Therapeutic effects of bone marrow mesenchymal stem cells-derived exosomes on osteoarthritis.

Mesenchymal stem cells (MSCs) have shown chondroprotective effects in clinical models of osteoarthritis (OA). However, effects of MSC-derived exosomes on OA remain unclear. The study aimed to investigate the therapeutic potential of exosomes from human bone marrow MSCs (BM-MSCs) in alleviating OA. The anterior cruciate ligament transection (ACLT) and destabilization of the medial meniscus (DMM) surgery were performed on the knee joints of a rat OA model, followed by intra-articular injection of BM-MSCs or their exosomes. In addition, BM-MSC-derived exosomes were administrated to primary human chondrocytes to observe the functional and molecular alterations. Both of BM-MSCs and BM-MSC-derived exosomes alleviated cartilage destruction and subchondral bone remodelling in OA rat model. Administration of BM-MSCs and exosomes could reduce joint damage and restore the trabecular bone volume fraction, trabecular number and connectivity density of OA rats. In addition, in vitro assays showed that BM-MSCs-exosomes could maintain the chondrocyte phenotype by increasing collagen type II synthesis and inhibiting IL-1ß-induced senescence and apoptosis. Furthermore, exosomal lncRNA MEG-3 also reduced the senescence and apoptosis of chondrocytes induced by IL-1ß, indicating that lncRNA MEG-3 might partially account the anti-OA effects of BM-MSC exosomes. The exosomes from BM-MSCs exerted beneficial therapeutic effects on OA by reducing the senescence and apoptosis of chondrocytes, suggesting that MSC-derived exosomes might provide a candidate therapy for OA treatment.

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.

α-Tocopherol protected against cobalt nanoparticles and cocl2 induced cytotoxicity and inflammation in Balb/3T3 cells.

CONTEXT: Currently, tissue damage induced by cobalt nanoparticles (CoNPs) and cobalt ions (Co2+) are the most serious adverse effect in the patients with metal-on-metal hip prostheses. Therefore, an urgent need exists for the identification of the mechanisms and the development of therapeutic strategies to limit it. OBJECTIVE: We aimed to explore the mechanisms of cytotoxicity of CoNPs and Co2+ and developed strategies to reduce this cytotoxicity with α-tocopherol treatment. METHODS: To evaluate the protective effect of α-tocopherol, Balb/3T3 cells were pretreated with 10 µM α-tocopherol for 24 h. The cells were then exposed to different concentrations of CoNPs and Co2+ for 12 h, 24 h and 48 h. The cell viabilities, reactive oxygen species (ROS), inflammatory cytokines and MAP kinase (MAPK) levels were measured. RESULTS: CoNPs and Co2+ can induce the increase of ROS and inflammatory cytokines in Balb/3T3 cells, such as tumor necrosis factor α (TNF-α), interleukin-1ß (IL-1ß) and interleukin-6 (IL-6). However, α-tocopherol pretreatment can significantly prevent cytotoxicity induced by CoNPs and Co2+, decrease ROS production and decrease levels of inflammatory cytokines in Balb/3T3 cells. Additionally, MAPK pathway may be involved in the protection of α-tocopherol against cytotoxicity induced by CoNPs and Co2+ in vitro. CONCLUSIONS: Our results provide new insights into the potential therapeutic use of α-tocopherol in the prevention and treatment of various oxidative- or inflammatory stress-related inflammation and injuries.

A prospective comparative study of hip resurfacing arthroplasty and large-diameter head metal-on-metal total hip arthroplasty in younger patients-a minimum of five year follow-up.

