Quantitative analysis of macrophage apoptosis vs. necrosis induced by cobalt and chromium ions in vitro

The relationships of metals exposure and disturbance of the vaginal microbiota with the risk of PROM: Results from a birth cohort study

The vaginal microbiota is proposed to be associated with reproductive health. Exposure to metals during pregnancy is a risk factor for premature rupture of membranes (PROM). PROM can lead to serious maternal complications, thus, identifying the cause and therapeutic targets for it is crucial. However, the role of vaginal microbiota in the association between metals exposure and the risk of PROM are not clear. Based on a prospective birth cohort study including 668 pregnant women, maternal blood levels of 15 metals in the first trimester (n=668) and microbiota of vaginal secretions in the third trimester (n=244) were assessed. The metals that significantly associated with the risk of PROM were screened out via four statistical models, the top three were barium (Ba), chromium (Cr) and thallium (Tl) according to their weight indices. The results from the BKMR model showed a positive association of the mixture (Ba, Cr and Tl) with the risk of PROM. PROM and non-PROM were characterised by different beta diversities, moreover, the relative abundances of Bifidobacterium, Corynebacterium and Collinsella were statistically and negatively related to the risk of PROM [the adjusted odds ratios (ORs) and 95 % confidence intervals (CIs) were 0.06 (0.00, 0.82), 0.32 (0.14, 0.74) and 0.50 (0.30, 0.84), respectively]. On the other hand, women with different levels of Ba exposure were also characterised by different beta diversities (p value = 0.047); and blood Ba levels were also negatively associated with the relative abundances of Collinsella; additionally, Cr levels were positively associated with alpha diversity indices [Shannon index: β (95 % CI) = 0.25 (0.01, 0.50); Simpson index: β (95 % CI) = 0.08 (0.00, 0.17), respectively]. The results from mediation analysis showed the proportion of the relationship between Ba exposure and PROM risk mediated by the relative abundance of Collinsella was 26.4 %. Further verification analysis exploring the potential cause of the above phenomenon indicated that the neutrophil count, one of blood inflammation indicators for PROM, was higher in women with the absence of Collinsella (p value = 0.039), moreover, the cumulative hazard of PROM for women with the presence of Collinsella was also significantly lower than that of those without Collinsella (p value = 0.007). Collectively, the changes in the diversity and composition of the bacterial community, especially the reduction in Collinsella abundance caused by metal exposure, may be related to the occurrence of PROM, which provides a new microbiota-based perspective for intervention in metal exposure-related PROM. Confirming these relationships and determining the possible processes at play will require more investigation.

An Overview of Hexavalent Chromium-Induced Necroptosis, Pyroptosis, and Ferroptosis

Heavy metals are common environmental industrial pollutants. Due to anthropogenic activity, chromium, especially its hexavalent form [Cr(VI)], is a widespread environmental contaminant that poses a threat to human health. In this review paper, we summarize the currently reported molecular mechanisms involved in chromium toxicity with a focus on the induction of pro-inflammatory non-apoptotic cell death pathways such as necroptosis, pyroptosis, and ferroptosis. The review highlights the ability of chromium to induce necroptosis, pyroptosis, and ferroptosis revealing the signaling pathways involved. Cr(VI) can induce RIPK1/RIPK3-dependent necroptosis both in vitro and in vivo. Chromium toxicity is associated with pyroptotic NLRP3 inflammasome/caspase-1/gasdermin D-dependent secretion of IL-1β and IL-18. Furthermore, this review emphasizes the role of redox imbalance and intracellular iron accumulation in Cr(VI)-induced ferroptosis. Of note, the crosstalk between the investigated lethal subroutines in chromium-induced toxicity is primarily mediated by reactive oxygen species (ROS), which are suggested to act as a rheostat determining the cell death pathway in cells exposed to chromium. The current study provides novel insights into the pro-inflammatory effects of chromium, since necroptosis, pyroptosis, and ferroptosis affect inflammation owing to their immunogenic properties linked primarily with damage-associated molecular patterns. Inhibition of these non-apoptotic lethal subroutines can be considered a therapeutic strategy to reduce the toxicity of heavy metals, including chromium.

Cobalt ions induce a cellular senescence secretory phenotype in human synovial fibroblast-like cells that may be an early event in the development of adverse local tissue reactions to hip implants

Objectives

Total hip arthroplasty is a successful procedure for treating advanced osteoarthritis (OA). Metal bearing surfaces remain one of the most widely implanted prosthesis, however approximately 10% of patients develop adverse local tissue reactions (ALTRs), namely lymphocytic predominant soft tissue reaction with or without necrosis and osteolysis resulting in high revision rates. The mechanism(s) for these reactions remains unclear although T lymphocyte mediated type IV hypersensitivity to cobalt (Co) and chromium (Cr) ions have been described. The purpose of this study was to determine the prolonged effects of Co and Cr metal ions on synovial fibroblasts to better understand the impact of the synovial membrane in the development of ALTRs.

Methods

Human synovial fibroblast-like cells were isolated from donors undergoing arthroplasty. DNA content and Alamar blue assay were used to determine cellular viability against exposure to Co and Cr. A beta-galactosidase assay was used to determine the development of cellular senescence. Western blotting and RT-qPCR were employed to determine changes in senescent associated secretory factors, signaling and anti-oxidant enzyme expression. A fluorescent assay was used to measure accumulation of hydrogen peroxide.

Results

We demonstrate that prolonged cobalt exposure results in a downregulation of the enzyme catalase resulting in cytosolic accumulation of hydrogen peroxide, decreased Akt activity and cellular senescence. Senescent fibroblasts demonstrated upregulation of proinflammatory cytokines IL-1β and TNFα in addition to the neurotrophic factor NGF.

Conclusion

Our results provide evidence that metal ions induce a senescent associated secretory phenotype in synovial fibroblasts that could contribute to the development of adverse local tissue reactions.

An Update Overview on Mechanistic Data and Biomarker Levels in Cobalt and Chromium-Induced Neurodegenerative Diseases

There is increasing evidence that the imbalance of metals as cobalt (Co) and chromium (Cr) may increase the risk of development and progression of neurodegenerative diseases (NDDs). The human exposure to Co and Cr is derived mostly from industry, orthopedic implants, and polluted environments. Neurological effects of Co and Cr include memory deficit, olfactory dysfunction, spatial disorientation, motor neuron disease, and brain cancer. Mechanisms of Co and Cr neurotoxicity included DNA damage and genomic instability, epigenetic changes, mitochondrial disturbance, lipid peroxidation, oxidative stress, inflammation, and apoptosis. This paper seeks to overview the Co and Cr sources, the mechanisms by which these metals induce NDDs, and their levels in fluids of the general population and patients affected by NDDs. To this end, evidence of Co and Cr unbalance in the human body, mechanistic data, and neurological symptoms were collected using in vivo mammalian studies and human samples.

A review on manufacturing processes of cobalt-chromium alloy implants and its impact on corrosion resistance and biocompatibility

Cobalt-Chromium (CoCr) alloys are currently used for various cardiovascular, orthopedic, fracture fixation, and dental implants. A variety of processes such as casting, forging, wrought processing, hot isostatic pressing, metal injection molding, milling, selective laser melting, and electron beam melting are used in the manufacture of CoCr alloy implants. The microstructure and precipitates (carbides, nitrides, carbonitrides, and intermetallic compounds) formed within the alloy are primarily determined by the type of manufacturing process employed. Although the effects of microstructure and precipitates on the physical and mechanical properties of CoCr alloys are well reviewed and documented in the literature, the effects on corrosion resistance and biocompatibility are not comprehensively reviewed. This article reviews the various processes used to manufacture CoCr alloy implants and discusses the effects of manufacturing processes on corrosion resistance and biocompatibility. This review concludes that the microstructure and precipitates formed in the alloy are unique to the manufacturing process employed and have a significant impact on the corrosion resistance and biocompatibility of CoCr alloys. Additionally, a historical and scientific overview of corrosion and biocompatibility for metallic implants is included in this review. Specifically, the failure of CoCr alloys when used in metal-on-metal bearing surfaces of total hip replacements is highlighted. It is recommended that the type of implant/application (orthopedic, dental, cardiovascular, etc.) should be the first and foremost factor to be considered when selecting biomaterials for medical device development.

