Biomaterials with mechanical or biological competence are ubiquitous in musculoskeletal disorders, and understanding the inflammatory response they trigger is key to guide tissue regeneration. While macrophage role has been widely investigated, immune response is regulated by other immune cells, including neutrophils, the most abundant leukocyte in human blood. As first responders to injury, infection or material implantation, neutrophils recruit other immune cells, and therefore influence the onset and resolution of chronic inflammation, and macrophage polarization. This response depends on the physical and chemical properties of the biomaterials, among other factors. In this study we report an in vitro culture model to describe the most important neutrophil functions in relation to tissue repair. We identified neutrophil survival and death, neutrophils extracellular trap formation, release of reactive oxygen species and degranulation with cytokines release as key functions and introduced a corresponding array of assays. These tests were suitable to identify clear differences in the response by neutrophils that were cultured on material of different origin, stiffness and chemical composition. Overall, substrates from biopolymers of natural origin resulted in increased survival, less neutrophil extracellular trap formation, and more reactive oxygen species production than synthetic polymers. Within the range of mechanical properties explored (storage modulus below 5 k Pa), storage modulus of covalently crosslinked hyaluronic acid hydrogels did not significantly alter neutrophils response, whereas polyvinyl alcohol gels of matching mechanical properties displayed a response indicating increased activation. Additionally, we present the effect of material stiffness, charge, coating and culture conditions in the measured neutrophils response. Further studies are needed to correlate the neutrophil response to tissue healing. By deciphering how neutrophils initiate and modulate the immune response to material implantation, we aim at introducing new principles to design immunomodulatory biomaterials for musculoskeletal disorders. Acknowledgments. This work was supported by the AO Foundation, AO CMF, grant AOCMF-21-04S

Objectives. The cytotoxicity induced by cobalt ions (Co. 2+. ) and cobalt nanoparticles (Co-NPs) which released following the insertion of a total hip prosthesis, has been reported. However, little is known about the underlying mechanisms. In this study, we investigate the toxic effect of Co. 2+. and Co-NPs on liver cells, and explain further the potential mechanisms. Methods. Co-NPs were characterised for size, shape, elemental analysis, and hydrodynamic diameter, and were assessed by Transmission Electron Microscope, Scanning Electron Microscope, Energy Dispersive X-ray Spectroscopy and Dynamic Light Scattering. BRL-3A cells were used in this study. Cytotoxicity was evaluated by MTT and lactate dehydrogenase release assay. In order to clarify the potential mechanisms, reactive oxygen species, Bax/Bcl-2 mRNA expression, IL-8 mRNA expression and DNA damage were assessed on BRL-3A cells after Co. 2+. or Co-NPs treatment. Results. Results showed cytotoxic effects of Co. 2+. and Co-NPs were dependent upon time and dosage, and the cytotoxicity of Co-NPs was greater than that of Co. 2+. In addition, Co-NPs elicited a significant (p < 0.05) reduction in cell viability with a concomitant increase in lactic dehydrogenase release, reactive oxygen species generation, IL-8 mRNA expression, Bax/Bcl-2 mRNA expression and DNA damage after 24 hours of exposure. Conclusion. Co-NPs induced greater cytotoxicity and genotoxicity in BRL-3A cells than Co. 2+. Cell membrane damage, oxidative stress, immune inflammation and DNA damage may play an important role in the effects of Co-NPs on liver cells. Cite this article: Y. K. Liu, X. X. Deng, H.L. Yang. Cytotoxicity and genotoxicity in liver cells induced by cobalt nanoparticles and ions. Bone Joint Res 2016;5:461–469. DOI: 10.1302/2046-3758.510.BJR-2016-0016.R1

Objectives. Recently, high failure rates of metal-on-metal (MOM) hip implants have raised concerns of cobalt toxicity. Adverse reactions occur to cobalt nanoparticles (CoNPs) and cobalt ions (Co. 2+. ) during wear of MOM hip implants, but the toxic mechanism is not clear. Methods. To evaluate the protective effect of zinc ions (Zn. 2+. ), Balb/3T3 mouse fibroblast cells were pretreated with 50 μM Zn. 2+. for four hours. The cells were then exposed to different concentrations of CoNPs and Co. 2+. for four hours, 24 hours and 48 hours. The cell viabilities, reactive oxygen species (ROS) levels, and inflammatory cytokines were measured. Results. CoNPs and Co. 2+. can induce the increase of ROS and inflammatory cytokines, such as tumour necrosis factor α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6). However, Zn pretreatment can significantly prevent cytotoxicity induced by CoNPs and Co. 2+. , decrease ROS production, and decrease levels of inflammatory cytokines in Balb/3T3 mouse fibroblast cells. Conclusion. These results suggest that Zn pretreatment can provide protection against inflammation and cytotoxicity induced by CoNPs and Co. 2+. in Balb/3T3 cells. Cite this article: Y. Liu, H. Zhu, H. Hong, W. Wang, F. Liu. Can zinc protect cells from the cytotoxic effects of cobalt ions and nanoparticles derived from metal-on-metal joint arthroplasties? Bone Joint Res 2017;6:649–655. DOI: 10.1302/2046-3758.612.BJR-2016-0137.R2

