The clinical application of magnesium(Mg)and its alloys for bone fractures has been well supported by in vitro and in vivo trials.However,there were studies indicating negative effects of high dose Mg intake and susta...The clinical application of magnesium(Mg)and its alloys for bone fractures has been well supported by in vitro and in vivo trials.However,there were studies indicating negative effects of high dose Mg intake and sustained local release of Mg ions on bone metabolism or repair,which should not be ignored when developing Mg-based implants.Thus,it remains necessary to assess the biological effects of Mg implants in animal models relevant to clinical treatment modalities.The primary purpose of this study was to validate the beneficial effects of intramedullary Mg implants on the healing outcome of femoral fractures in a modified rat model.In addition,the mineralization parameters at multiple anatomical sites were evaluated,to investigate their association with healing outcome and potential clinical applications.Compared to the control group without Mg implantation,postoperative imaging at week 12 demonstrated better healing outcomes in the Mg group,with more stable unions in 3D analysis and high-mineralized bridging in 2D evaluation.The bone tissue mineral density(TMD)was higher in the Mg group at the non-operated femur and lumbar vertebra,while no differences between groups were identified regarding the bone tissue volume(TV),TMD and bone mineral content(BMC)in humerus.In the surgical femur,the Mg group presented higher TMD,but lower TV and BMC in the distal metaphyseal region,as well as reduced BMC at the osteotomy site.Principal component analysis(PCA)-based machine learning revealed that by selecting clinically relevant parameters,radiological markers could be constructed for differentiation of healing outcomes,with better performance than 2D scoring.The study provides insights and preclinical evidence for the rational investigation of bioactive materials,the identification of potential adverse effects,and the promotion of diagnostic capabilities for fracture healing.展开更多
Historically,the rapid degradation and massive gas release from magnesium(Mg)implants resulted in severe emphysema and mechanical failure.With the advent of new alloys and surface treatment methods,optimized Mg implan...Historically,the rapid degradation and massive gas release from magnesium(Mg)implants resulted in severe emphysema and mechanical failure.With the advent of new alloys and surface treatment methods,optimized Mg implants have re-entered clinics since last decade with reliable performance.However,the optimization aims at slowing down the degradation process,rather than exemption of the gas release.This study involved a systematic evaluation of current preclinical and clinical evidence,regarding the physical signs,symptoms,radiological features,pathological findings and complications potentially associated with peri±implant gas accumulation(PIGA)after musculoskeletal Mg implantation.The literature search identified 196 potentially relevant publications,and 51 papers were enrolled for further analysis,including 22 preclinical tests and 29 clinical studies published from 2005 to 2023.Various Mg-based materials have been evaluated in animal research,and the application of pure Mg and Mg alloys have been reported in clinical follow-ups involving multiple anatomical sites and musculoskeletal disorders.Soft tissue and intraosseous PIGA are common in both animal tests and clinical follow-ups,and potentially associated with certain adverse events.Radiological examinations especially micro-CT and clinical CT scans provide valuable information for quantitative and longitudinal analysis.While according to simulation tests involving Mg implantation and chemical processing,tissue fixation could lead to an increase in the volume of gas cavity,thus the results obtained from ex vivo imaging or histopathological evaluations should be interpreted with caution.There still lacks standardized procedures or consensus for both preclinical and clinical evaluation of PIGA.However,by providing focused insights into the topic,this evidence-based study will facilitate future animal tests and clinical evaluations,and support developing biocompatible Mg implants for the treatment of musculoskeletal disorders.展开更多
With the growing demand for weight reduction,the application of joint lightweight structural materials is increasing.Magnesium alloys feature low density,high specific strength and good formability,offering significan...With the growing demand for weight reduction,the application of joint lightweight structural materials is increasing.Magnesium alloys feature low density,high specific strength and good formability,offering significant advantages for fuel efficiency and load capacity.Combined with Ti,a dissimilar Ti/Mg composite material provides great flexibility combining the properties of each material.However,because of the great differences in chemical and electrochemical properties between Mg and Ti,it is imperative to address the galvanic corrosion problem of such dissimilar Ti/Mg components.This work presents an investigation of the PEO processing of sintered Ti/Mg0.6Ca couples,aiming to improve the corrosion resistance of such dissimilar alloy combinations using a phosphate-aluminate electrolyte.The results show that uniform and continuous coatings can be formed on the dissimilar Ti/Mg0.6Ca couple.The coating mainly contains MgO and MgAl_(2)O_(4)on the Mg0.6Ca side,and Al_(2)TiO_(5)is the dominant phase on the Ti side.The work also took advantage of synchrotron X-ray computed tomography(CT)scanning to achieve 3D reconstruction of the coating morphology,which can be a fast method to assess the porosity and compactness of the coating and further predict the coating corrosion resistance.The coating effectively improved the corrosion resistance of the dissimilar Ti/Mg0.6Ca couple.展开更多
Magnesium and its alloys have such advantages with lightweight, high specific strength, good damping, high castability and machinability,which make them an attractive choice for applications where weight reduction is ...Magnesium and its alloys have such advantages with lightweight, high specific strength, good damping, high castability and machinability,which make them an attractive choice for applications where weight reduction is important, such as in the aerospace and automotive industries.However, their practical applications are still limited because of their poor corrosion resistance, low high temperature strength and ambient formability. Based on such their property shortcomings, recently degradable magnesium alloys were developed for broadening their potential applications. Considering the degradable Mg alloys for medical applications were well reviewed, the present review put an emphasis on such degradable magnesium alloys for structural and functional applications, especially the applications in the environmental and energy fields. Their applications as fracture ball in fossil energy, sacrificial anode, washing ball, and as battery anodes, transient electronics, were summarized. The roles of alloying elements in magnesium and the design concept of such degradable magnesium alloys were discussed. The existing challenges for extending their future applications are explored.展开更多
In this study,a binder based 3D-printing technology viz.Fused Granular Fabrication(FGF)technique was used to produce interconnected and open porous Mg-6.3Gd bone scaffolds for compression test analyses.The consolidati...In this study,a binder based 3D-printing technology viz.Fused Granular Fabrication(FGF)technique was used to produce interconnected and open porous Mg-6.3Gd bone scaffolds for compression test analyses.The consolidation of the green parts(as printed scaffolds)was performed using solvent debinding in cyclohexane and subsequent conventional sintering in argon atmosphere.Compression tests were performed on as sintered parts.Additionally,a simulation strategy was developed for modeling the compression behavior of the sintered parts,utilizing the data from the experimental results.The experimental compression test results and the simulation strategy for the compression behavior of the 3D-printed scaffolds demonstrated good agreement.展开更多
