Selenomethionine protects hematopoietic stem/progenitor cells against cobalt nanoparticles by stimulating antioxidant actions and DNA repair functions.

Hematopoietic stem cells (HSCs) and hematopoietic progenitor cells (HPCs) can differentiate into all blood lineages to maintain hematopoiesis, wound healing, and immune functions. Recently, cobalt-chromium alloy casting implants have been used extensively in total hip replacements; however, cobalt nanoparticles (CoNPs) released from the alloy were toxic to HSCs and HPCs. We aimed to investigate the mechanism underlying the toxic effect of CoNPs on HSCs/HPCs and to determine the protective effect of selenomethionine (SeMet) against CoNPs in vitro and in vivo. Human and rat CD34+ HSCs/HPCs were isolated from cord blood and bone marrow, respectively. CoNPs decreased the viability of CD34+ HSCs/HPCs and increased apoptosis. SeMet attenuated the toxicity of CoNPs by enhancing the antioxidant ability of cells. The protective effect of SeMet was not completely abolished after adding H2O2 to abrogate the improvement of the antioxidant capacity by SeMet. SeMet and CoNPs stimulated ATM/ATR DNA damage response signals and inhibited cell proliferation. Unlike CoNPs, SeMet did not damage the DNA, and cell proliferation recovered after removing SeMet. SeMet inhibited the CoNP-induced upregulation of hypoxia inducible factor (HIF)-1α, thereby disrupting the inhibitory effect of HIF-1α on breast cancer type 1 susceptibility protein (BRCA1). Moreover, SeMet promoted BRCA1-mediated ubiquitination of cyclin B by upregulating UBE2K. Thus, SeMet enhanced cell cycle arrest and DNA repair post-CoNP exposure. Overall, SeMet protected CD34+ HSCs/HPCs against CoNPs by stimulating antioxidant activity and DNA repair.

A paradox: Fe2+-containing agents decreased ROS and apoptosis induced by CoNPs in vascular endothelial cells by inhibiting HIF-1α.

Cobalt nanoparticles (CoNPs) released from hip joint implants are known to have a toxic effect on several organs probably through increasing reactive oxygen species (ROS). Ferrous ion (Fe2+) is well-known to enhance oxidative stress by catalysing the production of ROS. However, in our pilot study, we found that Fe2+ conversely inhibited the ROS production induced by CoNPs. To elucidate the underlying mechanism, the present study treated vascular endothelial HUVEC and HMEC-1 cells with CoNPs alone or in combination with ferrous lactate [Fe(CH3CHOHCOO)2], ferrous succinate [Fe(CH2COO)2], and ferrous chloride (FeCl2). CoNP toxicity was evaluated by measuring cell viability, rate of apoptosis and lactose dehydrogenase (LDH) release, and intracellular ROS levels. Treatment with CoNPs decreased cell viability, LDH release, and ROS production and increased apoptosis. CoNPs increased hypoxia-inducible factor-1α (HIF-1α) protein level and mRNA levels of vascular endothelial growth factor (VEGF) and glucose transporter 1 (GLUT1) downstream of HIF-1α signalling. Silencing HIF-1α attenuated CoNP toxicity, as seen by recovery of cell viability, LDH release, and ROS levels and reduced apoptosis. CoNPs caused a pronounced reduction of Fe2+ in cells, but supplementation with Fe(CH3CHOHCOO)2, Fe(CH2COO)2, and FeCl2 restored Fe2+ levels and inhibited HIF-1α activation. Moreover, all three Fe2+-containing agents conferred protection from CoNPs; Fe(CH3CHOHCOO)2 and Fe(CH2COO)2 more effectively than FeCl2. In summary, the present study revealed that CoNPs exert their toxicity on human vascular endothelial cells by depleting intracellular Fe2+ level, which causes activation of HIF-1α signalling. Supplements of Fe2+, especially in the form of Fe(CH3CHOHCOO)2 and Fe(CH2COO)2, mitigated CoNP toxicity.

Alpha lipoic acid antagonizes cytotoxicity of cobalt nanoparticles by inhibiting ferroptosis-like cell death.

As a main element in the hard metal industry, cobalt is one of the major components of human metal implants. Cobalt-containing implants, especially joint prostheses used for artificial joint replacement, can be corroded due to the complex physiological environment in vivo, producing a large number of nanoscale cobalt particles (Cobalt Nanoparticles, CoNPs). These CoNPs can be first accumulated around the implant to cause adverse local reactions and then enter into the blood vessels followed by reaching the liver, heart, brain, kidney, and other organs through systematic circulation, which leads to multi-system toxicity symptoms. To ensure the long-term existence of cobalt-containing implants in the body, it is urgently required to find out a safe and effective detoxification drug. Herein, we have demonstrated that CoNPs could induce the ferroptosis-like cell death through the enhancement of intracellular reactive oxygen species (ROS) level, cytoplasmic Fe2+ level, lipid peroxidation, and consumption of reduced glutathione (GSH) as well as inhibition of glutathione peroxidase 4 (GPX4) activity. Importantly, α-lipoic acid (ALA), a natural antioxidant with the capability to scavenge free radicals and chelate toxic metals, was found to efficiently alleviate the adverse effects of CoNPs. The present study illustrates a new mechanism of CoNPs mediated by ferroptosis-like cytotoxicity and discloses an effective method for the detoxification of CoNPs by employing the natural antioxidant of ALA, providing a basis for further in vivo detoxification study.