Cobalt and Chromium Ions Impair Macrophage Response to Staphylococcus aureus Infection

Cobalt-chromium-molybdenum (CoCrMo) alloys are routinely used in arthroplasty. CoCrMo wear particles and ions derived from arthroplasty implants lead to macrophage-driven adverse local tissue reactions, which have been linked to an increased risk of periprosthetic joint infection after revision arthroplasty. While metal-induced cytotoxicity is well characterized in human macrophages, direct effects on their functionality have remained elusive. Synchrotron radiation X-ray microtomography and X-ray fluorescence mapping indicated that peri-implant tissues harvested during aseptic revision of different arthroplasty implants are exposed to Co and Cr in situ. Confocal laser scanning microscopy revealed that macrophage influx is predominant in patient tissue. While in vitro exposure to Cr3+ had only minor effects on monocytes/macrophage phenotype, pathologic concentrations of Co2+ significantly impaired both, monocyte/macrophage phenotype and functionality. High concentrations of Co2+ led to a shift in macrophage subsets and loss of surface markers, including CD14 and CD16. Both Co2+ and Cr3+ impaired macrophage responses to Staphylococcus aureus infection, and particularly, Co2+-exposed macrophages showed decreased phagocytic activity. These findings demonstrate the immunosuppressive effects of locally elevated metal ions on the innate immune response and support further investigations, including studies exploring whether Co2+ and Cr3+ or CoCrMo alloys per se expose the patients to a higher risk of infections post-revision arthroplasty.

Plastic response of macrophages to metal ions and nanoparticles in time mimicking metal implant body environment

The paradigm of using metal biomaterials could be viewed from two sides - treatment of wide spectrum of degenerative diseases, and debris release from materials. After implant insertion, metal nanoparticles (NPs) and ions are released not only upon the first contact with cells/tissues, but in continual manner, which is immediately recognized by immune cells. In this work, the effects of metal nanoparticles (TiO2, Ni) and ions (Ni2+, Co2+, Cr3+, Mo6+) on primary human M0 macrophages from the blood samples of osteoarthritic patients undergoing total arthroplasty were studied in order to monitor immunomodulatory effects on the cells in a real-time format. The highest NiNPs concentration of 10 µg/ml had no effect on any of macrophage parameters, while the Ni2+ ions cytotoxicity limit for the cells is 0.5 mM. The cytotoxic effects of higher Ni2+ concentration revealed mitochondrial network fragmentation leading to mitochondrial dysfunction, accompanied by increased lysosomal activity and changes in pro-apoptotic markers. The suppression of M2 cell formation ability was connected to presence of Ni2+ ions (0.5 mM) and TiO2NPs (10 µg/ml). The immunomodulatory effect of Mo6+ ions, controversially, inhibit the formation of the cells with M1 phenotype and potentiate the thread-like shape M2s with increased chaotic cell movement. To summarize, metal toxicity depends on the debris form. Both, metal ions and nanoparticles affect macrophage size, morphological and functional parameters, but the effect of ions is more complex and likely more harmful, which has potential impact on healing and determines post-implantation reactions.

Bone and Soft Tissue Reaction to Co(II)/Cr(III) Ions Stimulation in a Murine Calvaria Model: A Pioneering in vivo Study

Metal ions released during wear and corrosion of the artificial knee/hip joints are considered to contribute to aseptic implant failure. However, there are few convincing in vivo studies that demonstrate the effects of metal ions on bone and soft tissue. This study examined the in vivo effects of Co(II)/Cr(III) ions on mouse calvaria and the supra-calvaria soft tissue in an original mouse model. With the implantation of a helmet-like structure, we set up a subcutaneous cavity on the calvaria in which Co(II) Chloride or Cr(III) Chloride solutions were administered respectively. A layer of interface membrane formed on the calvaria along with the implantation of the helmet. The administered Cr(III) ions accumulated in the interface membranes while Co(II) disseminated into the circulation. Accumulated Cr(III) and related products induced local massive macrophage infiltration and skewed the bone metabolic balance. At last, we revealed that lymphocyte aggregates, which are the pathologic hallmark of human periprosthetic tissue, could be caused by either Co(II) or Cr(III) stimulation. These in vivo results may shed light on the effects and pathogenic mechanism of the Co(II)/Cr(III) ions released from the joint prosthesis. STATEMENT OF SIGNIFICANCE: Macrophage infiltration and lymphocyte aggregates are hallmarks of human joint periprosthetic tissue. We chronically administered Co(II)/Cr(III) ions on mouse calvaria and reproduced these two histopathologic hallmarks on mouse tissue based on an implanted helmet-like structure. Our results reveal that Cr(III) ions are locally accumulated and are effective in inducing macrophage infiltration and they can be phagocytosed and stored. However, the lymphocytes aggregates could be induced by both Co(II), Cr(III) and other unspecific inflammatory stimuli.

Magnetic particle based MRI thermometry at 0.2 T and 3 T

This study provides insight into the advantages and disadvantages of using ferrite particles embedded in agar gel phantoms as MRI temperature indicators for low-magnetic field scanners. We compare the temperature-dependent intensity of MR images at low-field (0.2 T) to those at high-field (3.0 T). Due to a shorter T₁ relaxation time at low-fields, MRI scanners operating at 0.2 T can use shorter repetition times and achieve a significant T₂^⁎ weighting, resulting in strong temperature-dependent changes of MR image brightness in short acquisition times. Although the signal-to-noise ratio for MR images at 0.2 T MR is much lower than at 3.0 T, it is sufficient to achieve a temperature measurement uncertainty of about ±1.0 °C at 37 °C for a 90 μg/mL concentration of magnetic particles.

Do total shoulder arthroplasty implants corrode?

BACKGROUND

Total shoulder arthroplasty (TSA) has become the gold-standard treatment to relieve joint pain and disability in patients with glenohumeral osteoarthritis who do not respond to conservative treatment. An adverse reaction to metal debris released due to fretting corrosion has been a major concern in total hip arthroplasty. To date, it is unclear how frequently implant corrosion occurs in TSA and whether it is a cause of implant failure. This study aimed to characterize and quantify corrosion and fretting damage in a single anatomic TSA design and to compare the outcomes to the established outcomes of total hip arthroplasty.

METHODS

We analyzed 21 surgically retrieved anatomic TSAs of the same design (Tornier Aequalis Pressfit). The retrieved components were microscopically examined for taper corrosion, and taper damage was scored. Head and stem taper damage was quantitatively measured with a non-contact optical coordinate-measuring machine. In selected cases, damage was further characterized at high magnifications using scanning electron microscopy. Energy-dispersive x-ray spectroscopy and metallographic evaluations were performed to determine underlying alloy microstructure and composition. Comparisons between groups with different damage features were performed with independent-samples t tests; Mann-Whitney tests and multivariate linear regression were conducted to correlate damage with patient factors. The level of statistical significance was set at P < .05.

RESULTS

The average material loss for head and stem tapers was 0.007 mm3 and 0.001 mm3, respectively. Material loss was not correlated with sex, age, previous implant, or time in situ (P > .05). We observed greater volume loss in head tapers compared with stem tapers (P = .002). Implants with evidence of column damage had larger volumetric material loss than those without such evidence (P = .003). Column damage aligned with segregation bands within the alloy (preferential corrosion sites). The average angular mismatch was 0.03° (standard deviation, 0.0668°), with negative values indicating distal engagement and positive values indicating proximal engagement. Implants with proximal engagement were significantly more likely to have column damage than those with distal engagement (P = .030).

DISCUSSION

This study has shown not only that the metal components of TSA implants can corrode but also that the risk of corrosion can be reduced by (1) eliminating preferential corrosion sites and (2) ensuring distal engagement to prevent fluid infiltration into the modular junction.