The present work reports the creep behavior and microstructural evolution of the sand-cast Mg-14Gd-0.4Zr alloy(wt.%) prepared by the differential pressure casting machine. Their compressive creep tests at 250 ℃ were ...The present work reports the creep behavior and microstructural evolution of the sand-cast Mg-14Gd-0.4Zr alloy(wt.%) prepared by the differential pressure casting machine. Their compressive creep tests at 250 ℃ were performed under various applied stresses(i.e., 60, 80 and100 MPa). Among them, the sand-cast Mg-14Gd-0.4Zr samples examined under 250 ℃/80 MPa for 39 and 95 h, respectively, were chosen to systemically analyze their creep mechanisms using high-angle annular dark field-scanning transmission electron microscopy(HAADF-STEM).The obtained results showed that the enhancement of creep resistance can be mainly attributed to the coherent β' and β'_F phases with an alternate distribution, effectively impeding the basal dislocations movement. However, with the creep time increasing, the fine β'+β'_F precipitate chains coarsened and transformed to semi-coherent β_1 phase and even to large incoherent β phase(surrounded by precipitate-free areas) in grain interiors. The precipitate-free zones(PFZs) at grain boundaries(GBs) were formed, and they could expand during creep deformation. Apart from the main cross-slip of basal and prismatic dislocations, type dislocations were activated and tended to distribute near the GBs. The aforementioned phenomena induced the stress concentrations, consequently leading to the increment of the creep strain.展开更多
The interaction between organic molecules and biomaterial surfaces determines the fate of biomaterials during their service life,which is also the research hotspots in the field of biomaterials.To understand the mecha...The interaction between organic molecules and biomaterial surfaces determines the fate of biomaterials during their service life,which is also the research hotspots in the field of biomaterials.To understand the mechanism of protein interaction with magnesium(Mg)degradation,alloying elements,immersion time,protein concentration and surface conditions have been previously considered for the effect of proteins on Mg degradation.However,fluid flow,as one of the critical factors,drew little attention in this case.In the present study,the effect of bovine serum albumin(BSA)and fetal bovine serum(FBS)on Mg degradation was compared under static and dynamic conditions.The results revealed that both BSA and FBS slightly decreased the degradation rate of Mg in Hanks’balanced salt solution(HBSS)under static immersion due to the protein adsorption and the formation of a Ca/P-rich top layer on Mg surface,whereas under dynamic flow condition the degradation of Mg was significantly accelerated in the presence of BSA or FBS.The reasons seemed to stem from the weakened protein adsorption on Mg surface in this case and the dynamically enhanced interaction between proteins and ions/products in solutions,which largely weaken the combination of the top Ca/P-rich layer with the inner corrosion product layer.These results highlight the importance of testing conditions for Mg characterization in vitro and the synergistic effect between different parameters on Mg degradation.展开更多
The effect of Ag in solid solution on the microstructure,texture and the deformation behaviour of indirectly extruded Mg was investigated.Ag as a solid solution strengthener affects the behaviour during extrusion,resu...The effect of Ag in solid solution on the microstructure,texture and the deformation behaviour of indirectly extruded Mg was investigated.Ag as a solid solution strengthener affects the behaviour during extrusion,resulting in enhanced deformation related heating and corresponding coarser grained microstructures.No substantial effect on the texture development is revealed.The mechanical properties simultaneously increase in stress and strain levels with increasing Ag content,especially in tension as a result of the changing impact of the slip modes which can be associated with a decrease of the lattice parameters as well as the c/a ratio of the hcp lattice structure.In compression tests with twin dominated flow,the impact is much smaller on the compressive yield stress but higher with respect to the twinning related strain hardening rate.Solid solution strength functions for Fleischer and Labusch were determined,also confirming the anisotropic behaviour of the extruded Mg alloys.展开更多
In silico methods to study biodegradable implants have recently received increasing attention due to their potential in reducing experimental time and cost. An important application case for in silico methods are magn...In silico methods to study biodegradable implants have recently received increasing attention due to their potential in reducing experimental time and cost. An important application case for in silico methods are magnesium(Mg)-based biodegradable implants, as they represent a powerful alternative to traditional materials used for temporary orthopaedic applications. Controlling Mg alloy degradation is critical to designing an implant that supports the bone healing process. To simulate different aspects of this biodegradation process, several mathematical models have been proposed with the ultimate aim of replacing laboratory experiments with computational modeling. In this review, we provide a comprehensive and critical discussion of the published models and their performance with respect to capturing the complexity of the biodegradation process. This complexity is presented initially. Additionally, the present review discusses the different approaches of optimizing and quantifying the different sources of errors and uncertainties within the proposed models.展开更多
To have a better understand on the change of microstructure via kinetics, the diffusion behavior of Mg alloys is of special interest to researchers. Meanwhile, diffusion coefficients of Mg based alloys can explain and...To have a better understand on the change of microstructure via kinetics, the diffusion behavior of Mg alloys is of special interest to researchers. Meanwhile, diffusion coefficients of Mg based alloys can explain and represent their diffusion behavior well. The evolution of experimental and calculated methods for detecting and extracting diffusion coefficients was discussed briefly. The reasonable diffusion data, especially self-diffusion coefficients, impurity diffusion coefficients and inter-diffusion coefficients of Mg alloys, were reviewed in detail serving to design the Mg alloys with higher accuracy. Then the practical applications of diffusion coefficients of Mg alloys were summarized,including diffusional mobility establishing, precipitation simulation and mechanical properties prediction.展开更多
Biodegradable implants are taking an increasingly important role in the area of orthopedic implants with the aim to replace permanent implants for temporary bone healing applications.During the implant preparation pro...Biodegradable implants are taking an increasingly important role in the area of orthopedic implants with the aim to replace permanent implants for temporary bone healing applications.During the implant preparation process,the material’s surface and microstructure are being changed by stresses induced by machining.Hence degradable metal implants need to be fully characterized in terms of the influence of machining on the resulting microstructure and corrosion performance.In this study,micro-computed tomography(μCT)is used for the quantification of the degradation rate of biodegradable implants.To our best knowledge,for the first time quantitative measures are introduced to describe the degradation homogeneity in 3D.This information enables a prediction in terms of implant stability during the degradation in the body.Two magnesium gadolinium alloys,Mg-5Gd and Mg-10 Gd(all alloy compositions are given in weight%unless otherwise stated),in the shape of M2 headless screws have been investigated for their microstructure and their degradation performance up to 56 days.During the microstructure investigations particular attention was paid to the localized deformation of the alloys,due to the machining process.In vitro immersion testing was performed to assess the degradation performance quantified by subsequent weight loss and volume loss(usingμCT)measurements.Although differences were observed in the degree of screw’s near surface microstructure being influenced from machining,the degradation rates of both materials appeared to be suitable for application in orthopedic implants.From the degradation homogeneity point of view no obvious contrast was detected between both alloys.However,the higher degradation depth ratios between the crests and roots of Mg-5Gd ratios may indicated a less homogeneous degradation of the screws of these alloys on contract to the ones made of Mg-10Gd alloys.Due to its lower degradation rates,its more homogeneous microstructure,its weaker texture and better degradation performance extruded Mg-10Gd emerged more suitable as implant material than Mg-5Gd.展开更多
