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Zhang K, Liu Y, Lu Y, Liu G, Shen X. Involvement of icaritin in the regulation of osteocyte exosomal microRNAs. J Orthop Surg Res 2025; 20:164. [PMID: 39953581 PMCID: PMC11827220 DOI: 10.1186/s13018-025-05583-9] [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: 10/21/2024] [Accepted: 02/06/2025] [Indexed: 02/17/2025] Open
Abstract
OBJECTIVE To explore the effects of Icaritin (ICA) on the regulation of osteocyte exosomal miRNAs and to promote the understanding of the potential molecular mechanisms involved in bone repair by ICA. METHODS MLO-Y4 cells were treat with PBS or 10 µM ICA for 24 h and the supernatant was collected. Exosomes were isolated and purified according to standard methods, and identified by transmission electron microscopy, nanoparticle tracking analysis and protein blotting. Exosomal miRNAs were analysed by RNA sequencing. RESULTS Osteocyte exosomes were successfully isolated and characterised. MiRNA sequencing showed that two known exosomal miRNAs (miR-128-3p, miR-30a-5p) were significantly up-regulated and two were significantly down-regulated (miR-5112, miR-1285) after ICA intervention. CONCLUSION Based on the findings, ICA regulates several miRNAs of osteocytes, which deepen our understanding of the therapeutic effects and mechanisms of ICA on skeletal diseases. THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE Osteocytes are the most abundant cell type in bone tissue, of which the impact on bone homeostasis is still not clear. This study explored the impact of icaritin on osteocytes and their derived exosomes. By doing so, we hope to contribute to the understanding the therapeutic potential of ICA and osteocytes in maintaining bone health and treating conditions such as osteoporosis.
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Affiliation(s)
- Kaijia Zhang
- Suzhou TCM Hospital, Nanjing University of Chinese Medicine, Suzhou, 215003, P. R. China
| | - Yujiang Liu
- Suzhou TCM Hospital, Nanjing University of Chinese Medicine, Suzhou, 215003, P. R. China
| | - Yue Lu
- Suzhou TCM Hospital, Nanjing University of Chinese Medicine, Suzhou, 215003, P. R. China
| | - Gongwen Liu
- Suzhou TCM Hospital, Nanjing University of Chinese Medicine, Suzhou, 215003, P. R. China
| | - Xiaofeng Shen
- Suzhou TCM Hospital, Nanjing University of Chinese Medicine, Suzhou, 215003, P. R. China.
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The role of copper chromite nanoparticles on physical and bio properties of scaffolds based on poly(glycerol-azelaic acid) for application in tissue engineering fields. Cell Tissue Res 2023; 391:357-373. [PMID: 36454270 DOI: 10.1007/s00441-022-03708-8] [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: 03/27/2022] [Accepted: 11/06/2022] [Indexed: 12/05/2022]
Abstract
Tissue engineering combines suitable cells, engineering methods, and proper biochemical factors to develop functional and biological tissues and repair damaged tissues. In this study, we focused on synthesizing and characterizing a nanocomposite scaffold based on glycerol and azelaic acid (Gl-Az) combined with copper chromite (CuCr2O4) nanoparticles in order to increase the osteogenic differentiation efficiency of human adipose-derived stem cells (hADSCs) on fabricated scaffolds. The degradability and hydrophobicity properties as well as mechanical and thermal behaviors of nanocomposite scaffolds were investigated. Next, the cell toxicity of glycerol, azelaic acid and CuCr2O4 nanoparticles was studied by MTT assay test and acridine orange staining. Finally, the osteogenic differentiation of hADSCs on Gl-Az-CuCr2O4 scaffolds was examined using alkaline phosphatase activity (ALP) and calcium content. The obtained results demonstrated that Gl-Az-1%CuCr2O4 not only showed appropriate mechanical strength, biocompatibility and degradability but also influenced the capability of hADSCs to differentiate into osteogenic lineages. The hADSCs culture in Gl-Az-1%CuCr2O4 showed a significant increase in ALP activity levels and calcium biomineralization after 14 days of osteogenic differentiation. In conclusion, the Gl-Az-1%CuCr2O4 nanocomposite could be used as a biocompatible and degradable scaffold to induce the bone differentiation of hADSCs and it could be a promising scaffold in bone regenerative medicine.