INTRODUCTION: Both hip resurfacing arthroplasty (HRA) and large-diameter head metal-on-metal total hip arthroplasty (LDH MoM THA) are generally used for young and active patients. A number of comparative studies of HRA and total hip arthroplasty have been published in the literature. However, studies that have compared HRA with LDH MoM THA are rare. The purpose of this study is to compare the mid-term results of HRA with those of LDH MoM THA in young patients. PATIENTS AND METHODS: Between 2007 and 2011, 68 patients were enrolled in the study and randomized into two groups: HRA group (28 hips) and LDH MoM THA group (40 hips). Peri-operative data including blood loss, surgery duration, size of the implant, and post-operative complications were recorded. All patients were assessed clinically and radiologically at six weeks; one, three and five years; and at the time of final review. Functional outcome were assessed using Harris hip (HHS), University of California Los Angeles (UCLA) and Oxford hip (OHS) scores. The mean follow-up for all patients was 7.4 years (5 to 9). RESULTS: Patient groups matched similarly in age, percent female, body mass index, preoperative HHS, and follow-up time. No differences were observed between the two groups in blood loss or in head size or acetabular inclination angle. HRA group had significantly longer surgery duration but less blood loss. The two groups had comparable HHS, UCLA, and OHS at the latest follow-up. Major complications, such as fracture, dislocation, infection, and adverse reactions to the metal debris (ARMD) were not found in the two groups. Only one case in LDH MoM THA group underwent revision surgery due to unexplained pain. CONCLUSION: Comparison of HRA and LDH MoM THA shows similar mid-term clinical results. HRA may be preferable due to the well-preserved bone stock and restoration of the native anatomy. LDH MoM THA may be used with caution due to the excessive metal ion release.

Protective effects of Zn2+ against cobalt nanoparticles and cobalt chloride-induced cytotoxicity of RAW 264.7cells via ROS pathway.

Recent concerns have emerged surrounding the toxicity that cobalt may represent when used in MOM implants. Owing to corrosion and wear of MOM implants, the subsequent released cobalt nanoparticles (CoNPs) or Co ions (Co2+) can cause adverse reactions, such as the generation of pseudotumors, extensive necrosis, early osteolysis, and implants failure. The present study confirmed that CoNPs and Co2+ can induce dose- and time-dependent cytotoxicity with increasing reactive oxygen species (ROS) levels. Additionally, using metallothionein (MT), a heavy metal-binding protein, the present study assessed the protective effects of Zn2+ against CoNPs and Co2+-induced cytotoxicity of RAW 264.7 cells through ROS pathway. Further studies are needed to explore the underlying protective mechanisms in vitro. However, the current findings indicate that the ROS pathway may be a potential target for therapeutic interventions.

Endoplasmic reticulum stress participates in the progress of senescence and apoptosis of osteoarthritis chondrocytes.

Endoplasmic reticulum stress (ERS) has been shown to participate in many disease pathologies. Recent reports have reported that ERS exists in human osteoarthritis (OA) chondrocytes. During OA, chondrocytes exhibit increased level of some senescence marker, such as senescence-associated ß-galactosidase (SA ß-gal) activity. However, the persistence and accumulation of senescent cells in various tissues can also impair function and have been involved in the pathogenesis of many age-related diseases, including OA. In this present study, we used IL-1ß (10 ng/ml) to mimic OA chondrocytes and we found that IL-1ß stimulated chondrocytes caused the increasing expression of ADAMTS5 and MMP13, decreasing COL2A1 expression, which were in accord with OA chondrocytes changes. Our data also showed that ERS is involved in the OA chondrocytes, SA ß-gal activity significantly increases and inhibition of ERS can decrease the SA ß-gal activity, apoptosis of OA chondrocytes and increase cell viability. These results help us to open new perspectives for the development of molecular-targeted treatment approaches and thus present an effective novel therapeutic approach for OA.

Transcriptome changes during TNF-α promoted osteogenic differentiation of dental pulp stem cells (DPSCs).

Dental pulp stem cells (DPSCs), due to the ease of isolation and their capacities of multi-lineage differentiation, are considered as attractive resources for regenerative medicine. In a previous study, we showed that TNF-α promoted the osteogenic differentiation of DPSCs via the NF-κB signaling pathway. However, the mechanisms of such differentiation were largely unknown. Here, we examined the gene expression profiles between undifferentiated, partially differentiated and fully differentiated DPSCs induced by TNF-α by performing the next-generation sequencing technique (RNA-Seq). Our results revealed a continuous transition of the transcriptome changes during TNF-α promoted osteogenic differentiation of DPSC. Bioinformatics analysis revealed a relatively general to specific transformation of the involved signaling pathways from the early to late stages of differentiation. Gene regulatory network analysis highlighted novel, key genes that are essential for osteogenic differentiation at different time points. These results were further validated by quantitative RT-PCR, confirming the high reliability of the RNA-Seq. Our data therefore will not only provide novel insights into the molecular mechanisms that drive the osteogenic differentiation of DPSCs, but also promote the studies of bone tissue engineering that utilizes DPSCs as a crucial resource.