Magnesium alloys are highly attractive for the use as temporary implant materials, due to their high biocompatibility and biodegradability.However, the prediction of the degradation rate of the implants is difficult, ...Magnesium alloys are highly attractive for the use as temporary implant materials, due to their high biocompatibility and biodegradability.However, the prediction of the degradation rate of the implants is difficult, therefore, a large number of experiments are required. Computational modelling can aid in enabling the predictability, if sufficiently accurate models can be established. This work presents a generalized model of the degradation of pure magnesium in simulated body fluid over the course of 28 days considering uncertainty aspects. The model includes the computation of the metallic material thinning and is calibrated using the mean degradation depth of several experimental datasets simultaneously. Additionally, the formation and precipitation of relevant degradation products on the sample surface is modelled, based on the ionic composition of simulated body fluid. The computed mean degradation depth is in good agreement with the experimental data(NRMSE=0.07). However, the quality of the depth profile curves of the determined elemental weight percentage of the degradation products differs between elements(such as NRMSE=0.40 for phosphorus vs. NRMSE=1.03 for magnesium). This indicates that the implementation of precipitate formation may need further developments. The sensitivity analysis showed that the model parameters are correlated and which is related to the complexity and the high computational costs of the model. Overall, the model provides a correlating fit to the experimental data of pure Mg samples of different geometries degrading in simulated body fluid with reliable error estimation.展开更多
Several material parameters affect degradation characteristics of Mg and its alloys under physiological conditions.Porous Mg materials are interesting for their simultaneous degradation and drug delivery capabilities....Several material parameters affect degradation characteristics of Mg and its alloys under physiological conditions.Porous Mg materials are interesting for their simultaneous degradation and drug delivery capabilities.However,an increase in pore surface area is detrimental to both degradation resistance and subsequent mechanical properties.The present work aims at determining the threshold porosity value in Mg–0.6 Ca specimens produced by powder metallurgy(PM)below which low degradation rates persist with acceptable mechanical properties.Seven different porous Mg–0.6 Ca specimens containing both closed and open pore structures were fabricated with porosities ranging from 3%to 21%.Degradation profiles were obtained via a semi static immersion test over 16 days under physiological conditions using Dulbecco’s modified Eagle’s medium with Glutamax and 10%fetal bovine serum as supplements.The results are related to morphological pore parameters like pore size distribution,pore interconnectivity and pore curvatures that were quantified using an ex situμCT analysis.In general,with decreasing porosity a decrease in pore interconnectivity is seen followed by rounding of the pores.Low degradation rates(MDR<0.3 mm/year)are observed in specimens until 10%porosity,however,the upper bound for reproducible degradation is observed to be in specimens until 12%porosity.This porosity level also marks the transition from closed to open pore nature with a simultaneous change in pore interconnectivity from less than 10%to greater than 95%,below and above this porosity level,respectively.The tensile strength and elongation to failure recorded for specimens with 10%porosity were 70 MPa and 2%,respectively displaying positive traits of both homogenous degradation and mechanical properties.The results suggest that high pore interconnectivity is the dominant factor controlling degradation and mechanical properties in porous Mg-0.6 Ca specimens.The results also indicate a good sintering response of Mg-0.6 Ca specimens providing further material development towards biomaterial applications.展开更多
Magnesium(Mg)–based alloys are becoming attractive materials for medical applications as temporary bone implants for support of fracture healing,e.g.as a suture anchor.Due to their mechanical properties and biocompat...Magnesium(Mg)–based alloys are becoming attractive materials for medical applications as temporary bone implants for support of fracture healing,e.g.as a suture anchor.Due to their mechanical properties and biocompatibility,they may replace titanium or stainless-steel implants,commonly used in orthopedic field.Nevertheless,patient safety has to be assured by finding a long-term balance between metal degradation,osseointegration,bone ultrastructure adaptation and element distribution in organs.In order to determine the implant behavior and its influence on bone and tissues,we investigated two Mg alloys with gadolinium contents of 5 and 10 wt percent in comparison to permanent materials titanium and polyether ether ketone.The implants were present in rat tibia for 10,20 and 32 weeks before sacrifice of the animal.Synchrotron radiation-based micro computed tomography enables the distinction of features like residual metal,degradation layer and bone structure.Additionally,X-ray diffraction and X-ray fluorescence yield information on parameters describing the bone ultrastructure and elemental composition at the bone-to-implant interface.Finally,with element specific mass spectrometry,the elements and their accumulation in the main organs and tissues are traced.The results show that Mg-xGd implants degrade in vivo under the formation of a stable degradation layer with bone remodeling similar to that of Ti after 10 weeks.No accumulation of Mg and Gd was observed in selected organs,except for the interfacial bone after 8 months of healing.Thus,we confirm that Mg-5Gd and Mg-10Gd are suitable material choices for bone implants.展开更多
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...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 Mg-based 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.展开更多
Implants made of magnesium(Mg)are increasingly employed in patients to achieve osteosynthesis while degrading in situ.Since Mg implants and Mg^(2+)have been suggested to possess anti-inflammatory properties,the clinic...Implants made of magnesium(Mg)are increasingly employed in patients to achieve osteosynthesis while degrading in situ.Since Mg implants and Mg^(2+)have been suggested to possess anti-inflammatory properties,the clinically observed soft tissue inflammation around Mg implants is enigmatic.Here,using a rat soft tissue model and a 1-28 d observation period,we determined the temporo-spatial cell distribution and behavior in relation to sequential changes of pure Mg implant surface properties and Mg^(2+)release.Compared to nondegradable titanium(Ti)implants,Mg degradation exacerbated initial inflammation.Release of Mg degradation products at the tissue-implant interface,culminating at 3 d,actively initiated chemotaxis and upregulated mRNA and protein immunomodulatory markers,particularly inducible nitric oxide synthase and toll-like receptor-4 up to 6 d,yet without a cytotoxic effect.Increased vascularization was demonstrated morphologically,preceded by high expression of vascular endothelial growth factor.The transition to appropriate tissue repair coincided with implant surface enrichment of Ca and P and reduced peri-implant Mg^(2+)concentration.Mg implants revealed a thinner fibrous encapsulation compared with Ti.The detailed understanding of the relationship between Mg material properties and the spatial and time-resolved cellular processes provides a basis for the interpretation of clinical observations and future tailoring of Mg implants.展开更多
