bone. Our main findings show that carbonate content combined with morphometric analysis of bone organic matrix can separate several major classes of bone cancer-associated diagnostic categories with an average accuracy of 92%. This proof-of-principle study demonstrates that quantitative multimodal imaging and machine learning-based analysis of bony tissue can provide crucial diagnostic information for guiding clinical decisions in orthopedic oncology. Moreover, the general methodology of morphological and chemical imaging combined with machine learning can be readily extended to other tissue types for tissue diagnosis in intraoperative and other clinical settings.
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Affiliation(s)
- Kseniya S Shin
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States.,School of Medicine, University of Washington, Seattle, Washington 98195, United States
| | - Shuaiqian Men
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Angel Wong
- Department of Bioengineering, University of Washington, Seattle, Washington 98195, United States
| | - Colburn Cobb-Bruno
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Eleanor Y Chen
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington 98195, United States
| | - Dan Fu
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
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16
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Aguirre JI, Castillo EJ, Kimmel DB. Biologic and pathologic aspects of osteocytes in the setting of medication-related osteonecrosis of the jaw (MRONJ). Bone 2021; 153:116168. [PMID: 34487892 PMCID: PMC8478908 DOI: 10.1016/j.bone.2021.116168] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 08/02/2021] [Accepted: 08/31/2021] [Indexed: 02/08/2023]
Abstract
Medication-related osteonecrosis of the jaw (MRONJ) is a potentially severe, debilitating condition affecting patients with cancer and patients with osteoporosis who have been treated with powerful antiresorptives (pARs) or angiogenesis inhibitors (AgIs). Oral risk factors associated with the development of MRONJ include tooth extraction and inflammatory dental disease (e.g., periodontitis, periapical infection). In bone tissues, osteocytes play a bidirectional role in which they not only act as the "receiver" of systemic signals from blood vessels, such as hormones and drugs, or local signals from the mineralized matrix as it is deformed, but they also play a critical role as "transmitter" of signals to the cells that execute bone modeling and remodeling (osteoclasts, osteoblasts and lining cells). When the survival capacity of osteocytes is overwhelmed, they can die. Osteocyte death has been associated with several pathological conditions. Whereas the causes and mechanisms of osteocyte death have been studied in conditions like osteonecrosis of the femoral head (ONFH), few studies of the causes and mechanisms of osteocyte death have been done in MRONJ. The three forms of cell death that affect most of the different cells in the body (apoptosis, autophagy, and necrosis) have been recognized in osteocytes. Notably, necroptosis, a form of regulated cell death with "a necrotic cell death phenotype," has also been identified as a form of cell death in osteocytes under certain pathologic conditions. Improving the understanding of osteocyte death in MRONJ may be critical for preventing disease and developing treatment approaches. In this review, we intend to provide insight into the biology of osteocytes, cell death, in general, and osteocyte death, in particular, and discuss hypothetical mechanisms involved in osteocyte death associated with MRONJ.
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Affiliation(s)
- J I Aguirre
- Department of Physiological Sciences, University of Florida (UF), Gainesville, FL, United States of America.
| | - E J Castillo
- Department of Physiological Sciences, University of Florida (UF), Gainesville, FL, United States of America.
| | - D B Kimmel
- Department of Physiological Sciences, University of Florida (UF), Gainesville, FL, United States of America
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17
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Goff E, Buccino F, Bregoli C, McKinley JP, Aeppli B, Recker RR, Shane E, Cohen A, Kuhn G, Müller R. Large-scale quantification of human osteocyte lacunar morphological biomarkers as assessed by ultra-high-resolution desktop micro-computed tomography. Bone 2021; 152:116094. [PMID: 34186251 DOI: 10.1016/j.bone.2021.116094] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 06/19/2021] [Accepted: 06/24/2021] [Indexed: 02/07/2023]
Abstract
Ultra-high-resolution imaging of the osteocyte lacuno-canalicular network (LCN) three-dimensionally (3D) in a high-throughput fashion has greatly improved the morphological knowledge about the constituent structures - positioning them as potential biomarkers. Technologies such as serial focused ion beam/scanning electron microscopy (FIB/SEM) and confocal scanning laser microscopy (CLSM) can image in extremely high resolution, yet only capture a small number of lacunae. Synchrotron radiation computed tomography (SR-CT) can image with both high resolution and high throughput but has a limited availability. Desktop micro-computed tomography (micro-CT) provides an attractive balance: high-throughput imaging on the micron level without the restrictions of SR-CT availability. In this study, accuracy, reproducibility, and sensitivity of large-scale quantification of human osteocyte lacunar morphometries were assessed by ultra-high-resolution desktop micro-computed tomography. For this purpose, thirty-one transiliac human bone biopsies containing trabecular and cortical regions were imaged using ultra-high-resolution desktop micro-CT at a nominal isotropic voxel resolution of 1.2 µm. The resulting 3D images were segmented, component labeled, and the following morphometric parameters of 7.71 million lacunae were measured: Lacunar number (Lc.N), density (Lc.N/BV), porosity (Lc.TV/BV), volume (Lc.V), surface area (Lc.S), surface area to volume ratio (Lc.S/Lc.V), stretch (Lc.St), oblateness (Lc.Ob), sphericity (Lc.Sr), equancy (Lc.Eq), and angle (Lc.θ). Accuracy was quantified by comparing automated lacunar identification to manual identification. Mean true positive rate (TPR), false positive rate (FPR), and false negative rate (FNR) were 89.0%, 3.4%, and 11.0%, respectively. Regarding the reproducibility of lacunar morphometry from repeated measurements, precision errors were low (0.2-3.0%) and intraclass correlation coefficients were high (0.960-0.999). Significant differences between cortical and trabecular regions (p<0.001) existed for Lc.N/BV, Lc.TV/BV, local lacunar surface area (<Lc.S>), and local lacunar volume (<Lc.V>), all of which demonstrate the sensitivity of the method and are possible biomarker candidates. This study provides the foundation required for future large-scale morphometric studies using ultra-high-resolution desktop micro-CT and high-throughput analysis of millions of osteocyte lacunae in human bone samples.
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Affiliation(s)
- Elliott Goff
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
| | | | - Chiara Bregoli
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
| | - Jonathan P McKinley
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland; Department of Mechanical Engineering, University of California Berkeley, Berkeley, CA, USA
| | - Basil Aeppli
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
| | - Robert R Recker
- Department of Medicine, Creighton University Medical Center, Omaha, NE, USA
| | - Elizabeth Shane
- Department of Medicine, Columbia University Vagelos College of Physicians & Surgeons, New York, NY, USA
| | - Adi Cohen
- Department of Medicine, Columbia University Vagelos College of Physicians & Surgeons, New York, NY, USA
| | - Gisela Kuhn
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
| | - Ralph Müller
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland.
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18
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Hemmatian H, Bakker AD, Klein-Nulend J, van Lenthe GH. Alterations in osteocyte lacunar morphology affect local bone tissue strains. J Mech Behav Biomed Mater 2021; 123:104730. [PMID: 34438250 DOI: 10.1016/j.jmbbm.2021.104730] [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] [Received: 02/05/2021] [Revised: 06/16/2021] [Accepted: 07/17/2021] [Indexed: 11/17/2022]
Abstract
Osteocytes are capable of remodeling their perilacunar bone matrix, which causes considerable variations in the shape and size of their lacunae. If these variations in lacunar morphology cause changes in the mechanical environment of the osteocytes, in particular local strains, they would subsequently affect bone mechanotransduction, since osteocytes are likely able to directly sense these strains. The purpose of this study is to quantify the effect of alterations in osteocyte lacunar morphology on peri-lacunar bone tissue strains. To this end, we related the actual lacunar shape in fibulae of six young-adult (5-month) and six old (23-month) mice, quantified by high-resolution micro-computed tomography, to microscopic strains, analyzed by micro-finite element modeling. We showed that peak effective strain increased by 12.6% in osteocyte cell bodies (OCYs), 9.6% in pericellular matrix (PCM), and 5.3% in extra cellular matrix (ECM) as the lacunae volume increased from 100-200 μm3 to 500-600 μm3. Lacunae with a larger deviation (>8°) in orientation from the longitudinal axis of the bone are exposed to 8% higher strains in OCYs, 6.5% in PCM, 4.2% in ECM than lacunae with a deviation in orientation below 8°. Moreover, increased lacuna sphericity from 0 to 0.5 to 0.7-1 led to 25%, 23%, and 13% decrease in maximum effective strains in OCYs, PCM, and ECM, respectively. We further showed that due to the presence of smaller and more round lacunae in old mice, local bone tissue strains are on average 5% lower in the vicinity of lacunae and their osteocytes of old mice compared to young. Understanding how changes in lacunar morphology affect the micromechanical environment of osteocytes presents a first step in unraveling their potential role in impaired bone mechanoresponsiveness with e.g. aging.
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Affiliation(s)
- Haniyeh Hemmatian
- Biomechanics Section, Department of Mechanical Engineering, KU Leuven, Leuven, Belgium; Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, the Netherlands; Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Astrid D Bakker
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, the Netherlands
| | - Jenneke Klein-Nulend
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, the Netherlands
| | - G Harry van Lenthe
- Biomechanics Section, Department of Mechanical Engineering, KU Leuven, Leuven, Belgium.
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19
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Jähn-Rickert K, Zimmermann EA. Potential Role of Perilacunar Remodeling in the Progression of Osteoporosis and Implications on Age-Related Decline in Fracture Resistance of Bone. Curr Osteoporos Rep 2021; 19:391-402. [PMID: 34117624 DOI: 10.1007/s11914-021-00686-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/22/2021] [Indexed: 12/21/2022]
Abstract
PURPOSE OF REVIEW We took an interdisciplinary view to examine the potential contribution of perilacunar/canalicular remodeling to declines in bone fracture resistance related to age or progression of osteoporosis. RECENT FINDINGS Perilacunar remodeling is most prominent as a result of lactation; recent advances further elucidate the molecular players involved and their effect on bone material properties. Of these, vitamin D and calcitonin could be active during aging or osteoporosis. Menopause-related hormonal changes or osteoporosis therapies affect bone material properties and mechanical behavior. However, investigations of lacunar size or osteocyte TRAP activity with age or osteoporosis do not provide clear evidence for or against perilacunar remodeling. While the occurrence and potential role of perilacunar remodeling in aging and osteoporosis progression are largely under-investigated, widespread changes in bone matrix composition in OVX models and following osteoporosis therapies imply osteocytic maintenance of bone matrix. Perilacunar remodeling-induced changes in bone porosity, bone matrix composition, and bone adaptation could have significant implications for bone fracture resistance.
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Affiliation(s)
- Katharina Jähn-Rickert
- Heisenberg Research Group, Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 55a, 22529, Hamburg, Germany.