Environmentally Relevant Hexavalent Chromium Disrupts Elemental Homeostasis and Induces Apoptosis in Zebrafish Liver

Although hexavalent chromium Cr [VI] is known as a toxicant in the aquatic environment, its effect in low, environmentally relevant concentration (ERC; 2 mg L^-1) is less characterized. Against this backdrop, the effects of Cr [VI] in ERC on zebrafish liver has been investigated in this study. Fluorescence microscopy and gel electrophoresis detected excess DNA damage and cell death via apoptosis in 2 mg L^-1 Cr [VI]-treated fish when compared with that of control. Besides, there were transcriptional activations of p53, Bax, Caspase 9 and Caspase 3 genes but downregulation of Bcl2 gene in the treated group, confirming the apoptotic pathway. Energy dispersive X-ray fluorescence (EDXRF) data showed significant (p < 0.05) increase in hepatic content of Cr, selenium, iron, manganese, calcium, sulfur and magnesium but depletion of zinc, copper and cobalt in the treated group. Collectively, the study shows that even a low, ERC of Cr [VI] is toxic to the zebrafish as it elicited marked apoptosis in the hepatocytes and altered the liver elemental profile.

Concentration-Dependent Effects of Cobalt and Chromium Ions on Osteoarthritic Chondrocytes

OBJECTIVE

Cobalt and chromium (CoCr) ions from metal implants are released into the joint due to biotribocorrosion, inducing apoptosis and altering gene expression in various cell types. Here, we asked whether CoCr ions concentration-dependently changed viability, transcriptional activity, and inflammatory response in human articular chondrocytes.

DESIGN

Human articular chondrocytes were exposed to Co (1.02-16.33 ppm) and Cr (0.42-6.66 ppm) ions and cell viability and early/late apoptosis (annexin V and 7-AAD) were assessed in 2-dimensional cell cultures using the XTT assay and flow cytometry, respectively. Changes in chondrocyte morphology were assessed using transmitted light microscopy. The effects of CoCr ions on transcriptional activity of chondrocytes were evaluated by quantitative polymerase chain reaction (qPCR). The inflammatory responses were determined by measuring the levels of released pro-inflammatory cytokines (interleukin-1β [IL-1β], IL-6, IL-8, and tumor necrosis factor-α [TNF-α]).

RESULTS

CoCr ions concentration-dependently reduced metabolic activity and induced early and late apoptosis after 24 hours in culture. After 72 hours, the majority of chondrocytes (>90%) were apoptotic at the highest concentrations of CoCr ions (16.33/6/66 ppm). SOX9 expression was concentration-dependently enhanced, whereas expression of COL2A1 linearly decreased after 24 hours. IL-8 release was enhanced proportionally to CoCr ions levels, whereas IL-1β, IL-6, and TNF-α levels were not affected by the treatments.

CONCLUSIONS

CoCr ions showed concentration- and time-dependent effects on articular chondrocytes. Fractions of apoptotic articular chondrocytes were proportional to CoCr ion concentrations. In addition, metabolic activity and expression of chondrocyte-specific genes were decreased by CoCr ions. Furthermore, exposure to CoCr ions caused a release of pro-inflammatory cytokines.

Genotoxicity of chromium (III) and cobalt (II) and interactions between them

Introduction. Chromium and cobalt are essential trace elements that are required only in a small amount, otherwise their excess can cause toxic effects.

Aim. The aim of this study was to determine the effects of chromium (III) and cobalt (II) and their combinations on genotoxicity in human fibroblasts cells (BJ).

Material and methods. In this work, comet and micronucleus assays were used. The BJ cells were exposed to chromium chloride and cobalt chloride at concentration ranges from 100 to 1400 µM. Mixtures of these elements were prepared so as to examine interactions between them.

Results. The present study shows the genotoxic effects of chromium (III) and cobalt (II) and their mixtures on BJ cells. In the comet assay, no comets were observed at the lowest concentrations; in the higher, a significant increase in their percentage was observed. In the other assay (formation of micronuclei), a statistically significant increase in the number of cells with micronuclei was observed in the BJ cells spiked with cobalt chloride and chromium chloride. In the case of simultaneous incubation of chromium chloride at 200 µM and cobalt chloride at 1000 µM in the BJ line, antagonism was observed. However, the interaction of chromium chloride at the 1000 µM and cobalt chloride at 200 µM leads to synergism between the studied elements.

Conclusions. Cobalt (II) and chromium (III) show genotoxic properties, they induce breaks in double and single-stranded DNA and they cause formation of AP-sites that do not have purine or pyrimidine bases.

The Expression Levels of Toll-like Receptors after Metallic Particle and Ion Exposition in the Synovium of a Murine Model

To date, the exact role of specific Toll-like receptors (TLRs) in regulating immune reactivity to metallic byproducts of orthopedic implants has not been fully clarified. In light of the situation, our objective in this investigation was to assess the expression levels of surface TLRs after metallic particle and ion exposure in an established animal model. Ten female BALB/c mice in each group received intra-articular injections of phosphate buffer (PBS) (control), metallic particles (MP), and metallic ions (MI), respectively. Seven days later, immunohistochemical staining was undertaken in the synovial layer of the murine knee joints using anti-TLR 1, 2, 4, 5, and 6 polyclonal antibodies. In addition to increased cellular infiltrates and a hyperplastic synovial membrane, the MP group showed significantly elevated TLR expression compared to the control group and had higher TLR 1-, 4-, and 6-positive cells than the MI group (p < 0.0167). TLR 4- and TLR 6-positive cells were significantly augmented for the MI group compared to the control group (p < 0.0167). Additionally, greenish corrosion particles found in the necrotic tissue suggested that metallic particles might release a certain level of locally toxic metallic ions in vivo.

Prenatal exposure to barium and the occurrence of neural tube defects in offspring

Neural tube defects (NTDs) have a complex etiology. Few studies have assessed alkaline earth metals exposures and occurrence of NTDs. We examined the association between prenatal exposure to magnesium (Mg), calcium (Ca), strontium (Sr) and barium (Ba) and risk for NTDs in a case-control study, and assessed the teratogenic effects of Ba on mice. Placentas were collected from 408 women with NTD-affected pregnancies and 593 women who delivered healthy infants, and concentrations of these metals were determined as prenatal exposure markers. The single effect of individual exposure and joint effect of coexposure to these metals were evaluated with logistic regression and Bayesian kernel machine regression (BKMR), respectively. Barium chloride (BaCl₂) was intragastrically administered to pregnant ICR mice and fetal mice were examined for NTDs. Median concentrations of Mg and Ba were higher in NTD cases than in controls (P_all < 0.001). In logistic regression, higher levels of Ba were associated with 1.6-fold increased risk for NTDs (95% confidence interval: 1.06-2.43). In BKMR, the joint effect of the four-metal mixture on NTD risk increased steadily with the levels of the mixture. A change in Ba concentration from the 25^th to 75^th percentile displayed a risk effect when the other three metals were fixed at the 25^th, 50^th or 75^th percentile, while such a change in Ca concentration showed a protective effect when the other metals were held at the 25^th or 50^th percentile. No interactions among metals were found. In the mouse experiment, dams treated with 200 mg/kg BaCl₂ showed 16.8% of NTDs in fetal mice, compared to 2.6% in the untreated control group (P < 0.01). Taken together, higher mixture levels of the four alkaline earth metals were associated with increased risk for NTDs, with Ba being the major contributor for the joint effect. Intragastric administration of Ba can induce NTDs in mice.

Association between selected alkaline earth elements concentrations in umbilical cord and risk for cleft lip with or without cleft palate

The relationship between alkaline earth elements in utero exposure and the risk of cleft lip with or without cleft palate (CL ± P) remains unclear. We aimed to investigate the associations between the concentration of alkaline earth elements in umbilical cord and risk for CL ± P. A case-control study was carried out in this study, including 78 cases and 142 controls. Association between each metals and the risk of CL ± P were evaluated with conventional logistic regression, bayesian kernel machine regression and weighted quantile sum regression models. Logistic regression model indicated that in utero exposure to higher levels of Barium was associated with increasing risk for CL ± P (odds ratio = 2.79, 95% confidence interval, 1.22-6.38) and for cleft lip with cleft palate (odds ratio = 3.94, 95% confidence interval, 1.45-10.72). Bayesian kernel machine regression model showed the statistical association between the metals mixture and risk difference of CL ± P, and barium was associated with CL ± P risk when all other metals were held fixed at the 25th percentiles (risk difference = 1.07, 95% confidence interval, 1.01-1.14). In weighted quantile sum model, barium accounted for most of the weight index in the combined effect of the metals mixture. The weighted quantile sum index showed that a quartile increase in the index resulted in an increase odds of 1.69 (95% confidence interval, 1.16-2.46) for CL ± P and of 2.11 (95% confidence interval, 1.34-3.35) for CLP. No associations were found in the three statistical models between Calcium, Magnesium and Strontium and the risks of CL ± P. In conclusion, in utero exposure to mixtures of alkaline earth elements was associated with an increased risk for CL ± P, of which barium was likely to be important factors in the development.