An increasing prevalence of bone-related injuries and aging geriatric populations continue to drive the orthopaedic implant market.A hierarchical analysis of bone remodelling after material implantation is necessary t...An increasing prevalence of bone-related injuries and aging geriatric populations continue to drive the orthopaedic implant market.A hierarchical analysis of bone remodelling after material implantation is necessary to better understand the relationship between implant and bone.Osteocytes,which are housed and communicate through the lacuno-canalicular network(LCN),are integral to bone health and remodelling processes.Therefore,it is essential to examine the framework of the LCN in response to implant materials or surface treatments.Biodegradable materials offer an alternative solution to permanent implants,which may require revision or removal surgeries.Magnesium alloys have resurfaced as promising materials due to their bone-like properties and safe degradation in vivo.To further tailor their degradation capabilities,surface treatments such as plasma electrolytic oxidation(PEO)have demonstrated to slow degradation.For the first time,the influence of a biodegradable material on the LCN is investigated by means of non-destructive 3D imaging.In this pilot study,we hypothesize noticeable variations in the LCN caused by altered chemical stimuli introduced by the PEO-coating.Utilising synchrotron-based transmission X-ray microscopy,we have characterised morphological LCN differences around uncoated and PEO-coated WE43 screws implanted into sheep bone.Bone specimens were explanted after 4,8,and 12 weeks and regions near the implant surface were prepared for imaging.Findings from this investigation indicate that the slower degradation of PEO-coated WE43 induces healthier lacunar shapes within the LCN.However,the stimuli perceived by the uncoated material with higher degradation rates induces a greater connected LCN better prepared for bone disturbance.展开更多
Magnesium(Mg)-based implants have re-emerged in orthopaedic surgery as an alternative to permanent implants.Literature reveals little information on how the degradation of biodegradable implants may introduce safety i...Magnesium(Mg)-based implants have re-emerged in orthopaedic surgery as an alternative to permanent implants.Literature reveals little information on how the degradation of biodegradable implants may introduce safety implications for patient follow-up using medical imaging.Magnetic resonance imaging(MRI)benefits post-surgery monitoring of bone healing and implantation sites.Previous studies demonstrated radiofrequency(RF)heating of permanent implants caused by electromagnetic fields used in MRI.Our investigation is the first to report the effect of the degradation layer on RF-induced heating of biodegradable orthopaedic implants.WE43 orthopaedic compression screws underwent in vitro degradation.Imaging techniques were applied to assess the corrosion process and the material composition of the degraded screws.Temperature measurements were performed to quantify implant heating with respect to the degradation layer.For comparison,a commercial titanium implant screw was used.Strongest RF induced heating was observed for non-degraded WE43 screw samples.Implant heating had shown to decrease with the formation of the degradation layer.No statistical differences were observed for heating of the non-degraded WE43 material and the titanium equivalent.The highest risk of implant RF heating is most pronounced for Mg-based screws prior to degradation.Amendment to industry standards for MRI safety assessment is warranted to include biodegradable materials.展开更多
Treatment of physeal fractures(15%–30%of all paediatric fractures)remains a challenge as in approximately 10%of the cases,significant growth disturbance may occur.Bioresorbable Magnesium-based implants represent a st...Treatment of physeal fractures(15%–30%of all paediatric fractures)remains a challenge as in approximately 10%of the cases,significant growth disturbance may occur.Bioresorbable Magnesium-based implants represent a strategy to minimize damage(i.e.,load support until bone healing without second surgery).Nevertheless,the absence of harmful effects of magnesium-implants and their degradation products on the growth plate should be confirmed.Here,the proteome of human mesenchymal stem cells undergoing chondrogenesis was evaluated when exposed to the products of various Magnesium-based materials degradation.The results of this study indicate that the materials induced regulation of proteins associated with cell chondrogenesis and cartilage formation,which should be beneficial for cartilage regeneration.展开更多
Osteosarcoma is one of the most common cancers in young adults and is commonly treated using surgery and chemotherapy.During the past years,these therapy approaches improved but failed to ameliorate the outcomes.There...Osteosarcoma is one of the most common cancers in young adults and is commonly treated using surgery and chemotherapy.During the past years,these therapy approaches improved but failed to ameliorate the outcomes.Therefore,novel,targeted therapeutic approaches should be established to enhance treatment success while preserving patient’s quality of life.Recent studies suggest the application of degradable magnesium(Mg)alloys as orthopedic implants bearing a potential antitumor activity.Here,we examined the influence of Mg-based materials on an osteosarcoma-fibroblast coculture.Both,Mg and Mg-6Ag did not lead to tumor cell apoptosis at low degradation rates.Instead,the Mg-based materials induced cellular dormancy in the cancer cells indicated by a lower number of Ki-67 positive cancer cells and a higher p38 expression.This dormancy-like state could be reversed by reseeding on non-degrading glass slides but could not be provoked by inhibition of the protein kinase R-like endoplasmic reticulum kinase.By investigating the influence of the disjunct surface-near effects of the Mg degradation on cell proliferation,an increased pH was found to be a main initiator of Mg degradation-dependent tumor cell proliferation inhibition.展开更多
文摘The clinical application of magnesium(Mg)and its alloys for bone fractures has been well supported by in vitro and in vivo trials.However,there were studies indicating negative effects of high dose Mg intake and sustained local release of Mg ions on bone metabolism or repair,which should not be ignored when developing Mg-based implants.Thus,it remains necessary to assess the biological effects of Mg implants in animal models relevant to clinical treatment modalities.The primary purpose of this study was to validate the beneficial effects of intramedullary Mg implants on the healing outcome of femoral fractures in a modified rat model.In addition,the mineralization parameters at multiple anatomical sites were evaluated,to investigate their association with healing outcome and potential clinical applications.Compared to the control group without Mg implantation,postoperative imaging at week 12 demonstrated better healing outcomes in the Mg group,with more stable unions in 3D analysis and high-mineralized bridging in 2D evaluation.The bone tissue mineral density(TMD)was higher in the Mg group at the non-operated femur and lumbar vertebra,while no differences between groups were identified regarding the bone tissue volume(TV),TMD and bone mineral content(BMC)in humerus.In the surgical femur,the Mg group presented higher TMD,but lower TV and BMC in the distal metaphyseal region,as well as reduced BMC at the osteotomy site.Principal component analysis(PCA)-based machine learning revealed that by selecting clinically relevant parameters,radiological markers could be constructed for differentiation of healing outcomes,with better performance than 2D scoring.The study provides insights and preclinical evidence for the rational investigation of bioactive materials,the identification of potential adverse effects,and the promotion of diagnostic capabilities for fracture healing.