Gender differences of venous thromboembolism risk after total hip and total knee arthroplasty: a meta-analysis.

We performed a meta-analysis to evaluate gender differences of venous thromboembolism (VTE) risk after total hip (THA) and total knee arthroplasty (TKA). We searched PubMed and Web of Knowledge from their beginning to 25 July 2015. Pooled odds ratio (OR) and 95 % confidence interval (CI) for VTE risk were calculated. Twenty studies with 7,892,585 patients were included in our study. The VTE incidence ranged from 0.27 to 61.0 %. The sex ratio (male/female) was 0.623 (3,016,648/4,839,785) in no VTE group versus 0.492 (11,926/24,226) in VTE group. The pooled OR was 1.184 (95 % CI 1.070-1.310; Z = 3.28, P = 0.001). The Begg's test (z = 1.46, P = 0.144) and the Egger's test (t = 0.58, P = 0.571), and the funnel plot suggested there was no significant publication bias. Sensitivity analysis by omitted a study with largest simple size showed the pooled OR was 1.166 (95 % CI 1.051-1.294; Z = 2.91, P = 0.004) by random-effects model. Meta-regression showed VTE risk was not related with THA and TKA incidence (t = 0.35, P = 0.732). Our meta-analysis showed female patients have slightly higher risk of VTE than male patients after THA and TKA.

Prevention of Surgical Site Infection After Ankle Surgery Using Vacuum-Assisted Closure Therapy in High-Risk Patients With Diabetes.

Patients with diabetes have a high risk of surgical site infection (SSI) after ankle surgery. The aim of the present study was to investigate the efficacy of vacuum-assisted closure (VAC) in the prevention of SSI after ankle surgery compared with the efficacy of standard moist wound care (SMWC). A retrospective study was performed of unstable ankle fractures for surgical fixation in patients with diabetes from January 2012 to December 2014. VAC and SMWC were used for surgical incision coverage. The primary outcome was the incidence of SSI, and the secondary outcomes were the length of hospital stay and crude hospital costs. The data from 76 patients were analyzed, with 22 (28.95%) in the VAC group and 54 (71.05%) in the SMWC group. The incidence of SSI was 4.6% in the VAC group compared with 27.8% in the SMWC group (chi-square 5.076; p = .024), and the crude odds ratio for SSI in the VAC group was 0.124 (95% confidence interval 0.002 to 0.938). The length of hospital stay was lower in the VAC group than in the SMWC group (12.6 ± 2.7 days and 15.2 ± 3.5 days, respectively; t = 3.122, p = .003). The crude hospital costs were also lower in the VAC group than in the SMWC group (Chinese yuan 8643.2 ± 1195.3 and 9456.2 ± 1106.3, respectively; t = 2.839, p = .006). After logistic regression analysis, the adjusted odds ratio for the total SSI rate comparing VAC and SMWC was 0.324 (95% confidence interval 0.092 to 0.804; p = .021). Compared with SMWC, VAC can decrease the SSI rate after ankle surgery in patients with diabetes. This finding should be confirmed by prospective, randomized controlled clinical trials.

Evaluation of sex differences in rodent anterior cruciate ligament injury.

The relative contributions of sex differences in anatomy, biomechanics, and hormones to the increased risk of anterior cruciate ligament (ACL) injury in female athletes remains unknown. The purpose of this study is to investigate sex differences in anatomy and biomechanics of the native and reconstructed ACL using our established murine model. A total of 140 12-week-old wild-type C57Bl/6 (70 male vs. 70 female) mice were used for this study. ACL reconstruction was performed on 120 mice who were split into four groups: Group 1 (30 males sacrificed at 14 days), Group 2 (30 females sacrificed at 14 days), Group 3 (30 males sacrificed at 28 days), and Group 4 (30 females sacrificed at 28 days). Tendon graft-to-bone healing was assessed by biomechanical, histological, and micro-CT analysis. Twenty mice were used for baseline testing. Females showed significantly higher anterior (p < 0.05) and total displacement (p < 0.05). Males demonstrated a significantly higher load-to-failure force of native ACLs compared to females (p < 0.05). There was no significant difference in load-to-failure force in the ACL autograft. There were no significant sex differences in histological analysis of graft integration or tibial slope. The increased knee laxity and reduced load-to-failure of the native ACL observed in the female mice are consistent with some of the proposed risk factors driving the increased risk of ACL injury in females. Understanding the relative contributions of factors driving sex differences in material properties of the ACL will provide insight into the sex differences in ACL injury and future prevention strategies.