Supplementation with Fe2+-containing agents mitigated the toxic effect of CoNPs in vascular endothelial cells by inhibiting activation of hypoxia-inducible factor.

Cobalt nanoparticles (CoNPs) released from hip joint implants are known to have a toxic effect on several organs. The aim of this study was to examine the effects of CoNP toxicity on vascular endothelium and to elucidate the underlying mechanisms. Moreover, the role of three ferrous ion (Fe2+)containing agents in conferring resistance to the effects of CoNPs was investigated. Vascular endothelial HUVEC and HMEC-1 cells were cultured in a medium supplemented with CoNPs. Ferrous lactate [Fe(CH3CHOHCOO)2], ferrous succinate [Fe(CH2COO)2], and ferrous chloride (FeCl2) were added to the cells in varying concentrations. CoNP toxicity was evaluated by measuring cell viability, rate of apoptosis and LDH release, and intracellular ROS levels. Treatment with CoNPs decreased cell viability, LDH release, and ROS production and increased apoptosis. CoNPs increased hypoxia-inducible factor-1α (HIF-1α) protein level and mRNA levels of VEGF and GLUT1 downstream of HIF-1α signalling. Silencing HIF-1α attenuated CoNP toxicity, as seen by recovery of cell viability, LDH release, and ROS levels and reduced apoptosis. CoNPs caused a pronounced reduction of Fe2+ in cells, but supplementation with Fe(CH3CHOHCOO)2, Fe(CH2COO)2, and FeCl2 restored Fe2+ levels and inhibited HIF-1α activation. Moreover, all three Fe2+-containing agents conferred protection from CoNPs; Fe(CH3CHOHCOO)2 and Fe(CH2COO)2 more effectively than FeCl2. In summary, this study revealed that CoNPs exert their toxicity on human vascular endothelial cells by depleting intracellular Fe2+ level, which causes activation of HIF-1α signalling. Supplements of Fe2+, especially in the form of Fe(CH3CHOHCOO)2 and Fe(CH2COO)2, mitigated CoNP toxicity.

Applied anatomical study of the modified anconeus flap approach.

PURPOSE: Conventional surgical therapy for an intercondylar humerus fracture might result in multiple potential complications. Our study was conducted to evaluate the modified anconeus flap approach by adequately exposing the distal humeral articular surface, avoiding osteotomy of the olecranon and transection of the main part of the triceps brachial tendon from the olecranon. METHODS: Preparations of 20 upper limb specimens from adult cadavers were used in this study. We investigated the anatomical features of the distal tendon of the triceps brachii. Then, we designed a modified anconeus flap approach in cadaver specimens combined with the medial paratricipital approach, and we compared the extent of exposure of the distal humeral articular surface between the triceps-reflecting anconeus pedicle approach and this modified approach. RESULTS: The downward neurovascular bundles supplying the anconeus were located far from the intramuscular tendon of the triceps brachii. In addition, the medial head of the triceps was continuous with the anconeus near the lateral epicondyle of the humerus. These anatomical properties could assist in reducing adverse events in surgery. The percentage of the exposed humerus distal articular surface was 42.7% by applying the modified anconeus flap approach combined with the medial paratricipital approach. The modified anconeus flap approach can overcome the shortcomings of osteotomy or triceps transverse and fulfill reduction and internal fixation of most distal humerus intercondylar fractures. CONCLUSIONS: The present study has demonstrated a new approach for adequately exposing the distal humeral articular surface during surgery for an intercondylar humerus fracture. With this modified approach, osteotomy of the olecranon and the separation or transection of the main part of the triceps brachial tendon from the olecranon are not necessarily required. Therefore, we suggest that this novel approach could be applied as the primary surgical approach in intercondylar humerus fracture surgeries if the surgeons are familiar with the regional features of distal tendon of the triceps brachii and anconeus.

Relationships of common polymorphisms in IL-6, IL-1A, and IL-1B genes with susceptibility to osteoarthritis: a meta-analysis.

Observational and experimental studies have arrived at inconsistent conclusions about whether common polymorphisms in IL-6, IL-1A, and IL-1B genes are associated with an increased risk of osteoarthritis (OA). Therefore, we undertook a comprehensive meta-analysis to more systematically summarize the relationships of IL-6, IL-1A, and IL-1B genetic polymorphisms with susceptibility to OA. We screened the PubMed, Embase, Web of Science, Cochrane Library, CISCOM, CINAHL, Google Scholar, China BioMedicine (CBM), and China National Knowledge Infrastructure (CNKI) databases up to 31 March 2014. We used STATA software to analyze statistical data. Odds ratios (ORs) and their corresponding 95 % confidence intervals (95 % CIs) were calculated. Seventeen independent case-control studies were included in this meta-analysis with a total number of 7,491 subjects, comprised of 3,293 OA patients and 4,729 healthy controls. Our results indicate that IL-6, IL-1A, and IL-1B genetic polymorphisms are statistically correlated with an increased risk of OA under the allele and dominant models. According to a subgroup analysis based on disease, a higher frequency of IL-6 genetic polymorphisms was observed among knee OA and hand OA patients, but not among hip OA and DIP OA patients. A higher frequency of IL-1A genetic polymorphisms were found among hip OA patients, hand OA, hip OA and DIP OA patients. Furthermore, we observed a higher IL-1B polymorphism frequency among knee OA and hip OA patients, but not among hand OA patients. Our findings provide evidence that IL-6, IL-1A, and IL-1B genetic polymorphisms may be correlated with susceptibility to OA.