基金a grant from the state of Schleswig-Holstein and the European Union ERDF-European Regional Development Fund(Zukunftsprogramm Wirtschaft)。
文摘Historically,the rapid degradation and massive gas release from magnesium(Mg)implants resulted in severe emphysema and mechanical failure.With the advent of new alloys and surface treatment methods,optimized Mg implants have re-entered clinics since last decade with reliable performance.However,the optimization aims at slowing down the degradation process,rather than exemption of the gas release.This study involved a systematic evaluation of current preclinical and clinical evidence,regarding the physical signs,symptoms,radiological features,pathological findings and complications potentially associated with peri±implant gas accumulation(PIGA)after musculoskeletal Mg implantation.The literature search identified 196 potentially relevant publications,and 51 papers were enrolled for further analysis,including 22 preclinical tests and 29 clinical studies published from 2005 to 2023.Various Mg-based materials have been evaluated in animal research,and the application of pure Mg and Mg alloys have been reported in clinical follow-ups involving multiple anatomical sites and musculoskeletal disorders.Soft tissue and intraosseous PIGA are common in both animal tests and clinical follow-ups,and potentially associated with certain adverse events.Radiological examinations especially micro-CT and clinical CT scans provide valuable information for quantitative and longitudinal analysis.While according to simulation tests involving Mg implantation and chemical processing,tissue fixation could lead to an increase in the volume of gas cavity,thus the results obtained from ex vivo imaging or histopathological evaluations should be interpreted with caution.There still lacks standardized procedures or consensus for both preclinical and clinical evaluation of PIGA.However,by providing focused insights into the topic,this evidence-based study will facilitate future animal tests and clinical evaluations,and support developing biocompatible Mg implants for the treatment of musculoskeletal disorders.
基金We also thank DESY(Hamburg,Germany)for granting beamtime to the proposal I-20221296 and support of the PETRAⅢP05 end-station.
文摘With the growing demand for weight reduction,the application of joint lightweight structural materials is increasing.Magnesium alloys feature low density,high specific strength and good formability,offering significant advantages for fuel efficiency and load capacity.Combined with Ti,a dissimilar Ti/Mg composite material provides great flexibility combining the properties of each material.However,because of the great differences in chemical and electrochemical properties between Mg and Ti,it is imperative to address the galvanic corrosion problem of such dissimilar Ti/Mg components.This work presents an investigation of the PEO processing of sintered Ti/Mg0.6Ca couples,aiming to improve the corrosion resistance of such dissimilar alloy combinations using a phosphate-aluminate electrolyte.The results show that uniform and continuous coatings can be formed on the dissimilar Ti/Mg0.6Ca couple.The coating mainly contains MgO and MgAl_(2)O_(4)on the Mg0.6Ca side,and Al_(2)TiO_(5)is the dominant phase on the Ti side.The work also took advantage of synchrotron X-ray computed tomography(CT)scanning to achieve 3D reconstruction of the coating morphology,which can be a fast method to assess the porosity and compactness of the coating and further predict the coating corrosion resistance.The coating effectively improved the corrosion resistance of the dissimilar Ti/Mg0.6Ca couple.
文摘Magnesium and its alloys have such advantages with lightweight, high specific strength, good damping, high castability and machinability,which make them an attractive choice for applications where weight reduction is important, such as in the aerospace and automotive industries.However, their practical applications are still limited because of their poor corrosion resistance, low high temperature strength and ambient formability. Based on such their property shortcomings, recently degradable magnesium alloys were developed for broadening their potential applications. Considering the degradable Mg alloys for medical applications were well reviewed, the present review put an emphasis on such degradable magnesium alloys for structural and functional applications, especially the applications in the environmental and energy fields. Their applications as fracture ball in fossil energy, sacrificial anode, washing ball, and as battery anodes, transient electronics, were summarized. The roles of alloying elements in magnesium and the design concept of such degradable magnesium alloys were discussed. The existing challenges for extending their future applications are explored.
基金Alexander von Humboldt Foundation for the award of the Post-Doctoral Fellowship to M.Marvi-Mashhadi to undertake this research workthe support from the Bundesministerium für Bildung und Forschung(BMBF)through Bio Mag3D project code Nr.03VP09852 to undertake this research。
文摘In this study,a binder based 3D-printing technology viz.Fused Granular Fabrication(FGF)technique was used to produce interconnected and open porous Mg-6.3Gd bone scaffolds for compression test analyses.The consolidation of the green parts(as printed scaffolds)was performed using solvent debinding in cyclohexane and subsequent conventional sintering in argon atmosphere.Compression tests were performed on as sintered parts.Additionally,a simulation strategy was developed for modeling the compression behavior of the sintered parts,utilizing the data from the experimental results.The experimental compression test results and the simulation strategy for the compression behavior of the 3D-printed scaffolds demonstrated good agreement.