Multivariate use of MRI biomarkers to classify histologically confirmed necrosis in symptomatic total hip arthroplasty

The failure of total hip arthroplasty (THA) is commonly associated with the necrosis of the periprosthetic tissue. To date, there is no established method to noninvasively quantify the progression of such necrosis. Magnetic resonance imaging (MRI) of soft tissues near implants has undergone a recent renaissance due to the development of multispectral metal-artifact reduction techniques. Advanced analysis of multispectral MRI has been shown capable of detecting small magnetism effects of metallic debris in periprosthetic tissue. The purpose of this study is to demonstrate the diagnostic utility of these MRI-based tissue-magnetism signatures. Together with morphological MRI metrics, such as synovial volume and thickness, these measurements are utilized as biomarkers to noninvasively detect soft-tissue necrosis in symptomatic THA patients ( N = 78 ). All subjects underwent an advanced MRI scan before revision surgery and tissue biopsies utilized for necrosis grading. Statistical analyses demonstrated a weak, but significant positive correlation (P = .04) between MRI magnetism signatures and necrosis scores, while indicating no meaningful association between the latter and serum cobalt and chromium ion levels. Receiver-operating characteristic (ROC) analyses were then performed based on uni- and multivariate logistic regression models utilizing the measured MRI biomarkers as predictors of severe necrosis. The area under the curve of the ROC plots for MRI biomarkers as combined predictors were found to be 0.70 and 0.84 for cross-validation and precision-recall tests, respectively.

Recovery ability of human adipose stem cells exposed to cobalt nanoparticles: outcome of dissolution

Aim: To demonstrate that cobalt nanoparticles doses are safe for use in humans and to understand the consequences of the particulate effects, which may persist inside the cells. Materials & methods: Human adipose stem cells were used. We evaluated cell recovery by viability test, morphology and ultrastructure using electronic and optical microscopy, while gene expression was assessed utilizing real-time PCR. Results: After exposure, most stem cells recovered their normal function. Co₃O₄-nanoparticles remained inside the cell for the entirety of the considered time. A slight modification of gene expression was observed in the exposed cells. Conclusion: After exposure to 100 M cobalt nanoparticles, most cells returned to normal function. Nanoparticle toxicity was due to ions released by dissolution as well as from the nanoparticles themselves.

Modulating the cobalt dose range to manipulate multisystem cooperation in bone environment: a strategy to resolve the controversies about cobalt use for orthopedic applications

The paradoxical effect of cobalt on biological processes has aroused controversy regarding the application of cobalt-based biomaterials in bone regeneration. Tuning the dose range of cobalt ions may be a valid strategy to resolve the controversies about cobalt use for orthopedic applications. Recent progress in bone biology has highlighted the effects of multisystem cooperation (especially of osteoimmune, skeletal, and vascular systems) on bone dynamics. Before the application of this dose-tuning strategy, a deeper understanding of its dose-dependent effect on the cooperation of osteoimmune, skeletal, and vascular systems is needed. However, due to the difficulties with investigating the interaction of multiple systems in vitro, the multimodal effects of cobalt on bone homeostasis were investigated here, in an in vivo scenario. Methods: In vitro CCK8 assay and cytoskeletal staining were preformed to detecte the cell cytotoxic reaction in response to 0.1-100 ppm cobalt stimulation. Blood clot containing 0.1 to 5 ppm of cobalt were implanted in the rat calvarium defect. The gene profile of osteoimmune, skeletal, and vascular system as well as the systemic toxicity were evaluated via RT-qPCR, histological analysis and inductively coupled plasma mass spectrometry. The bone regeneration, osteoclastogenesis and vascularization were assessed by micro-ct and histological analysis. Results: Cobalt concentration below 5 ppm did not cause cell toxicity in vitro. No systemic toxicity was observed in vivo at 0.1-5 ppm cobalt concentration. It was found that the early cytokine profiles of the multiple interacting systems were different in response to different cobalt doses. Most of the anti-inflammatory, osteogenic, and proangiogenic factors were upregulated in the 1 ppm cobalt group at the early stage. In the late stage, the 1ppm group was most superior in bone regenerative effect while the 5 ppm group displayed the strongest osteoclastogenesis activity. Conclusions: The 1 ppm concentration of cobalt yielded the most favorable cooperation of the osteoimmune, skeletal, and vascular systems and subsequently optimal bone regeneration outcomes. Tuning the cobalt dose range to manipulate the cooperation of osteoimmune, skeletal, and vascular systems could be a promising and valuable strategy to prevent paradoxical effects of cobalt while preserving its beneficial effects.

Quantifying Mycobacterium avium subspecies paratuberculosis infection of bovine monocyte derived macrophages by confocal microscopy

Quantification of Mycobacterium avium subspecies paratuberculosis (MAP) during in vitro infection experiments is challenging due to limitations of currently utilised methods, such as colony counting. Here we describe quantifying MAP infection of bovine macrophages (Mφ) using confocal microscopy. Bovine monocyte derived macrophages were infected with MAP at a high or low dose and the number of intracellular bacteria calculated at 2 h post infection using confocal microscopy. Bacteria within simultaneously infected Mφ were quantified by colony counting in order to compare confocal microscopy results with results obtained by an established method. Confocal microscopy provided a robust alternative quantification method that allowed for assessment of the infection at the individual Mφ level. This demonstrated that MAP infection was not homogeneous, and that there were higher numbers of both infected Mφ and intracellular bacteria and bacterial aggregates at the high dose compared to the low dose, potentially impacting the Mφ response to infection. Confocal microscopy can therefore provide a level of detail regarding the infection unobtainable by other quantification methods.

Mechanisms of Adverse Local Tissue Reactions to Hip Implants

Adverse Local Tissue Reactions (ALTRs) are one of the main causes of hip implant failures. Although the metal release from the implants is considered as a main etiology, the mechanisms, and the roles of the released products are topics of ongoing research. The alloys used in the hip implants are considered biocompatible and show negligible corrosion in the body environment under static conditions. However, modularity and its associated mechanically assisted corrosion have been shown to release metal species into the body fluids. ALTRs associated with metal release have been observed in hip implants with metal-on-metal articulation initially, and later with metal-on-polyethylene articulation, the most commonly used design in current hip replacement. The etiological factors in ALTRs have been the topics of many studies. One commonly accepted theory is that the interactions between the metal species and body proteins and cells generate a delayed type IV hypersensitivity reaction leading to ALTRs. However, lymphocyte reactions are not always observed in ALTRS, and the molecular mechanisms have not been clearly demonstrated. A more accepted mechanism is that cell damage generated by metal ions may trigger the secretion of cytokines leading to the inflammatory reactions observed in ALTRs. In this inflammatory environment, some patients would develop hypersensitivity that is associated with poor outcomes. Concerns over ALTRS have brought significant impact to both the clinical selection and development of hip implants. This review is focused on the mechanisms of ALTRs, specifically, the metal release process and the roles of the metal species released in the etiology and pathogenesis of the disease. Hopefully, our presentation and discussion of this biological process from a material perspective could improve our current understanding on the ALTRs and provide useful guidance in developing preventive solutions.