Objectives. The aim of this study was to investigate the effect of hyperglycaemia on oxidative stress markers and inflammatory and matrix gene expression within tendons of normal and diabetic rats and to give insights into the processes involved in tendinopathy. Methods. Using tenocytes from normal Sprague-Dawley rats, cultured both in control and high glucose conditions, reactive oxygen species (ROS) production, cell proliferation, messenger RNA (mRNA) expression of NADPH oxidase (NOX) 1 and 4, interleukin-6 (IL-6), matrix metalloproteinase (MMP)-2, tissue inhibitors of matrix metalloproteinase (TIMP)-1 and -2 and type I and III collagens were determined after 48 and 72 hours in vitro. In an in vivo study, using diabetic rats and controls, NOX1 and 4 expressions in Achilles tendon were also determined. Results. In tenocyte cultures grown under high glucose conditions, gene expressions of NOX1, MMP-2, TIMP-1 and -2 after 48 and 72 hours, NOX4 after 48 hours and IL-6, type III collagen and TIMP-2 after 72 hours were significantly higher than those in control cultures grown under control glucose conditions. Type I collagen expression was significantly lower after 72 hours. ROS accumulation was significantly higher after 48 hours, and cell proliferation after 48 and 72 hours was significantly lower in high glucose than in control glucose conditions. In the diabetic rat model, NOX1 expression within the Achilles tendon was also significantly increased. Conclusion. This study suggests that high glucose conditions upregulate the expression of mRNA for NOX1 and IL-6 and the production of ROS. Moreover, high glucose conditions induce an abnormal tendon matrix expression pattern of type I collagen and a decrease in the proliferation of rat tenocytes. Cite this article: Y. Ueda, A. Inui, Y. Mifune, R. Sakata, T. Muto, Y. Harada, F. Takase, T. Kataoka, T. Kokubu, R. Kuroda. The effects of high glucose condition on rat tenocytes in vitro and rat Achilles tendon in vivo. Bone Joint Res 2018;7:362–372. DOI: 10.1302/2046-3758.75.BJR-2017-0126.R2

Chondrocytic activity is downregulated by compromised autophagy and mitochondrial dysfunction to accelerate the development of osteoarthritis (OA). Irisin is a cleaved form of fibronectin type III domain containing 5 (FNDC5) and known to regulate bone turnover and muscle homeostasis. However, little is known about the role of irisin in chondrocytes and the development of OA. This talk will shed light on FNDC5 expression by human articular chondrocytes and compare normal and osteoarthritic cells with respect to autophagosome marker LC3-II and oxidative DNA damage marker 8-hydroxydeoxyguanosine (8-OHdG). In chondrocytes in vitro, irisin improves IL-1β-mediated growth inhibition, loss of specific cartilage markers and glycosaminoglycan production. Irisin further suppressed Sirt3 and UCP- 1 to improve mitochondrial membrane potential, ATP production, and catalase. This attenuated IL-1β-mediated production of reactive oxygen species, mitochondrial fusion, mitophagy, and autophagosome formation. In a surgical murine model of destabilization of the medial meniscus (DMM) intra-articular administration of irisin alleviates symptoms like cartilage erosion and synovitis. Furthermore, gait profiles of the treated limbs improved. In chondrocytes, irisin treatment upregulates autophagy, 8-OHdG and apoptosis in cartilage of DMM limbs. Loss of FNDC5 in chondrocytes correlates with human knee OA and irisin repressed inflammation-mediated oxidative stress and deficient extracellular matrix synthesis through retaining mitochondrial biogenesis and autophagy. The talk sheds new light on the chondroprotective actions of this myokine and highlights the remedial effects of irisin during progression of OA

Extensive bone defects, caused by severe trauma or resection of large bone tumors, are difficult to treat. Regenerative medicine, including stem cell transplantation, may provide a novel solution for these intractable problems and improve the quality of life in affected patients. Adipose-derived stromal/stem cells (ASCs) have been extensively studied as cell sources for regenerative medicine due to their excellent proliferative capacity and the ability to obtain a large number of cells with minimal donor morbidity. However, the osteogenic potential of ASCs is lower than that of bone marrow-derived stromal/stem cells. To address this disadvantage, our group has employed various methods to enhance osteogenic differentiation of ASCs, including factors such as bone morphogenetic protein or Vitamin D, coculture with bone marrow stem cells, VEGF transfection, and gene transfer of Runx-2 and osterix. Recently, we mined a marker that can predict the osteogenic potential of ASC clones and also investigated the usefulness of the molecule as the enhancer of osteogenic differentiation of ASCs as well as its mechanism of action. Through RNA-seq gene analysis, we discovered that GSTT1 was the most distinguished gene marker between highly osteogenic and poorly osteogenic ASC clones. Knockdown of GSTT1 in high osteogenic ASCs by siGSTT1 treatment reduced mineralized matrix formation while GSTT1 overexpression by GSTT1 transfection or GSTT1 recombinant protein treatment enhanced osteogenic differentiation of low osteogenic ASCs. Metabolomic analysis confirmed significant changes of metabolites related to bone differentiation in ASCs transfected with GSTT1. A high total antioxidant capacity, low levels of cellular reactive oxygen species and increased GSH/GSSG ratios were also detected in GSTT1- transfected ASCs. GSTT1 can be a useful marker to screen the highly osteogenic ASC clones and also a therapeutic factor to enhance the osteogenic differentiation of poorly osteogenic ASC clones