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Lei X, Liu Q, Li S, Zhang Z, Yang X. Effects of fluid shear stress on expression of focal adhesion kinase in MG-63 human osteoblast-like cells on different surface modification of titanium. Bioengineered 2021; 12:4962-4971. [PMID: 34374319 PMCID: PMC8806473 DOI: 10.1080/21655979.2021.1962686] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This study aimed to investigate the effect of fluid shear stress (FSS) on cell proliferation and expression of focal adhesion kinase (FAK) in MG-63 cells on different modified titanium surfaces. MG63 cells were cultured on three different surfaces: glass slide, polished treatment (PT) titanium surface and sandblasted/acid-etched surfaces (SLA) titanium surface. The surface topography and roughness were evaluated by scanning electron microscopy (SEM) and atomic force microscopy (AFM), respectively. The cells were subjected to FSS, and the cell appearance before and after the stress was evaluated. MTT assay was applied to estimate cell proliferation. The mRNA and protein levels of FAK were determined by qRT-PCR and western blotting. Titanium plates demonstrated different surface microtopography. Parameter Ra values of SLA group were around 3.4 µm, which was higher than PT group. Exposure to the FSS of 12 dynes/cm2 significantly induced positive upregulation of cellular proliferation and the expression of FAK, which were directly correlated with the duration of exposure and surface. Cells in SLA group were able to endurance the longtime of FSS, especially under the FSS of 16 dynes/cm2. SLA surface had a positive influence on the expression of FAK. Different surface modifications created different microtopography of titanium plates. Cell proliferation and the mRNA and protein expression of FAK were stimulated by FSS and regulated by a marked synergistic effect of surface topography and the level and duration of FSS.
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Affiliation(s)
- Xin Lei
- Department of Stomatology, Shenzhen Longhua District Central Hospital, Shenzhen, China
| | - Qiong Liu
- Stomatological Hospital, Southern Medical University, Guangzhou Guangdong, China
| | - Shiyi Li
- Stomatological Hospital, Southern Medical University, Guangzhou Guangdong, China
| | - Zhaoqiang Zhang
- Stomatological Hospital, Southern Medical University, Guangzhou Guangdong, China
| | - Xiaoyu Yang
- Stomatological Hospital, Southern Medical University, Guangzhou Guangdong, China
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Distinct Concentration-Dependent Molecular Pathways Regulate Bone Cell Responses to Cobalt and Chromium Exposure from Joint Replacement Prostheses. Int J Mol Sci 2021; 22:ijms22105225. [PMID: 34069294 PMCID: PMC8156984 DOI: 10.3390/ijms22105225] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 05/07/2021] [Accepted: 05/08/2021] [Indexed: 12/27/2022] Open
Abstract
Systemic cobalt (Co) and chromium (Cr) concentrations may be elevated in patients with metal joint replacement prostheses. Several studies have highlighted the detrimental effects of this exposure on bone cells in vitro, but the underlying mechanisms remain unclear. In this study, we use whole-genome microarrays to comprehensively assess gene expression in primary human osteoblasts, osteoclast precursors and mature resorbing osteoclasts following exposure to clinically relevant circulating versus local periprosthetic tissue concentrations of Co2+ and Cr3+ ions and CoCr nanoparticles. We also describe the gene expression response in osteoblasts on routinely used prosthesis surfaces in the presence of metal exposure. Our results suggest that systemic levels of metal exposure have no effect on osteoblasts, and primarily inhibit osteoclast differentiation and function via altering the focal adhesion and extracellular matrix interaction pathways. In contrast, periprosthetic levels of metal exposure inhibit both osteoblast and osteoclast activity by altering HIF-1α signaling and endocytic/cytoskeletal genes respectively, as well as increasing inflammatory signaling with mechanistic implications for adverse reactions to metal debris. Furthermore, we identify gene clusters and KEGG pathways for which the expression correlates with increasing Co2+:Cr3+ concentrations, and has the potential to serve as early markers of metal toxicity. Finally, our study provides a molecular basis for the improved clinical outcomes for hydroxyapatite-coated prostheses that elicit a pro-survival osteogenic gene signature compared to grit-blasted and plasma-sprayed titanium-coated surfaces in the presence of metal exposure.
