406 research outputs found
Degradation rates and products of pure magnesium exposed to different aqueous media under physiological conditions
As magnesium and many of its alloys are a promising class of degradable implant materials, a thorough understanding of their degradation under physiological conditions is a key challenge in the field of biomaterial science. In order to increase the predictive power of in vitro studies, it is necessary to imitate the in vivo conditions, track the decomposition process and identify the products that form during the degradation pathway. In this in vitro study, slices of pure magnesium were exposed to Hank's Balanced Salt Solution (HBSS), Dulbecco's Modified Eagle Medium (DMEM) and simulated body fluid (SBF), respectively, under cell culture conditions, which included CO2 gassing. The series were repeated with supplements of fetal bovine serum (FBS), added to the respective media. Degradation rates, osmolality and pH were found to vary with the choice of medium and supplementation with proteins. In order to identify the crystalline degradation products, the crusts formed on the specimens were investigated via X-ray diffraction (XRD) measurements. As expected, brucite, Mg(OH)2, was found among the degradation products; interestingly, nesquehonite, Mg(HCO3)(OH)·2H2O, was found to be the dominant degradation product in this study. The experimental data are well in accordance with solubility calculations
Degradation rates and products of pure magnesium exposed to different aqueous media under physiological conditions
As magnesium and many of its alloys are a promising class of degradable implant materials, a thorough understanding of their degradation under physiological conditions is a key challenge in the field of biomaterial science. In order to increase the predictive power of in vitro studies, it is necessary to imitate the in vivo conditions, track the decomposition process and identify the products that form during the degradation pathway. In this in vitro study, slices of pure magnesium were exposed to Hank's Balanced Salt Solution (HBSS), Dulbecco's Modified Eagle Medium (DMEM) and simulated body fluid (SBF), respectively, under cell culture conditions, which included CO2 gassing. The series were repeated with supplements of fetal bovine serum (FBS), added to the respective media. Degradation rates, osmolality and pH were found to vary with the choice of medium and supplementation with proteins. In order to identify the crystalline degradation products, the crusts formed on the specimens were investigated via X-ray diffraction (XRD) measurements. As expected, brucite, Mg(OH)2, was found among the degradation products; interestingly, nesquehonite, Mg(HCO3)(OH)·2H2O, was found to be the dominant degradation product in this study. The experimental data are well in accordance with solubility calculations
Mg-based materials diminish tumor spreading and cancer metastases
Cancer metastases are the most common causes of cancer-related deaths. The formation of secondary tumors at different sites in the human body can impair multiple organ function and dramatically decrease the survival of the patients. In this stage, it is difficulty to treat tumor growth and spreading due to arising therapy resistances. Therefore, it is important to prevent cancer metastases and to increase subsequent cancer therapy success. Cancer metastases are conventionally treated with radiation or chemotherapy. However, these treatments elicit lots of side effects, wherefore novel local treatment approaches are currently discussed. Recent studies already showed anticancer activity of specially designed degradable magnesium (Mg) alloys by reducing the cancer cell proliferation. In this work, we investigated the impact of these Mg-based materials on different steps of the metastatic cascade including cancer cell migration, invasion, and cancer-induced angiogenesis. Both, Mg and Mg-6Ag reduced cell migration and invasion of osteosarcoma cells in coculture with fibroblasts. Furthermore, the Mgbased materials used in this study diminished the cancer-induced angiogenesis. Endothelial cells incubated with conditioned media obtained from these Mg and Mg-6Ag showed a reduced cell layer permeability, a reduced proliferation and inhibited cell migration. The tube formation as a last step of angiogenesis was stimulated with the presence of Mg under normoxia and diminished under hypoxia
Small-sized magnesium cylinders influence subchondral bone quality in osteoarthritic rabbits an â in vivo pilot study