Senescent chondrocyte and subchondral osteoclast overburden aggravate inflammatory cytokine and pro-catabolic proteinase overproduction, accelerating extracellular matrix degradation and pain during osteoarthritis (OA). Fibronectin type III domain containing 5 (FNDC5) is found to promote tissue homeostasis and alleviate inflammation. This study aimed to characterize what role Fndc5 may play in chondrocyte aging and OA development. Serum and macroscopically healthy and osteoarthritic cartilage were biopsied from patients with knee OA who received total knee replacement. Murine chondrocytes were transfected with Fndc5 RNAi or cDNA. Mice overexpressing Fndc5 (Fndc5Tg) were operated to have destabilized medial meniscus mediated (DMM) joint injury as an experimental OA model. Cellular senescence was characterized using RT-PCR analysis of p16INK4A, p21CIP1, and p53 expression together with ß-galactosidase activity staining. Articular cartilage damage and synovitis were graded using OARSI scores. Osteophyte formation and mechanical allodynia were quantified using microCT imaging and von Frey filament, respectively. Osteoclast formation was examined using tartrate-resistant acid phosphatase staining. Senescent chondrocyte and subchondral osteoclast overburden together with decreased serum FNDC5 levels were present in human osteoarthritic cartilage. Fndc5 knockdown upregulated senescence program together with increased IL-6, MMP9 and Adamts5 expression, whereas Alcian blue-stained glycosaminoglycan production were inhibited. Forced Fndc5 expression repressed senescence, apoptosis and IL-6 expression, reversing proliferation and extracellular matrix production in inflamed chondrocytes. Fndc5Tg mice showed few OA signs, including articular cartilage erosion, synovitis, osteophyte formation, subchondral plate sclerosis and mechanical allodynia together with decreased IL-6 production and few senescent chondrocytes and subchondral osteoclast formation during DMM-induced joint injury. Mechanistically, Fndc5 reversed histone H3K27me3-mediated IL-6 transcription repression to reduce reactive oxygen species production. Fndc5 loss correlated with OA development. It was indispensable in chondrocyte growth and anabolism. This study sheds light onto the anti-ageing and anti-inflammatory actions of Fndc5 to chondrocytes; and highlights the chondroprotective function of Fndc5 to compromise OA

Objectives. Triamcinolone acetonide (TA) is widely used for the treatment of rotator cuff injury because of its anti-inflammatory properties. However, TA can also produce deleterious effects such as tendon degeneration or rupture. These harmful effects could be prevented by the addition of platelet-rich plasma (PRP), however, the anti-inflammatory and anti-degenerative effects of the combined use of TA and PRP have not yet been made clear. The objective of this study was to determine how the combination of TA and PRP might influence the inflammation and degeneration of the rotator cuff by examining rotator cuff-derived cells induced by interleukin (IL)-1ß. Methods. Rotator cuff-derived cells were seeded under inflammatory stimulation conditions (with serum-free medium with 1 ng/ml IL-1ß for three hours), and then cultured in different media: serum-free (control group), serum-free + TA (0.1mg/ml) (TA group), serum-free + 10% PRP (PRP group), and serum-free + TA (0.1mg/ml) + 10% PRP (TA+PRP group). Cell morphology, cell viability, and expression of inflammatory and degenerative mediators were assessed. Results. Exposure to TA significantly decreased cell viability and changed the cell morphology; these effects were prevented by the simultaneous administration of PRP. Compared with the control group, expression levels of inflammatory genes and reactive oxygen species production were reduced in the TA, PRP, and TA+PRP groups. PRP significantly decreased the expression levels of degenerative marker genes. Conclusions. The combination of TA plus PRP exerts anti-inflammatory and anti-degenerative effects on rotator cuff-derived cells stimulated by IL-1ß. This combination has the potential to relieve the symptoms of rotator cuff injury. Cite this article: T. Muto, T. Kokubu, Y. Mifune, A. Inui, R. Sakata, Y. Harada, F. Takase, M. Kurosaka. Effects of platelet-rich plasma and triamcinolone acetonide on interleukin-1ß-stimulated human rotator cuff-derived cells. Bone Joint Res 2016;5:602–609. DOI: 10.1302/2046-3758.512.2000582

