The regenerative capacity of hyaline cartilage is greatly limited. To prevent the onset of osteoarthritis, cartilage defects have to be properly treated. Cartilage, tissue engineered by mean of bioactive glass (BG) scaffolds presents a promising approach. Until now, conventional BGs have been used mostly for bone regeneration, as they are able to form a hydroxyapatite (HA) layer and are therefore, less suited for cartilage reconstruction. The aim of this study is to compare two BGs based on a novel BG composition tailored specifically for cartilage (CAR12N) and patented by us with conventional BG (BG1393) with a similar topology. The highly porous scaffolds consisting of 100% BG (CAR12N, CAR12N with low Ca2+/Mg2+ and BG1393) were characterized and dynamically seeded with primary porcine articular chondrocytes (pACs) or primary human mesenchymal stem cells (hMSCs) for up to 21 days. Subsequently, cell viability, DNA and glycosaminoglycan contents, cartilage-specific gene and protein expression were evaluated. The manufacturing process led to a comparable high (over 80%) porosity in all scaffold variants. Ion release and pH profiles confirmed bioactivity for them. After both, 7 and 21 days, more than 60% of the total surfaces of all three glass scaffold variants was densely colonized by cells with a vitality rate of more than 80%. The GAG content was significantly higher in BG1393 colonized with pACs. In general, the GAG content was higher in pAC colonized scaffolds in comparison to those seeded with hMSCs. The gene expression of cartilage-specific collagen type II, aggrecan, SOX9 and FOXO1 could be detected in all scaffold variants, irrespectively whether seeded with pACs or hMSCs. Cartilage-specific ECM components could also be detected at the protein level. In conclusion, all three BGs allow the maintenance of the chondrogenic phenotype or chondrogenic differentiation of hMSCs and thus, they present a high potential for cartilage regeneration

Heterotopic ossification (HO) is lamellar bone formation that occurs within tissues that do not normally have properties of ossification. The pathoaetiology of HO is poorly understood. We conducted a genome wide association study to better understand the genetic architecture of HO. 891 patients of European descent (410 HO cases) following THA for primary osteoarthritis were recruited from the UK. HO was assessed from plain AP radiographs of the pelvis. Genomic DNA was extracted, genotyped using the Illumina 610 beadchip and referenced using the 1000 Genome Project panel. HO susceptibility case-control analysis and an evaluation of disease severity in those with HO was undertaken using SNPTESTv2.3.0 on>10 million variants. We tested variants most strongly associated with HO in an independent UK THA replication cohort comprising 209 cases and 211 controls. The datasets were meta-analysed using PLINK. In the discovery cohort 70 signals with an index variant at p<9×10–5 were suggestively associated with HO susceptibility. The strongest signal lay just downstream of the gene ARHGAP18 (rs59084763, effect allele frequency (EAF) 0.19, OR1.87 [1.48–2.38], p=2.48×10–8), the second strongest signal lay within the long non-coding (LNC) RNA gene CASC20 (rs11699612, EAF 0.25, OR1.73 [1.1.40–2.16, p=9.3×10–8). In the discovery cohort 73 signals with an index variant at p<9×10–5 were associated with HO severity. At replication, 12 of the leading 14 susceptibility signals showed a concordant direction of allelic effect and 5 replicated at nominal significance. Following meta-analysis, the lead replicating susceptibility signal was the CASC20 variant rs11699612 (p=2.71×10–11). We identify consistent replicating association of variation within the LNC RNA CASC20 with HO susceptibility after THA. Although the function of CASC20 is currently unknown, possible mechanisms include transcriptional, post-transcriptional and epigenetic regulation of downstream target genes. The work presented here provides new avenues for the development of novel predictive and therapeutic approaches towards HO