- Mildred Scheel Cancer Career Center Hamburg, University Cancer Center Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
| | - Elizabeth A Zimmermann
- Faculty of Dentistry, McGill University, Strathcona Anatomy and Dentistry Building, 3640 Rue University, Montreal, Canada.
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Chang B, Liu X. Osteon: Structure, Turnover, and Regeneration. TISSUE ENGINEERING PART B-REVIEWS 2021; 28:261-278. [PMID: 33487116 DOI: 10.1089/ten.teb.2020.0322] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Bone is composed of dense and solid cortical bone and honeycomb-like trabecular bone. Although cortical bone provides the majority of mechanical strength for a bone, there are few studies focusing on cortical bone repair or regeneration. Osteons (the Haversian system) form structural and functional units of cortical bone. In recent years, emerging evidences have shown that the osteon structure (including osteocytes, lamellae, lacunocanalicular network, and Haversian canals) plays critical roles in bone mechanics and turnover. Therefore, reconstruction of the osteon structure is crucial for cortical bone regeneration. This article provides a systematic summary of recent advances in osteons, including the structure, function, turnover, and regenerative strategies. First, the hierarchical structure of osteons is illustrated and the critical functions of osteons in bone dynamics are introduced. Next, the modeling and remodeling processes of osteons at a cellular level and the turnover of osteons in response to mechanical loading and aging are emphasized. Furthermore, several bioengineering approaches that were recently developed to recapitulate the osteon structure are highlighted. Impact statement This review provides a comprehensive summary of recent advances in osteons, especially the roles in bone formation, remodeling, and regeneration. Besides introducing the hierarchical structure and critical functions of osteons, we elucidate the modeling and remodeling of osteons at a cellular level. Specifically, we highlight the bioengineering approaches that were recently developed to mimic the hierarchical structure of osteons. We expect that this review will provide informative insights and attract increasing attentions in orthopedic community, shedding light on cortical bone regeneration in the future.
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Affiliation(s)
- Bei Chang
- Department of Biomedical Sciences, Texas A&M University College of Dentistry, Dallas, Texas, USA
| | - Xiaohua Liu
- Department of Biomedical Sciences, Texas A&M University College of Dentistry, Dallas, Texas, USA
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21
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Finite element analysis on multi-toughening mechanism of microstructure of osteon. J Mech Behav Biomed Mater 2021; 117:104408. [PMID: 33657473 DOI: 10.1016/j.jmbbm.2021.104408] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 09/20/2020] [Accepted: 02/13/2021] [Indexed: 11/22/2022]
Abstract
The toughening mechanism of cortical bone is closely related to its hierarchical microstructure. Osteon is the most important microstructure of cortical bone. Therefore, it is very important to study the toughening mechanism of the microstructure of osteon. There are three main kinds of cracks in cortical bone: external crack of osteon, internal radial cracks of osteon and microporous damage cracks. Numerical models for these three kinds of cracks are established by XFEM and the progressive damage approach, respectively. The multi-toughening mechanisms of microstructure of osteon are found. The cement line on the outside of osteon is its first toughening mechanism, which can make the crack deflection and improve the fracture resistance of osteon. The resistance of cement line to fracture increases with the decrease of the strength and the increase of the thickness. The second toughening mechanism is elliptical osteocyte lacunae, which can attract the crack into the elliptical lacunae and cause stress redistribution to prevent the crack propagation. The annularly elliptical lacuna structure is an optimized arrangement and shape of microstructure, which is the third toughening mechanism of osteon. This microstructure can determine the location of the crack initiation and make the microcracks propagate along the annular direction rather than penetrating into the haversian cannal to protect the integrity of the osteon. The study of these toughening mechanisms provides new ideas for the research and design of synthetic composite structures.
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22
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Vahidi G, Rux C, Sherk VD, Heveran CM. Lacunar-canalicular bone remodeling: Impacts on bone quality and tools for assessment. Bone 2021; 143:115663. [PMID: 32987198 PMCID: PMC7769905 DOI: 10.1016/j.bone.2020.115663] [Citation(s) in RCA: 6] [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: 07/15/2020] [Revised: 09/23/2020] [Accepted: 09/23/2020] [Indexed: 01/06/2023]
Abstract
Osteocytes can resorb as well as replace bone adjacent to the expansive lacunar-canalicular system (LCS). Suppressed LCS remodeling decreases bone fracture toughness, but it is unclear how altered LCS remodeling impacts bone quality. The first goal of this review is to assess how LCS remodeling impacts LCS morphology as well as the composition and mechanical properties of surrounding bone tissue. The second goal is to compare tools available for the assessment of bone quality at length-scales that are physiologically-relevant to LCS remodeling. We find that changes to LCS morphology occur in response to a variety of physiological conditions and diseases and can be classified in two general phenotypes. In the 'aging phenotype', seen in aging and in some disuse models, the LCS is truncated and osteocytes apoptosis is increased. In the 'osteocytic osteolysis' phenotype, which is adaptive in some physiological settings and possibly maladaptive in others, the LCS enlarges and osteocytes generally maintain viability. Bone composition and mechanical properties vary near the osteocyte and change with at least some conditions that alter LCS morphology. However, few studies have evaluated bone composition and mechanical properties close to the LCS and so the impacts of LCS remodeling phenotypes on bone tissue quality are still undetermined. We summarize the current understanding of how LCS remodeling impacts LCS morphology, tissue-scale bone composition and mechanical properties, and whole-bone material properties. Tools are compared for assessing tissue-scale bone properties, as well as the resolution, advantages, and limitations of these techniques.
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Affiliation(s)
- G Vahidi
- Department of Mechanical & Industrial Engineering, Montana State University, United States of America
| | - C Rux
- Department of Mechanical & Industrial Engineering, Montana State University, United States of America
| | - V D Sherk
- Department of Orthopedics, University of Colorado Anschutz School of Medicine, United States of America
| | - C M Heveran
- Department of Mechanical & Industrial Engineering, Montana State University, United States of America.
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23
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Ferson ND, Uhl AM, Andrew JS. Piezoelectric and Magnetoelectric Scaffolds for Tissue Regeneration and Biomedicine: A Review. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2021; 68:229-241. [PMID: 32866097 DOI: 10.1109/tuffc.2020.3020283] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Electric fields are ubiquitous throughout the body, playing important role in a multitude of biological processes including osteo-regeneration, cell signaling, nerve regeneration, cardiac function, and DNA replication. An increased understanding of the role of electric fields in the body has led to the development of devices for biomedical applications that incorporate electromagnetic fields as an intrinsically novel functionality (e.g., bioactuators, biosensors, cardiac/neural electrodes, and tissues scaffolds). However, in the majority of the aforementioned devices, an implanted power supply is necessary for operation, and therefore requires highly invasive procedures. Thus, the ability to apply electric fields in a minimally invasive manner to remote areas of the body remains a critical and unmet need. Here, we report on the potential of magnetoelectric (ME)-based composites to overcome this challenge. ME materials are capable of producing localized electric fields in response to an applied magnetic field, which the body is permeable to. Yet, the use of ME materials for biomedical applications is just beginning to be explored. Here, we present on the potential of ME materials to be utilized in biomedical applications. This will be presented alongside current state-of-the-art for in vitro and in vivo electrical stimulation of cells and tissues. We will discuss key findings in the field, while also identifying challenges, such as the synthesis and characterization of biocompatible ME materials, challenges in experimental design, and opportunities for future research that would lead to the increased development of ME biomaterials and their applications.
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24
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Shipov A, Zaslansky P, Riesemeier H, Segev G, Atkins A, Kalish-Achrai N, Weiner S, Shahar R. The influence of estrogen deficiency on the structural and mechanical properties of rat cortical bone. PeerJ 2021; 9:e10213. [PMID: 33520431 PMCID: PMC7811283 DOI: 10.7717/peerj.10213] [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] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 09/28/2020] [Indexed: 11/20/2022] Open
Abstract
Background Post-menopausal osteoporosis is a common health problem worldwide, most commonly caused by estrogen deficiency. Most of the information regarding the skeletal effects of this disease relates to trabecular bone, while cortical bone is less studied. The purpose of this study was to evaluate the influence of estrogen deficiency on the structure and mechanical properties of cortical bone. Methods Eight ovariectomized (OVH) and eight intact (control) Sprague Dawley rats were used.Structural features of femoral cortical bone were studied by light microscopy, scanning electron microscopy and synchrotron-based microcomputer-tomography and their mechanical properties determined by nano-indentation. Results Cortical bone of both study groups contains two distinct regions: organized circumferential lamellae and disordered bone with highly mineralized cartilaginous islands. Lacunar volume was lower in the OVH group both in the lamellar and disorganized regions (182 ± 75 µm3 vs 232 ± 106 µm3, P < 0.001 and 195 ± 86 µm3 vs. 247 ± 106 µm3, P < 0.001, respectively). Lacunar density was also lower in both bone regions of the OVH group (40 ± 18 ×103 lacunae/mm3 vs. 47 ± 9×103 lacunae/mm3 in the lamellar region, P = 0.003 and 63 ± 18×103lacunae/mm3 vs. 75 ± 13×103 lacunae/mm3 in the disorganized region, P < 0.001). Vascular canal volume was lower in the disorganized region of the bone in the OVH group compared to the same region in the control group (P < 0.001). Indentation moduli were not different between the study groups in both bone regions. Discussion Changes to cortical bone associated with estrogen deficiency in rats require high-resolution methods for detection. Caution is required in the application of these results to humans due to major structural differences between human and rat bone.