Stem cells are known to have low levels of intracellular reactive oxygen species (ROS) and high levels of glutathione. ROS are thought to interact with several pathways that affect the transcription machinery required for stem cell differentiation, and are critical for maintaining stem cell function. In this study, we are developing a new fluorescent probe that rapidly and reversibly reacts with glutathione (GSH), the most abundant non-protein thiol in living cells that acts as an antioxidant and redox regulator. Multipotent perivascular progenitor cells derived from human ESCs (hESC-PVPCs): Differentiated ESCs as embryoid bodies in the presence of BMP4 to induce mesoderm differentiation followed by a simple cell selection strategy using attachment of single cells onto collagen-coated dishes. Differential gene expression profiling was performed among H9 hESCs, EBs induced by BMP4 and naturally selected CD140B+CD44+ population at Day 7 (PVPCs). Colony-forming assay: GSHhigh and GSHlow PVPCs were plated on 10-cm tissue culture-treated polystyrene dishes in triplicate in growth medium and cultured for 14 days. Transwell migration assay: GSHhigh and GSHlow PVPCs at passage 4 were resuspended at 1 × 10. 6. /mL in the migration medium and seeded in the upper chamber. The following human recombinant SDF-1 and PDGF-AA proteins were used as chemoattractants in the lower compartment. Probe-GSH conjugate shows shifts in fluorescence excitation and emission spectra that enables ratiometric measurement of GSH levels. Using these properties, stem cells can be purified by FACS-based technology according to intracellular GSH level. We are developing a protocol both for comparing GSH level in stem cell from different culture conditions and for preparing stem cells with high-GSH level . Our results reveal that GSHhigh PVPC purified by FACS show increased colony forming ability compared with that GSHlow PVPC, indicating that intracellular GSH contributes to the maintenance of stemness. Moreover, transplantation of GSHlow PVPC is more effective than that of GSHlow PVPC for cartilage regeneration in osteochondral defect. This technique enable FACS-based sorting of stem cells according to intracellular GSH levels and thus investigation of functional role of GSH (high antioxidant capacity) in the stem cell maintenance and chondrogenic differentiation

Introduction and Objective. Hyaluronic acid (HA) is an effective option for the treatment of osteoarthritis (OA) patients due to several properties such as normalization of the mechanical and rheological properties of the synovial fluid and amelioration of OA symptoms and joints function by promoting cartilage nutrition. Since OA progression is also significantly related to oxidative stress and reactive oxygen species (ROS), sodium succinate (SS) is envisioned as a promising compound for cartilage treatment by providing antioxidant defense able to normalize intracellular metabolism and tissue respiration via mitochondrial mechanism of action. The scope of this study was to investigate on an in vitro inflammatory model the efficacy of Diart. ®. product, a combination of HA and SS. Materials and Methods. Donor-matched chondrocytes and synoviocytes were obtained from KL 3–4 OA patients undergoing total knee replacement. At passage 4, inflammation was promoted with 1 ng/ml IL-1B for 48 hours in absence and presence of Diart. ®. at 1:3 dilution rate. Nitric oxide (NO) from cell culture supernatant was measured by Griess reaction. Mitochondrial and cytoplasmatic ROS evaluation was assessed by flow cytometry with MitoSox and dichlorodihydrofluorescein diacetate (DCFDA) assays. Gene expression of inflammation/oxidative stress-related transcripts (MMP1/MMP3/INOS/COX2) was evaluated by qRT-PCR using TBP as reference. Results. NO was detected only in inflamed chondrocytes and Diart® was able to abolish its levels. NO was not detected in synoviocytes in all conditions. IL-1B reduced both cytoplasmic (−66%) and mitochondrial (−68%) ROS in chondrocytes, with Diart® partially restoring (+40%) mitochondrial levels. In synoviocytes, IL-1B did not alter ROS, with Diart® modestly increasing (+27%) mitochondrial levels. Inflammation was able to increase transcript levels of all tested markers, with the exception of INOS in synoviocytes. In chondrocytes, Diart® significantly (p < 0.05) reduced COX2 (−75%) and MMP1 (−33%). In synoviocytes, Diart® significantly reduced COX2 (−77%) and MMP3 (−84%), with MMP1 53% decreased albeit without reaching statistical significance. Conclusions. Diart. ®. biochemical and physiologic properties in the tested in vitro model of inflammation on donor-matched chondrocytes and synoviocytes allowed reducing inflammation and oxidative stress-related markers, prompting the use of this combination as successful strategy to manage OA-related symptoms