Neuroprotection by luteolin and gallic acid against cobalt chloride-induced behavioural, morphological and neurochemical alterations in Wistar rats

Cobalt (Co) intoxication arising from occupational exposures and ion release from metal implants has been associated with neurological alterations such as cognitive decline, incoordination and depression. The present study evaluated the mechanisms of neuro-protection exerted by Luteolin (Lut; 100 mg/kg) and Gallic acid (GA; 120 mg/kg) in Wistar rats exposed to cobalt chloride (CoCl₂) at 150 mg/kg for 7 consecutive days. Results indicate that CoCl₂ induced neuro-behavioural deficits specifically by decreasing exploratory activities of CoCl₂-exposed rats, increased anxiety, as well as significant reduction in hanging latency. Co-treatment with Lut or GA, however, restored these parameters to values near those of normal controls. Moreover, Lut and GA prevented CoCl₂-induced increases in hydrogen peroxide (H₂O₂), malondialdehyde (MDA) and nitric oxide (NO) in the brain, while also restoring the activities of acetylcholinesterase, glutathione S-transferase (GST) and superoxide dismutase (SOD). In addition, Lut and GA produced significant reversal of CoCl_2-induced elevation in levels of serum Interleukin 1 beta (IL-1β) and Tumor necrosis factor (TNFα). Meanwhile, immunohistochemistry revealed increased astrocytic expression of glial fibrillary acidic protein (GFAP), with intense calbindin (CB) D-28k staining and pronounced dendrites in the Purkinje cells. In contrast, the CoCl₂ group was characterized by decreased number of neurons expressing CB and dendritic loss. Taken together, mechanisms of luteolin and/or gallic acid protection against Co toxicity involved restoration of Ca²⁺ homeostasis, acetylcholinesterase and antioxidant enzyme activities, as well as inhibition of lipid peroxidation in the brain.

In vitro cyto-toxic assessment of heavy metals and their binary mixtures on mast cell-like, rat basophilic leukemia (RBL-2H3) cells

We investigated the cytotoxicity and mechanisms of cell death induced by salts of Cadmium (Cd²⁺), Lead (Pb²⁺), Arsenic (AsO₄^3-) and Chromium (Cr⁺⁶) on RBL-2H3 cells (a model mast cell line). In addition, cyto-toxic effect on cell viability was assessed to reveal their nature of interaction in binary mixture. The individual cytotoxic characteristics of these metals on RBL-2H3 cell viability showed a concentration-dependent reduction of cell viability. We observed that concentration-dependent cytotoxic potency on RBL-2H3 cells of these metals range in the following order Cd²⁺>Cr⁺⁶>As O₄^3-> Pb²⁺ with LC₅₀ values of 0.11 μM, 93.58 μM, 397.9 μM and 485.3 μM respectively. Additive effects were observed with Pb²⁺ + Cd²⁺, Pb²⁺ + AsO₄^3-, Pb²⁺ + Cr⁺⁶ and AsO₄^3- + Cr⁺⁶. The study revealed that Pb²⁺, Cd²⁺, AsO₄^3- and Cr⁺⁶ could induce significant (P < 0.01) cell death by apoptosis in RBL-2H3. Highly significant necrotic cell death was observed with Pb²⁺ and Cr⁺⁶ (P < 0.01) than Cd²⁺ and AsO₄^3- (P < 0.05). Overall, it can be deduced that several cell death executing pathways may be concomitantly activated on exposure to heavy metals and the predominance of one over others might depend on the type of heavy metal, concentration and the metabolic state of the cell. Eventually, binary mixtures of some of these metals showed less cytotoxicity than would be expected from their individual actions and may depend on the co-exposure of the metal ions and their modes of action.

Differentially expressed coding and noncoding RNAs in CoCl2-induced cytotoxicity of C2C12 cells

Aim: We aimed to explore potential regulators of coding and noncoding RNAs (ncRNAs) in Co(II) ion-induced myo cytotoxicity. Materials & methods: We confirmed the toxic effects of Co(II) on mouse skeletal C2C12 myotubes by CoCl2, and performed the expression profiles of circular RNAs (circRNAs), long noncoding RNAs (lncRNAs) and mRNAs using microarray analysis. We constructed co-expression, competing endogenous RNA and cis/trans regulation networks for ncRNAs, and filtered 71 candidate circRNAs with coding potential. Results: We identify 605 differentially expressed circRNAs, 4409 long noncoding RNAs and 3965 mRNAs. We also provided several ncRNAs regulation networks and presumed functions of circRNAs with coding potential. Conclusion: Our findings may reveal novel regulatory mechanisms underlying the noxious effects of CoCl2 in skeletal muscle.

Association between concentrations of barium and aluminum in placental tissues and risk for orofacial clefts

Natural exposure to and increasing use of barium and aluminum in various products, such as plastics, rubber, and food additives, raise concerns for their potential health impacts on pregnant women and vulnerable fetuses. We investigated whether there are associations between barium and aluminum concentrations in placental tissues and the risk for orofacial clefts (OFCs) in offspring. In this case-control study, we recruited 103 women with OFC-affected pregnancies and 206 women who delivered healthy newborns. Concentrations of barium and aluminum in placental tissues were measured using inductively coupled plasma-mass spectrometry. Information on maternal sociodemographic characteristics and diet was collected via face-to-face interviews using a structured questionnaire. Aluminum concentrations in placental tissues were not associated with OFC risk. However, a higher concentration of barium in placental tissues was associated with an increased risk for OFCs, with an adjusted odds ratio (OR) of 2.42 (95% confidence interval [95% CI] 1.34-4.40) for total cleft lip with or without cleft palate (CL ± P), and 1.90 (95% CI 1.03-3.50) for isolated CL ± P. There was a positive dose-response relationship between placental barium concentrations and OFC risk. Maternal exposure to barium may increase the risk for OFCs in offspring.

Correlating Live Cell Viability with Membrane Permeability Disruption Induced by Trivalent Chromium

Cr(III) is often regarded as a trace essential micronutrient that can be found in many dietary supplements due to its participation in blood glucose regulation. However, increased levels of exposure have been linked to adverse health effects in living organisms. Herein, scanning electrochemical microscopy (SECM) was used to detect variation in membrane permeability of single cells (T24) resulting from exposure to a trivalent Cr-salt, CrCl₃. By employing electrochemical mediators, ferrocenemethanol (FcMeOH) and ferrocenecarboxylic acid (FcCOO^-), initially semipermeable and impermeable, respectively, complementary information was obtained. Three-dimensional COMSOL finite element analysis simulations were successfully used to quantify the permeability coefficients of each mediator by matching experimental and simulated results. Depending on the concentration of Cr(III) administered, three regions of membrane response were detected. Following exposure to low concentrations (up to 500 μM Cr(III)), their permeability coefficients were comparable to that of control cells, 80 μm/s for FcMeOH and 0 μm/s for FcCOO^-. This was confirmed for both mediators. As the incubation concentrations were increased, the ability of FcMeOH to permeate the membrane decreased to a minimum of 17 μm/s at 7500 μM Cr(III), while FcCOO^- remained impermeable. At the highest examined concentrations, both mediators were found to demonstrate increased membrane permeability. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide cell viability studies were also conducted on Cr(III)-treated T24 cells to correlate the SECM findings with the toxicity effects of the metal. The viability experiments revealed a similar concentration-dependent trend to the SECM cell membrane permeability study.

Effects of cobalt and chromium ions on oxidative stress and energy metabolism in macrophages in vitro

Cobalt and chromium ions released from cobalt-chromium-molybdenum (CoCrMo)-based implants are a potential health concern, especially since both ions have been shown to induce oxidative stress in macrophages, the predominant immune cells in periprosthetic tissues. Ions of other transition metals (Cd, Ni) have been reported to inhibit the activity of mitochondrial enzymes in the electron transport chain. However, the effects of Co and Cr ions on the energy metabolism of macrophages remain largely unknown. The objective of the present study was to analyze the effects of Co²⁺ and Cr³⁺ on oxidative stress and energy metabolism in macrophages in vitro. RAW 264.7 murine macrophages were exposed to 6-18 ppm Co²⁺ or 50-150 ppm Cr³⁺ . Results showed a significant increase in two markers of oxidative stress, reactive oxygen species level and protein carbonyl content, with increasing concentrations of Co²⁺ , but not with Cr³⁺ . In addition, oxygen consumption rates (OCR; measured using an extracellular flux analyzer) showed significant decreases in both mitochondrial respiration and non-mitochondrial oxygen consumption with increasing concentrations of Co²⁺ , but not with Cr³⁺ . OCR results further showed that Co²⁺ , but not Cr³⁺ , induced mitochondrial dysfunction, including a decrease in oxidative phosphorylation capacity. Overall, this study suggests that mitochondrial dysfunction may contribute to Co²⁺ -induced oxidative stress in macrophages, and thereby to the inflammatory response observed in periprosthetic tissues. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:3178-3187, 2018.

Differential Effect of Cobalt and Chromium Ions as Well as CoCr Particles on the Expression of Osteogenic Markers and Osteoblast Function

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.