基金the Shanghai Sailing Program (23YF1417100)National Natural Science Foundation of China (U2037601)China Scholarship Council (Grant No: 202006890008) for the financial support。
文摘The present work reports the creep behavior and microstructural evolution of the sand-cast Mg-14Gd-0.4Zr alloy(wt.%) prepared by the differential pressure casting machine. Their compressive creep tests at 250 ℃ were performed under various applied stresses(i.e., 60, 80 and100 MPa). Among them, the sand-cast Mg-14Gd-0.4Zr samples examined under 250 ℃/80 MPa for 39 and 95 h, respectively, were chosen to systemically analyze their creep mechanisms using high-angle annular dark field-scanning transmission electron microscopy(HAADF-STEM).The obtained results showed that the enhancement of creep resistance can be mainly attributed to the coherent β' and β'_F phases with an alternate distribution, effectively impeding the basal dislocations movement. However, with the creep time increasing, the fine β'+β'_F precipitate chains coarsened and transformed to semi-coherent β_1 phase and even to large incoherent β phase(surrounded by precipitate-free areas) in grain interiors. The precipitate-free zones(PFZs) at grain boundaries(GBs) were formed, and they could expand during creep deformation. Apart from the main cross-slip of basal and prismatic dislocations, type dislocations were activated and tended to distribute near the GBs. The aforementioned phenomena induced the stress concentrations, consequently leading to the increment of the creep strain.
基金the financial supports from China Scholarship Council(CSC,201509350010)Helmholtz Association of German Research Centres.
文摘The interaction between organic molecules and biomaterial surfaces determines the fate of biomaterials during their service life,which is also the research hotspots in the field of biomaterials.To understand the mechanism of protein interaction with magnesium(Mg)degradation,alloying elements,immersion time,protein concentration and surface conditions have been previously considered for the effect of proteins on Mg degradation.However,fluid flow,as one of the critical factors,drew little attention in this case.In the present study,the effect of bovine serum albumin(BSA)and fetal bovine serum(FBS)on Mg degradation was compared under static and dynamic conditions.The results revealed that both BSA and FBS slightly decreased the degradation rate of Mg in Hanks’balanced salt solution(HBSS)under static immersion due to the protein adsorption and the formation of a Ca/P-rich top layer on Mg surface,whereas under dynamic flow condition the degradation of Mg was significantly accelerated in the presence of BSA or FBS.The reasons seemed to stem from the weakened protein adsorption on Mg surface in this case and the dynamically enhanced interaction between proteins and ions/products in solutions,which largely weaken the combination of the top Ca/P-rich layer with the inner corrosion product layer.These results highlight the importance of testing conditions for Mg characterization in vitro and the synergistic effect between different parameters on Mg degradation.
基金This research was partly funded by Helmholtz Association in the frame of Helmholtz-Russian Science Foundation Joint Research Group grant num-ber HRSF-0025.
文摘The effect of Ag in solid solution on the microstructure,texture and the deformation behaviour of indirectly extruded Mg was investigated.Ag as a solid solution strengthener affects the behaviour during extrusion,resulting in enhanced deformation related heating and corresponding coarser grained microstructures.No substantial effect on the texture development is revealed.The mechanical properties simultaneously increase in stress and strain levels with increasing Ag content,especially in tension as a result of the changing impact of the slip modes which can be associated with a decrease of the lattice parameters as well as the c/a ratio of the hcp lattice structure.In compression tests with twin dominated flow,the impact is much smaller on the compressive yield stress but higher with respect to the twinning related strain hardening rate.Solid solution strength functions for Fleischer and Labusch were determined,also confirming the anisotropic behaviour of the extruded Mg alloys.
基金funding from the Helmholtz-Incubator project Uncertainty Quantification。
文摘In silico methods to study biodegradable implants have recently received increasing attention due to their potential in reducing experimental time and cost. An important application case for in silico methods are magnesium(Mg)-based biodegradable implants, as they represent a powerful alternative to traditional materials used for temporary orthopaedic applications. Controlling Mg alloy degradation is critical to designing an implant that supports the bone healing process. To simulate different aspects of this biodegradation process, several mathematical models have been proposed with the ultimate aim of replacing laboratory experiments with computational modeling. In this review, we provide a comprehensive and critical discussion of the published models and their performance with respect to capturing the complexity of the biodegradation process. This complexity is presented initially. Additionally, the present review discusses the different approaches of optimizing and quantifying the different sources of errors and uncertainties within the proposed models.
基金financially supported by the China Scholarship Council (Grant No: 202006890008), ChinaScience and Technology Committee of Shanghai (19010500400)+1 种基金the “111” project (D16002)the Independent Research Project of State Key Laboratory of Mechanical Transmissions (Grant No. SKLMT-ZZKT-2021M11)。
文摘To have a better understand on the change of microstructure via kinetics, the diffusion behavior of Mg alloys is of special interest to researchers. Meanwhile, diffusion coefficients of Mg based alloys can explain and represent their diffusion behavior well. The evolution of experimental and calculated methods for detecting and extracting diffusion coefficients was discussed briefly. The reasonable diffusion data, especially self-diffusion coefficients, impurity diffusion coefficients and inter-diffusion coefficients of Mg alloys, were reviewed in detail serving to design the Mg alloys with higher accuracy. Then the practical applications of diffusion coefficients of Mg alloys were summarized,including diffusional mobility establishing, precipitation simulation and mechanical properties prediction.