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Zhang D, Li X, Pi C, Cai L, Liu Y, Du W, Yang W, Xie J. Osteoporosis-decreased extracellular matrix stiffness impairs connexin 43-mediated gap junction intercellular communication in osteocytes. Acta Biochim Biophys Sin (Shanghai) 2020; 52:517-526. [PMID: 32286624 DOI: 10.1093/abbs/gmaa025] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 12/20/2019] [Accepted: 02/24/2020] [Indexed: 02/05/2023] Open
Abstract
Osteocytes are the main sensitive and responsive cells for mechanical stimuli in bone. The connexin family enables them to communicate with each other via forming functional gap junctions. However, how osteoporosis-impaired extracellular mechanical property modulates gap junction intercellular communication in osteocytes remains elusive. In this study, we established an ovariectomy (OVX)-induced osteoporosis mouse model in vivo and a polydimethylsiloxane (PDMS)-based cell culture substrate model in vitro to explore the influence of extracellular matrix (ECM) stiffness on cell-to-cell communication in osteocytes. Firstly, we established an OVX-induced osteoporosis mouse model by characterizing the changes in radiography, morphology and histochemistry of femurs. Our results showed that osteoporosis decreased the bone matrix stiffness together with the changes including the loss of osteocytes and the decrease of protein markers. Meanwhile, the dendritic process interconnection and channel-forming protein, Cx43, were reduced in osteoporosis mice. Next we mimicked ECM stiffness changes in vitro by using PDMS substrates at ratios 1:5 for normal stiffness and 1:45 for osteoporosis stiffness. Our results showed that the decreased ECM stiffness reduced the number of dendritic processes in a single cell and gap junctions between adjacent osteocytes. We further detected the decreased expression of Cx43, in the substrate with decreased stiffness. Finally, we found that gap junction-based intercellular communication was reduced in living osteocytes in the substrate with decreased stiffness. This study demonstrates the correlation between ECM mechanical property and cell-to-cell communication in osteocytes and might pave the way for further exploration of osteoporosis in terms of biomechanics.
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Affiliation(s)
- Demao Zhang
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610064, China
| | - Xin Li
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610064, China
| | - Caixia Pi
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610064, China
| | - Linyi Cai
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610064, China
| | - Yang Liu
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610064, China
| | - Wei Du
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610064, China
| | - Wenbin Yang
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610064, China
- National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610064, China
| | - Jing Xie
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610064, China
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Thorkildsen RD, Johansson CB, Hogmalm J, Johansson PH, Røkkum M. Early Cup Loosening After Metal-on-Metal Total Joint Replacement of the Trapeziometacarpal Joint: A Retrieval Study. J Hand Surg Am 2020; 45:213-222. [PMID: 31537396 DOI: 10.1016/j.jhsa.2019.06.020] [Citation(s) in RCA: 7] [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: 01/18/2019] [Revised: 05/21/2019] [Accepted: 06/28/2019] [Indexed: 02/02/2023]
Abstract
PURPOSE To investigate the possible mechanisms behind early cup loosening in a metal-on-metal trapeziometacarpal joint replacement. METHODS The trapezia from 5 female patients were removed as part of a salvage procedure after a median of 22 months (range, 7-43 months) after implantation. Three osteoarthritic patients with symptomatic cup loosening and 2 with instability had a median age of 62 years (range, 59-65 years) at primary surgery. The trapezia with cups in situ were preserved and processed for histomorphometry. Studies with laser ablation inductively coupled plasma mass spectrometry and scanning electron microscopy with energy dispersive x-ray spectroscopy were also performed on 2 of the specimens. RESULTS In all 5 specimens, osteolytic lesions undermined the cups and were also seen at the cup edges, completely surrounding the loose cups. Large amounts of dark particular material were seen in the periprosthetic tissues, mostly internalized by macrophages. The presence of chrome and cobalt in these regions was confirmed. Four of the 5 cups showed marked or complete loss of hydroxyapatite. CONCLUSIONS We have found several possible explanations for the poor performance of this cup, including its cannulated design and metal-on-metal bearing. The changes seen are early and advanced, raising serious concerns about the implant and particularly the articulation. TYPE OF STUDY/LEVEL OF EVIDENCE Therapeutic V.