The human amniotic membrane (hAM) contains cells of stem cell characteristics with low immunogenicity and anti-inflammatory properties and has for centuries been applied in the clinics especially for ophthalmology and wound care. It has recently been shown to be promising for novel applications such as tissue engineering and regenerative medicine. Towards these novel applications, we have demonstrated the potential of hAM in toto to differentiate towards bone, cartilage, Schwann like cells and recently also a producer of surfactant. We have further investigated the relevance of the location of origin for the therapeutic potential of the membrane. We show that placental and reflected hAM differs distinctly in morphology and functional activity. The placental region has significantly higher mitochondrial activity, however lower levels of reactive oxygen species, which suggests that placental and reflected regions may have different potential for tissue regeneration. We have further investigated the suitability of hAM to support therapeutic cells and have improved its maintenance in vitro towards xeno-free conditions

Intervertebral disc (IVD) degeneration is a major cause of low back pain (LBP). Degenerate discs are associated with accelerated cellular senescence. Cell senescence is associated with a secretory phenotype characterised by increased production of catabolic enzymes and cytokines. However, to date, the mechanism of cell senescence within disc degeneration is unclear. Senescence can be induced by increased replication or induced by stress such as reactive oxygen species or cytokines. This study investigated the association of cellular senescence with markers of DNA damage and presence of cytoplasmic DNA (which in cancer cells has been shown to be a key regulator of the secretory phenotype), to determine mechanisms of senescence in disc degeneration. Immunohistochemistry for the senescence marker: p16INK4A was firstly utilised to screen human intervertebral discs for discs displaying at least 30% immunopostivity. These discs were then subsequently analysed for immunopostivity for DNA damage markers γH2AX and cGAS and the presence of cytoplasmic DNA. The number of immunopositive cells for p16 INK4A positively correlated with the expression of γH2AX and cGAS. Senescent cells were also associated with the presence of cytoplasmic DNA. These new findings elucidated a role of cGAS and γH2AX as a link from genotoxic stress to cytokine expression which is associated with senescent cells. The findings indicate that cellular senescence in vivo is associated with DNA damage and presence of cytoplasmic DNA. Whether this DNA damage is a result of replicative senescence or stress induced is currently being investigated in vitro

Cartilage injury is generally associated with cytokine release and accumulation of reactive oxygen species. These mediators trigger pathologic behaviour of the surviving chondrocytes, which respond by excessive expression of catabolic enzymes, such as matrix metalloproteinase 13 (MMP-13), reduced synthesis of type II collagen (COL2A1) and apoptosis. In the long run, these pathologic conditions can cause a posttraumatic osteoarthritis. With the objective to attenuate the progressive degradation of the extracellular matrix and, what is more, promote chondroanabolic processes, a multidirectional treatment of trauma-induced pathogenesis was tested for the first time. Therefore, we evaluated the combinations of one anabolic growth factor (IGF-1, FGF18 or BMP7) with the antioxidant N-acetyl cysteine (NAC) in a human ex vivo cartilage trauma model and compared the findings with the corresponding monotherapy. Human cartilage tissue was obtained with informed consent from donors undergoing knee joint replacement (n=24). Only macroscopically intact tissue was used to prepare explants. Cartilage explants were subjected to a blunt impact (0.59 J) by a drop-tower and treated by IGF-1 [100 ng/mL], FGF18 [200 ng/mL] or BMP7 [100 ng/mL] and/or NAC [2 mM] for 7 days. Following parameters were analysed: cell viability (live/dead staining), gene expression (qRT-PCR) as well as biosynthesis (ELISA) of type II collagen and MMP-13. For statistical analysisKruskal-Wallis or One-way ANOVA was used. All data were collected in the orthopedic research laboratory of the University of Ulm, Germany. Trauma-induced cell death was completely prevented by NAC treatment and FGF18 or BMP7 to a large extent, respectively (p<0.0001). IGF-1 exhibited only poor cell protection. Combination of NAC and FGF18 or BMP7 did not result in enhanced effectiveness; however, IGF-1 significantly reduced NAC-mediated cell protection. While IGF-1 or BMP7 induced collagen type II gene expression (p=0.0069 and p<0.0001, respectively) and its biosynthesis (p<0.0001 and p=0.0131, respectively), NAC or FGF18 caused significant suppression of this matrix component (each p<0.001). Although COL2A1 mRNA was significantly increased by NAC plus IGF-1 (p<0.0001), biosynthesis of collagen type II was generally abolished after multidirectional treatment. Except for IGF-1, all tested therapeutics exhibited chondroprotective qualities, as demonstrated by attenuated MMP-13 expression and breakdown of type II collagen. In combination with IGF-1, NAC-mediated chondroprotection was reduced. Overall, both chondroanabolic and antioxidative therapy had individual advantages. Since adverse interactions were found by simultaneous application of the therapeutics, a sequential approach might improve the efficacy. In support of this strategy current experiments showed that though cell and chondroprotective effects of NAC were maintained after withdrawal of the antioxidant, type II collagen expression recovered by time