Ionic cobalt but not metal particles induces ROS generation in immune cells in vitro

Total joint replacement is one of the most successful procedures in orthopedic surgery today. However, metal implant materials undergo wear and corrosion processes. Generated particles and ions can cause a variety of cellular reactions. Cobalt-containing alloys are used frequently in implant materials. Some studies suggest that cobalt exhibits potential cytotoxic effects, for example, via generation of reactive oxygen species (ROS). To further elucidate the effects of cobalt on human cells, we determined cell viability and cytosolic and mitochondrial superoxide formation after incubation of either ions or particles with different cells. MM-6 and Jurkat cell lines were treated for 24, 48 and 72 h with either CoCrMo particles or cobalt ions (supplied as CoCl₂ ). A total of 24 h exposure of both forms of cobalt did not induce cell death using terminal deoxynucleotidyl transferase (TUNEL) and trypan blue assay. Interestingly, the formation of superoxide (O₂ ^.- ) is evoked mainly by ionic CoCl₂ but not cobalt particles. Cobalt alloy particles are likely to even suppress O₂ ^.- formation in mitochondria in both used cell lines. Furthermore, we did not observe any effect of cobalt particles on O₂ ^.- formation in peripheral blood mononuclear cells (PBMCs) from healthy donors. We also found that the O₂ ^- formation by CoCl₂ within mitochondria is a generalized effect for all cell types used, while the formation of superoxide in cytosolic compartment is cell-type dependent. In summary, our data suggest that cobalt ions specifically induce the formation of O₂ ^.- , whereas the cobalt particles were better tolerated. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1246-1253, 2019.

Differential toxicity of processed and non-processed states of CoCrMo degradation products generated from a hip simulator on neural cells

Physico-chemical characteristics of the CoCrMo degradation products have played an important role in cytotoxicity and clinical complications on the orthopedic patients who have metal implants. Previous studies have limited reflection on the physicochemical characteristics of the degradation products generated in vivo, which are very different from individual metal particles and/or ions obtained from different commercial sources. In this study, we aimed to understand the differences in toxicity induced by the degradation products in as-synthesized form as well as those obtained after post-processing. The degradation products were generated using a hip-simulator by maintaining physiological conditions closer to in vivo and separated into two batches, one with processing by washing and drying called processed degradation products (PDP) and another batch as 'as-synthesized' degradation product (DP). We studied the dose-dependent toxicity response by neural cells derived from induced pluripotent stem cells. The results of the study show that as-synthesized DPs are more toxic to neural cells even at lower concentrations studied with evident low TC50 (1-5 μg/ml) concentrations compared to PDP (25 μg/ml). Flow cytometric analysis showed a significant (p<.01) increase in uptake of the particles after 24 h and corresponding ROS production in DP-treated cells. RT-PCR analysis of oxidative specific gene expression showed, elevated mRNA levels of NADPH oxidase-1, nuclear transcription factor, superoxide dismutase-2 and glutaredoxin-2 in DP-treated cells after 6 h. The results of the study provided a clear evidence of the differential response of neural cells on the degradation products as a function of concentrations and their chemical nature.

Influence of Cobalt Ions on Collagen Gel Formation and Their Interaction with Osteoblasts

Metals on metal implants have long been used in arthroplasties because of their robustness and low dislocation rate. Several relatively low-corrosion metals have been used in arthroplasty, including 316L stainless steel, titanium, and cobalt-chromium-molybdenum alloy. Debris from these implants, however, has been found to cause inflammatory responses leading to unexpected failure rates approaching 10% 7 years surgery. Safety assessment of these materials traditionally relies on the use of simple two-dimensional assays, where cells are grown on the surface of the material over a relatively short time frame. It is now well-known that the composition and stiffness of the extracellular matrix (ECM) have a critical effect on cell function. In this work, we have evaluated how cobalt ions influence the assembly of type I collagen, the principle component of the ECM in bone. We found that cobalt had a significant effect on collagen matrix formation, and its presence results in local variations in collagen density. This increase in heterogeneity causes an increase in localized mechanical properties but a decrease in the bulk stiffness of the material. Moreover, when collagen matrices contained cobalt ions, there was a significant change in how the cells interacted with the collagen matrix. Fluorescence images and biological assays showed a decrease in cell proliferation and viability with an increase in cobalt concentration. We present evidence that the cobalt ion complex interacts with the hydroxyl group present in the carboxylic terminal of the collagen fibril, preventing crucial stabilizing bonds within collagen formation. This demonstrates that the currently accepted toxicity assays are poor predictors of the longer-term biological performance of a material.

Effects of metal ions on caspase-1 activation and interleukin-1β release in murine bone marrow-derived macrophages

Ions released from metal implants have been associated with adverse tissue reactions and are therefore a major concern. Studies with macrophages have shown that cobalt, chromium, and nickel ions can activate the NLRP3 inflammasome, a multiprotein complex responsible for the activation of caspase-1 (a proteolytic enzyme converting pro-interleukin [IL]-1β to mature IL-1β). However, the mechanism(s) of inflammasome activation by metal ions remain largely unknown. The objectives of the present study were to determine if, in macrophages: 1. caspase-1 activation and IL-1β release induced by metal ions are oxidative stress-dependent; and 2. IL-1β release induced by metal ions is NF-κB signaling pathway-dependent. Lipopolysaccharide (LPS)-primed murine bone marrow-derived macrophages (BMDM) were exposed to Co2+ (6-48 ppm), Cr3+ (100-500 ppm), or Ni2+ (12-96 ppm), in the presence or absence of a caspase-1 inhibitor (Z-WEHD-FMK), an antioxidant (L-ascorbic acid [L-AA]), or an NF-κB inhibitor (JSH-23). Culture supernatants were analyzed for caspase-1 by western blotting and/or IL-1β release by ELISA. Immunoblotting revealed the presence of caspase-1 (p20 subunit) in supernatants of BMDM incubated with Cr3+, but not with Ni2+ or Co2+. When L-AA (2 mM) was present with Cr3+, the caspase-1 p20 subunit was undetectable and IL-1β release decreased down to the level of the negative control, thereby demonstrating that caspase-1 activation and IL-1β release induced by Cr3+ was oxidative stress-dependent. ELISA demonstrated that Cr3+ induced the highest release of IL-1β, while Co2+ had no or limited effects. In the presence of Ni2+, the addition of L-AA (2 mM) also decreased IL-1β release, below the level of the negative control, suggesting that IL-1β release induced by Ni2+ was also oxidative stress-dependent. Finally, when present during both priming with LPS and activation with Cr3+, JSH-23 blocked IL-1β release, demonstrating NF-κB involvement. Overall, this study showed that while both Cr3+ and Ni2+ may be inducing inflammasome activation, Cr3+ is likely a more potent activator, acting through oxidative stress and the NF-κB signaling pathway.

Use of SU8 as a stable and biocompatible adhesion layer for gold bioelectrodes

Gold is the most widely used electrode material for bioelectronic applications due to its high electrical conductivity, good chemical stability and proven biocompatibility. However, it adheres only weakly to widely used substrate materials such as glass and silicon oxide, typically requiring the use of a thin layer of chromium between the substrate and the metal to achieve adequate adhesion. Unfortunately, this approach can reduce biocompatibility relative to pure gold films due to the risk of the underlying layer of chromium becoming exposed. Here we report on an alternative adhesion layer for gold and other metals formed from a thin layer of the negative-tone photoresist SU-8, which we find to be significantly less cytotoxic than chromium, being broadly comparable to bare glass in terms of its biocompatibility. Various treatment protocols for SU-8 were investigated, with a view to attaining high transparency and good mechanical and biochemical stability. Thermal annealing to induce partial cross-linking of the SU-8 film prior to gold deposition, with further annealing after deposition to complete cross-linking, was found to yield the best electrode properties. The optimized glass/SU8-Au electrodes were highly transparent, resilient to delamination, stable in biological culture medium, and exhibited similar biocompatibility to glass.