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Affiliation(s)
- Rasmus D Thorkildsen
- Division of Orthopedic Surgery, Oslo University Hospital, Gothenburg, Sweden; Institute of Clinical Medicine, University of Oslo, Oslo, Norway, Gothenburg, Sweden.
| | - Carina B Johansson
- Department of Prosthodontics/Dental Materials Science, Institute of Odontology, The Sahlgrenska Academy, Gothenburg, Sweden
| | - Johan Hogmalm
- Department of Earth Sciences, University of Gothenburg, Gothenburg, Sweden
| | - Petra H Johansson
- Department of Prosthodontics/Dental Materials Science, Institute of Odontology, The Sahlgrenska Academy, Gothenburg, Sweden
| | - Magne Røkkum
- Division of Orthopedic Surgery, Oslo University Hospital, Gothenburg, Sweden; Institute of Clinical Medicine, University of Oslo, Oslo, Norway, Gothenburg, Sweden
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Wang X, He Y, Tian S, Zhu F, Huang B, Zhang J, Chen Z, Wang H. Fluid Shear Stress Increases Osteocyte and Inhibits Osteoclasts via Downregulating Receptor-Activator of Nuclear Factor κB (RANK)/Osteoprotegerin Expression in Myeloma Microenvironment. Med Sci Monit 2019; 25:5961-5968. [PMID: 31400110 PMCID: PMC6699202 DOI: 10.12659/msm.915986] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Background The aim of this study was to determine the effects of myeloma cells exposed to fluid shear stress on osteocytes and osteoclasts, and clarify the potential underlying mechanisms. Material/methods A flow and a non-flow model were established using a flow fluid chamber. The myeloma cell line U266 and murine osteocytic MLO-Y4 cells were cultured in vitro. The osteocytes and osteoclasts were examined under a microscope. Osteoclasts were stained for tartrate-resistant acid phosphatase (TRAP) activity. RANKL and osteoprotegerin (OPG) gene expression were detected using reverse transcription-quantitative polymerase chain reaction. Results Compared with the controls, Y4 cells cultured with U266 culture supernatant showed altered morphology, fewer osteocytes, increased RANKL gene expression, a higher RANKL/OPG gene ratio, and a greater number of TRAP-positive osteoclasts (P<0.05 for all). Compared to the no-flow model, the flow model showed a higher number of Y4 cells, increased OPG gene expression, decreased RANKL gene expression, a lower RANKL/OPG gene ratio, and fewer TRAP-positive osteoclasts (P<0.05 for all). Conclusions Our study revealed that fluid shear stress ameliorated the inhibitory effects of myeloma cells on osteocyte growth and inhibited osteoclast proliferation by means of decreasing RANKL/OPG gene expression. This may have clinical implications in patients with multiple myeloma in that mechanical loading with low-intensity vibration or mild exercise may prevent the progression of myeloma bone disease.