Healthcare associated infections (HAI) pose a major threat to patients admitted to hospitals, and infection rates following orthopaedic arthroplasty surgery are as high as 4%, while the infection rates are even higher after revision surgery. 405 nm High-Intensity Narrow Spectrum (HINS) light has been proven to reduce environmental contamination in hospital isolation rooms, and there is potential to develop this technology for application in orthopaedic surgery. Cultured rat osteoblasts were exposed to 405 nm light to investigate if bactericidal doses of light could be used safely in the presence of mammalian cells. Cell viability was measured by MTT reduction and microscopy techniques, function by alkaline phosphatase activity, and proliferation by the BrdU assay. Exposures of up to a dose of 36 J/cm. 2. had no significant effect on osteoblast cell viability, whilst exposure of a variety of clinically relevant bacteria, to 36 J/cm. 2. resulted in up to 100% kill. Exposure to a higher dose of 54 J/cm. 2. significantly affected the osteoblast cell viability, indicating dose dependency. Work also demonstrated that 405 nm light exposure induces reactive oxygen species (ROS) production in both mammalian and bacterial cells, as shown by fluorescence generated from 6-carboxy-2′,7′-dichlorodihydrofluorescein diacetate dye. The mammalian cells were significantly protected from dying at 54 J/cm. 2. by catalase, which detoxifies H. 2. O. 2. Bacterial cells were significantly protected by sodium pyruvate (H. 2. O. 2. scavenger) and by a combination of free radical scavengers (sodium pyruvate, dimethyl thiourea (·OH scavenger), catalase) at 162 and 324 J/cm. 2. Thus the cytotoxic mechanism of 405 nm light in mammalian cells and bacteria is likely oxidative stress involving predominantly H. 2. O. 2. generation, with other ROS contributing to the damage. Additional work describing the potential for incorporation of this antimicrobial light within operating theatre lighting systems will also be discussed, and this, coupled with the cell viability and cytotoxicity results, suggests that 405 nm light could have great potential for continual patient safe decontamination during orthopaedic replacement surgeries and thereby reduce the incidence of infections

Osteosarcoma (OS) is a highly malignant primary tumor frequently occurring in children and adolescents. The mainstay of therapy is neoadjuvant chemotherapy and surgical removal of the lesion yielding a 50–70% of 5-year survival rate. Unfortunately, chemotherapy is currently unable to induce complete tumor necrosis leaving residual tumor cells free to metastasize or recidivate, thus resulting in a 30% mortality. The major limitation in those patients is the development of multidrug resistance (MDR) and the low water solubility of drugs such as Paclitaxel (PTX) that is in fact not included in the majority of chemotherapy protocols for OS treatment. We thus hypothesized to prevent the emergence of MDR and obtain significant tumor reduction, by engineering innovative nanoparticles (NPs) able to vehiculate the PTX and induce a dual synergic action: the cytostatic effect of PTX and the cytotoxicity generated by reactive oxygen species produced from light triggered photoactivation (PDT) of Chlorin e6 photosensitizer. To further improve the efficacy and reduce the side effects of NPs systemic administration, Mesenchymal Stromal Cells (MSC) are used as a “Trojan horse” to deliver the NPs directly to tumor cells, taking advantage of MSC ability to selectively recognize and efficiently engraft in OS tumor stroma. HSA were conjugated with photosensitizer Ce6 and the functionalized protein was used to produce PTX loaded nanoparticles through desolvation technique and drug-induced protein self-assembly (PTX-Ce6@HSA NP). Human MSC lines, isolated from the Bone marrow (BM) of different donors, were then loaded with different dosages of nanoparticles and their ability to internalize and transport the NPs, migrate and induce cytotoxic ROS upon light treatment were tested in in vitro cultures. Preliminary results showed that MSC efficiently internalize PTX-Ce6@HSA NPs and the photosensitizer Ce6 remains active inside the cells for at least 3 days after loading. Electron microscopy performed onto loaded MSC showed that NPs internalization take places via clathrin mediated transport, whereas HPLC analysis demonstrated a release kinetics of PTX mediated by exocytosis. Finally, PTX-Ce6@HSA NPs loaded MSC co-cultured with the OS tumor cell line SaOS-2 showed a significant tumor cell growth reduction. So fare, advances in drug delivery have failed to produce specific tool to improve the overall survival of OS patients. However, given our preliminary in vitro data we believe that the proposed multimodal therapy will minimize the side effects of the systemic chemotherapy and enhance the efficacy through the synergic effect of PTX and PDT. In the future, our strategy could be intended as an innovative co-adjuvant approach for OS treatment to be performed right before surgery to eliminate residual tumors cells after tumor mass removal

