101
|
3D printed Ti6Al4V implant surface promotes bone maturation and retains a higher density of less aged osteocytes at the bone-implant interface. Acta Biomater 2016; 30:357-367. [PMID: 26577985 DOI: 10.1016/j.actbio.2015.11.013] [Citation(s) in RCA: 122] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Revised: 09/28/2015] [Accepted: 11/09/2015] [Indexed: 01/15/2023]
Abstract
For load-bearing orthopaedic applications, metal implants having an interconnected pore structure exhibit the potential to facilitate bone ingrowth and the possibility for reducing the stiffness mismatch between the implant and bone, thus eliminating stress-shielding effects. 3D printed solid and macro-porous Ti6Al4V implants were evaluated after six-months healing in adult sheep femora. The ultrastructural composition of the bone-implant interface was investigated using Raman spectroscopy and electron microscopy, in a correlative manner. The mineral crystallinity and the mineral-to-matrix ratios of the interfacial tissue and the native bone were found to be similar. However, lower Ca/P ratios, lower carbonate content, but higher proline, phenylalanine and tyrosine levels indicated that the interfacial tissue remained less mature. Bone healing was more advanced at the porous implant surface (vs. the solid implant surface) based on the interfacial tissue ν1 CO3(2-)/ν2 PO4(3-) ratio, phenylalanine and tyrosine levels approaching those of the native bone. The mechanosensing infrastructure in bone, the osteocyte lacuno-canalicular network, retained ∼40% more canaliculi per osteocyte lacuna, i.e., a 'less aged' morphology at the interface. The osteocyte density per mineralised surface area was ∼36-71% higher at the interface after extended healing periods. STATEMENT OF SIGNIFICANCE In osseointegration research, the success of an implant surface or design is commonly determined by quantifying the amount of new bone, rather than its maturation, composition and structure. This work describes a novel correlative methodology to investigate the ultrastructure and composition of bone formed around and within 3D printed Ti6Al4V implants having an interconnected open-pore structure. Raman spectroscopy demonstrates that the molecular composition of the interfacial tissue at different implant surfaces may vary, suggesting differences in the extent to which bone maturation occurs even after long-term healing. Bone maturation corresponded well with the structural parameters associated with remodelling kinetics, for example, the osteocyte density and the average number of canaliculi per osteocyte lacuna.
Collapse
|
102
|
Abstract
The regulation of organ size is essential to human health and has fascinated biologists for centuries. Key to the growth process is the ability of most organs to integrate organ-extrinsic cues (eg, nutritional status, inflammatory processes) with organ-intrinsic information (eg, genetic programs, local signals) into a growth response that adapts to changing environmental conditions and ensures that the size of an organ is coordinated with the rest of the body. Paired organs such as the vertebrate limbs and the long bones within them are excellent models for studying this type of regulation because it is possible to manipulate one member of the pair and leave the other as an internal control. During development, growth plates at the end of each long bone produce a transient cartilage model that is progressively replaced by bone. Here, we review how proliferation and differentiation of cells within each growth plate are tightly controlled mainly by growth plate-intrinsic mechanisms that are additionally modulated by extrinsic signals. We also discuss the involvement of several signaling hubs in the integration and modulation of growth-related signals and how they could confer remarkable plasticity to the growth plate. Indeed, long bones have a significant ability for "catch-up growth" to attain normal size after a transient growth delay. We propose that the characterization of catch-up growth, in light of recent advances in physiology and cell biology, will provide long sought clues into the molecular mechanisms that underlie organ growth regulation. Importantly, catch-up growth early in life is commonly associated with metabolic disorders in adulthood, and this association is not completely understood. Further elucidation of the molecules and cellular interactions that influence organ size coordination should allow development of novel therapies for human growth disorders that are noninvasive and have minimal side effects.
