An integrated benefit-risk assessment of cobalt-containing alloys used in medical devices: Implications for regulatory requirements in the European Union.

In 2017, the European Union (EU) Committee for Risk Assessment (RAC) recommended the classification of metallic cobalt (Co) as Category 1B with respect to its carcinogenic and reproductive hazard potential and Category 2 for mutagenicity but did not evaluate the relevance of these classifications for patients exposed to Co-containing alloys (CoCA) used in medical devices. CoCA are inherently different materials from Co metal from a toxicological perspective and thus require a separate assessment. CoCA are biocompatible materials with a unique combination of properties including strength, durability, and a long history of safe use that make them uniquely suited for use in a wide-range of medical devices. Assessments were performed on relevant preclinical and clinical carcinogenicity and reproductive toxicity data for Co and CoCA to meet the requirements under the EU Medical Device Regulation triggered by the ECHA re-classification (adopted in October 2019 under the 14th Adaptation to Technical Progress to CLP) and to address their relevance to patient safety. The objective of this review is to present an integrated overview of these assessments, a benefit-risk assessment and an examination of potential alternative materials. The data support the conclusion that the exposure to CoCA in medical devices via clinically relevant routes does not represent a hazard for carcinogenicity or reproductive toxicity. Additionally, the risk for the adverse effects that are known to occur with elevated Co concentrations (e.g., cardiomyopathy) are very low for CoCA implant devices (infrequent reports often reflecting a unique catastrophic failure event out of millions of patients) and negligible for CoCA non-implant devices (not measurable/no case reports). In conclusion, the favorable benefit-risk profile also in relation to possible alternatives presented herein strongly support continued use of CoCA in medical devices.

Carcinogenic hazard assessment of cobalt-containing alloys in medical devices: Review of in vivo studies.

Cobalt (Co) alloys have been used for over seven decades in a wide range of medical devices, including, but not limited to, hip and knee implants, surgical tools, and vascular stents, due to their favorable biocompatibility, durability, and mechanical properties. A recent regulatory hazard classification review by the European Chemicals Agency (ECHA) resulted in the classification of metallic Co as a Class 1B Carcinogen (presumed to have carcinogenic potential for humans), primarily based on inhalation rodent carcinogenicity studies with pure metallic Co. The ECHA review did not specifically consider the carcinogenicity hazard potential of forms or routes of Co that are relevant for medical devices. The purpose of this review is to present a comprehensive assessment of the available in vivo preclinical data on the carcinogenic hazard potential of exposure to Co-containing alloys (CoCA) in medical devices by relevant routes. In vivo data were reviewed from 33 preclinical studies that examined the impact of Co exposure on local and systemic tumor incidence in rats, mice, guinea pigs, and hamsters. Across these studies, there was no significant increase of local or systemic tumors in studies relevant for medical devices. Taken together, the relevant in vivo data led to the conclusion that CoCA in medical devices are not a carcinogenic hazard in available in vivo models. While specific patient and implant factors cannot be fully replicated using in vivo models, the available in vivo preclinical data support that CoCA in medical devices are unlikely a carcinogenic hazard to patients.

Synthesis, activity evaluation, and pro-apoptotic properties of novel 1,2,4-triazol-3-amine derivatives as potent anti-lung cancer agents.

In this study, a series of 4,5-bis(substituted phenyl)-4H-1,2,4-triazol-3-amine compounds was designed, synthesised, and evaluated to determine their potential as anti-lung cancer agents. According to the results of screening of lung cancer cell lines A549, NCI-H460, and NCI-H23 in vitro, most of the synthesised compounds have potent cytotoxic activities with IC50 values ranging from 1.02 to 48.01 µM. Particularly, compound 4,5-bis(4-chlorophenyl)-4H-1,2,4-triazol-3-amine (BCTA) was the most potent anti-cancer agent, with IC50 values of 1.09, 2.01, and 3.28 µM against A549, NCI-H460, and NCI-H23 cells, respectively, meaning many-fold stronger anti-lung cancer activity than that of the chemotherapeutic agent 5-fluorouracil. We also explored the effects of BCTA on apoptosis in lung cancer cells by flow cytometry and western blotting. Our results indicated that BCTA induced apoptosis by upregulating proteins BAX, caspase 3, and PARP. Thus, the potential application of compound BCTA as a drug should be further examined.