Summary Statement. Ischaemic preconditioning protected skeletal myotubes against the effects of ischaemia-reperfusion in vitro. This protection was associated with increased Nrf2 signalling. Introduction. Ischaemic preconditioning (IPC) is a well recognised and powerful phenomenon where a tissue becomes more tolerant to a period of prolonged ischaemia when it is first subjected to short bursts of ischaemia/reperfusion. While much is known about the ability of ischaemic preconditioning to protect myocardial tissue against ischaemia-reperfusion injury, its potential to confer benefit in an orthopaedic setting by protecting skeletal muscle remains relatively unexplored to date. One mechanism by which ischaemic preconditioning may induce protection is through a reduction in oxidative stress. Reactive oxygen species (ROS) are generated both during prolonged ischaemia and also upon reperfusion by infiltrating neutrophils, thereby leading to an increase in oxidative stress. The transcription factor, NF-E2-related factor 2 (Nrf2), is a key regulator of the cells response to oxidative stress as it regulates the expression of a network of anti-oxidant/detoxifying enzymes. Nrf2 signalling has recently been shown to protect against ischaemia-reperfusion injury in both a kidney cell line and in liver biopsies, indicating that this transcription factor may play a key role in the protection provided by ischaemic preconditioning. To date, the involvement of Nrf2 in the response of skeletal muscle to ischaemia-reperfusion has not been investigated. Thus, the aims of this study were to investigate the ability of ischaemic preconditioning to protect skeletal myotubes against ischaemia-reperfusion and to determine the role of Nrf2 signalling in this protection. Materials & Methods. C2C12 mouse myoblasts were maintained at 37. o. C in a humidified atmosphere of 95% air and 5% CO. 2. in DMEM containing 20% FBS. When cultures were approximately 90% confluent, myoblasts were differentiated to myotubes by changing to DMEM supplemented with 2% horse serum and culturing for 7–10 days. Differentiated myotubes were then exposed to simulated ischaemia for 4h (1% O. 2. ) followed by 2h reoxygenation (21% O. 2. ). To precondition myotubes, cells were subjected to 30 min of simulated ischaemia followed by 1 hour reoxygenation prior to the prolonged ischaemic event. Cell survival was assessed by lactate dehydrogenase release. Changes in Nrf2 expression were assessed using real-time PCR, Western blotting and immunofluorescence. Changes in sequestosome-1 (SQSTM1), catalase (CAT), glutathione S-transferase theta-1 (GSTT1), heme oxygenase-1 (HO-1) expression were assessed using a combination of real-time PCR and Western blotting. Results. Preconditioned myotubes showed greater viability both after 4h of ischaemia, and after 4h ischaemia followed by 2h of reoxygenation. This increase in cell viability was associated with increased Nrf2 expression. In addition, increased expression of SQSTM1, and the antioxidant enzymes, CAT, GSTT1 and HO-1 was observed in preconditioned myotubes. Discussion. Our findings indicate that ischaemic preconditioning can protect skeletal myotubes against the effects of ischaemia-reperfusion in vitro. This protection is associated with increased Nrf2 signalling indicating that this transcription factor may play a role in mediating the protection induced by ischaemic preconditioning. By modulating the response of skeletal muscle to ischaemia, ischaemic preconditioning has the potential to limit reperfusion injury, which in turn, may lead to improvements in outcome following orthopaedic surgery

Summary Statement. The incidence of osteonecrosis was significantly lower in the anti-vasospasm agent group (32%) than that in the control group (75%). Vasospasm is one of the important factors involved in the pathogenesis of steroid-induced osteonecrosis. Introduction. A number of studies have suggested that ischemia is the principal pathomechanism of osteonecrosis, however, the detailed mechanism responsible for ischemia remains unclear. It has recently been reported that the Rho/Rho-kinase mediated pathway (Rho-kinase pathway) is considered to be involved in the possible pathogenesis of various cardiovascular disorders as well as cerebral vasospasm. We examined the effects of fasudil (Rho-kinase inhibitor), an anti-vasospasm agent, on the development of steroid-induced osteonecrosis in rabbits. Materials & Methods. One group of rabbits received 15 mg/kg of fasudil intravenously, which were then injected once intramuscularly with 20 mg/kg of methylprednisolone (n = 33, MF group), and one received methylprednisolone alone as a control (n = 28, M group). Eight rabbits from each group were sacrificed 24 hour after the methylprednisolone injection to analyze them by immunohistochemical staining, a Western blotting analysis. Two weeks after the steroid injection, the femora and humeri were examined histopathologically for the incidence of osteonecrosis. Results. The incidence of osteonecrosis was significantly lower in the MF group (32%) than that in the M group (75%) (P < 0.01). Immunohistochemically, endothelin. A. -receptor (ET. A. Rc) expressions levels were decreased in the smooth muscle of the bone marrow in the MF group in comparison to that in the M group. In the M group, the average relative phospho-myosin light chain (p-MLC) expression level in the bone marrow tissue was significantly higher than that observed in the MF group (P < 0.01). In the MF group, the average relative total-eNOS expression level as well as the average relative phospho-eNOS (p-eNOS) expression level was almost 1.5 times higher than that observed in the M group (P < 0.05). The eNOS expressions levels in both serum and bone marrow in the MF group were significantly higher than those in the M group (P < 0.05). Discussion/Conclusion. The potential mechanisms resulting in vasospasm include the increased release of vasoconstrictors or increased sensitivity to these vasoconstrictors. ET-1 has been demonstrated to cause vascular smooth muscle cell constriction via ET. A. Rc stimulation. The expression of ET. A. Rc in rabbits treated with methylprednisolone plus fasudil (MF group) decreased in comparison with that in rabbits treated with the methylprednisolone alone (M group). In this study, both the eNOS and p-eNOS expressions levels in the M group were decreased in comparison to those observed in the MF group. A previous study suggested that high-dose steroid administration causes the overproduction of reactive oxygen species, and thereby perturbs nitric oxide (NO) availability in the vascular endothelium, leading to vascular endothelial dysfunction in patients receiving high-dose steroid therapy. Considering the pathogenesis of the development of osteonecrosis, we speculate that endothelial dysfunction may thus be a preliminary condition leading to the vasospasm. In conclusion, this study indicates that vasospasm is one of the important factors involved in the pathogenesis of steroid-induced osteonecrosis and that the anti-vasospasm agents seem to decrease the incidence of steroid-induced osteonecrosis