Collapse
Affiliation(s)
- Alberto Roselló-Díez
- Developmental Biology Program, Sloan Kettering Institute, New York, New York 10065
| | - Alexandra L Joyner
- Developmental Biology Program, Sloan Kettering Institute, New York, New York 10065
| |
Collapse
|
103
|
Sugiyama T, Kono Y, Sekiguchi K, Kim YT, Oda H. Age-related fragility fracture: insights from the natural homeostatic system in the skeleton. Arch Osteoporos 2015; 10:45. [PMID: 26628422 DOI: 10.1007/s11657-015-0251-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Accepted: 11/17/2015] [Indexed: 02/03/2023]
Affiliation(s)
- Toshihiro Sugiyama
- Department of Orthopaedic Surgery, Saitama Medical University, 38 Morohongo, Moroyama, Saitama, 350-0495, Japan.
| | - Yoshihiko Kono
- Department of Orthopaedic Surgery, Saitama Medical University, 38 Morohongo, Moroyama, Saitama, 350-0495, Japan
| | - Kogoro Sekiguchi
- Department of Orthopaedic Surgery, Saitama Medical University, 38 Morohongo, Moroyama, Saitama, 350-0495, Japan
| | - Yoon Taek Kim
- Department of Orthopaedic Surgery, Saitama Medical University, 38 Morohongo, Moroyama, Saitama, 350-0495, Japan
| | - Hiromi Oda
- Department of Orthopaedic Surgery, Saitama Medical University, 38 Morohongo, Moroyama, Saitama, 350-0495, Japan
| |
Collapse
|
104
|
Sasaki M, Kuroshima S, Aoki Y, Inaba N, Sawase T. Ultrastructural alterations of osteocyte morphology via loaded implants in rabbit tibiae. J Biomech 2015; 48:4130-4141. [DOI: 10.1016/j.jbiomech.2015.10.025] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Revised: 07/29/2015] [Accepted: 10/18/2015] [Indexed: 11/25/2022]
|
105
|
Zimmermann EA, Busse B, Ritchie RO. The fracture mechanics of human bone: influence of disease and treatment. BONEKEY REPORTS 2015; 4:743. [PMID: 26380080 PMCID: PMC4562496 DOI: 10.1038/bonekey.2015.112] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2015] [Revised: 06/30/2015] [Accepted: 07/03/2015] [Indexed: 01/09/2023]
Abstract
Aging and bone diseases are associated with increased fracture risk. It is therefore pertinent to seek an understanding of the origins of such disease-related deterioration in bone's mechanical properties. The mechanical integrity of bone derives from its hierarchical structure, which in healthy tissue is able to resist complex physiological loading patterns and tolerate damage. Indeed, the mechanisms through which bone derives its mechanical properties make fracture mechanics an ideal framework to study bone's mechanical resistance, where crack-growth resistance curves give a measure of the intrinsic resistance to the initiation of cracks and the extrinsic resistance to the growth of cracks. Recent research on healthy cortical bone has demonstrated how this hierarchical structure can develop intrinsic toughness at the collagen fibril scale mainly through sliding and sacrificial bonding mechanisms that promote plasticity. Furthermore, the bone-matrix structure develops extrinsic toughness at much larger micrometer length-scales, where the structural features are large enough to resist crack growth through crack-tip shielding mechanisms. Although healthy bone tissue can generally resist physiological loading environments, certain conditions such as aging and disease can significantly increase fracture risk. In simple terms, the reduced mechanical integrity originates from alterations to the hierarchical structure. Here, we review how human cortical bone resists fracture in healthy bone and how changes to the bone structure due to aging, osteoporosis, vitamin D deficiency and Paget's disease can affect the mechanical integrity of bone tissue.