MiRNA-199a-3p: A potential circulating diagnostic biomarker for early gastric cancer.

BACKGROUND: Tumor-associated miRNAs have been detected in serum or plasma. We investigated whether plasma miRNA-199a-3p could be a potential circulating biomarker for early gastric cancer (EGC). METHODS: By using real-time qRT-PCR, the expression of miRNA-199a-3p were compared between these pre-operative plasmas from 30 EGC patients and 70 healthy controls, and between these pre-operative and post-operative plasmas. Further validation was on an independent set of plasmas from 50 EGC patients. RESULTS: The expression of miRNA-199a-3p (47.5 ± 6.5) in plasma in EGC patients was significantly higher than that from healthy controls (13.9 ± 2.7, P < 0.001) and gastric precancerous diseases (GPD) patients (19.2 ± 2.5, P = 0.004), respectively. Furthermore, the expression levels of miRNA-199a-3p (11.8 ± 2.9, P = 0.012) in the post-operative plasmas were significantly reduced when compared to the pre-operative plasmas. With respect of clinicopathological characteristics, the expression of miRNA-199a-3p in plasma was not associated with the depth of tumor invasion. Moreover, the AUC of the expression of miRNA-199a-3p in plasma for EGC diagnosis was 0.818, which was significantly higher than that of combined tumor markers (0.556). The sensitivity, specificity and accuracy of miRNA-199a-3p expression in plasma for EGC diagnosis were 76%, 74%, and 75%, respectively. CONCLUSIONS: Plasma miRNA-199a-3p could be a novel potential diagnostic biomarkers for EGC.

miRNA-199a-3p in plasma as a potential diagnostic biomarker for gastric cancer.

BACKGROUND: MicroRNA (miRNA) has been shown the potential of cancer diagnosis. We investigated whether plasma miRNA expression could discriminate between patients with and without gastric cancer. METHODS: This study was divided into three steps: (1) miRNA microarray profiling on plasma samples from 20 gastric cancer patients and 20 healthy controls; (2) miRNA selection by real-time qRT-PCR on 30 pairs of plasma from patients and controls; and (3) qRT-PCR validation on an independent set of plasma from 180 gastric cancer patients, 80 healthy controls, and 20 patients with gastric precancerous diseases. RESULTS: Of the 959 human miRNAs analyzed by microarray, 37 up-regulated miRNAs and seven down-regulated miRNAs were found in gastric cancer plasma. Of the seven discrepant miRNAs validated on the plasma from 30 gastric cancer patients and 30 healthy controls, both miRNA-199a-3p and miRNA-151-5p were significantly elevated (p < 0.05) and were significantly reduced after surgery (p < 0.05) in gastric cancer patients. Further large-scale validation showed that these two miRNAs expressions in plasma were significantly higher in gastric cancer patients than healthy controls and patients with gastric precancerous diseases, respectively. However, only the expression of miRNA-199a-3p in plasma was significantly associated with tumor invasion and with lymph node metastasis and tumor, node, metastasis stage. This marker yielded an area under the receiver operating characteristic curve area of 0.837 with 80 % sensitivity and 74 % specificity in discriminating gastric cancer patients from healthy controls. In gastric cancer tissue, miRNA-199a-3p was expressed in the cytoplasm of tumor cells. CONCLUSIONS: miRNA-199a-3p in plasma could be a novel potential diagnostic biomarker for gastric cancer detection.

Inactivation of bacterial spores and viruses in biological material using supercritical carbon dioxide with sterilant.