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Affiliation(s)
- Anna Shipov
- Koret School of Veterinary Medicine, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Paul Zaslansky
- Department for Operative and Preventive Dentistry. Centrum für Zahn-, Mund- und Kieferheilkunde, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | | | - Gilad Segev
- Koret School of Veterinary Medicine, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Ayelet Atkins
- Department of Chemistry and Bar Ilan Institute of Nanotechnology and Advanced Materials (BINA), Bar-Ilan University, Ramat Gan, Israel
| | - Noga Kalish-Achrai
- Koret School of Veterinary Medicine, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Stephen Weiner
- Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Ron Shahar
- Koret School of Veterinary Medicine, The Hebrew University of Jerusalem, Rehovot, Israel
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25
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Gohin S, Javaheri B, Hopkinson M, Pitsillides AA, Arnett TR, Chenu C. Applied mechanical loading to mouse hindlimb acutely increases skeletal perfusion and chronically enhanced vascular porosity. J Appl Physiol (1985) 2020; 128:838-846. [PMID: 32163331 DOI: 10.1152/japplphysiol.00416.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Blood supply is essential for osteogenesis, yet its relationship to load-related increases in bone mass is poorly defined. Herein, we aim to investigate the link between load-induced osteogenesis and the blood supply (bone perfusion and vascular porosity) using an established osteogenic noninvasive model of axial loading. Accordingly, 12 N mechanical loads were applied to the right tibiae of six male C57BL6 mice at 10-12 wk of age, 3 times/wk for 2 wk. Skeletal perfusion was measured acutely (postloading) and chronically in loaded and contralateral, nonloaded hindlimbs by laser-Doppler imaging. Vascular and lacunar porosity of the cortical bone and tibia load-related changes in trabecular and cortical bone was measured by nanoCT and micro-CT, respectively. We found that the mean skeletal perfusion (loaded: nonloaded limb ratio) increased by 56% immediately following the first loading episode (vs. baseline, P < 0.01), and a similar increase was observed after all loading episodes, demonstrating that these acute responses were conserved for 2 wk of loading. Loading failed, however, to engender any significant chronic changes in mean perfusion between the beginning and the end of the experiment. In contrast, 2 wk of loading engendered an increased vascular canal number in the tibial cortical compartment (midshaft) and, as expected, also increased trabecular and cortical bone volumes and modified tibial architecture in the loaded limb. Our results indicate that each episode of loading both generates acute enhancement in skeletal blood perfusion and also stimulates chronic vascular architectural changes in the bone cortices, which coincide with load-induced increases in bone mass.NEW & NOTEWORTHY This study investigated modifications to the blood supply (bone perfusion and intracortical vascular canals) in mechanoadaptive responses in C57BL6 mice. Each episode of mechanical loading acutely increases skeletal perfusion. Two weeks of mechanical loading increased bone mass and cortical vascular canal number, while there was no chronic increase in hindlimb perfusion. Our findings suggest that the blood supply may participate in the processes that govern load-induced bone formation.
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Affiliation(s)
- Stephanie Gohin
- Department of Comparative Biomedical Sciences, Royal Veterinary College, London, United Kingdom
| | - Behzad Javaheri
- Department of Comparative Biomedical Sciences, Royal Veterinary College, London, United Kingdom
| | - Mark Hopkinson
- Department of Comparative Biomedical Sciences, Royal Veterinary College, London, United Kingdom
| | | | - Timothy R Arnett
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Chantal Chenu
- Department of Comparative Biomedical Sciences, Royal Veterinary College, London, United Kingdom
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26
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Loundagin LL, Haider IT, Cooper DM, Edwards WB. Association between intracortical microarchitecture and the compressive fatigue life of human bone: A pilot study. Bone Rep 2020; 12:100254. [PMID: 32258250 PMCID: PMC7110329 DOI: 10.1016/j.bonr.2020.100254] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 02/26/2020] [Accepted: 03/02/2020] [Indexed: 11/18/2022] Open
Abstract
Many mechanical properties of cortical bone are largely governed by the underlying microarchitecture; however, the influence of microarchitecture on the fatigue life of bone is poorly understood. Furthermore, imaging-based studies investigating intracortical microarchitecture may expose bone samples to large doses of radiation that may compromise fatigue resistance. The purpose of this pilot study was to 1) investigate the relationship between intracortical microarchitecture and the fatigue life of human bone in compression and 2) examine the effects of synchrotron irradiation on fatigue life measurements. Cortical samples were prepared from the femoral and tibial shafts of three cadaveric donors. A subset of samples was imaged using synchrotron X-ray microCT to quantify microarchitecture, including porosity, canal diameter, lacunar density, lacunar volume, and lacunar orientation. A second group of control samples was not imaged and used only for mechanical testing. Fatigue life was quantified by cyclically loading both groups in zero-compression until failure. Increased porosity and larger canal diameter were both logarithmically related to a shorter fatigue life, whereas lacunar density demonstrated a positive linear relationship with fatigue life (r2 = 45–73%, depending on measure). Irradiation from microCT scanning reduced fatigue life measurements by 91%, but relationships with microarchitecture measurements remained. Additional research is needed to support the findings of this pilot study and fully establish the relationship between intracortical microarchitecture and the compressive fatigue life of bone. Increased porosity and larger canal diameters were associated with a shorter compressive fatigue life. A higher lacunar density was related to a longer compressive fatigue life. Irradiation from synchrotron X-ray microCT scanning reduced fatigue life by 91%. The influence of microarchitecture on fatigue life exhibited similar trends for both irradiated and non-irradiated bone.
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Affiliation(s)
- Lindsay L. Loundagin
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada
- McCaig Institute for Bone and Joint Health, University of Calgary, 3280 Hospital Dr NW, Calgary, AB T2N 4Z6, Canada
- Corresponding author at: Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada.
| | - Ifaz T. Haider
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada
- McCaig Institute for Bone and Joint Health, University of Calgary, 3280 Hospital Dr NW, Calgary, AB T2N 4Z6, Canada
| | - David M.L. Cooper
- Department of Anatomy, Physiology and Pharmacology, University of Saskatchewan, 105 Administration Place, Saskatoon, SK S7N 5A2, Canada
| | - W. Brent Edwards
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada
- McCaig Institute for Bone and Joint Health, University of Calgary, 3280 Hospital Dr NW, Calgary, AB T2N 4Z6, Canada
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27
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Iezzi G, Mangano C, Barone A, Tirone F, Baggi L, Tromba G, Piattelli A, Giuliani A. Jawbone remodeling: a conceptual study based on Synchrotron High-resolution Tomography. Sci Rep 2020; 10:3777. [PMID: 32123216 PMCID: PMC7052147 DOI: 10.1038/s41598-020-60718-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 02/10/2020] [Indexed: 12/13/2022] Open
Abstract
One of the most important aspects of bone remodeling is the constant turnover mainly driven by the mechanical loading stimulus. The remodeling process produces changes not only in the bone microarchitecture but also in the density distribution of the mineralized matrix - i.e. in calcium concentrations- and in the osteocyte lacunar network. Synchrotron radiation-based X-ray microtomography (microCT) has proven to be an efficient technique, capable to achieve the analysis of 3D bone architecture and of local mineralization at different hierarchical length scales, including the imaging of the lacuno-canalicular network. In the present study, we used microCT within a conceptual study of jawbone remodeling, demonstratively focusing the investigation in two critical contexts, namely in the peri-dental and the peri-implant tissues. The microCT analysis showed that a relevant inhomogeneity was clearly present in both peri-dental and peri-implant biopsies, not only in terms of microarchitecture and mineralization degree, but also considering the lacunar network, i.e. size and numerical density of the osteocyte lacunae. The correlated histological results obtained on the same samples confirmed these observations, also adding information related to non-mineralized tissues. Despite its demonstrative nature, it was concluded that the proposed method was powerful in studying jawbone remodeling because it revealed a direct correlation of its rate with the lacunar density, as achieved by the analysis of the osteocyte lacunar network, and an inverse correlation with the local bone mineral density, as revealed with the Roschger approach.
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Affiliation(s)
- Giovanna Iezzi
- Department of Medical, Oral and Biotechnological Sciences, University of Chieti-Pescara, Chieti Scalo, CH, Italy
| | | | - Antonio Barone
- Department of Medical, Surgical, Molecular and of the Critical Area Pathologies, University of Pisa, Pisa, Italy
| | | | - Luigi Baggi
- Department of Social Dentistry, National Institute for Health, Migration and Poverty, Rome, Italy.,School of Dentistry, University of Rome "Tor Vergata", Rome, Italy
| | | | - Adriano Piattelli
- Department of Medical, Oral and Biotechnological Sciences, University of Chieti-Pescara, Chieti Scalo, CH, Italy.,Chair of Biomaterials Engineering, Catholic University of Murcia (UCAM), Murcia, Spain.,Villa Serena Foundation for Research, Città Sant'Angelo (Pescara), Italy
| | - Alessandra Giuliani
- Department of Clinical Sciences, Polytechnic University of Marche, Ancona, Italy.
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28
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Liu Y, Li A, Chen B. Effects of Structure Characteristics of Osteocyte Lacunae on Squeeze Damage Resistance of Osteons. Cells Tissues Organs 2020; 208:142-147. [PMID: 32069449 DOI: 10.1159/000505135] [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: 07/20/2018] [Accepted: 12/01/2019] [Indexed: 11/19/2022] Open
Abstract
Scanning electron-microscopic observations show that there are many osteocyte lacunae between the circumferential lamellae, which are nonuniform in distribution. The lacunae are elliptical, and their major axes are along the circumferential direction of the osteon, which can be denoted as circumferential elliptical lacunae (CE). The observations also show that there are many circumferential microcracks in the osteons, and these microcracks are initiated from 2 endpoints of the major CE axis. To investigate the effects of the structural characteristics of osteocyte lacunae on the crack-propagated route and squeeze damage resistance of oste-ons, 3 different osteon models - CE, radially elliptical lacunae (RE), and circular lacunae (CL) - were created. The microcrack initiation and propagation of the 3 different osteon models were calculated and simulated based on progressive damage analysis. The results show that the crack-propagated route of the CE osteons is along the circumferential direction of the osteon, which is consistent with experimental observations, while those of the RE and CL are in the radial direction of the osteon. CE around the osteon in the bone is the result of long-term natural evolution, which is an important factor for bone to have strong fracture toughness.
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Affiliation(s)
- Yuxi Liu
- College of Mechanical Engineering, Chongqing Vocational Institute of Engineering, Chongqing, China, .,College of Aerospace Engineering, Chongqing University, Chongqing, China,
| | - Aihua Li
- Key Laboratory for Biorheological Science and Technology of Ministry of Education, Chongqing University Cancer Hospital, Chongqing, China
| | - Bin Chen
- College of Aerospace Engineering, Chongqing University, Chongqing, China
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29
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Relucenti M, Miglietta S, Bove G, Donfrancesco O, Battaglione E, Familiari P, Barbaranelli C, Covelli E, Barbara M, Familiari G. SEM BSE 3D Image Analysis of Human Incus Bone Affected by Cholesteatoma Ascribes to Osteoclasts the Bone Erosion and VpSEM dEDX Analysis Reveals New Bone Formation. SCANNING 2020; 2020:9371516. [PMID: 32158510 PMCID: PMC7048945 DOI: 10.1155/2020/9371516] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 01/22/2020] [Indexed: 06/10/2023]
Abstract
Bone erosion is considered a typical characteristic of advanced or complicated cholesteatoma (CHO), although it is still a matter of debate if bone erosion is due to osteoclast action, being the specific literature controversial. The purpose of this study was to apply a novel scanning characterization approach, the BSE 3D image analysis, to study the pathological erosion on the surface of human incus bone involved by CHO, in order to definitely assess the eventual osteoclastic resorptive action. To do this, a comparison of BSE 3D image of resorption lacunae (resorption pits) from osteoporotic human femur neck (indubitably of osteoclastic origin) with that of the incus was performed. Surface parameters (area, mean depth, and volume) were calculated by the software Hitachi MountainsMap© from BSE 3D-reconstructed images; results were then statistically analyzed by SPSS statistical software. Our findings showed that no significant differences exist between the two groups. This quantitative approach implements the morphological characterization, allowing us to state that surface erosion of the incus is due to osteoclast action. Moreover, our observation and processing image workflow are the first in the literature showing the presence not only of bone erosion but also of matrix vesicles releasing their content on collagen bundles and self-immuring osteocytes, all markers of new bone formation on incus bone surface. On the basis of recent literature, it has been hypothesized that inflammatory environment induced by CHO may trigger the osteoclast activity, eliciting bone erosion. The observed new bone formation probably takes place at a slower rate in respect to the normal bone turnover, and the process is uncoupled (as recently demonstrated for several inflammatory diseases that promote bone loss) thus resulting in an overall bone loss. Novel scanning characterization approaches used in this study allowed for the first time the 3D imaging of incus bone erosion and its quantitative measurement, opening a new era of quantitative SEM morphology.