GLI1 Deficiency Impairs the Tendon-Bone Healing after Anterior Cruciate Ligament Reconstruction: In Vivo Study Using Gli1-Transgenic Mice.

Hedgehog (Hh) signaling plays a fundamental role in the enthesis formation process and GLI-Kruppel family member GLI1 (Gli1) is a key downstream mediator. However, the role of Gli1 in tendon-bone healing after anterior cruciate ligament reconstruction (ACLR) is unknown. To evaluate the tendon-bone healing after ACLR in Gli1LacZ/LacZ (GLI1-NULL) mice, and compare Gli1LacZ/WT (GLI1-HET) and Gli1WT/WT wild type (WT) mice, a total of 45 mice, 15 mice each of GLI1-NULL, GLI1-HET and WT were used in this study. All mice underwent microsurgical ACLR at 12 weeks of age. Mice were euthanized at 4 weeks after surgery and were used for biomechanical testing, histological evaluation, and micro-CT analysis. The GLI1-NULL group had significantly lower biomechanical failure force, poorer histological healing, and lower BV/TV when compared with the WT and GLI1-HET groups. These significant differences were only observed at the femoral tunnel. Immunohistology staining showed positive expression of Indian hedgehog (IHH) and Patched 1(PTCH1) in all three groups, which indicated the activation of the Hh signal pathway. The GLI1 was negative in the GLI1-NULL group, validating the absence of GLI1 protein in these mice. These results proved that activation of the Hh signaling pathway occurs during ACL graft healing, and the function of Gli1 was necessary for tendon-bone healing. Healing in the femoral tunnel is more obviously impaired by Gli1 deficiency. Our findings provide further insight into the molecular mechanism of tendon-bone healing and suggest that Gli1 might represent a novel therapeutic target to improve tendon-bone healing after ACLR.

Ferrostatin-1 alleviates cytotoxicity of cobalt nanoparticles by inhibiting ferroptosis.

Cobalt is the main component of metal prostheses in hip arthroplasty. Studies have shown that metal particles mainly composed of cobalt nanoparticles (CoNPs) can cause systemic and local toxic reactions due to various physical and chemical factors. Therefore, elucidating the underlying mechanisms of metal prosthesis action, coupled with identification of effective detoxification drugs are imperative to minimizing postoperative complications and prolonging the service life of these clinical tools. In this study, we treated Balb/3T3 mouse fibroblast cell line with CoNPs and ferrostatin-1, then measured cell viability via the CCK-8 assay. Next, we determined levels of reactive oxygen species (ROS), malondialdehyde (MDA), glutathione (GSH), cobalt and iron contents, as well as glutathione peroxidase 4 (GPX4), and solute carrier family 7 member 11 (SLC7A11) expression in each group. Finally, we employed transmission electron microscopy (TEM) to detect changes in the ultrastructure of each group of cells. Exposure of cells to CoNPs significantly suppressed their viability, and downregulated expression of GSH, GPX4, and SLC7A11 proteins. Conversely, this treatment mediated a significant increase in ROS, MDA, cobalt, and iron levels in the cells. TEM images revealed a marked increase in density of the mitochondrial membrane of cells in the CoNPs group, while the outer membrane was broken. Notably, treatment with ferroptosis inhibitor Ferrostatin-1 alleviated the cytotoxic response caused by CoNPs. These findings suggest that CoNP-induced cytotoxicity may be closely related to ferroptosis, indicating that inhibition of ferroptosis is a potential therapeutic strategy for reducing CoNP toxicity.