Collapse
Affiliation(s)
- Elizabeth A Zimmermann
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Björn Busse
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Robert O Ritchie
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Department of Materials Science & Engineering, University of California, Berkeley, CA, USA
| |
Collapse
|
106
|
Milovanovic P, Adamu U, Simon MJK, Rolvien T, Djuric M, Amling M, Busse B. Age- and Sex-Specific Bone Structure Patterns Portend Bone Fragility in Radii and Tibiae in Relation to Osteodensitometry: A High-Resolution Peripheral Quantitative Computed Tomography Study in 385 Individuals. J Gerontol A Biol Sci Med Sci 2015; 70:1269-75. [DOI: 10.1093/gerona/glv052] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 04/02/2015] [Indexed: 11/12/2022] Open
|
107
|
Shah FA, Wang X, Thomsen P, Grandfield K, Palmquist A. High-Resolution Visualization of the Osteocyte Lacuno-Canalicular Network Juxtaposed to the Surface of Nanotextured Titanium Implants in Human. ACS Biomater Sci Eng 2015; 1:305-313. [DOI: 10.1021/ab500127y] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
| | - Xiaoyue Wang
- Department
of Materials Science and Engineering, McMaster University, Hamilton, ON L8S 4L7, Canada
| | | | - Kathryn Grandfield
- Department
of Materials Science and Engineering, McMaster University, Hamilton, ON L8S 4L7, Canada
| | | |
Collapse
|
108
|
Activation of HIFa pathway in mature osteoblasts disrupts the integrity of the osteocyte/canalicular network. PLoS One 2015; 10:e0121266. [PMID: 25806791 PMCID: PMC4373796 DOI: 10.1371/journal.pone.0121266] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2014] [Accepted: 01/29/2015] [Indexed: 12/19/2022] Open
Abstract
The hypoxia-inducible factors (HIFs), HIF-1α and HIF-2α, are the central mediators of the homeostatic response that enables cells to survive and differentiate in low-oxygen conditions. Previous studies indicated that disruption of the von Hippel-Lindau gene (Vhl) coincides with the activation of HIFα signaling. Here we show that inactivation of Vhl in mature osteoblasts/osteocytes induces their apoptosis and disrupts the cell/canalicular network. VHL-deficient (ΔVHL) mice exhibited a significantly increased cortical bone area resulting from enhanced proliferation and osteogenic differentiation of the bone marrow stromal cells (BMSCs) by inducing the expression of β-catenin in the BMSC. Our data suggest that the VHL/HIFα pathway in mature osteoblasts/osteocytes plays a critical role in the bone cell/canalicular network and that the changes of osteocyte morphology/function and cell/canalicular network may unleash the bone formation, The underlying mechanism of which was the accumulation of β-catenin in the osteoblasts/osteoprogenitors of the bone marrow.
Collapse
|
109
|
Kuroshima S, Yasutake M, Tsuiki K, Nakano T, Sawase T. Structural and Qualitative Bone Remodeling Around Repetitive Loaded Implants in Rabbits. Clin Implant Dent Relat Res 2015; 17 Suppl 2:e699-710. [DOI: 10.1111/cid.12318] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Shinichiro Kuroshima
- Department of Applied Prosthodontics; Graduate School of Biomedical Sciences; Nagasaki University; Nagasaki Japan
| | - Munenori Yasutake
- Department of Applied Prosthodontics; Graduate School of Biomedical Sciences; Nagasaki University; Nagasaki Japan
| | - Kotaro Tsuiki
- Department of Applied Prosthodontics; Graduate School of Biomedical Sciences; Nagasaki University; Nagasaki Japan
| | - Takayoshi Nakano
- Division of Materials and Manufacturing Science, Graduate School of Engineering; Osaka University; Osaka Japan
| | - Takashi Sawase
- Department of Applied Prosthodontics; Graduate School of Biomedical Sciences; Nagasaki University; Nagasaki Japan
| |
Collapse
|
110
|
Kobayashi K, Nojiri H, Saita Y, Morikawa D, Ozawa Y, Watanabe K, Koike M, Asou Y, Shirasawa T, Yokote K, Kaneko K, Shimizu T. Mitochondrial superoxide in osteocytes perturbs canalicular networks in the setting of age-related osteoporosis. Sci Rep 2015; 5:9148. [PMID: 25779629 PMCID: PMC5376208 DOI: 10.1038/srep09148] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 02/20/2015] [Indexed: 12/21/2022] Open
Abstract
Osteocytes are major bone cells that play a crucial role in maintaining the quality of and healing damage to bone tissue. The number of living osteocytes and canalicular networks declines in an age-dependent manner. However, the pathological effects of mitochondrial redox imbalances on osteocytes and bone metabolism have not been fully elucidated. We generated mice lacking mitochondrial superoxide dismutase 2 (Sod2) in osteocytes. Like an aged bone, Sod2 depletion in the osteocytes positively enhanced the production of cellular superoxide in vivo. A bone morphological analysis demonstrated that the Sod2-deficient femurs showed remarkable bone loss in an age-dependent manner. Interestingly, Sod2 loss induced markedly disorganized osteocytic canalicular networks and decreased the number of live osteocytes. Furthermore, Sod2 deficiency significantly suppressed bone formation and increased bone resorption concomitant with the upregulation of sclerostin and receptor activator of NF-κB ligand (RANKL). In vitro experiments also revealed that treatment with paraquat, a superoxide inducer in mitochondria, promoted the RANKL expression via, in part, ERK phosphorylation. These findings demonstrate that the mitochondrial superoxide induced in osteocytes by Sod2 ablation causes age-related bone loss due to the impairment of canalicular networks and bone metabolism via the deregulation of the sclerostin and RANKL expression.