基金carried out within the Synchro Load project(BMBF project number 05K16CGA)which is funded by the Röntgen-Angström Cluster(RAC),a bilateral research collaboration of the Swedish government and the German Federal Ministry of Education and Research(BMBF)the project Mg Bone(BMBF project number 05K16CGB)
文摘Biodegradable implants are taking an increasingly important role in the area of orthopedic implants with the aim to replace permanent implants for temporary bone healing applications.During the implant preparation process,the material’s surface and microstructure are being changed by stresses induced by machining.Hence degradable metal implants need to be fully characterized in terms of the influence of machining on the resulting microstructure and corrosion performance.In this study,micro-computed tomography(μCT)is used for the quantification of the degradation rate of biodegradable implants.To our best knowledge,for the first time quantitative measures are introduced to describe the degradation homogeneity in 3D.This information enables a prediction in terms of implant stability during the degradation in the body.Two magnesium gadolinium alloys,Mg-5Gd and Mg-10 Gd(all alloy compositions are given in weight%unless otherwise stated),in the shape of M2 headless screws have been investigated for their microstructure and their degradation performance up to 56 days.During the microstructure investigations particular attention was paid to the localized deformation of the alloys,due to the machining process.In vitro immersion testing was performed to assess the degradation performance quantified by subsequent weight loss and volume loss(usingμCT)measurements.Although differences were observed in the degree of screw’s near surface microstructure being influenced from machining,the degradation rates of both materials appeared to be suitable for application in orthopedic implants.From the degradation homogeneity point of view no obvious contrast was detected between both alloys.However,the higher degradation depth ratios between the crests and roots of Mg-5Gd ratios may indicated a less homogeneous degradation of the screws of these alloys on contract to the ones made of Mg-10Gd alloys.Due to its lower degradation rates,its more homogeneous microstructure,its weaker texture and better degradation performance extruded Mg-10Gd emerged more suitable as implant material than Mg-5Gd.
基金funding from the Helmholtz-Incubator project Uncertainty Quantification.
文摘Magnesium alloys are highly attractive for the use as temporary implant materials, due to their high biocompatibility and biodegradability.However, the prediction of the degradation rate of the implants is difficult, therefore, a large number of experiments are required. Computational modelling can aid in enabling the predictability, if sufficiently accurate models can be established. This work presents a generalized model of the degradation of pure magnesium in simulated body fluid over the course of 28 days considering uncertainty aspects. The model includes the computation of the metallic material thinning and is calibrated using the mean degradation depth of several experimental datasets simultaneously. Additionally, the formation and precipitation of relevant degradation products on the sample surface is modelled, based on the ionic composition of simulated body fluid. The computed mean degradation depth is in good agreement with the experimental data(NRMSE=0.07). However, the quality of the depth profile curves of the determined elemental weight percentage of the degradation products differs between elements(such as NRMSE=0.40 for phosphorus vs. NRMSE=1.03 for magnesium). This indicates that the implementation of precipitate formation may need further developments. The sensitivity analysis showed that the model parameters are correlated and which is related to the complexity and the high computational costs of the model. Overall, the model provides a correlating fit to the experimental data of pure Mg samples of different geometries degrading in simulated body fluid with reliable error estimation.
基金funding from the Helmholtz Virtual Institute“In vivo studies of biodegradable magnesium based implant materials(Met Bio Mat)”under grant agreement no.VH-VI-523
文摘Several material parameters affect degradation characteristics of Mg and its alloys under physiological conditions.Porous Mg materials are interesting for their simultaneous degradation and drug delivery capabilities.However,an increase in pore surface area is detrimental to both degradation resistance and subsequent mechanical properties.The present work aims at determining the threshold porosity value in Mg–0.6 Ca specimens produced by powder metallurgy(PM)below which low degradation rates persist with acceptable mechanical properties.Seven different porous Mg–0.6 Ca specimens containing both closed and open pore structures were fabricated with porosities ranging from 3%to 21%.Degradation profiles were obtained via a semi static immersion test over 16 days under physiological conditions using Dulbecco’s modified Eagle’s medium with Glutamax and 10%fetal bovine serum as supplements.The results are related to morphological pore parameters like pore size distribution,pore interconnectivity and pore curvatures that were quantified using an ex situμCT analysis.In general,with decreasing porosity a decrease in pore interconnectivity is seen followed by rounding of the pores.Low degradation rates(MDR<0.3 mm/year)are observed in specimens until 10%porosity,however,the upper bound for reproducible degradation is observed to be in specimens until 12%porosity.This porosity level also marks the transition from closed to open pore nature with a simultaneous change in pore interconnectivity from less than 10%to greater than 95%,below and above this porosity level,respectively.The tensile strength and elongation to failure recorded for specimens with 10%porosity were 70 MPa and 2%,respectively displaying positive traits of both homogenous degradation and mechanical properties.The results suggest that high pore interconnectivity is the dominant factor controlling degradation and mechanical properties in porous Mg-0.6 Ca specimens.The results also indicate a good sintering response of Mg-0.6 Ca specimens providing further material development towards biomaterial applications.
基金This publication is part of a project that has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Sk lodowska-Curie grant,agreement No 811226Röntgen-Angström Cluster in project SynchroLoad(05K16CGA)+5 种基金Swedish Research Council 2015-06109German Bundesministerium für Bildung und Forschung in project MgBone(05K16CGB)We acknowledge DESY(Hamburg,Germany),a member of the Helmholtz Association HGF,for the provision of experimental facilities.Parts of this research were carried out at PETRA IIIThe authors would like to thank Diamond Light Source for beamtime(proposal MG25078)Miguel Gomez Gonzalez and Julia Parker for assistance during the experiment at the I14 beamline and during the data analysisThis research was carried out in collaboration with the Quantitative Bio Element Analysis and Mapping(QBEAM)Center at Michigan State University and The National Research Resource for Quantitative Elemental Mapping for the Life Sciences(QE-Map)under Grant P41 GM135018(as well as Grant S10OD026786)from the National Institute of General Medical Sciences of the National Institutes of Health.
文摘Magnesium(Mg)–based alloys are becoming attractive materials for medical applications as temporary bone implants for support of fracture healing,e.g.as a suture anchor.Due to their mechanical properties and biocompatibility,they may replace titanium or stainless-steel implants,commonly used in orthopedic field.Nevertheless,patient safety has to be assured by finding a long-term balance between metal degradation,osseointegration,bone ultrastructure adaptation and element distribution in organs.In order to determine the implant behavior and its influence on bone and tissues,we investigated two Mg alloys with gadolinium contents of 5 and 10 wt percent in comparison to permanent materials titanium and polyether ether ketone.The implants were present in rat tibia for 10,20 and 32 weeks before sacrifice of the animal.Synchrotron radiation-based micro computed tomography enables the distinction of features like residual metal,degradation layer and bone structure.Additionally,X-ray diffraction and X-ray fluorescence yield information on parameters describing the bone ultrastructure and elemental composition at the bone-to-implant interface.Finally,with element specific mass spectrometry,the elements and their accumulation in the main organs and tissues are traced.The results show that Mg-xGd implants degrade in vivo under the formation of a stable degradation layer with bone remodeling similar to that of Ti after 10 weeks.No accumulation of Mg and Gd was observed in selected organs,except for the interfacial bone after 8 months of healing.Thus,we confirm that Mg-5Gd and Mg-10Gd are suitable material choices for bone implants.