The purpose of this study was to validate supercritical carbon dioxide (SC-CO(2)) as a terminal sterilization method for biological materials, specifically acellular dermal matrix. In this study, bacterial spores, Bacillus atrophaeus, were inoculated onto porcine acellular dermal matrix to serve as a "worst case" challenge device. The inactivation of the spores by SC-CO(2) with peracetic acid (PAA) sterilant was analyzed as a function of exposure times ranging from 1 to 30 min. A linear inactivation profile for the Bacillus atrophaeus spores was observed, and a SC-CO(2) exposure time of 27 min was determined to achieve a sterility assurance level of 10(-6). The inactivation of viruses was also studied using Encephalomyocarditis (EMC) viruses. After 15 min of exposure to SC-CO(2) with PAA sterilant, more than a 6 log(10) reduction was observed for EMC viruses. Biochemical and biomechanical evaluations showed that the SC-CO(2) treatment with PAA sterilant did not cause significant changes in porcine acellular matrix's susceptibility to collagenase digestion, tensile or tear strength, indicating limited alteration of the tissue structure following SC-CO(2) sterilization.

Effects of e-beam radiation, storage, and hydration on osteoinductivity of DBM/AM composite.

E-beam irradiation is often used to sterilize medical devices including demineralized bone matrix (DBM) products. In this study, the effect of e-beam on osteoinductivity of a DBM product in hydrous and anhydrous configurations has been evaluated at 0-, 6- and 12-month ambient storage using a nude rat muscle pouch model. The thermal and structural stabilities of DBM and acellular dermal matrix (AM) composites were analyzed using differential scanning calorimetry (DSC) and trypsin digestion assay. Both hydrous and anhydrous DBM/AM composites exhibited osteoinductivity after e-beam irradiation of 15 kGy. After 12-month ambient storage, the osteoinductivity of hydrous DBM/AM was diminished, whereas the anhydrous DBM/AM retained its osteoinductive potential. However, the DSC and trypsin analysis revealed that the DBM in anhydrous DBM/AM was more vulnerable to damage from e-beam irradiation than its hydrous counterpart. This study has found that although the anhydrous DBM has more structural damage than hydrous DBM from e-beam irradiation, it has retained its osteoinductivity better after 1-year ambient storage.

Effects of gamma-irradiation, storage and hydration on osteoinductivity of DBM and DBM/AM composite.

This study investigated the effect of gamma-irradiation dose, irradiation temperature, hydration and storage condition on osteoinductivity of demineralized bone matrix (DBM) and demineralized bone matrix/acellular dermal matrix (DBM/AM) composite. DBM and DBM/AM in dry and hydrated form were treated with gamma-irradiation of 15-40 kGy at ambient or low temperature (-40 degrees C approximately -70 degrees C) and then stored at ambient condition for 6 months. The athymic rat muscle implant model was used to evaluate the osteoinductive potential of the DBM and DBM/AM composites. Histological and alkaline phosphatase (ALPase) activity assessments were carried out at 28 days after implantation to determine the new bone formation and ALPase activity. Both histological and ALPase activity analysis showed that the osteoinductivity of DBM decreased with the increase of gamma-irradiation dose at ambient temperature, whereas no decrease occurred when treated with gamma-irradiation at low temperature. However, the hydrated DBM showed diminishing osteoinductivity after 6-month storage at ambient condition, whereas the DBM in dry form retained their osteoinductivity after the 6-months storage. The findings in this study indicate that DBM and DBM/AM composites could retain their osteoinductivity when they are in dry configuration and are irradiated at low temperature (-40 degrees C approximately -70 degrees C) using the custom-made cold gamma-irradiation system.

Evaluation of bone regeneration at critical-sized calvarial defect by DBM/AM composite.

This study investigated the bone-regenerative potential of a demineralized bone and acellular matrix (DBM/AM) composite (AlloCraft DBM) in comparison with autologous bone using an in vivo model. Critical-sized calvarial defects (5 mm) were created in athymic rats. The defects were grafted with either the DBM/AM composite or the acellular human dermal matrix (AM), and compared with the defects filled with autologous bone (positive control) and the empty defect (negative control). Histological and radiographic assessments were carried out at 4 and 8 weeks after surgery to determine the biological healing, the amount and type of new bone formation and the percentage of new bone filled in the critical defects. At 4 weeks, DBM/AM composite group had the highest percentage of the defect filled with new bone (84%), which was significantly greater than autologous bone (62%), AM (41%), and untreated control (32%) groups. At 8 weeks, the DBM/AM continued to have the highest percentage of the defect filled with new bone (91%). The autologous bone group increased the percentage of bone fill to 83%. The defects either filled with AM or left untreated still had less of the defect filled with new bone, 57% and 33%, respectively. The total healing of defects grafted with DBM/AM was comparable with autologous bone group at 8 weeks. The results demonstrated that the DBM/AM composite promoted new bone formation more rapidly than autologous bone at calvarial defect in athymic rats. The study supports that DBM/AM is a potential substitute of autologous bone for bone repair.