Collapse
Affiliation(s)
- Keiji Kobayashi
- 1] Department of Advanced Aging Medicine, Chiba University Graduate School of Medicine, Chiba, Japan [2] Department of Orthopaedics, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Hidetoshi Nojiri
- Department of Orthopaedics, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Yoshitomo Saita
- Department of Orthopaedics, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Daichi Morikawa
- 1] Department of Advanced Aging Medicine, Chiba University Graduate School of Medicine, Chiba, Japan [2] Department of Orthopaedics, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Yusuke Ozawa
- Department of Advanced Aging Medicine, Chiba University Graduate School of Medicine, Chiba, Japan
| | - Kenji Watanabe
- Department of Advanced Aging Medicine, Chiba University Graduate School of Medicine, Chiba, Japan
| | - Masato Koike
- 1] Department of Advanced Aging Medicine, Chiba University Graduate School of Medicine, Chiba, Japan [2] Department of Orthopaedics, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Yoshinori Asou
- Department of Orthopedic Surgery, Tokyo Medical and Dental University, Tokyo, Japan
| | - Takuji Shirasawa
- Department of Aging Control Medicine, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Koutaro Yokote
- Department of Medicine, Chiba University Graduate School of Medicine, Chiba, Japan
| | - Kazuo Kaneko
- Department of Orthopaedics, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Takahiko Shimizu
- Department of Advanced Aging Medicine, Chiba University Graduate School of Medicine, Chiba, Japan
| |
Collapse
|
111
|
Sugiyama T, Kim YT, Oda H. Osteoporosis therapy: a novel insight from natural homeostatic system in the skeleton. Osteoporos Int 2015; 26:443-7. [PMID: 25288445 DOI: 10.1007/s00198-014-2923-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Accepted: 09/25/2014] [Indexed: 01/22/2023]
Abstract
The skeleton normally responds to mechanical environment to maintain the resulting elastic deformation (strain) of bone, while increased bone strength by an osteoporosis drug results in decreased bone strain. Thus, it can be hypothesized that the effect of osteoporosis therapy is limited by natural homeostatic system in the skeleton. This logic is consistent with the fact that there exists a powerful effect that returns bone mass to its pre-treatment level after the withdrawal of treatment with osteoporosis agents. The present hypothesis provides a new significant insight into the mechanisms by which osteoporosis drugs improve bone fragility. Here we briefly discuss the effects of teriparatide, romosozumab, and odanacatib on bones in animals and humans.
Collapse
Affiliation(s)
- T Sugiyama
- Department of Orthopaedic Surgery, Saitama Medical University, 38 Morohongo, Moroyama, Saitama, 350-0495, Japan,
| | | | | |
Collapse
|
112
|
Milovanovic P, Zimmermann EA, Riedel C, vom Scheidt A, Herzog L, Krause M, Djonic D, Djuric M, Püschel K, Amling M, Ritchie RO, Busse B. Multi-level characterization of human femoral cortices and their underlying osteocyte network reveal trends in quality of young, aged, osteoporotic and antiresorptive-treated bone. Biomaterials 2015; 45:46-55. [PMID: 25662494 DOI: 10.1016/j.biomaterials.2014.12.024] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Revised: 12/11/2014] [Accepted: 12/20/2014] [Indexed: 01/04/2023]
Abstract
Characterization of bone's hierarchical structure in aging, disease and treatment conditions is imperative to understand the architectural and compositional modifications to the material and its mechanical integrity. Here, cortical bone sections from 30 female proximal femurs - a frequent fracture site - were rigorously assessed to characterize the osteocyte lacunar network, osteon density and patterns of bone matrix mineralization by backscatter-electron imaging and Fourier-transform infrared spectroscopy in relation to mechanical properties obtained by reference-point indentation. We show that young, healthy bone revealed the highest resistance to mechanical loading (indentation) along with higher mineralization and preserved osteocyte-lacunar characteristics. In contrast, aging and osteoporosis significantly alter bone material properties, where impairment of the osteocyte-lacunar network was evident through accumulation of hypermineralized osteocyte lacunae with aging and even more in osteoporosis, highlighting increased osteocyte apoptosis and reduced mechanical competence. But antiresorptive treatment led to fewer mineralized lacunae and fewer but larger osteons signifying rejuvenated bone. In summary, multiple structural and compositional changes to the bone material were identified leading to decay or maintenance of bone quality in disease, health and treatment conditions. Clearly, antiresorptive treatment reflected favorable effects on the multifunctional osteocytic cells that are a prerequisite for bone's structural, metabolic and mechanosensory integrity.