Summary Statement. A novel transcutaneous CO. 2. therapy significantly enhanced the antitumor effectiveness of X-ray irradiation in human MFH xenografts The results strongly suggest that transcutaneous CO. 2. therapy could be a novel therapeutic tool for overcoming radioresistance in human malignancies. Introduction. Hypoxia contributes to tumor radioresistance. In the presence of oxygen, reactive oxygen species (ROS) play crucial roles in cellular apoptosis to irradiation. We previously showed that a novel transcutaneous application of CO. 2. can improve hypoxia and that it induces apoptosis and decreases the expression of HIF-1α in sarcoma. Therefore, we hypothesised that a transcutaneous application of CO. 2. may increase radiosensitivity in sarcoma by improvement of hypoxic condition and increasing ROS production in tumors. The purpose of this study is to examine the effect of transcutaneous application of CO. 2. on radiosensitivity in human malignant fibrous histiocytoma (MFH) cells. Methods. Cells. We used a human MFH cell line, Nara-H in this study. X-ray irradiation. X-ray irradiation was performed at a dose rate of 0.64 to 0.66 Gy/min. Colony formation assay. In vitro cell viability after X-ray irradiation was assessed by colony formation assay. In vivo studies. Nara-H cells were subcutaneously implanted to 24 nude mice which were randomly divided into 4 groups; CO. 2. group, X-ray group, Combination group and Control group. CO. 2. therapy was performed as we previously reported (1, 2). In combination group, mice were treated twice a week by X-ray at 3.2 Gy shortly after CO. 2. therapy for 2 weeks. The changes in body weight and tumor volume were monitored for 14 days in all 4 groups. The implanted tumors were excised at the end of experiment. We also excised tumors on the first day of each treatment in all 4 groups, and examined apoptosis and ROS expression by FACS analysis. The animal experiments were approved by the Animal Committee in our institute. Immunoblot analysis. The protein expression of HIF-1α, ROS-related proteins (p38 and JNK/SAPK), and apoptosis-related proteins (caspase-3 and PARP) were assessed by immunoblot analysis. FACS analysis. DNA fragmentation and ROS production in tumors were assessed by FACS analysis. Statistical analysis. ANOVA with post hoc test to compare for continuous values. All tests were considered significant at p<0.05. Results. Approximately 50% of Nara-H cells survived after a total of 3.2 Gy X-ray irradiation. Tumor volume in combination group was significantly reduced at the end of experiment (47% of that in X-ray group and 28% of that in control group). In Combination group, apoptosis with ROS production markedly increased when compared with those in Control, CO. 2. or X-ray group at 24 hours after treatment. Immunoblot analysis showed that, in combination group, the expression of phospho-p38, phospho-JNK/SPAK, and cleavage of both caspase-3 and PARP were increased compared with other groups, conversely, the expression of HIF-1α was decreased. Discussion/Conclusion. In this study, we demonstrated that the combination therapy showed more significant effects on apoptosis and ROS production through improving hypoxia in MFH cells in vivo. Our findings strongly suggest that the combination therapy of CO. 2. and X-ray could be a novel therapeutic strategy for the treatment of human MFH, and that transcutaneous application of CO. 2. may be one of the best radiosensitisers

Aims

This study intended to investigate the effect of vericiguat (VIT) on titanium rod osseointegration in aged rats with iron overload, and also explore the role of VIT in osteoblast and osteoclast differentiation.

Objectives

The surface of pure titanium (Ti) shows decreased histocompatibility over time; this phenomenon is known as biological ageing. UV irradiation enables the reversal of biological ageing through photofunctionalisation, a physicochemical alteration of the titanium surface. Ti implants are sterilised by UV irradiation in dental surgery. However, orthopaedic biomaterials are usually composed of the alloy Ti6Al4V, for which the antibacterial effects of UV irradiation are unconfirmed. Here we evaluated the bactericidal and antimicrobial effects of treating Ti and Ti6Al4V with UV irradiation of a lower and briefer dose than previously reported, for applications in implant surgery.