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Affiliation(s)
- Xiaotao Wang
- Department of Hematology, The Second Affiliated Hospital of Guilin Medical University, Guilin, Guangxi, China (mainland)
| | - Yuchan He
- Department of Hematology, The Second Affiliated Hospital of Guilin Medical University, Guilin, Guangxi, China (mainland)
| | - Shen Tian
- Department of Hematology, The Second Affiliated Hospital of Guilin Medical University,, Guilin, Guangxi, China (mainland)
| | - Fangxiao Zhu
- Department of Rheumatic Immunology, The Affiliated Hospital of Guilin Medical University, Guilin, Guangxi, China (mainland)
| | - Bo Huang
- Department of Hematology, The Second Affiliated Hospital of Guilin Medical University, Guilin, Guangxi, China (mainland)
| | - Junyan Zhang
- Department of Hematology, The Second Affiliated Hospital of Guilin Medical University, Guilin, Guangxi, China (mainland)
| | - Zhong Chen
- Department of Hematology, The Second Affiliated Hospital of Guilin Medical University, Guilin, Guangxi, China (mainland)
| | - Hangfei Wang
- Department of Hematology, The Second Affiliated Hospital of Guilin Medical University, Guilin, Guangxi, China (mainland)
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Drynda A, Drynda S, Kekow J, Lohmann CH, Bertrand J. Differential Effect of Cobalt and Chromium Ions as Well as CoCr Particles on the Expression of Osteogenic Markers and Osteoblast Function. Int J Mol Sci 2018; 19:ijms19103034. [PMID: 30301134 PMCID: PMC6213485 DOI: 10.3390/ijms19103034] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 09/30/2018] [Accepted: 10/01/2018] [Indexed: 01/18/2023] Open
Abstract
The balance of bone formation and resorption is the result of a regulated crosstalk between osteoblasts, osteoclasts, and osteocytes. Inflammation, mechanical load, and external stimuli modulate this system. Exposure of bone cells to metal ions or wear particles are thought to cause osteolysis via activation of osteoclasts and inhibition of osteoblast activity. Co2+ ions have been shown to impair osteoblast function and the expression of the three transforming growth factor (TGF)-β isoforms. The current study was performed to analyze how Co2+ and Cr3+ influence the expression, proliferation, and migration profile of osteoblast-like cells. The influence of Co2+, Cr3+, and CoCr particles on gene expression was analyzed using an osteogenesis PCR Array. The expression of different members of the TGF-β signaling cascade were down-regulated by Co2+, as well as several TGF-β regulated collagens, however, Cr3+ had no effect. CoCr particles partially affected similar genes as the Co2+treatment. Total collagen production of Co2+ treated osteoblasts was reduced, which can be explained by the reduced expression levels of various collagens. While proliferation of MG63 cells appears unaffected by Co2+, the migration capacity was impaired. Our data may improve the knowledge of changes in gene expression patterns, and the proliferation and migration effects caused by artificial materials.
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Affiliation(s)
- Andreas Drynda
- Department of Orthopaedic Surgery, Otto-von-Guericke University, Leipziger Straße 44, D-39120 Magdeburg, Germany.
| | - Susanne Drynda
- Department of Orthopaedic Surgery, Otto-von-Guericke University, Leipziger Straße 44, D-39120 Magdeburg, Germany.
- Clinic for Rheumatology, Otto-von-Guericke University, Leipziger Straße 44, D-39120 Magdeburg, Germany.
| | - Jörn Kekow
- Clinic for Rheumatology, Otto-von-Guericke University, Leipziger Straße 44, D-39120 Magdeburg, Germany.
| | - Christoph Hubertus Lohmann
- Department of Orthopaedic Surgery, Otto-von-Guericke University, Leipziger Straße 44, D-39120 Magdeburg, Germany.
| | - Jessica Bertrand
- Department of Orthopaedic Surgery, Otto-von-Guericke University, Leipziger Straße 44, D-39120 Magdeburg, Germany.