Collapse
Affiliation(s)
- Petar Milovanovic
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestrasse 59, 22529 Hamburg, Germany; Laboratory for Anthropology, Institute of Anatomy, Faculty of Medicine, University of Belgrade, Dr Subotica 4/2, 11000 Belgrade, Serbia
| | - Elizabeth A Zimmermann
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestrasse 59, 22529 Hamburg, Germany
| | - Christoph Riedel
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestrasse 59, 22529 Hamburg, Germany
| | - Annika vom Scheidt
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestrasse 59, 22529 Hamburg, Germany
| | - Lydia Herzog
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestrasse 59, 22529 Hamburg, Germany
| | - Matthias Krause
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestrasse 59, 22529 Hamburg, Germany
| | - Danijela Djonic
- Laboratory for Anthropology, Institute of Anatomy, Faculty of Medicine, University of Belgrade, Dr Subotica 4/2, 11000 Belgrade, Serbia
| | - Marija Djuric
- Laboratory for Anthropology, Institute of Anatomy, Faculty of Medicine, University of Belgrade, Dr Subotica 4/2, 11000 Belgrade, Serbia
| | - Klaus Püschel
- Department of Forensic Medicine, University Medical Center Hamburg-Eppendorf, Butenfeld 34, 22529 Hamburg, Germany
| | - Michael Amling
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestrasse 59, 22529 Hamburg, Germany
| | - Robert O Ritchie
- Department of Materials Science and Engineering, University of California, Berkeley, USA; Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley CA 94720, USA
| | - Björn Busse
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestrasse 59, 22529 Hamburg, Germany; Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley CA 94720, USA.
| |
Collapse
|
113
|
Synchrotron X-ray phase nano-tomography-based analysis of the lacunar–canalicular network morphology and its relation to the strains experienced by osteocytes in situ as predicted by case-specific finite element analysis. Biomech Model Mechanobiol 2014; 14:267-82. [DOI: 10.1007/s10237-014-0601-9] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Accepted: 06/06/2014] [Indexed: 11/26/2022]
|
114
|
Simon MJK, Beil FT, Rüther W, Busse B, Koehne T, Steiner M, Pogoda P, Ignatius A, Amling M, Oheim R. High fluoride and low calcium levels in drinking water is associated with low bone mass, reduced bone quality and fragility fractures in sheep. Osteoporos Int 2014; 25:1891-903. [PMID: 24777741 PMCID: PMC4048471 DOI: 10.1007/s00198-014-2707-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Accepted: 02/28/2014] [Indexed: 11/25/2022]
Abstract
UNLABELLED Chronic environmental fluoride exposure under calcium stress causes fragility fractures due to osteoporosis and bone quality deterioration, at least in sheep. Proof of skeletal fluorosis, presenting without increased bone density, calls for a review of fracture incidence in areas with fluoridated groundwater, including an analysis of patients with low bone mass. INTRODUCTION Understanding the skeletal effects of environmental fluoride exposure especially under calcium stress remains an unmet need of critical importance. Therefore, we studied the skeletal phenotype of sheep chronically exposed to highly fluoridated water in the Kalahari Desert, where livestock is known to present with fragility fractures. METHODS Dorper ewes from two flocks in Namibia were studied. Chemical analyses of water, blood and urine were executed for both cohorts. Skeletal phenotyping comprised micro-computer tomography (μCT), histological, histomorphometric, biomechanical, quantitative backscattered electron imaging (qBEI) and energy-dispersive X-ray (EDX) analysis. Analysis was performed in direct comparison with undecalcified human iliac crest bone biopsies of patients with fluoride-induced osteopathy. RESULTS The fluoride content of water, blood and urine was significantly elevated in the Kalahari group compared to the control. Surprisingly, a significant decrease in both cortical and trabecular bones was found in sheep chronically exposed to fluoride. Furthermore, osteoid parameters and the degree and heterogeneity of mineralization were increased. The latter findings are reminiscent of