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Affiliation(s)
- Michela Relucenti
- Department SAIMLAL Section of Human Anatomy, Laboratory of Electron Microscopy “Pietro M. Motta”, Sapienza University of Rome, Via Alfonso Borelli 50, 00161 Rome, Italy
| | - Selenia Miglietta
- Department SAIMLAL Section of Human Anatomy, Laboratory of Electron Microscopy “Pietro M. Motta”, Sapienza University of Rome, Via Alfonso Borelli 50, 00161 Rome, Italy
| | - Gabriele Bove
- Department SAIMLAL Section of Human Anatomy, Laboratory of Electron Microscopy “Pietro M. Motta”, Sapienza University of Rome, Via Alfonso Borelli 50, 00161 Rome, Italy
| | - Orlando Donfrancesco
- Department SAIMLAL Section of Human Anatomy, Laboratory of Electron Microscopy “Pietro M. Motta”, Sapienza University of Rome, Via Alfonso Borelli 50, 00161 Rome, Italy
| | - Ezio Battaglione
- Department SAIMLAL Section of Human Anatomy, Laboratory of Electron Microscopy “Pietro M. Motta”, Sapienza University of Rome, Via Alfonso Borelli 50, 00161 Rome, Italy
| | - Pietro Familiari
- Department NESMOS, Neurosurgery Unit, Sapienza University of Rome, Via di Grottarossa 1039, 00189 Rome, Italy
| | - Claudio Barbaranelli
- Department of Psychology, Sapienza University of Rome, Via dei Marsi 78, 00185 Rome, Italy
| | - Edoardo Covelli
- Department NESMOS, ENT Unit, Sapienza University of Rome, Via di Grottarossa 1039, 00189 Rome, Italy
| | - Maurizio Barbara
- Department NESMOS, ENT Unit, Sapienza University of Rome, Via di Grottarossa 1039, 00189 Rome, Italy
| | - Giuseppe Familiari
- Department SAIMLAL Section of Human Anatomy, Laboratory of Electron Microscopy “Pietro M. Motta”, Sapienza University of Rome, Via Alfonso Borelli 50, 00161 Rome, Italy
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30
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Kegelman CD, Coulombe JC, Jordan KM, Horan DJ, Qin L, Robling AG, Ferguson VL, Bellido TM, Boerckel JD. YAP and TAZ Mediate Osteocyte Perilacunar/Canalicular Remodeling. J Bone Miner Res 2020; 35:196-210. [PMID: 31610061 PMCID: PMC7066596 DOI: 10.1002/jbmr.3876] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 08/13/2019] [Accepted: 09/07/2019] [Indexed: 12/31/2022]
Abstract
Bone fragility fractures are caused by low bone mass or impaired bone quality. Osteoblast/osteoclast coordination determines bone mass, but the factors that control bone quality are poorly understood. Osteocytes regulate osteoblast and osteoclast activity on bone surfaces but can also directly reorganize the bone matrix to improve bone quality through perilacunar/canalicular remodeling; however, the molecular mechanisms remain unclear. We previously found that deleting the transcriptional regulators Yes-associated protein (YAP) and transcriptional co-activator with PDZ-motif (TAZ) from osteoblast-lineage cells caused lethality in mice due to skeletal fragility. Here, we tested the hypothesis that YAP and TAZ regulate osteocyte-mediated bone remodeling by conditional ablation of both YAP and TAZ from mouse osteocytes using 8 kb-DMP1-Cre. Osteocyte-conditional YAP/TAZ deletion reduced bone mass and dysregulated matrix collagen content and organization, which together decreased bone mechanical properties. Further, YAP/TAZ deletion impaired osteocyte perilacunar/canalicular remodeling by reducing canalicular network density, length, and branching, as well as perilacunar flourochrome-labeled mineral deposition. Consistent with recent studies identifying TGF-β as a key inducer of osteocyte expression of matrix-remodeling enzymes, YAP/TAZ deletion in vivo decreased osteocyte expression of matrix proteases MMP13, MMP14, and CTSK. In vitro, pharmacologic inhibition of YAP/TAZ transcriptional activity in osteocyte-like cells abrogated TGF-β-induced matrix protease gene expression. Together, these data show that YAP and TAZ control bone matrix accrual, organization, and mechanical properties by regulating osteocyte-mediated bone remodeling. Elucidating the signaling pathways that control perilacunar/canalicular remodeling may enable future therapeutic targeting of bone quality to reverse skeletal fragility. © 2019 American Society for Bone and Mineral Research.
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Affiliation(s)
- Christopher D Kegelman
- Department of Orthopaedic Surgery, University of Pennsylvania, Philadelphia, PA, USA.,Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
| | - Jennifer C Coulombe
- Department of Mechanical Engineering, University of Colorado, Boulder, CO, USA
| | - Kelsey M Jordan
- Department of Orthopaedic Surgery, University of Pennsylvania, Philadelphia, PA, USA.,Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
| | - Daniel J Horan
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Ling Qin
- Department of Orthopaedic Surgery, University of Pennsylvania, Philadelphia, PA, USA
| | - Alexander G Robling
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Virginia L Ferguson
- Department of Mechanical Engineering, University of Colorado, Boulder, CO, USA
| | - Teresita M Bellido
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Joel D Boerckel
- Department of Orthopaedic Surgery, University of Pennsylvania, Philadelphia, PA, USA.,Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
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31
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Chen H, Zhang J, Wang Y, Cheuk KY, Hung ALH, Lam TP, Qiu Y, Feng JQ, Lee WYW, Cheng JCY. Abnormal lacuno-canalicular network and negative correlation between serum osteocalcin and Cobb angle indicate abnormal osteocyte function in adolescent idiopathic scoliosis. FASEB J 2019; 33:13882-13892. [PMID: 31626573 PMCID: PMC6894095 DOI: 10.1096/fj.201901227r] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 09/10/2019] [Indexed: 12/28/2022]
Abstract
Adolescent idiopathic scoliosis (AIS) is a prevalent spinal deformity occurring during peripubertal growth period that affects 1-4% of adolescents globally without clear etiopathogenetic mechanism. Low bone mineral density is an independent and significant prognostic factor for curve progression. Currently, the cause underlying low bone mass in AIS remains elusive. Osteocytes play an important role in bone metabolism and mineral homeostasis, but its role in AIS has not been studied. In the present study, iliac bone tissues were harvested from 21 patients with AIS (mean age of 14.3 ± 2.20 yr old) with a mean Cobb angle of 55.6 ± 10.61° and 13 non-AIS controls (mean age of 16.5 ± 4.79 yr old) intraoperatively. Acid-etched scanning electron microscopy (SEM) images of AIS demonstrated abnormal osteocytes that were more rounded and cobblestone-like in shape and were aligned in irregular clusters with shorter and disorganized canaliculi. Further quantitative analysis with FITC-Imaris technique showed a significant reduction in the canalicular number and length as well as an increase in lacunar volume and area in AIS. SEM with energy-dispersive X-ray spectroscopy analysis demonstrated a lower calcium-to-phosphorus ratio at the perilacunar/canalicular region. Moreover, microindentaion results revealed lower values of Vickers hardness and elastic modulus in AIS when compared with controls. In addition, in the parallel study of 99 AIS (27 with severe Cobb angle of 65.8 ± 14.1° and 72 with mild Cobb angle of 26.6 ± 9.1°) with different curve severity, the serum osteocalcin level was found to be significantly and negatively associated with the Cobb angle. In summary, the findings in this series of studies demonstrated the potential link of abnormal osteocyte lacuno-canalicular network structure and function to the observed abnormal bone mineralization in AIS, which may shed light on etiopathogenesis of AIS.-Chen, H., Zhang, J., Wang, Y., Cheuk, K.-Y., Hung, A. L. H., Lam, T.-P., Qiu, Y., Feng, J. Q., Lee, W. Y. W., Cheng, J. C. Y. Abnormal lacuno-canalicular network and negative correlation between serum osteocalcin and Cobb angle indicate abnormal osteocyte function in adolescent idiopathic scoliosis.
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Affiliation(s)
- Huanxiong Chen
- Department of Spine and Osteopathic Surgery, The
First Affiliated Hospital of Hainan Medical University, Hai-kou, China
- Department of Orthopaedics and Traumatology, S. H.
Ho Scoliosis Research Laboratory, The Chinese University of Hong Kong, Shatin, NT,
Hong Kong, China
- Joint Scoliosis Research Center of The Chinese
University of Hong Kong–Nanjing University, The Chinese University of Hong
Kong, Hong Kong, China
| | - Jiajun Zhang
- Department of Orthopaedics and Traumatology, S. H.
Ho Scoliosis Research Laboratory, The Chinese University of Hong Kong, Shatin, NT,
Hong Kong, China
- Joint Scoliosis Research Center of The Chinese
University of Hong Kong–Nanjing University, The Chinese University of Hong
Kong, Hong Kong, China
| | - Yujia Wang
- Department of Orthopaedics and Traumatology, S. H.
Ho Scoliosis Research Laboratory, The Chinese University of Hong Kong, Shatin, NT,
Hong Kong, China
- Joint Scoliosis Research Center of The Chinese
University of Hong Kong–Nanjing University, The Chinese University of Hong
Kong, Hong Kong, China
| | - Ka-Yee Cheuk
- Department of Orthopaedics and Traumatology, S. H.
Ho Scoliosis Research Laboratory, The Chinese University of Hong Kong, Shatin, NT,
Hong Kong, China
- Joint Scoliosis Research Center of The Chinese
University of Hong Kong–Nanjing University, The Chinese University of Hong
Kong, Hong Kong, China
| | - Alec L. H. Hung
- Department of Orthopaedics and Traumatology, S. H.