Evaluation of DBM/AM composite as a graft substitute for posterolateral lumbar fusion.

Demineralized bone matrix (DBM) has been investigated as a bone graft substitute for spinal fusion with less morbidity. Various carriers have been added to DBM to enhance its handling characteristics. This study investigates the spinal fusion induced by a composite of DBM and acellular dermal matrix (AM) in comparison with autologous bone in an athymic rat spinal fusion model. Single-level intertransverse process fusions were performed in 60 athymic nude rats grafted with 2 mL/kg of DBM/AM composite, AM alone, or autologous bone. Fusion was assessed at 6 weeks by radiography, manual palpation, and histology. At 6 weeks, 70% of the animals from the DBM/AM composite group exhibited complete spine fusion, whereas 35% from the autologous bone group and 20% from AM group showed bridging with some gaps. The DBM/AM composite induced a significantly higher fusion rate than both the autologous bone and AM groups (p < 0.001) in all measured parameters. The current study demonstrated that using DBM/AM composite can have more robust fusion than autologous bone at 6 weeks in an athymic rat spinal fusion model.

Nanocrystalline diamond modified gold electrode for glucose biosensing.

Boron-doped diamond has drawn much attention in electrochemical sensors. However there are few reports on non-doped diamond because of its weak conductivity. Here, we reported a glucose biosensor based on electrochemical pretreatment of non-doped nanocrystalline diamond (N-NCD) modified gold electrode for the selective detection of glucose. N-NCD was coated on gold electrode and glucose oxidase (GOx) was immobilized onto the surfaces of N-NCD by forming amide linkages between enzyme amine residues and carboxylic acid groups on N-NCD. The anodic pretreatment of N-NCD modified electrode not only promoted the electron transfer rate in the N-NCD thin film, but also resulted in a dramatic improvement in the reduction of the dissolved oxygen. This performance could be used to detect glucose at negative potential through monitoring the current change of oxygen reduction. The biosensor effectively performs a selective electrochemical analysis of glucose in the presence of common interferents, such as ascorbic acid (AA), acetaminophen (AP) and uric acid (UA). A wide linear calibration range from 10 microM to 15 mM and a low detection limit of 5 microM were achieved for the detection of glucose.

Bioactive, degradable composite microspheres: effect of filler material on surface reactivity.

Composite microspheres with two different fillers were developed using a solid-in-oil-in-water (s/o/w) emulsion solvent removal method. Two types of bioactive ceramic powders, specifically calcium hydroxyapatite (HA) and modified bioactive glass (MBG), were incorporated into degradable poly(lactic acid) (PLA) polymer matrix to form composite microspheres. For each filler material, microspheres with three different weight ratios of filler material to polymer, namely, 1: 1, 1: 3, and 1: 9, were synthesized. In vitro immersion using simulated physiological fluid (SPF) was employed to evaluate the surface reactivity of the microspheres. SEM analysis revealed that after a 14-day immersion the surface of the microspheres containing 50% MBG was fully transformed into a bone-like apatite. In contrast, a limited number of mineral nodules were present on the surface of microspheres containing HA. The solution chemical analyses performed to determine changes of Ca, P, and Si concentrations as a function of the immersion time showed that the ion concentration profiles were similar for all microspheres, except the [Si] profile. A higher Si concentration was detected in the SPF immersed with MBG-containing microspheres. These data show that the MBG filler significantly enhances the surface reactivity of the composite microspheres. This observation enables us to conclude that the composite MBG-containing microspheres are the preferable microspheres for three-dimensional bone tissue engineering.