those found in osteoporotic patients with treatment-induced fluorosis. Mechanical testing revealed a significant decrease in the bending strength, concurrent with the clinical observation of fragility fractures in sheep within an area of environmental fluoride exposure. CONCLUSIONS Our data suggest that fluoride exposure with concomitant calcium deficit (i) may aggravate bone loss via reductions in mineralized trabecular and cortical bone mass and (ii) can cause fragility fractures and (iii) that the prevalence of skeletal fluorosis especially due to groundwater exposure should be reviewed in many areas of the world as low bone mass alone does not exclude fluorosis.
Collapse
Affiliation(s)
- M. J. K. Simon
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
| | - F. T. Beil
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
- Department of Orthopedics, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
| | - W. Rüther
- Department of Orthopedics, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
| | - B. Busse
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
| | - T. Koehne
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
| | - M. Steiner
- Institute of Orthopaedic Research and Biomechanics, Center of Musculoskeletal Research, University of Ulm, 89081 Ulm, Germany
| | - P. Pogoda
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
| | - A. Ignatius
- Institute of Orthopaedic Research and Biomechanics, Center of Musculoskeletal Research, University of Ulm, 89081 Ulm, Germany
| | - M. Amling
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
| | - R. Oheim
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
| |
Collapse
|
115
|
Disrupted bone remodeling leads to cochlear overgrowth and hearing loss in a mouse model of fibrous dysplasia. PLoS One 2014; 9:e94989. [PMID: 24788917 PMCID: PMC4006800 DOI: 10.1371/journal.pone.0094989] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Accepted: 03/20/2014] [Indexed: 02/05/2023] Open
Abstract
Normal hearing requires exquisite cooperation between bony and sensorineural structures within the cochlea. For example, the inner ear secretes proteins such as osteoprotegrin (OPG) that can prevent cochlear bone remodeling. Accordingly, diseases that affect bone regulation can also result in hearing loss. Patients with fibrous dysplasia develop trabecular bone overgrowth resulting in hearing loss if the lesions affect the temporal bones. Unfortunately, the mechanisms responsible for this hearing loss, which could be sensorineural and/or conductive, remain unclear. In this study, we used a unique transgenic mouse model of increased Gs G-protein coupled receptor (GPCR) signaling induced by expression of an engineered receptor, Rs1, in osteoblastic cells. These ColI(2.3)+/Rs1+ mice showed dramatic bone lesions that histologically and radiologically resembled fibrous dysplasia. We found that ColI(2.3)+/Rs1+ mice showed progressive and severe conductive hearing loss. Ossicular chain impingement increased with the size and number of dysplastic lesions. While sensorineural structures were unaffected, ColI(2.3)+/Rs1+ cochleae had abnormally high osteoclast activity, together with elevated tartrate resistant acid phosphatase (TRAP) activity and receptor activator of nuclear factor kappa-B ligand (Rankl) mRNA expression. ColI(2.3)+/Rs1+ cochleae also showed decreased expression of Sclerostin (Sost), an antagonist of the Wnt signaling pathway that normally increases bone formation. The osteocyte canalicular networks of ColI(2.3)+/Rs1+ cochleae were disrupted and showed abnormal osteocyte morphology. The osteocytes in the ColI(2.3)+/Rs1+ cochleae showed increased expression of matrix metalloproteinase 13 (MMP-13) and TRAP, both of which can support osteocyte-mediated peri-lacunar remodeling. Thus, while the ossicular chain impingement is sufficient to account for the progressive hearing loss in fibrous dysplasia, the deregulation of bone remodeling extends to the cochlea as well. Our findings suggest that factors regulating bone remodeling, including peri-lacunar remodeling by osteocytes, may be useful targets for treating the bony overgrowths and hearing changes of fibrous dysplasia and other bony pathologies.