Ho Scoliosis Research Laboratory, The Chinese University of Hong Kong, Shatin, NT,
Hong Kong, China
- Joint Scoliosis Research Center of The Chinese
University of Hong Kong–Nanjing University, The Chinese University of Hong
Kong, Hong Kong, China
| | - Tsz-Ping Lam
- Department of Orthopaedics and Traumatology, S. H.
Ho Scoliosis Research Laboratory, The Chinese University of Hong Kong, Shatin, NT,
Hong Kong, China
- Joint Scoliosis Research Center of The Chinese
University of Hong Kong–Nanjing University, The Chinese University of Hong
Kong, Hong Kong, China
| | - Yong Qiu
- Joint Scoliosis Research Center of The Chinese
University of Hong Kong–Nanjing University, The Chinese University of Hong
Kong, Hong Kong, China
- Spine Surgery, Nanjing Drum Tower Hospital,
Nanjing University, Nanjing, China
| | - Jian Q. Feng
- Department of Biomedical Sciences, Texas
A&M College of Dentistry, Dallas, Texas, USA
| | - Wayne Y. W. Lee
- Department of Orthopaedics and Traumatology, S. H.
Ho Scoliosis Research Laboratory, The Chinese University of Hong Kong, Shatin, NT,
Hong Kong, China
- Joint Scoliosis Research Center of The Chinese
University of Hong Kong–Nanjing University, The Chinese University of Hong
Kong, Hong Kong, China
| | - Jack C. Y. Cheng
- Department of Orthopaedics and Traumatology, S. H.
Ho Scoliosis Research Laboratory, The Chinese University of Hong Kong, Shatin, NT,
Hong Kong, China
- Joint Scoliosis Research Center of The Chinese
University of Hong Kong–Nanjing University, The Chinese University of Hong
Kong, Hong Kong, China
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Othman MIA, Abd-Elaziz EM. Effect of initial stress and Hall current on a magneto-thermoelastic porous medium with microtemperatures. INDIAN JOURNAL OF PHYSICS 2019; 93:475-485. [DOI: 10.1007/s12648-018-1313-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 07/12/2018] [Indexed: 09/02/2023]
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Hemmatian H, Jalali R, Semeins CM, Hogervorst JMA, van Lenthe GH, Klein-Nulend J, Bakker AD. Mechanical Loading Differentially Affects Osteocytes in Fibulae from Lactating Mice Compared to Osteocytes in Virgin Mice: Possible Role for Lacuna Size. Calcif Tissue Int 2018; 103:675-685. [PMID: 30109376 PMCID: PMC6208961 DOI: 10.1007/s00223-018-0463-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Accepted: 07/30/2018] [Indexed: 12/31/2022]
Abstract
Hormonal changes during lactation are associated with profound changes in bone cell biology, such as osteocytic osteolysis, resulting in larger lacunae. Larger lacuna shape theoretically enhances the transmission of mechanical signals to osteocytes. We aimed to provide experimental evidence supporting this theory by comparing the mechanoresponse of osteocytes in the bone of lactating mice, which have enlarged lacunae due to osteocytic osteolysis, with the response of osteocytes in bone from age-matched virgin mice. The osteocyte mechanoresponse was measured in excised fibulae that were cultured in hormone-free medium for 24 h and cyclically loaded for 10 min (sinusoidal compressive load, 3000 µε, 5 Hz) by quantifying loading-related changes in Sost mRNA expression (qPCR) and sclerostin and β-catenin protein expression (immunohistochemistry). Loading decreased Sost expression by ~ threefold in fibulae of lactating mice. The loading-induced decrease in sclerostin protein expression by osteocytes was larger in lactating mice (55% decrease ± 14 (± SD), n = 8) than virgin mice (33% decrease ± 15, n = 7). Mechanical loading upregulated β-catenin expression in osteocytes in lactating mice by 3.5-fold (± 0.2, n = 6) which is significantly (p < 0.01) higher than the 1.6-fold increase in β-catenin expression by osteocytes in fibulae from virgin mice (± 0.12, n = 4). These results suggest that osteocytes in fibulae from lactating mice with large lacunae may respond stronger to mechanical loading than those from virgin mice. This could indicate that osteocytes residing in larger lacuna show a stronger response to mechanical loading.
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Affiliation(s)
- Haniyeh Hemmatian
- Biomechanics Section, Department of Mechanical Engineering, KU Leuven, Leuven, Belgium
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Gustav Mahlerlaan 3004, 1081 LA, Amsterdam, The Netherlands
| | - Rozita Jalali
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Gustav Mahlerlaan 3004, 1081 LA, Amsterdam, The Netherlands
| | - Cornelis M Semeins
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Gustav Mahlerlaan 3004, 1081 LA, Amsterdam, The Netherlands
| | - Jolanda M A Hogervorst
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Gustav Mahlerlaan 3004, 1081 LA, Amsterdam, The Netherlands
| | - G Harry van Lenthe
- Biomechanics Section, Department of Mechanical Engineering, KU Leuven, Leuven, Belgium
| | - Jenneke Klein-Nulend
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Gustav Mahlerlaan 3004, 1081 LA, Amsterdam, The Netherlands.
| | - Astrid D Bakker
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Gustav Mahlerlaan 3004, 1081 LA, Amsterdam, The Netherlands
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34
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Hemmatian H, Laurent MR, Bakker AD, Vanderschueren D, Klein-Nulend J, van Lenthe GH. Age-related changes in female mouse cortical bone microporosity. Bone 2018; 113:1-8. [PMID: 29738854 DOI: 10.1016/j.bone.2018.05.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Revised: 04/04/2018] [Accepted: 05/02/2018] [Indexed: 12/23/2022]
Abstract
Osteocyte lacunae are small cavities within the bone matrix. Their dimensions and spatial arrangement affect bone mechanical properties. Furthermore, their size and shape affect the strain in bone tissue close to the lacunae; hence, they are supposed to affect the mechanosensory function of the osteocytes residing in the lacunae. It was the purpose of this study to quantify the morphological features of osteocyte lacunae, whether these are affected by aging and whether these vary among different anatomical location. In addition, we aimed at quantifying the vascular canals as these affect bone's microporosity too. We quantified the microporosity in the fibular midshaft of young-adult and old female C57BL/6 mice. Using micro-computed tomography (μCT), we found that advanced age was associated with a significantly decreased vascular canal number and volume density. In aged mice, the mean volume of the lacuna was significantly smaller than in young animals and they were more round. Lacuna number density close to the neutral axis of the fibula was higher in older mice than in young ones. The characterization of bone microporosity presents a first step in further unraveling their potential role in age-related reductions in bone strength.
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Affiliation(s)
- Haniyeh Hemmatian
- Biomechanics Section, Department of Mechanical Engineering, KU Leuven, Leuven, Belgium; Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, The Netherlands
| | - Michaël R Laurent
- Laboratory of Molecular Endocrinology, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium; Gerontology and Geriatrics, Department of Clinical and Experimental Medicine, KU Leuven, Leuven, Belgium
| | - Astrid D Bakker
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, The Netherlands
| | - Dirk Vanderschueren
- Clinical and Experimental Endocrinology, Department of Clinical and Experimental Medicine, KU Leuven, Leuven, Belgium
| | - Jenneke Klein-Nulend
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, The Netherlands
| | - G Harry van Lenthe
- Biomechanics Section, Department of Mechanical Engineering, KU Leuven, Leuven, Belgium.
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35
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Heveran CM, Rauff A, King KB, Carpenter RD, Ferguson VL. A new open-source tool for measuring 3D osteocyte lacunar geometries from confocal laser scanning microscopy reveals age-related changes to lacunar size and shape in cortical mouse bone. Bone 2018; 110:115-127. [PMID: 29374550 PMCID: PMC5878731 DOI: 10.1016/j.bone.2018.01.018] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Revised: 12/15/2017] [Accepted: 01/14/2018] [Indexed: 01/13/2023]
Abstract
Osteocytes can participate in systemic mineral homeostasis through perilacunar maintenance and remodeling, where changes to osteocyte lacunar morphology may affect bone structural integrity, tissue strains, and osteocyte mechanosensitivity. Though aging is associated with both decreased bone quality and altered mineral metabolism, it is not known if osteocyte lacunae undergo age-related changes in geometry. In order to survey lacunar changes with age, we developed an open-source program whereby 3D osteocyte lacunae are automatically segmented and then subsequently reconstructed from confocal laser scanning microscopy (CLSM) depth stacks for quantitative analysis of geometry and orientation. This approach takes advantage of the availability and speed of CLSM while avoiding time-consuming and bias-prone manual segmentation. Unlike conventional approaches used to quantify osteocyte lacunar morphology, CLSM enables facile analysis in three-dimensions with clear identification of osteocyte lacunae. We report that 3D osteocyte lacunae measured by CLSM become smaller, more spherical, more oblate, more spatially disorganized, and more sparsely populated with increased age in C57Bl/6 mouse cortical bone in groups spanning 6-24 months old. Critically, these age-related changes are in large part not observed in 2D analyses from the same samples. These results (1) demonstrate proof-of-concept of an efficient method to quantitatively assess osteocyte lacunae in 3D for application to a wide range of studies and (2) motivate further inquiry into how changes to osteocyte lacunar geometries and perilacunar material contribute to diminished bone quality in aging.
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Affiliation(s)
- Chelsea M Heveran
- Department of Mechanical Engineering, University of Colorado Boulder, United States
| | - Adam Rauff
- Department of Bioengineering, University of Colorado Denver, United States
| | - Karen B King
- Department of Orthopaedics, University of Colorado School of Medicine, United States
| | - R Dana Carpenter
- Department of Mechanical Engineering, University of Colorado Denver, United States
| | - Virginia L Ferguson
- Department of Mechanical Engineering, University of Colorado Boulder, United States.