No optimal therapy exists to stop or cure chondral degeneration in osteoarthritis (OA). While the pathogenesis is unclear, there is consensus on the etiological involvement of both articular cartilage and subchondral bone. Compared to original bone, the substance of sclerotic bone is mechanically less solid. The osteoproliferative effect of Mg has been shown repeatedly during development of Mg-based osteosynthesis implants. The aim of the present study was to examine the influence of implanted high-purity Mg cylinders on subchondral bone quality in a rabbit OA model. 10 New Zealand White rabbits received into the knee either 20 empty drill holes or 20 drill holes, which were additionally filled with one Mg cylinder each. Follow-up was at 8 weeks. Micro-computed tomography (”CT) was performed. After euthanasia, cartilage condition was determined, bone samples were collected and processed for histological evaluation and elemental imaging by micro-Xray fluorescence spectrometry (”XRF). Articular cartilage collected post-mortem showed different stages of lesions, from mild alterations up to exposed subchondral bone, which tended to be slightly lower in animals with implanted Mg cylinders. ”CT showed significantly increased bone volume in the Mg group. Also, histological evaluation revealed distinct differences. While right, operated limbs did not show any significant difference, left, non-operated controls showed significantly less changes in articular cartilage in the Mg group. A distinct influence of implanted cylinders of pure Mg on subchondral bone of osteoarthritic rabbits was shown. Subsequent evaluations, including other time points and alternative alloys, will show if this could alter OA progression
Influence of the Microstructure and Silver Content on Degradation, Cytocompatibility, and Antibacterial Properties of Magnesium-Silver Alloys In Vitro
Implantation is a frequent procedure in orthopedic surgery, particularly in the aging population. However, it possesses the risk of infection and biofilm formation at the surgical site. This can cause unnecessary suffering to patients and burden on the healthcare system. Pure Mg, as a promising metal for biodegradable orthopedic implants, exhibits some antibacterial effects due to the alkaline pH produced during degradation. However, this antibacterial effect may not be sufficient in a dynamic environment, for example, the human body. The aim of this study was to increase the antibacterial properties under harsh and dynamic conditions by alloying silver metal with pure Mg as much as possible. Meanwhile, the Mg-Ag alloys should not show obvious cytotoxicity to human primary osteoblasts. Therefore, we studied the influence of the microstructure and the silver content on the degradation behavior, cytocompatibility, and antibacterial properties of Mg-Ag alloys in vitro. The results indicated that a higher silver content can increase the degradation rate of Mg-Ag alloys. However, the degradation rate could be reduced by eliminating the precipitates in the Mg-Ag alloys via T4 treatment. By controlling the microstructure and increasing the silver content, Mg-Ag alloys obtained good antibacterial properties in harsh and dynamic conditions but had almost equivalent cytocompatibility to human primary osteoblasts as pure Mg
Proteomic Analysis of Mesenchymal Stem Cells and Monocyte Co-Cultures Exposed to a Bioactive Silica-Based SolâGel Coating
New methodologies capable of extensively analyzing the cell-material interactions are necessary to improve current in vitro characterization methods, and proteomics is a viable alternative. Also, many studies are focused on monocultures, even though co-cultures model better the natural tissue. For instance, human mesenchymal stem cells (MSCs) modulate immune responses and promote bone repair through interaction with other cell types. Here, label-free liquid chromatography tandem mass spectroscopy proteomic methods were applied for the first time to characterize HUCPV (MSC) and CD14+ monocytes co-cultures exposed to a bioactive solâgel coating (MT). PANTHER, DAVID, and STRING were employed for data integration. Fluorescence microscopy, enzyme-linked immunosorbent assay, and ALP activity were measured for further characterization. Regarding the HUCPV response, MT mainly affected cell adhesion by decreasing integrins, RHOC, and CAD13 expression. In contrast, MT augmented CD14+ cell areas and integrins, Rho family GTPases, actins, myosins, and 14-3-3 expression. Also, anti-inflammatory (APOE, LEG9, LEG3, and LEG1) and antioxidant (peroxiredoxins, GSTO1, GPX1, GSHR, CATA, and SODM) proteins were overexpressed. On co-cultures, collagens (CO5A1, CO3A1, CO6A1, CO6A2, CO1A2, CO1A1, and CO6A3), cell adhesion, and pro-inflammatory proteins were downregulated. Thus, cell adhesion appears to be mainly regulated by the material, while inflammation is impacted by both cellular cross-talk and the material. Altogether, we conclude that applied proteomic approaches show its potential in biomaterial characterization, even in complex systems.This work was supported by MINECO [MAT2017-86043-R; RTC-2017-6147-1], Generalitat Valenciana [GRISOLIAP/2018/091, BEFPI/2021/043, PROMETEO/2020/069], Universitat Jaume I [UJI-B2017-37], and the University of the Basque Country [GIU18/189]. Andreia Cerqueira was supported by the Margarita Salas postdoctoral contract MGS/2022/10 (UP2022-024) financed by the European Union-NextGenerationEU. The University Medical Centre Hamburg-Eppendorf (Hamburg, Germany) and the Clinics for Gynecology AGAPLESION BETHESDA Hospital provided the blood and tissue for cell isolation. The authors would like to thank Raquel Oliver, Jose Ortega, Iraide EscobĂ©s, and Anke Borkam-Schuster for their valuable technical assistance and Antonio Coso (GMI-Ilerimplant) for producing the titanium discs
Degradation rates and products of pure magnesium exposed to different aqueous media under physiological conditions