基金funded by the Helmholtz-Russian Science Foundation Joint Research Groups HRSF-0025.
文摘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 Mg-based 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.
文摘Implants made of magnesium(Mg)are increasingly employed in patients to achieve osteosynthesis while degrading in situ.Since Mg implants and Mg^(2+)have been suggested to possess anti-inflammatory properties,the clinically observed soft tissue inflammation around Mg implants is enigmatic.Here,using a rat soft tissue model and a 1-28 d observation period,we determined the temporo-spatial cell distribution and behavior in relation to sequential changes of pure Mg implant surface properties and Mg^(2+)release.Compared to nondegradable titanium(Ti)implants,Mg degradation exacerbated initial inflammation.Release of Mg degradation products at the tissue-implant interface,culminating at 3 d,actively initiated chemotaxis and upregulated mRNA and protein immunomodulatory markers,particularly inducible nitric oxide synthase and toll-like receptor-4 up to 6 d,yet without a cytotoxic effect.Increased vascularization was demonstrated morphologically,preceded by high expression of vascular endothelial growth factor.The transition to appropriate tissue repair coincided with implant surface enrichment of Ca and P and reduced peri-implant Mg^(2+)concentration.Mg implants revealed a thinner fibrous encapsulation compared with Ti.The detailed understanding of the relationship between Mg material properties and the spatial and time-resolved cellular processes provides a basis for the interpretation of clinical observations and future tailoring of Mg implants.
基金This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 811226.Author Flenner gratefully acknowledges the financial support from the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)-Project number 192346071,SFB 986(project Z2).
文摘An increasing prevalence of bone-related injuries and aging geriatric populations continue to drive the orthopaedic implant market.A hierarchical analysis of bone remodelling after material implantation is necessary to better understand the relationship between implant and bone.Osteocytes,which are housed and communicate through the lacuno-canalicular network(LCN),are integral to bone health and remodelling processes.Therefore,it is essential to examine the framework of the LCN in response to implant materials or surface treatments.Biodegradable materials offer an alternative solution to permanent implants,which may require revision or removal surgeries.Magnesium alloys have resurfaced as promising materials due to their bone-like properties and safe degradation in vivo.To further tailor their degradation capabilities,surface treatments such as plasma electrolytic oxidation(PEO)have demonstrated to slow degradation.For the first time,the influence of a biodegradable material on the LCN is investigated by means of non-destructive 3D imaging.In this pilot study,we hypothesize noticeable variations in the LCN caused by altered chemical stimuli introduced by the PEO-coating.Utilising synchrotron-based transmission X-ray microscopy,we have characterised morphological LCN differences around uncoated and PEO-coated WE43 screws implanted into sheep bone.Bone specimens were explanted after 4,8,and 12 weeks and regions near the implant surface were prepared for imaging.Findings from this investigation indicate that the slower degradation of PEO-coated WE43 induces healthier lacunar shapes within the LCN.However,the stimuli perceived by the uncoated material with higher degradation rates induces a greater connected LCN better prepared for bone disturbance.
基金This project has received funding from the European Union’s Horizon 2020 Research and Innovation Programme under the Marie Skłodowska-Curie Grant Agreement No 811226.
文摘Magnesium(Mg)-based implants have re-emerged in orthopaedic surgery as an alternative to permanent implants.Literature reveals little information on how the degradation of biodegradable implants may introduce safety implications for patient follow-up using medical imaging.Magnetic resonance imaging(MRI)benefits post-surgery monitoring of bone healing and implantation sites.Previous studies demonstrated radiofrequency(RF)heating of permanent implants caused by electromagnetic fields used in MRI.Our investigation is the first to report the effect of the degradation layer on RF-induced heating of biodegradable orthopaedic implants.WE43 orthopaedic compression screws underwent in vitro degradation.Imaging techniques were applied to assess the corrosion process and the material composition of the degraded screws.Temperature measurements were performed to quantify implant heating with respect to the degradation layer.For comparison,a commercial titanium implant screw was used.Strongest RF induced heating was observed for non-degraded WE43 screw samples.Implant heating had shown to decrease with the formation of the degradation layer.No statistical differences were observed for heating of the non-degraded WE43 material and the titanium equivalent.The highest risk of implant RF heating is most pronounced for Mg-based screws prior to degradation.Amendment to industry standards for MRI safety assessment is warranted to include biodegradable materials.
基金financially supported by the Helmholtz Virtual Institute VH-VI-523(in vivo studies of biodegradable magnesium based implant materials)。
文摘Treatment of physeal fractures(15%–30%of all paediatric fractures)remains a challenge as in approximately 10%of the cases,significant growth disturbance may occur.Bioresorbable Magnesium-based implants represent a strategy to minimize damage(i.e.,load support until bone healing without second surgery).Nevertheless,the absence of harmful effects of magnesium-implants and their degradation products on the growth plate should be confirmed.Here,the proteome of human mesenchymal stem cells undergoing chondrogenesis was evaluated when exposed to the products of various Magnesium-based materials degradation.The results of this study indicate that the materials induced regulation of proteins associated with cell chondrogenesis and cartilage formation,which should be beneficial for cartilage regeneration.
文摘Osteosarcoma is one of the most common cancers in young adults and is commonly treated using surgery and chemotherapy.During the past years,these therapy approaches improved but failed to ameliorate the outcomes.Therefore,novel,targeted therapeutic approaches should be established to enhance treatment success while preserving patient’s quality of life.Recent studies suggest the application of degradable magnesium(Mg)alloys as orthopedic implants bearing a potential antitumor activity.Here,we examined the influence of Mg-based materials on an osteosarcoma-fibroblast coculture.Both,Mg and Mg-6Ag did not lead to tumor cell apoptosis at low degradation rates.Instead,the Mg-based materials induced cellular dormancy in the cancer cells indicated by a lower number of Ki-67 positive cancer cells and a higher p38 expression.This dormancy-like state could be reversed by reseeding on non-degrading glass slides but could not be provoked by inhibition of the protein kinase R-like endoplasmic reticulum kinase.By investigating the influence of the disjunct surface-near effects of the Mg degradation on cell proliferation,an increased pH was found to be a main initiator of Mg degradation-dependent tumor cell proliferation inhibition.