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36
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Sharma D, Larriera AI, Palacio-Mancheno PE, Gatti V, Fritton JC, Bromage TG, Cardoso L, Doty SB, Fritton SP. The effects of estrogen deficiency on cortical bone microporosity and mineralization. Bone 2018; 110:1-10. [PMID: 29357314 PMCID: PMC6377161 DOI: 10.1016/j.bone.2018.01.019] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 01/09/2018] [Accepted: 01/15/2018] [Indexed: 12/22/2022]
Abstract
Recent studies have demonstrated matrix-mineral alterations in bone tissue surrounding osteocytes in estrogen-deficient animals. While cortical bone porosity has been shown to be a contributor to the mechanical properties of bone tissue, little analysis has been done to investigate the effects of estrogen deficiency on bone's microporosities, including the vascular and osteocyte lacunar porosities. In this study we examined alterations in cortical bone microporosity, mineralization, and cancellous bone architecture due to estrogen deficiency in the ovariectomized rat model of postmenopausal osteoporosis. Twenty-week-old female Sprague-Dawley rats were subjected to either ovariectomy or sham surgery. Six weeks post-surgery tibiae were analyzed using high-resolution micro-CT, backscattered electron imaging, nanoindentation, and dynamic histomorphometry. Estrogen deficiency caused an increase in cortical bone vascular porosity, with enlarged vascular pores and little change in tissue mineral density in the proximal tibial metaphysis. Measurements of cancellous architecture corresponded to previous studies reporting a decrease in bone volume fraction, an increase in trabecular separation, and a decrease in trabecular number in the proximal tibia due to estrogen deficiency. Nanoindentation results showed no differences in matrix stiffness in osteocyte-rich areas of the proximal tibia of estrogen-deficient rats, and bone labeling and backscattered electron imaging showed no significant changes in mineralization around the vascular pores. The findings demonstrate local surface alterations of vascular pores due to estrogen deficiency. An increase in cortical vascular porosity may diminish bone strength as well as alter bone mechanotransduction via interstitial fluid flow, both of which could contribute to bone fragility during postmenopausal osteoporosis.
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Affiliation(s)
- Divya Sharma
- Department of Biomedical Engineering, The City College of New York, New York, NY 10031, United States
| | - Adriana I Larriera
- Department of Biomedical Engineering, The City College of New York, New York, NY 10031, United States
| | - Paolo E Palacio-Mancheno
- Department of Biomedical Engineering, The City College of New York, New York, NY 10031, United States
| | - Vittorio Gatti
- Department of Biomedical Engineering, The City College of New York, New York, NY 10031, United States
| | - J Christopher Fritton
- Department of Orthopaedics, New Jersey Medical School, Rutgers University, Newark, NJ 07103, United States
| | - Timothy G Bromage
- Department of Biomaterials, New York University College of Dentistry, New York, NY 10010, United States
| | - Luis Cardoso
- Department of Biomedical Engineering, The City College of New York, New York, NY 10031, United States
| | - Stephen B Doty
- Research Division, Hospital for Special Surgery, New York, NY 10021, United States
| | - Susannah P Fritton
- Department of Biomedical Engineering, The City College of New York, New York, NY 10031, United States.
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Quantitative correlation between the void morphology of niobium-tin wires and their irreversible critical current degradation upon mechanical loading. Sci Rep 2018; 8:6589. [PMID: 29700359 PMCID: PMC5920112 DOI: 10.1038/s41598-018-24966-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 03/29/2018] [Indexed: 11/09/2022] Open
Abstract
Understanding the critical current performance variation of Nb3Sn superconducting wires under mechanical loading is a crucial issue for the design of next generation accelerator and fusion magnets. In these applications, the mechanical properties of the conductors may become a limiting factor due to the strong electro-magnetic forces resulting from the combination of large magnets and intense magnetic fields. In particular, the presence of voids in the superconducting filament structure, which are formed during the fabrication and the reaction heat treatment, determines localized stress concentrations and possibly the formation of cracks. In this work, we demonstrate a quantitative correlation between the void morphology and the electro-mechanical limits measured on different Bronze route Nb3Sn wires. Hot Isostatic Pressing (HIP) prior to the reaction heat treatment is utilized to partially eliminate the voids. The wires' void distributions - with and without HIP treatment - are detected and statistically analyzed using high energy X-ray micro tomography. The stress concentration due to the shape and distribution of the voids as well as their impact on the electro-mechanical properties are determined through finite element method modeling. Finally, the results are quantitatively correlated with the experimentally determined limits of the irreversible critical current degradation upon mechanical loading.
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38
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Asgharzadeh P, Özdemir B, Reski R, Röhrle O, Birkhold AI. Computational 3D imaging to quantify structural components and assembly of protein networks. Acta Biomater 2018; 69:206-217. [PMID: 29378323 DOI: 10.1016/j.actbio.2018.01.020] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 12/21/2017] [Accepted: 01/16/2018] [Indexed: 12/11/2022]
Abstract
Traditionally, protein structures have been described by the secondary structure architecture and fold arrangement. However, the relatively novel method of 3D confocal microscopy of fluorescent-protein-tagged networks in living cells allows resolving the detailed spatial organization of these networks. This provides new possibilities to predict network functionality, as structure and function seem to be linked at various scales. Here, we propose a quantitative approach using 3D confocal microscopy image data to describe protein networks based on their nano-structural characteristics. This analysis is constructed in four steps: (i) Segmentation of the microscopic raw data into a volume model and extraction of a spatial graph representing the protein network. (ii) Quantifying protein network gross morphology using the volume model. (iii) Quantifying protein network components using the spatial graph. (iv) Linking these two scales to obtain insights into network assembly. Here, we quantitatively describe the filamentous temperature sensitive Z protein network of the moss Physcomitrella patens and elucidate relations between network size and assembly details. Future applications will link network structure and functionality by tracking dynamic structural changes over time and comparing different states or types of networks, possibly allowing more precise identification of (mal) functions or the design of protein-engineered biomaterials for applications in regenerative medicine. STATEMENT OF SIGNIFICANCE Protein networks are highly complex and dynamic structures that play various roles in biological environments. Analyzing the detailed spatial structure of these networks may lead to new insight into biological functions and malfunctions. Here, we propose a tool set that extracts structural information at two scales of the protein network and allows therefore to address questions such as "how is the network built?" or "how networks grow?".
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Computational Investigation on the Biomechanical Responses of the Osteocytes to the Compressive Stimulus: A Poroelastic Model. BIOMED RESEARCH INTERNATIONAL 2018; 2018:4071356. [PMID: 29581973 PMCID: PMC5822791 DOI: 10.1155/2018/4071356] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 12/02/2017] [Accepted: 12/19/2017] [Indexed: 11/17/2022]
Abstract
Osteocytes, the major type of bone cells embedded in the bone matrix and surrounded by the lacunar and canalicular system, can serve as biomechanosensors and biomechanotranducers of the bone. Theoretical analytical methods have been employed to investigate the biomechanical responses of osteocytes in vivo; the poroelastic properties have not been taken into consideration in the three-dimensional (3D) finite element model. In this study, a 3D poroelastic idealized finite element model was developed and was used to predict biomechanical behaviours (maximal principal strain, pore pressure, and fluid velocity) of the osteocyte-lacunar-canalicular system under 150-, 1000-, 3000-, and 5000-microstrain compressive loads, respectively, representing disuse, physiological, overuse, and pathological overload loading stimuli. The highest local strain, pore pressure, and fluid velocity were found to be highest at the proximal region of cell processes. These data suggest that the strain, pore pressure, and fluid velocity of the osteocyte-lacunar-canalicular system increase with the global loading and that the poroelastic material property affects the biomechanical responses to the compressive stimulus. This new model can be used to predict the mechanobiological behaviours of osteocytes under the four different compressive loadings and may provide an insight into the mechanisms of mechanosensation and mechanotransduction of the bone.
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40
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Macroscopic anisotropic bone material properties in children with severe osteogenesis imperfecta. J Biomech 2017; 64:103-111. [DOI: 10.1016/j.jbiomech.2017.09.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2017] [Revised: 07/12/2017] [Accepted: 09/04/2017] [Indexed: 01/06/2023]
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Abstract
PURPOSE OF REVIEW The bone is able to adapt its structure to mechanical signals via the bone remodeling process governed by mechanosensitive osteocytes. With aging, an imbalance in bone remodeling results in osteoporosis. In this review, we hypothesized that changes in lacunar morphology underlie the decreased bone mechanoresponsiveness to mechanical loading with aging. RECENT FINDINGS Several studies have reported considerable variations in the shape of osteocytes and their lacunae with aging. Since osteocytes can sense matrix strain directly via their cell bodies, the variations in osteocyte morphology may cause changes in osteocyte mechanosensitivity. As a consequence, the load-adaptive response of osteocytes may change with aging, even when mechanical loading would remain unchanged. Though extensive quantitative data is lacking, evidence exists that the osteocyte lacunae are becoming smaller and more spherical with aging. Future dedicated studies might reveal whether these changes would affect osteocyte mechanosensation and the subsequent biological response, and whether this is (one of) the pathways involved in age-related bone loss.
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Affiliation(s)
- Haniyeh Hemmatian
- Biomechanics Section, Department of Mechanical Engineering, KU Leuven, Celestijnenlaan 300c, 3001 Leuven, Belgium
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, The Netherlands
| | - Astrid D. Bakker
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, The Netherlands
| | - Jenneke Klein-Nulend
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, The Netherlands
| | - G. Harry van Lenthe
- Biomechanics Section, Department of Mechanical Engineering, KU Leuven, Celestijnenlaan 300c, 3001 Leuven, Belgium
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Mosey H, Núñez JA, Goring A, Clarkin CE, Staines KA, Lee PD, Pitsillides AA, Javaheri B. Sost Deficiency does not Alter Bone's Lacunar or Vascular Porosity in Mice. FRONTIERS IN MATERIALS 2017; 4:27. [PMID: 29349060 PMCID: PMC5769812 DOI: 10.3389/fmats.2017.00027] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
SCLEROSTIN (Sost) is expressed predominantly in osteocytes acting as a negative regulator of bone formation. In humans, mutations in the SOST gene lead to skeletal overgrowth and increased bone mineral density, suggesting that SCLEROSTIN is a key regulator of bone mass. The function of SCLEROSTIN as an inhibitor of bone formation is further supported by Sost knockout (KO) mice which display a high bone mass with elevated bone formation. Previous studies have indicated that Sost exerts its effect on bone formation through Wnt-mediated regulation of osteoblast differentiation, proliferation, and activity. Recent in vitro studies have also suggested that SCLEROSTIN regulates angiogenesis and osteoblast-to-osteocyte transition. Despite this wealth of knowledge of the mechanisms responsible for SCLEROSTIN action, no previous studies have examined whether SCLEROSTIN regulates osteocyte and vascular configuration in cortices of mouse tibia. Herein, we image tibiae from Sost KO mice and their wild-type (WT) counterparts with high-resolution CT to examine whether lack of SCLEROSTIN influences the morphometric properties of lacunae and vascular canal porosity relating to osteocytes and vessels within cortical bone. Male Sost KO and WT mice (n = 6/group) were sacrificed at 12 weeks of age. Fixed tibiae were analyzed using microCT to examine cortical bone mass and architecture. Then, samples were imaged by using benchtop and synchrotron nano-computed tomography at the tibiofibular junction. Our data, consistent with previous studies show that, Sost deficiency leads to significant enhancement of bone mass by cortical thickening and bigger cross-sectional area and we find that this occurs without modifications of tibial ellipticity, a measure of bone shape. In addition, our data show that there are no significant differences in any lacunar or vascular morphometric or geometric parameters between Sost KO mouse tibia and WT counterparts. We, therefore, conclude that the significant increases in bone mass induced by Sost deficiency are not accompanied by any significant modification in the density, organization, or shape of osteocyte lacunae or vascular content within the cortical bone. These data may imply that SCLEROSTIN does not modify the frequency of osteocytogenic recruitment of osteoblasts to initiate terminal osteocytic differentiation in mice.