Distinct Inflammatory Macrophage Populations Sequentially Infiltrate Bone-to-Tendon Interface Tissue After Anterior Cruciate Ligament (ACL) Reconstruction Surgery in Mice.

Macrophages are important for repair of injured tissues, but their role in healing after surgical repair of musculoskeletal tissues is not well understood. We used single-cell RNA sequencing (RNA-seq), flow cytometry, and transcriptomics to characterize functional phenotypes of macrophages in a mouse anterior cruciate ligament reconstruction (ACLR) model that involves bone injury followed by a healing phase of bone and fibrovascular interface tissue formation that results in bone-to-tendon attachment. We identified a novel "surgery-induced" highly inflammatory CD9+ IL1+ macrophage population that expresses neutrophil-related genes, peaks 1 day after surgery, and slowly resolves while transitioning to a more homeostatic phenotype. In contrast, CX3CR1+ CCR2+ macrophages accumulated more slowly and unexpectedly expressed an interferon signature, which can suppress bone formation. Deletion of Ccr2 resulted in an increased amount of bone in the surgical bone tunnel at the tendon interface, suggestive of improved healing. The "surgery-induced macrophages" identify a new cell type in the early phase of inflammation related to bone injury, which in other tissues is dominated by blood-derived neutrophils. The complex patterns of macrophage and inflammatory pathway activation after ACLR set the stage for developing therapeutic strategies to target specific cell populations and inflammatory pathways to improve surgical outcomes. © 2022 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Identification of key regulators responsible for dysregulated networks in osteoarthritis by large-scale expression analysis.

BACKGROUND: Osteoarthritis (OA) is a worldwide musculoskeletal disorder. However, disease-modifying therapies for OA are not available. Here, we aimed to characterize the molecular signatures of OA and to identify novel therapeutic targets and strategies to improve the treatment of OA. METHODS: We collected genome-wide transcriptome data performed on 132 OA and 74 normal human cartilage or synovium tissues from 7 independent datasets. Differential gene expression analysis and functional enrichment were performed to identify genes and pathways that were dysregulated in OA. The computational drug repurposing method was used to uncover drugs that could be repurposed to treat OA. RESULTS: We identified several pathways associated with the development of OA, such as extracellular matrix organization, inflammation, bone development, and ossification. By protein-protein interaction (PPI) network analysis, we prioritized several hub genes, such as JUN, CDKN1A, VEGFA, and FOXO3. Moreover, we repurposed several FDA-approved drugs, such as cardiac glycosides, that could be used in the treatment of OA. CONCLUSIONS: We proposed that the hub genes we identified would play a role in cartilage homeostasis and could be important diagnostic and therapeutic targets. Drugs such as cardiac glycosides provided new possibilities for the treatment of OA.

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.

Atlas of Human Skeleton Hardness Obtained Using the Micro-indentation Technique.

OBJECTIVES: Measure and systematically evaluate the distribution of microhardness in the human skeleton. METHODS: Three fresh corpses were obtained, aged 62 (male), 45 (female), and 58 years (male). Soft tissues were removed, and all axial and unilateral appendicular bones were freshly harvested. All three skeletons were examined by X-ray and computed tomography (CT) to exclude skeletal pathology. Only bones from donors with no known skeletal pathology were included in the study. Axial and unilateral appendicular skeleton bones from each of the three donors were obtained, except for ear ossicles, hyoid bone, tailbone, and 14 phalanges of the foot, for which samples were difficult to obtain. Precision bone specimens with a thickness of 3 mm, which were cut with a Buehler IsoMet 11-1280-250 low-speed diamond saw (Buehler, USA), were obtained from all important anatomic sites in a direction perpendicular to the mechanical axis of each bone. Micro-indentation (the Vickers hardness test) was performed on the surface of each specimen using a microhardness tester with a diamond indenter. Hardness value (HV) was computed for each indentation. Each bone specimen was divided into several regions of interest. Indentations were carefully made and computed. Then we analyzed the data to identify hardness distribution rules at different anatomic sites. RESULTS: In total, 5360 indentations were made in 1072 regions of interest in each donor. Hardness of the axial and appendicular bones were all inhomogeneous depending on the anatomic sites, but the distribution of microhardness followed certain rules. The mean hardness value ranged from 24.46 HV (HV = hardness value, kgf/mm2 ) for the sacrum to 53.20 HV for the shaft of the tibia. The diaphysis was harder than the metaphysis, and the proximal and distal epiphysis had lower values (8.85%- 40.39%) than the diaphysis. Among the long bone diaphyses, the tibia cortical bone (51.20 HV) was the hardest, harder than the humerus (47.25 HV), the ulna (43.26 HV), the radius (42.54 HV), and the femur (47.53 HV). However, in some anatomic sites such as the lumbar vertebra (cortical bone 32.86 HV, cancellous bone 31.25 HV), the cortical shells were sometimes not harder than the internal cancellous bones. The lumbar vertebra (32.86 HV) was harder than the cervical vertebra (28.51 HV) and the thoracic vertebra (29.01 HV). CONCLUSIONS: The distribution of microhardness in the human skeleton follows certain rules. These distribution rules could be used to predict the mechanical properties of bone and progress in this field could provide data for the basis of a new three-dimensional printing technique, which may lead to new perspectives for custom-made implants.