Collapse
|
116
|
Milovanovic P, Rakocevic Z, Djonic D, Zivkovic V, Hahn M, Nikolic S, Amling M, Busse B, Djuric M. Nano-structural, compositional and micro-architectural signs of cortical bone fragility at the superolateral femoral neck in elderly hip fracture patients vs. healthy aged controls. Exp Gerontol 2014; 55:19-28. [PMID: 24614625 DOI: 10.1016/j.exger.2014.03.001] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Revised: 02/18/2014] [Accepted: 03/02/2014] [Indexed: 12/13/2022]
Abstract
To unravel the origins of decreased bone strength in the superolateral femoral neck, we assessed bone structural features across multiple length scales at this cortical fracture initiating region in postmenopausal women with hip fracture and in aged-matched controls. Our combined methodological approach encompassed atomic force microscopy (AFM) characterization of cortical bone nano-structure, assessment of mineral content/distribution via quantitative backscattered electron imaging (qBEI), measurement of bone material properties by reference point indentation, as well as evaluation of cortical micro-architecture and osteocyte lacunar density. Our findings revealed a wide range of differences between the fracture group and the controls, suggesting a number of detrimental changes at various levels of cortical bone hierarchical organization that may render bone fragile. Namely, mineral crystals at external cortical bone surfaces of the fracture group were larger (65.22nm±41.21nm vs. 36.75nm±18.49nm, p<0.001), and a shift to a higher mineral content and more homogenous mineralization profile as revealed via qBEI were found in the bone matrix of the fracture group. Fracture cases showed nearly 35% higher cortical porosity and showed significantly reduced osteocyte lacunar density compared to controls (226±27 vs. 247±32#/mm(2), p=0.05). Along with increased crystal size, a shift towards higher mineralization and a tendency to increased cortical porosity and reduced osteocyte lacunar number delineate that cortical bone of the superolateral femoral neck bears distinct signs of fragility at various levels of its structural organization. These results contribute to the understanding of hierarchical bone structure changes in age-related fragility.
Collapse
Affiliation(s)
- Petar Milovanovic
- Laboratory for Anthropology, Institute of Anatomy, School of Medicine, University of Belgrade, 4/2 Dr Subotica, 11000 Belgrade, Serbia; Department of Osteology & Biomechanics, University Medical Center Hamburg-Eppendorf, 59 Lottestr., D-22529 Hamburg, Germany.
| | - Zlatko Rakocevic
- Laboratory for Atomic Physics, Institute of Nuclear Sciences Vinca, University of Belgrade, 11001 Belgrade, Serbia.
| | - Danijela Djonic
- Laboratory for Anthropology, Institute of Anatomy, School of Medicine, University of Belgrade, 4/2 Dr Subotica, 11000 Belgrade, Serbia.
| | - Vladimir Zivkovic
- Institute of Forensic Medicine, School of Medicine, University of Belgrade, 31a Deligradska, 11000 Belgrade, Serbia.
| | - Michael Hahn
- Department of Osteology & Biomechanics, University Medical Center Hamburg-Eppendorf, 59 Lottestr., D-22529 Hamburg, Germany.
| | - Slobodan Nikolic
- Institute of Forensic Medicine, School of Medicine, University of Belgrade, 31a Deligradska, 11000 Belgrade, Serbia.
| | - Michael Amling
- Department of Osteology & Biomechanics, University Medical Center Hamburg-Eppendorf, 59 Lottestr., D-22529 Hamburg, Germany.
| | - Bjoern Busse
- Department of Osteology & Biomechanics, University Medical Center Hamburg-Eppendorf, 59 Lottestr., D-22529 Hamburg, Germany.
| | - Marija Djuric
- Laboratory for Anthropology, Institute of Anatomy, School of Medicine, University of Belgrade, 4/2 Dr Subotica, 11000 Belgrade, Serbia.
| |
Collapse
|