Systemic and local toxicity of metal debris released from hip prostheses: A review of experimental approaches

Despite the technological improvements in orthopedic joint replacement implants, wear and corrosion products associated with the metal components of these implants may result in adverse local tissue and perhaps systemic reactions and toxicities. The current review encompasses a literature review of the local and systemic toxicity studies concerning the effect of CoCrMo wear debris released from wear and corrosion of orthopedic implants and prostheses. Release of metallic debris is mainly in the form of micro- and nano-particles, ions of different valences, and oxides composed of Co and Cr. Though these substances alter human biology, their direct effects of these substances on specific tissue types remain poorly understood. This may partially be the consequence of the multivariate research methodologies employed, leading to inconsistent reports. This review proposes the importance of developing new and more appropriate in-vitro methodologies to study the cellular responses and toxicity mediated by joint replacement wear debris in-vivo.

Analysis of bearing wear, whole blood and synovial fluid metal ion concentrations and histopathological findings in patients with failed ASR hip resurfacings

BACKGROUND

Adverse Reaction to Metal Debris (ARMD) is still a major reason for revision surgeries in patients with metal-on-metal (MoM) hip replacements. ARMD consists of a wide range of alterations in periprosthetic tissues, most important of which are metallosis, inflammation, pseudotumors and necrosis. Studies investigating histopathological findings and their association to implant wear or indirect measures of wear have yielded inconsistent results. Therefore, we aimed to investigate bearing surface wear volume, whole blood and synovial fluid metal ion concentrations, histopathological findings in periprosthetic tissues and their associations.

METHODS

Seventy-eight patients with 85 hips revised for ARMD were included in the study. Prior to revision surgery, all patients had whole blood chromium and cobalt ion levels assessed. In revision surgery, a synovial fluid sample was taken and analyzed for chromium and cobalt. Periprosthetic tissue samples were taken and analyzed for histopathological findings. Explanted implants were analyzed for bearing wear volume of both acetabular cup and femoral head components.

RESULTS

Volumetric wear of the failed components was highly variable. The total wear volume of the head and cup had a strong correlation with whole blood chromium and cobalt ion concentrations (Cr: ρ = 0.80, p < 0.001 and Co: ρ = 0.84, p < 0.001) and a bit weaker correlation with fluid chromium and cobalt ion concentrations (Cr: ρ = 0.50, p < 0.01 and Co: ρ = 0.41, p = 0.027). Most tissues displayed only low-to-moderate amounts of macrophages and lymphocytes. Total wear volume correlated with macrophage sheet thickness (ρ = 0.25, p = 0.020) and necrosis (ρ = 0.35, p < 0.01). Whole blood chromium and cobalt ion concentrations had similar correlations. Lymphocyte cuff thickness did not correlate with either total wear volume or whole blood metal ion concentrations, but correlated with the grade of necrosis.

CONCLUSIONS

Bearing wear volume correlated with blood metal ion levels and the degree of necrosis and macrophage infiltration in periprosthetic tissues suggesting a dose-response relationship. Whole blood metal ion levels are a useful tool for clinician to estimate bearing wear and subsequent tissue response.

Modularity in Total Hip Arthroplasty: Benefits, Risks, Mechanisms, Diagnosis, and Management

Modular implants are currently widely used in total hip arthroplasty because they give surgeons versatility during the operation, allow for easier revision surgery, and can be adjusted to better fit the anatomy of the specific patient. However, modular implants, specifically those that have metal-on-metal junctions, are susceptible to crevice and fretting corrosion. This can ultimately cause implant failure, inflammation, and adverse local tissue reaction, among other possible side effects. Surgeons should be aware of the possibility of implant corrosion and should follow a set of recommended guidelines to systematically diagnose and treat patients with corroded implants. Ultimately, surgeons will continue to use modular implants because of their widespread benefits. However, more research is needed to determine how to minimize corrosion and the negative side effects that have been associated with modular junctions in total hip arthroplasty. [Orthopedics. 2017; 40(6):355-366.].

The effect of metal ions released from different dental implant-abutment couples on osteoblast function and secretion of bone resorbing mediators

OBJECTIVES

The etiology of the reduced marginal bone loss observed around platform-switched implant-abutment connections is not clear but could be related to the release of variable amounts of corrosion products. The present study evaluated the effect of different concentrations of metal ions released from different implant abutment couples on osteoblastic cell viability, apoptosis and expression of genes related to bone resorption.

METHODS

Osteoblastic cells were exposed to five conditions of culture media prepared containing metal ions (titanium, aluminum, vanadium, cobalt, chromium and molybdenum) in different concentrations representing the amounts released from platform-matched and platform-switched implant-abutment couples as a result of an earlier accelerated corrosion experiment. Cell viability was evaluated over 21days using the Alamar Blue assay. Induction of apoptosis was measured after 24h of exposure using flow cytometry. Expression of interleukin-6, interleukin-8, cyclooxygenase-2, caspase-8, osteoprotegerin and receptor activator of nuclear factor kappa-B ligand (RANKL) by osteoblastic cells were analysed after exposure for 1, 3 and 21days using real-time quantitative polymerase chain reaction assay RESULTS: Metal ions in concentrations representing the platform-matched groups led to a reduction in cell viability (P<0.01) up to 7days of exposure. Stimulated cells showed higher rates of early apoptosis (P<0.01) compared to non-treated cells. Metal ions up-regulated the expression of interleukin-6, interleukin-8, cyclooxygenase-2 and RANKL in a dose dependent manner after 1day of exposure (P<0.05). The up-regulation was more pronounced in the groups containing the corrosion products of platform-matched implant-abutment couples.

CONCLUSION

Osteoblastic cell viability, apoptosis, and regulation of bone resorbing mediators were significantly altered in the presence of metal ions. The change in cytokine levels expressed was directly proportional to the metal ion concentration.

CLINICAL SIGNIFICANCE

The observed biological responses to decreased amounts of metal ions released from platform-switched implant-abutment couples compared to platform-matched couples may partly explain the positive radiographic findings in respect to crestal bone level when utilising the "platform-switching" concept, which highlights the possible role of corrosion products in the mediation of crestal bone loss around dental implants.

Off-resonance based assessment of metallic wear debris near total hip arthroplasty

PURPOSE

The presence of metallic debris near total hip arthroplasty can have a significant impact on longitudinal patient management. Methods for magnetic resonance imaging-based quantification of metallic debris near painful total hip replacements are described and applied to cohorts of symptomatic and control subject cases.

METHODS

A combination of metal artifact reduction, off-resonance mapping, off-resonance background removal, and spatial clustering methods are utilized to quantify off-resonance signatures in cases of suspected metallosis. These methods are applied to a cohort of symptomatic hip arthroplasties composed of cobalt-chromium alloys. Magnetostatic simulations and theoretical principles are used to illuminate the potential sources of the measured off-resonance effects. Reported metrics from histological tissue assays extracted during surgical revision procedures are also correlated with the proposed magnetic resonance imaging-based quantification results.

RESULTS

The presented methods identified quantifiable metallosis signatures in more than 70% of the symptomatic and none of the control cases. Preliminary correlations of the MR data with direct histological evaluation of retrieved tissue samples indicate that the observed off-resonance effect may be related to tissue necrosis.

CONCLUSIONS

Magnetostatic simulations, theoretical principles, and preliminary histological trends suggest that disassociated cobalt is the source of the observed off-resonance signature. Magn Reson Med 79:1628-1637, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Effects of cobalt and chromium ions on lymphocyte migration

A T cell-mediated hypersensitivity reaction has been reported in some patients with CoCrMo-based implants. However, the role of cobalt and chromium ions in this reaction remains unclear. The objective of the present study was to analyze the effects of Co²⁺ and Cr³⁺ in culture medium, as well as the effects of culture supernatants of macrophages exposed to Co²⁺ or Cr³⁺ , on the migration of lymphocytes. The release of cytokines/chemokines by macrophages exposed to Co²⁺ and Cr³⁺ was also analyzed. The migration of murine lymphocytes was quantified using the Boyden chamber assay and flow cytometry, while cytokine/chemokine release by J774A.1 macrophages was measured by ELISA. Results showed an ion concentration-dependent increase in TNF-α and MIP-1α release and a decrease in MCP-1 and RANTES release. Migration analysis showed that the presence of Co²⁺ (8 ppm) and Cr³⁺ (100 ppm) in culture medium increased the migration of T lymphocytes, while it had little or no effect on the migration of B lymphocytes, suggesting that Co²⁺ and Cr³⁺ can stimulate the migration of T but not B lymphocytes. Levels of T lymphocyte migration in culture medium containing Co²⁺ or Cr³⁺ were not statistically different from those in culture supernatants of macrophages exposed to Co²⁺ or Cr³⁺ , suggesting that the effects of the ions and chemokines were not additive, possibly because of ion interference with the chemokines and/or their cognate receptors. Overall, results suggest that Co²⁺ and Cr³⁺ are capable of stimulating the migration of T (but not B) lymphocytes in the absence of cytokines/chemokines, and could thereby contribute to the accumulation of more T than B lymphocytes in periprosthetic tissues of some patients with CoCrMo-based implants. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:916-924, 2017.