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.

[Treatment of type C intercondylar fractures of distal humerus using dual plating].

OBJECTIVE: To evaluate the clinical outcome of dual plating in the treatment of humeral intercondylar type-C fractures in adults. METHODS: From June 2004 to October 2007, 38 cases of type-C distal humeral fractures were stabilised with dual plating. There were 21 males and 17 females. The average age was 43 years with a range from 21 to 71 years. According to the AO classification, 9 cases were of type C1, 17 of C2 and 12 of C3. The posterior midline approach was selected. Twenty-one cases were exposed through the trans-olecranon osteotomy, 11 through the Campbell (Van Gorder) approach, 6 through triceps sparing approach. Autogenous bone graft was performed in 5 cases because of severe comminution. RESULTS: Thirty-five patients were followed-up for 14-30 months (mean 24.2 months). At the latest follow-up, the elbow flexion averaged 119 degrees (range 90 degrees - 135 degrees ), and the loss of extension averaged 16.2 degrees (range 5 degrees - 25 degrees ). All the patients got bony healing, the average healing period was 14 weeks. The patients were evaluated using the criteria of Aitken and Rorabeek and the scores were 13 excellent, 16 good, 6 fair. Twenty-nine patients (82.9%) had a good or excellent results. Complications included 4 cases of traumatic osteoarthritis, 2 heterotopic ossification, 1 ulnar neuropathy. Infection as well as loosening or breakage of the implant was not found. CONCLUSIONS: The dual plating is able to provide rigid fixation for the humeral intercondylar fractures. In addition, it can allow early functional exercise after operation, decrease the related complications significantly, and improve the functional results.

Profiling lncRNA alterations during TNF­α induced osteogenic differentiation of dental pulp stem cells.

The multipotent and easily accessible characteristics of dental pulp stem cells (DPSCs) make them a promising target for bone tissue engineering. Long non­coding RNAs (lncRNAs) have an important role in the osteogenic differentiation of mesenchymal stem cells. Nevertheless, whether lncRNAs are involved in the osteogenic differentiation of DPSCs remains unclear. The present study examined the expression alterations of lncRNAs in tumor necrosis factor­α induced osteogenic differentiation of DPSCs. Following identification of differentially expressed lncRNAs at different time points by reverse transcription­quantitative polymerase chain reaction, profiling analysis was performed and a profile was further validated, in which lncRNA expression levels demonstrated significant upregulation. The next generation sequencing analysis identified 77 (58 upregulated and 19 downregulated) and 133 differentially expressed lncRNAs (73 upregulated and 60 downregulated) at 7 and 14 days post­treatment, respectively. In addition, 34 lncRNAs were predicted to be strongly associated with 336 mRNA transcripts that underwent significant alterations during osteogenic differentiation. The present data demonstrated that one lncRNA, X inactive specific transcript, is essential for efficient osteogenic differentiation of DPSCs by alkaline phosphatase staining. In summary, the present findings provide insight for the understanding of how non­coding RNAs are involved in regulating the osteogenic differentiation of DPSCs, which may further advance the translational studies of bone tissue engineering.