As magnesium and many of its alloys are a promising class of degradable implant materials, a thorough understanding of their degradation under physiological conditions is a key challenge in the field of biomaterial science. In order to increase the predictive power of in vitro studies, it is necessary to imitate the in vivo conditions, track the decomposition process and identify the products that form during the degradation pathway. In this in vitro study, slices of pure magnesium were exposed to Hank's Balanced Salt Solution (HBSS), Dulbecco's Modified Eagle Medium (DMEM) and simulated body fluid (SBF), respectively, under cell culture conditions, which included CO2 gassing. The series were repeated with supplements of fetal bovine serum (FBS), added to the respective media. Degradation rates, osmolality and pH were found to vary with the choice of medium and supplementation with proteins. In order to identify the crystalline degradation products, the crusts formed on the specimens were investigated via X-ray diffraction (XRD) measurements. As expected, brucite, Mg(OH)2, was found among the degradation products; interestingly, nesquehonite, Mg(HCO3)(OH)·2H2O, was found to be the dominant degradation product in this study. The experimental data are well in accordance with solubility calculations
Lubrication synergy: Mixture of hyaluronan and dipalmitoylphosphatidylcholine (DPPC) vesicles
AbstractPhospholipids and hyaluronan have been implied to fulfil important roles in synovial joint lubrication. Since both components are present in synovial fluid, self-assembly structures formed by them should also be present. We demonstrate by small angle X-ray scattering that hyaluronan associates with the outer shell of dipalmitoylphophatidylcholine (DPPC) vesicles in bulk solution. Further, we follow adsorption to silica from mixed hyaluronan/DPPC vesicle solution by Quartz Crystal Microbalance with Dissipation measurements. Atomic Force Microscope imaging visualises the adsorbed layer structure consisting of non-homogeneous phospholipid bilayer with hyaluronan/DPPC aggregates on top. The presence of these aggregates generates a long-range repulsive surface force as two such surfaces are brought together. However, the aggregates are easily deformed, partly rearranged into multilayer structures and partly removed from between the surfaces under high loads. These layers offer very low friction coefficient (<0.01), high load bearing capacity (â23MPa), and self-healing ability. Surface bound DPPC/hyaluronan aggregates provide a means for accumulation of lubricating DPPC molecules on sliding surfaces
Surface functionalization of biomedical Ti-6Al-7Nb alloy by liquid metal dealloying
Surface functionalization is an effective approach to change the surface properties of a material to achieve a specific goal such as improving the biocompatibility of the material. Here, the surface of the commercial biomedical Ti-6Al-7Nb alloy was functionalized through synthesizing of a porous surface layer by liquid metal dealloying (LMD). During LMD, the Ti-6Al-7Nb alloy is immersed in liquid magnesium (Mg) and both materials react with each other. Particularly, aluminum (Al) is selectively dissolved from the Ti-6Al-7Nb alloy into liquid Mg while titanium (Ti) and niobium (Nb) diffuse along the metal/liquid interface to form a porous structure. We demonstrate that the porous surface layer in the Ti-6Al-7Nb alloy can be successfully tailored by LMD. Furthermore, the concentration of harmful Al in this porous layer is reduced by about 48% (from 5.62 ± 0.11 wt.% to 2.95 ± 0.05 wt.%) after 30 min of dealloying at 1150 K. The properties of the porous layer (e.g., layer thickness) can be tuned by varying the dealloying conditions. In-vitro tests suggest improved bone formation on the functionalized porous surface of the Ti-6Al-7Nb alloy. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.European Research Council, ERCTohoku UniversityMinistry of Science and Higher Education of the Russian FederationNanjing University of Science and Technology, NUST: K2-2020-020MA 3333/13-1Supervision, I.V.O., R.W.-R., L.Z., L.M., J.E. and H.K.; Validation, I.V.O., S.-H.J., and B.L.; Writing â original draft, I.V.O. and B.L.; Writing â review & editing, all. All authors have read and agreed to the published version Funding: The financial support was provided by the German Science Foundation under the Leibniz Program of the manuscript. (Grant MA 3333/13-1), by the European Research Council (ERC) under the ERC Advanced Grant INTELHYB (grant Funding: The financial support was provided by the German Science Foundation under the Leibniz Program Ministry of Science and Higher Education of the Russian Federation, in the framework of the Increase Competitiveness (Grant MA 3333/13-1), by the European Research Council (ERC) under the ERC Advanced Grant INTELHYB Program of NUST «MISiS» (grant number K2-2020-020). I.V.O. is grateful for the financial support provided by the International Collaboration Center, Institute for Materials Research (ICC-IMR), Tohoku University, Japan. 02.A03.21.0006), and the Ministry of Science and Higher Education of the Russian Federation, in the framework Conflicts of Interest: The authors declare no conflict of interest. of the Increase Competitiveness Program of NUST «MISiS» (grant number K2-2020-020). I.V.O. is grateful for the financial support provided by the International Collaboration Center, Institute for Materials Research (ICC-IMR), Tohoku University, Japan
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