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Yan Z, Wang P, Wu J, Feng X, Cai J, Zhai M, Li J, Liu X, Jiang M, Luo E, Jing D. Fluid shear stress improves morphology, cytoskeleton architecture, viability, and regulates cytokine expression in a time-dependent manner in MLO-Y4 cells. Cell Biol Int 2018; 42:1410-1422. [DOI: 10.1002/cbin.11032] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 07/13/2018] [Indexed: 12/19/2022]
Affiliation(s)
- Zedong Yan
- Department of Biomedical Engineering; Fourth Military Medical University; Xi'an China
| | - Pan Wang
- Department of Biomedical Engineering; Fourth Military Medical University; Xi'an China
| | - Junjie Wu
- State Key Laboratory of Military Stomatology and National Clinical Research Center for Oral Diseases and Shaanxi Clinical Research Center for Oral Diseases; Department of Orthodontics; School of Stomatology; Fourth Military Medical University; Xi'an China
| | - Xue Feng
- State Key Laboratory of Military Stomatology and National Clinical Research Center for Oral Diseases and Shaanxi Clinical Research Center for Oral Diseases; Department of Orthodontics; School of Stomatology; Fourth Military Medical University; Xi'an China
| | - Jing Cai
- College of Basic Medicine; Shaanxi University of Chinese Medicine; Xianyang China
| | - Mingming Zhai
- Department of Biomedical Engineering; Fourth Military Medical University; Xi'an China
| | - Juan Li
- Department of Neurosurgery; Xijing Hospital; Fourth Military Medical University; Xi'an China
| | - Xiyu Liu
- Department of Biomedical Engineering; Fourth Military Medical University; Xi'an China
| | - Maogang Jiang
- Department of Biomedical Engineering; Fourth Military Medical University; Xi'an China
| | - Erping Luo
- Department of Biomedical Engineering; Fourth Military Medical University; Xi'an China
| | - Da Jing
- Department of Biomedical Engineering; Fourth Military Medical University; Xi'an China
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Rentsch B, Bernhardt A, Henß A, Ray S, Rentsch C, Schamel M, Gbureck U, Gelinsky M, Rammelt S, Lode A. Trivalent chromium incorporated in a crystalline calcium phosphate matrix accelerates materials degradation and bone formation in vivo. Acta Biomater 2018; 69:332-341. [PMID: 29355718 DOI: 10.1016/j.actbio.2018.01.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Revised: 12/19/2017] [Accepted: 01/10/2018] [Indexed: 01/23/2023]
Abstract
Remodeling of calcium phosphate bone cements is a crucial prerequisite for their application in the treatment of large bone defects. In the present study trivalent chromium ions were incorporated into a brushite forming calcium phosphate cement in two concentrations (10 and 50 mmol/mol β-tricalcium phosphate) and implanted into a femoral defect in rats for 3 and 6 month, non-modified brushite was used as reference. Based on our previous in vitro findings indicating both an enhanced osteoclastic activity and cytocompatibility towards osteoprogenitor cells we hypothesized a higher in vivo remodeling rate of the Cr3+ doped cements compared to the reference. A significantly enhanced degradation of the modified cements was evidenced by micro computed tomography, X-ray and histological examinations. Furthermore the formation of new bone tissue after 6 month of implantation was significantly increased from 29% to 46% during remodeling of cements, doped with the higher Cr3+ amount. Time of flight secondary ion mass spectrometry (ToF-SIMS) of histological sections was applied to investigate the release of Cr3+ ions from the cement after implantation and to image their distribution in the implant region and the surrounding bone tissue. The relatively weak incorporation of chromium into the newly formed bone tissue is in agreement to the low chromium concentrations which were released from the cements in vitro. The faster degradation of the Cr3+ doped cements was also verified by ToF-SIMS. The positive effect of Cr3+ doping on both degradation and new bone formation is discussed as a synergistic effect of Cr3+ bioactivity on osteoclastic resorption on one hand and improvement of cytocompatibility and solubility by structural changes in the calcium phosphate matrix on the other hand. STATEMENT OF SIGNIFICANCE While biologically active metal ions like strontium, magnesium and zinc are increasingly applied for the modification of ceramic bone graft materials, the present study is the first report on the incorporation of low doses of trivalent chromium ions into a calcium phosphate based biomaterial and testing of its performance in bone defect regeneration in vivo. Chromium(III)-doped calcium phosphate bone cements show improved cytocompatibility and both degradation rate and new bone formation in vivo are significantly increased compared to the reference cement. This important discovery might be the starting point for the application of trivalent chromium salts for the modification of bone graft materials to increase their remodelling rate.
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