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Affiliation(s)
- Henry Mosey
- Skeletal Biology Group, Comparative Biomedical Sciences, The Royal Veterinary College, London, United Kingdom
| | - Juan A. Núñez
- Faculty of Natural and Environmental Sciences, Biological Sciences, University of Southampton, Southampton, United Kingdom
| | - Alice Goring
- Faculty of Natural and Environmental Sciences, Biological Sciences, University of Southampton, Southampton, United Kingdom
| | - Claire E. Clarkin
- Faculty of Natural and Environmental Sciences, Biological Sciences, University of Southampton, Southampton, United Kingdom
| | - Katherine A. Staines
- School of Applied Sciences, Edinburgh Napier University, Edinburgh, United Kingdom
| | - Peter D. Lee
- Manchester X-Ray Imaging Facility, University of Manchester, Manchester, United Kingdom
| | - Andrew A. Pitsillides
- Skeletal Biology Group, Comparative Biomedical Sciences, The Royal Veterinary College, London, United Kingdom
| | - Behzad Javaheri
- Skeletal Biology Group, Comparative Biomedical Sciences, The Royal Veterinary College, London, United Kingdom
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Cortical and trabecular morphology is altered in the limb bones of mice artificially selected for faster skeletal growth. Sci Rep 2017; 7:10527. [PMID: 28874773 PMCID: PMC5585176 DOI: 10.1038/s41598-017-10317-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Accepted: 08/07/2017] [Indexed: 12/26/2022] Open
Abstract
Bone strength is influenced by mineral density and macro- and microstructure. Research into factors that contribute to bone morphology and strength has focused on genetic, environmental and morphological factors (e.g., body mass index), but little is known regarding the impact of rates of skeletal elongation on adult skeletal morphology and strength. Using micro-CT, we examined the impact of rates of skeletal elongation on bone cortical and trabecular morphology, and on rates of estrogen-dependent bone loss in the tibia in CD-1 mice, and in mice with accelerated skeletal growth (Longshanks). Groups of adult mice (n = 7/group) were subjected to ovariectomy or sham surgeries, scanned for 6 weeks, and indices of bone morphology were collected. Results show that Longshanks mice had significantly less trabecular bone at skeletal maturity, characterized by fewer, thinner trabeculae, and furthermore lost trabecular bone more slowly in response to ovariectomy. Artificial selection for rapid skeletal growth relative to somatic growth thus had a significant impact on trabecular bone morphology in Longshanks. Our data do not unequivocally demonstrate a causal relationship between rapid bone growth and reduced trabecular bone quality, but suggest that rapid linear bone growth may influence the risk of cancellous bone fragility.
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Ouyang X, Zhang K, Wu J, Wong DSH, Feng Q, Bian L, Zhang AP. Optical µ-Printing of Cellular-Scale Microscaffold Arrays for 3D Cell Culture. Sci Rep 2017; 7:8880. [PMID: 28827528 PMCID: PMC5566436 DOI: 10.1038/s41598-017-08598-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Accepted: 07/12/2017] [Indexed: 01/07/2023] Open
Abstract
Guiding cell culture via engineering extracellular microenvironment has attracted tremendous attention due to its appealing potentials in the repair, maintenance, and development of tissues or even whole organs. However, conventional biofabrication technologies are usually less productive in fabricating microscale three-dimensional (3D) constructs because of the strident requirements in processing precision and complexity. Here we present an optical µ-printing technology to rapidly fabricate 3D microscaffold arrays for 3D cell culture and cell-scaffold interaction studies on a single chip. Arrays of 3D cubic microscaffolds with cubical sizes matching the single-cell size were fabricated to facilitate cell spreading on suspended microbeams so as to expose both apical and basal cell membranes. We further showed that the increasing of the cubical size of the microscaffolds led to enhanced spreading of the seeded human mesenchymal stem cells and activation of mechanosensing signaling, thereby promoting osteogenesis. Moreover, we demonstrated that the spatially selective modification of the surfaces of suspended beams with a bioactive coating (gelatin methacrylate) via an in-situ printing process allowed tailorable cell adhesion and spreading on the 3D microscaffolds.
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Affiliation(s)
- Xia Ouyang
- Photonics Research Center, Department of Electrical Engineering, The Hong Kong Polytechnic University, Hong Kong SAR, China
| | - Kunyu Zhang
- Department of Biomedical Engineering, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Jushuai Wu
- Photonics Research Center, Department of Electrical Engineering, The Hong Kong Polytechnic University, Hong Kong SAR, China
| | - Dexter Siu-Hong Wong
- Department of Biomedical Engineering, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Qian Feng
- Department of Biomedical Engineering, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Liming Bian
- Department of Biomedical Engineering, The Chinese University of Hong Kong, Hong Kong SAR, China.
| | - A Ping Zhang
- Photonics Research Center, Department of Electrical Engineering, The Hong Kong Polytechnic University, Hong Kong SAR, China.
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Hemmatian H, Laurent MR, Ghazanfari S, Vanderschueren D, Bakker AD, Klein-Nulend J, van Lenthe GH. Accuracy and reproducibility of mouse cortical bone microporosity as quantified by desktop microcomputed tomography. PLoS One 2017; 12:e0182996. [PMID: 28797125 PMCID: PMC5552254 DOI: 10.1371/journal.pone.0182996] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Accepted: 07/27/2017] [Indexed: 02/07/2023] Open
Abstract
Bone's microporosity plays important roles in bone biology and bone mechanical quality. In this study, we explored the accuracy and reproducibility of nondestructive desktop μCT for 3D visualization and subsequent morphometric analysis of mouse cortical bone microporosity including the vascular canal network and osteocyte lacunae. The accuracy of measurements was evaluated in five murine fibula using confocal laser scanning microscopy (CLSM) in conjunction with Fluorescein isothiocyanate (FITC) staining as the reference method. The reproducibility of μCT-derived cortical bone microstructural indices was examined in 10 fibulae of C57Bl/6J male mice at a nominal resolution of 700 nanometer. Three repeated measurements were made on different days. An excellent correlation between μCT and CLSM was observed for both mean lacuna volume (r = 0.98, p = 0.002) and for mean lacuna orientation (r = 0.93, p = 0.02). Whereas the two techniques showed no significant differences for these parameters, the mean lacuna sphericity acquired from μCT was significantly higher than CLSM (p = 0.01). Reproducibility was high, with precision errors (PE) of 1.57-4.69% for lacuna parameters, and of 1.01-9.45% for vascular canal parameters. Intraclass correlation coefficient (ICC) showed a high reliability of the measurements, ranging from 0.998-1.000 for cortical parameters, 0.973-0.999 for vascular canal parameters and 0.755-0.991 for lacuna parameters. In conclusion, desktop μCT is a valuable tool to quantify the 3D characteristics of bone vascular canals as well as lacunae which can be applied to intact murine bones with high accuracy and reproducibility. Thus, μCT might be an important tool to improve our understanding of the physiological and biomechanical significance of these cannular and lacunar structure in cortical bone.
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Affiliation(s)
- Haniyeh Hemmatian
- Biomechanics Section, Department of Mechanical Engineering, KU Leuven, Leuven, Belgium
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, The Netherlands
| | - Michaël R. Laurent
- Laboratory of Molecular Endocrinology, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
- Gerontology and Geriatrics, Department of Clinical and Experimental Medicine, KU Leuven, Leuven, Belgium
| | - Samaneh Ghazanfari
- Aachen-Maastricht Institute for Biobased Materials, Department of Humanities and Sciences, Maastricht University, Geleen, The Netherlands
| | - Dirk Vanderschueren
- Clinical and Experimental Endocrinology, Department of Clinical and Experimental Medicine, KU Leuven, Leuven, Belgium
| | - Astrid D. Bakker
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, The Netherlands
| | - Jenneke Klein-Nulend
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, The Netherlands
| | - G. Harry van Lenthe
- Biomechanics Section, Department of Mechanical Engineering, KU Leuven, Leuven, Belgium
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Akhter MP, Kimmel DB, Lappe JM, Recker RR. Effect of Macroanatomic Bone Type and Estrogen Loss on Osteocyte Lacunar Properties in Healthy Adult Women. Calcif Tissue Int 2017; 100:619-630. [PMID: 28251257 DOI: 10.1007/s00223-017-0247-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2016] [Accepted: 01/30/2017] [Indexed: 12/27/2022]
Abstract
This is the first study to examine clinical human bone specimens by three-dimensional imaging to characterize osteocyte lacunar properties as a function of macroanatomic bone type and estrogen loss. We applied laboratory-based instrumentation [3D X-ray microscope (3DXRM), MicroXCT-200; Carl Zeiss/Xradia, Inc.] that reaches the same resolution as synchrotron microscopy. We used serial transiliac bone biopsy specimens to examine the effect of macroanatomic bone type and estrogen status on osteocyte lacunar properties. These properties include lacunar size (volume, axes lengths of the ellipsoidal lacunar voids), distribution (density, average near-neighbor lacunar distance), and shape factors (sphericity ratio, average eigenvalues, degree of equancy, elongation, and flatness) in both cortical and trabecular bone tissue. The lacunar properties (volume, surface area, density, near-neighbor distance, etc.) and the shape factors (E1, L1, L2, degree of equancy, degree of elongation) were different between cortical and trabecular bone regardless of estrogen status. In cortical bone and trabecular nodes, the lacunar void volume and surface area were either smaller or tended to be smaller in postmenopausal as compared to premenopausal women. The void volume-to-bone volume ratio of cortical bone showed declining trends with estrogen loss. While there were differences between trabecular and cortical bone tissue, the lacunar void sphericity ratio for trabecular struts shows decreasing trends in postmenopausal women. These data suggest that using 3DXRM can provide new insight into osteocyte lacunar properties in transiliac bone biopsies from patients with various skeletal disease/conditions and pharmaceutical treatments.