Chemokines Associated with Pathologic Responses to Orthopedic Implant Debris

Despite the success in returning people to health saving mobility and high quality of life, the over 1 million total joint replacements implanted in the US each year are expected to eventually fail after approximately 15-25 years of use, due to slow progressive subtle inflammation to implant debris compromising the bone implant interface. This local inflammatory pseudo disease state is primarily caused by implant debris interaction with innate immune cells, i.e., macrophages. This implant debris can also activate an adaptive immune reaction giving rise to the concept of implant-related metal sensitivity. However, a consensus of studies agree the dominant form of this response is due to innate reactivity by macrophages to implant debris danger signaling (danger-associated molecular pattern) eliciting cytokine-based and chemokine inflammatory responses. This review covers implant debris-induced release of the cytokines and chemokines due to activation of the innate (and the adaptive) immune system and how this leads to subsequent implant failure through loosening and osteolysis, i.e., what is known of central chemokines (e.g., IL-8, monocyte chemotactic protein-1, MIP-1, CCL9, CCL10, CCL17, and CCL22) associated with implant debris reactivity as related to the innate immune system activation/cytokine expression, e.g., danger signaling (e.g., IL-1β, IL-18, IL-33, etc.), toll-like receptor activation (e.g., IL-6, tumor necrosis factor α, etc.), bone catabolism (e.g., TRAP5b), and hypoxia responses (HIF-1α). More study is needed, however, to fully understand these interactions to effectively counter cytokine- and chemokine-based orthopedic implant-related inflammation.

Protective effects of kolaviron and gallic acid against cobalt-chloride-induced cardiorenal dysfunction via suppression of oxidative stress and activation of the ERK signaling pathway

Cobalt (Co) toxicity is a potential public health problem due to recent renewed use of Co in orthopedic implants, dietary supplements, and blood doping in athletes and horses. We investigated the protective roles of kolaviron (KV), a bi-flavonoid of Garcinia kola, and gallic acid (GA) on cobalt chloride (CoCl2)-induced cardiorenal damage in rats. CoCl2 caused significant increases (p < 0.05) in serum creatine kinase–myocardial band (CK-MB), lactate dehydrogenase (LDH), aspartate transaminase (AST), xanthine oxidase (XO), urea, creatinine, malondialdehyde, H2O2, nitric oxide, as well as C-reactive protein expression, along with significant (p < 0.05) reduction in cardiac and renal expression of extracellular signal regulated kinase (ERK) and the activities of superoxide dismutase, catalase, and glutathione S-transferase. KV and GA prevented the toxic effects of CoCl2 by stimulating ERK expression and reversing Co-induced biochemical changes. Administration of CoCl2 alone did not significantly alter ECG patterns in the rats, although co-treatment with KV (200 mg/kg) produced QT-segment prolongation and also appeared to potentiate Co hypotension. Histopathology of the heart and kidneys of rats treated with KV and GA confirmed the biochemical data. KV and GA thus protected against cardiac and renal damage in Co intoxication via antioxidant and (or) cell survival mechanisms, possibly involving ERK activation.

Metal in Total Hip Arthroplasty: Wear Particles, Biology, and Diagnosis

Total hip arthroplasty (THA) has been performed for nearly 50 years. Between 2006 and 2012, more than 600,000 metal-on-metal THA procedures were performed in the United States. This article reviews the production of metal wear debris in a metal-on-metal articulation and the interaction of cobalt and chromium ions that ultimately led to a dramatic decline in the use of metal-on-metal THA articulations. Additionally, the article reviews mechanisms of metal wear, the biologic reaction to cobalt and chromium ions, the clinical presentation of failing metal-on-metal articulations, and current diagnostic strategies. Further, the article discusses the use of inflammatory markers, metal ion levels, radiographs, metal artifact reduction sequence magnetic resonance imaging, and ultrasound for failed metal-on-metal THA procedures. When adopting new technologies, orthopedic surgeons must weigh the potential increased benefits against the possibility of new mechanisms of failure. Metal-on-metal bearings are a prime example of the give and take between innovation and clinical results, especially in the setting of an already successful procedure such as THA. [Orthopedics. 2016; 39(6):371-379.].

The biological response to orthopaedic implants for joint replacement: Part I: Metals

Joint replacement is a commonly performed, highly successful orthopaedic procedure, for which surgeons have a large choice of different materials and implant designs. The materials used for joint replacement must be both biologically acceptable to minimize adverse local tissue reactions, and robust enough to support weight bearing during common activities of daily living. Modern joint replacements are made from metals and their alloys, polymers, ceramics, and composites. This review focuses on the biological response to the different biomaterials used for joint replacement. In general, modern materials for joint replacement are well tolerated by the body as long as they are in bulk (rather than in particulate or ionic) form, are mechanically stable and noninfected. If the latter conditions are not met, the prosthesis will be associated with an acute/chronic inflammatory reaction, peri-prosthetic osteolysis, loosening and failure. This article (Part 1 of 2) is dedicated to the use of metallic devices in orthopaedic surgery including the associated biological response to metallic byproducts is a review of the basic science literature regarding this topic. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2162-2173, 2017.

The pathobiology and pathology of aseptic implant failure

Pathological assessment of periprosthetic tissues is important, not only for diagnosis, but also for understanding the pathobiology of implant failure. The host response to wear particle deposition in periprosthetic tissues is characterised by cell and tissue injury, and a reparative and inflammatory response in which there is an innate and adaptive immune response to the material components of implant wear. Physical and chemical characteristics of implant wear influence the nature of the response in periprosthetic tissues and account for the development of particular complications that lead to implant failure, such as osteolysis which leads to aseptic loosening, and soft-tissue necrosis/inflammation, which can result in pseudotumour formation. The innate response involves phagocytosis of implant-derived wear particles by macrophages; this is determined by pattern recognition receptors and results in expression of cytokines, chemokines and growth factors promoting inflammation and osteoclastogenesis; phagocytosed particles can also be cytotoxic and cause cell and tissue necrosis. The adaptive immune response to wear debris is characterised by the presence of lymphoid cells and most likely occurs as a result of a cell-mediated hypersensitivity reaction to cell and tissue components altered by interaction with the material components of particulate wear, particularly metal ions released from cobalt-chrome wear particles.Cite this article: Professor N. A. Athanasou. The pathobiology and pathology of aseptic implant failure. Bone Joint Res 2016;5:162-168. DOI: 10.1302/2046-3758.55.BJR-2016-0086.

Systemic cobalt toxicity from total hip arthroplasties

Recently, the use of metal-on-metal articulations in total hip arthroplasty (THA) has led to an increase in adverse events owing to local soft-tissue reactions from metal ions and wear debris. While the majority of these implants perform well, it has been increasingly recognised that a small proportion of patients may develop complications secondary to systemic cobalt toxicity when these implants fail. However, distinguishing true toxicity from benign elevations in cobalt ion levels can be challenging.

The purpose of this two part series is to review the use of cobalt alloys in THA and to highlight the following related topics of interest: mechanisms of cobalt ion release and their measurement, definitions of pathological cobalt ion levels, and the pathophysiology, risk factors and treatment of cobalt toxicity. Historically, these metal-on-metal arthroplasties are composed of a chromium-cobalt articulation.

The release of cobalt is due to the mechanical and oxidative stresses placed on the prosthetic joint. It exerts its pathological effects through direct cellular toxicity.

This manuscript will highlight the pathophysiology of cobalt toxicity in patients with metal-on-metal hip arthroplasties.

Take home message: Patients with new or evolving hip symptoms with a prior history of THA warrant orthopaedic surgical evaluation. Increased awareness of the range of systemic symptoms associated with cobalt toxicity, coupled with prompt orthopaedic intervention, may forestall the development of further complications.

Cite this article: Bone Joint J 2016;98-B:6–13.