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Affiliation(s)
- Mohammed P Akhter
- Osteoporosis Research Center (ORC), Creighton University of School of Medicine, Suite #4820, 601 North 30th Street, Omaha, NE, 68131, USA.
| | - D B Kimmel
- Osteoporosis Research Center (ORC), Creighton University of School of Medicine, Suite #4820, 601 North 30th Street, Omaha, NE, 68131, USA
| | - J M Lappe
- Osteoporosis Research Center (ORC), Creighton University of School of Medicine, Suite #4820, 601 North 30th Street, Omaha, NE, 68131, USA
| | - R R Recker
- Osteoporosis Research Center (ORC), Creighton University of School of Medicine, Suite #4820, 601 North 30th Street, Omaha, NE, 68131, USA
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47
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Milovanovic P, Vukovic Z, Antonijevic D, Djonic D, Zivkovic V, Nikolic S, Djuric M. Porotic paradox: distribution of cortical bone pore sizes at nano- and micro-levels in healthy vs. fragile human bone. JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE 2017; 28:71. [PMID: 28357689 DOI: 10.1007/s10856-017-5878-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Accepted: 02/28/2017] [Indexed: 06/06/2023]
Abstract
Bone is a remarkable biological nanocomposite material showing peculiar hierarchical organization from smaller (nano, micro) to larger (macro) length scales. Increased material porosity is considered as the main feature of fragile bone at larger length-scales. However, there is a shortage of quantitative information on bone porosity at smaller length-scales, as well as on the distribution of pore sizes in healthy vs. fragile bone. Therefore, here we investigated how healthy and fragile bones differ in pore volume and pore size distribution patterns, considering a wide range of mostly neglected pore sizes from nano to micron-length scales (7.5 to 15000 nm). Cortical bone specimens from four young healthy women (age: 35 ± 6 years) and five women with bone fracture (age: 82 ± 5 years) were analyzed by mercury porosimetry. Our findings showed that, surprisingly, fragile bone demonstrated lower pore volume at the measured scales. Furtnermore, pore size distribution showed differential patterns between healthy and fragile bones, where healthy bone showed especially high proportion of pores between 200 and 15000 nm. Therefore, although fragile bones are known for increased porosity at macroscopic level and level of tens or hundreds of microns as firmly established in the literature, our study with a unique assessment range of nano-to micron-sized pores reveal that osteoporosis does not imply increased porosity at all length scales. Our thorough assessment of bone porosity reveals a specific distribution of porosities at smaller length-scales and contributes to proper understanding of bone structure which is important for designing new biomimetic bone substitute materials.
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Affiliation(s)
- Petar Milovanovic
- Laboratory for Anthropology, Institute of Anatomy, Faculty of Medicine, University of Belgrade, 4/2 Dr Subotica, Belgrade, 11000, Serbia
| | - Zorica Vukovic
- Department of Catalysis and Chemical Engineering, Institute of Chemistry, Technology and Metallurgy, University of Belgrade, 12 Njegoseva, Belgrade, 11000, Serbia
| | - Djordje Antonijevic
- Laboratory for Anthropology, Institute of Anatomy, Faculty of Medicine, University of Belgrade, 4/2 Dr Subotica, Belgrade, 11000, Serbia
| | - Danijela Djonic
- Laboratory for Anthropology, Institute of Anatomy, Faculty of Medicine, University of Belgrade, 4/2 Dr Subotica, Belgrade, 11000, Serbia
| | - Vladimir Zivkovic
- Institute of Forensic Medicine, Faculty of Medicine, University of Belgrade, 31a Deligradska, Belgrade, 11000, Serbia
| | - Slobodan Nikolic
- Institute of Forensic Medicine, Faculty of Medicine, University of Belgrade, 31a Deligradska, Belgrade, 11000, Serbia
| | - Marija Djuric
- Laboratory for Anthropology, Institute of Anatomy, Faculty of Medicine, University of Belgrade, 4/2 Dr Subotica, Belgrade, 11000, Serbia.
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48
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Andronowski JM, Mundorff AZ, Pratt IV, Davoren JM, Cooper DML. Evaluating differential nuclear DNA yield rates and osteocyte numbers among human bone tissue types: A synchrotron radiation micro-CT approach. Forensic Sci Int Genet 2017; 28:211-218. [PMID: 28315820 DOI: 10.1016/j.fsigen.2017.03.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 01/24/2017] [Accepted: 03/02/2017] [Indexed: 11/16/2022]
Abstract
Molecular human identification has conventionally focused on DNA sampling from dense, weight-bearing cortical bone tissue, typically from femora or tibiae. A comparison of skeletal elements from three contemporary individuals demonstrated that elements with high quantities of cancellous bone yielded nuclear DNA at the highest rates, suggesting that preferentially sampling cortical bone may be suboptimal (Mundorff & Davoren, 2014). Despite these findings, the reason for the differential DNA yields between cortical and cancellous bone tissues remains unknown. The primary goal of this work is to ascertain whether differences in bone microstructure can be used to explain differential nuclear DNA yield among bone tissue types observed by Mundorff and Davoren (2014), with a focus on osteocytes and the three-dimensional (3D) quantification of their associated lacunae. Osteocytes and other bone cells are recognized to house DNA in bone tissue, thus examining the density of their lacunae may explain why nuclear DNA yield rates differ among bone tissue types. Lacunae were visualized and quantified using synchrotron radiation-based micro-Computed Tomographic imaging (SR micro-CT). Volumes of interest (VOIs) from cortical and cancellous bone tissues (n=129) were comparatively analyzed from the three skeletons sampled for Mundorff and Davoren's (2014) study. Analyses tested the primary hypothesis that the abundance and density of osteocytes (inferred from their lacunar spaces) vary between cortical and cancellous bone tissue types. Results demonstrated that osteocyte lacunar abundance and density vary between cortical and cancellous bone tissue types, with cortical bone VOIs containing a higher lacunar abundance and density. We found that the osteocyte lacunar density values are independent of nuclear DNA yield, suggesting an alternative explanation for the higher nuclear DNA yields from bones with greater quantities of cancellous bone tissue. The use of SR micro-CT allowed for a scale of analysis that revealed a high range of variation in lacunar abundance in both tissue types. Moreover, high-resolution SR micro-CT imaging revealed potential soft tissue remnants within marrow spaces not visible macroscopically. It is hypothesized that soft tissue remnants observed among the trabeculae of skeletal elements with high quantities of cancellous bone tissue are responsible for the high nuclear DNA yields. These findings have significant implications for bone-sample selection for nuclear DNA analysis in a forensic context when skeletal remains are recovered from the ground surface.
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Affiliation(s)
- Janna M Andronowski
- Department of Anatomy and Cell Biology, University of Saskatchewan, 107 Wiggins Road, Saskatoon, SK, S7N 5E5, Canada.
| | - Amy Z Mundorff
- Department of Anthropology, The University of Tennessee, Knoxville, TN 37996, USA
| | - Isaac V Pratt
- Department of Anatomy and Cell Biology, University of Saskatchewan, 107 Wiggins Road, Saskatoon, SK, S7N 5E5, Canada
| | - Jon M Davoren
- Bode Cellmark Forensics, 10430 Furnace Road Suite 107, Lorton, VA 22079, USA
| | - David M L Cooper
- Department of Anatomy and Cell Biology, University of Saskatchewan, 107 Wiggins Road, Saskatoon, SK, S7N 5E5, Canada
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49
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Liu Y, Chen B, Yin D. Effects of direction and shape of osteocyte lacunae on resisting impact and micro-damage of osteon. JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE 2017; 28:38. [PMID: 28144850 DOI: 10.1007/s10856-017-5850-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 01/10/2017] [Indexed: 06/06/2023]
Abstract
Animal bones bear varied impact loadings during in the movements of animals. The impact resistance and micro-damage of bones are influenced by their various microstructures at different length scales. In this paper, according to the microstructure of osteon, three 2-D microstructure models (circumferential ellipse lacunae (Model A), radial elliptical lacunae (Model B) and circular lacunae (Model C) were constructed for investigating the influences of the arranged direction and shape of osteocyte lacunae on resisting impact and micro-damage. Impact analytical results show that the maximal stress of the Model A is the minimum and that of the Model B is the maximal under same boundary conditions, which indicates that the circumferentially elliptical lacunae, whose minor axis is along the radial direction of the osteon (Model A), can enhance impact resistance of osteons effectively. The investigated results of the progressive damage show that the circumferentially ellipse lacunae (Model A) are more benefit to resist micro-damage and that the micro-cracks in the model are mainly along the circumferential direction of the osteon. These investigated results for the novel microstructures found in osteon can serve engineers as guidance in the designs of biomimetic and bioinspired tubular structures or materials for engineering applications.
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Affiliation(s)
- Yuxi Liu
- State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing, 400044, China
- College of Aerospace Engineering, Chongqing University, Chongqing, 400044, China
| | - Bin Chen
- State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing, 400044, China.
- College of Aerospace Engineering, Chongqing University, Chongqing, 400044, China.
| | - Dagang Yin
- State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing, 400044, China
- College of Aerospace Engineering, Chongqing University, Chongqing, 400044, China
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50
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Bach-Gansmo FL, Brüel A, Jensen MV, Ebbesen EN, Birkedal H, Thomsen JS. Osteocyte lacunar properties and cortical microstructure in human iliac crest as a function of age and sex. Bone 2016; 91:11-9. [PMID: 27397700 DOI: 10.1016/j.bone.2016.07.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 06/27/2016] [Accepted: 07/06/2016] [Indexed: 12/24/2022]
Abstract
Osteocytes are suggested to play a central role in bone remodeling. Evaluation of iliac crest biopsies is a standard procedure for evaluating bone conditions in the clinical setting. Despite the widespread use of such biopsies, little is known about the population of osteocytes in the iliac crest from normal individuals. Contradicting results have been reported on osteocyte lacunar properties in human bone. Hence, a solid understanding of the osteocyte population in healthy bone and the effect of age and sex is needed as good reference data are lacking. Furthermore, the role of cortical bone in bone quality has recently been suggested to be more important than previously realized. Therefore, the present study assesses osteocyte lacunar properties and cortical microstructure of the iliac crest as a function of age and sex. A total of 88 iliac crest bone samples from healthy individuals (46 women, aged 18.5-96.4years and 42 men, aged 22.6-94.6years) with an even age-distribution were examined using synchrotron radiation μCT and in house μCT, with >5×10(6) osteocyte lacunae measured and analyzed. The study revealed that osteocyte lacunar volumes were unaffected by both age and sex. Osteocyte lacunar density did not differ between women and men, and only showed a significant decrease with age when pooling data from both sexes. Cortical porosity and Haversian canal density increased while cortical thickness decreased with age, with cortical thinning dominating the age-related cortical bone loss. None of the cortical microstructural parameters showed any sex dependency. Only weak links between osteocyte lacunar properties and cortical microstructural properties in iliac crest bone were found. Interestingly, the Haversian canal diameters were significantly but weakly negatively correlated with osteocyte lacunar volumes.
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Affiliation(s)
| | - Annemarie Brüel
- Department of Biomedicine, Aarhus University, Aarhus, Denmark.
| | | | | | - Henrik Birkedal
- Department of Chemistry and iNANO, Aarhus University, Aarhus, Denmark.
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