Introduction. A long nail is often recommended for treatment of complex trochanteric fractures but requires longer surgical and fluoroscopy times. A possible solution could be a nail with an appropriate length which can be locked in a minimally invasive manner by the main aiming device. We aimed to determine if such a nail model* offers similar structural stability on biomechanical testing on artificial bone as a standard long nail when used to treat complex trochanteric fractures. Method. An artificial osteoporotic bone model was chosen. As osteosynthesis material two cephalomedullary nails (CMN) were chosen: a superior locking nail (SL-Nail) which can be implanted with a singular targeting device, and a long nail (long-nail) with distal locking using free-hand technique. AO31-A2.2 fractures were simulated in a standardized manner. The insertion of the nail was strictly in accordance with the IFU and surgical manual of the manufacturer. The nail was locked dynamically proximally and statically distally. Axial height of the construct, varus collapse, and rotational deformity directly after nail insertion were simulated. A Universal Testing Machine was used. Measurements were made with a stereo-optic tracking system. Reactive movements were recorded and evaluated in all six degrees of freedom. A comparative analysis provided information about the stability and deformation of the assemblies to be compared. Result. There was a detectable difference in the axial fracture movement resulting in narrowing of the fracture gap. The load displacement was 1.7mm higher for the SL-Nail. There was no difference in varus collapse or rotational deformity between the nail variants. Conclusion. We conclude that there are small differences which are clinically insignificant and that a superior locking nail can safely be used to manage complex trochanteric fractures. *DCN SL nail, SWEMAC, Linköping, Sweden. Funding: no funding

We have developed a novel technique to analyse bone, using imaging mass cytometry (IMC) without the constraints of using immunofluorescent histochemistry. IMC can measure the expression of over 40 proteins simultaneously, without autofluorescence. We analysed mitochondrial respiratory chain (RC) protein deficiencies in human bone which are thought to contribute to osteoporosis with increasing age. Osteoporosis is characterised by reduced bone mineral density (BMD) and fragility fractures. Humans accumulate mitochondrial mutations and RC deficiency with age and this has been linked to the changing phenotype in advancing age and age-related disease. Mitochondrial mutations are detectable from the age of 30 onwards, coincidently the age BMD begins to decline. Mitochondria contain their own genome which accumulates somatic variants at around 10 times the rate of nuclear DNA. Once these mutations exceed a threshold, RC deficiency and cellular dysfunction occur. The PolgD257A/D257A mouse model expresses a proof-reading deficient version of PolgA, a mtDNA polymerase. These mice accumulate mutations 3-5 times higher than wild-type mice showing enhanced levels of age-related osteoporosis and RC deficiency in osteoblasts. Bone samples were analysed from young and old patients, developing a protocol and analysis framework for IMC in bone tissue sections to analyse osteoblasts in-situ for RC deficiency. Samples from the femoral neck of 10 older healthy volunteers aged 40 – 85 were compared with samples from young patients aged 1-19. We have identified RC complex I defect in osteoblasts from 6 of the older volunteers, complex II defects in 2 of the older volunteers, complex IV defect in just 1 older volunteer, and complex V defect in 4 of the older volunteers. These observations are consistent with the PolgD257A/D257A mouse-model and suggest that RC deficiency, due to age-related pathogenic mitochondrial DNA mutations, may play a significant role in the pathogenesis of human age-related osteoporosis

In orthopedic surgery, implant infections are a serious issue and difficult to treat. The aim of this study was to use superparamagnetic nanoporous silica nanoparticles (MNPSNP) as candidates for directed drug delivery. Currently, short blood circulation half-life due to interactions with the host's immune system hinder nanoparticles in general from being clinically used. PEGylation is an approach to reduce these interactions and to enhance blood circulation time. The effect of PEGylation of the used . 68. Ga-labelled MNPSNP on the distribution and implant accumulation was examined by PET/CT imaging and gamma counting in an implant mouse model. Female Balb/c mice (n=24) received a magnetic implant subcutaneously on the left and a titanium implant on the right hind leg. On day one, 12 of these mice received an additional clodronate®-injection for macrophage depletion. On the second postoperative day, mice were anaesthetized and MNPSNP (native or PEGylated) injected intravenously, followed by a dynamic PET-scan over 60 minutes, a CT- and a static PET-scan at 120 min. As control, 12 mice received only . 68. Ga-MNPSNP (native or PEGylated). Gamma counting of inner organs, urine, blood and implant area was performed as further final analysis. Although PEGylation of the nanoparticles already resulted in lower liver uptakes, both variants of . 68. Ga-labeled MNPSNP accumulated in liver and spleen. Combination of PEGylation with clodronate®-injection led to a highly significant effect whereas clodronate®-injection alone could not reveal significant differences. In gamma counting, a significantly higher %I.D./g was found for the tissue surrounding the magnetic implants compared to the titanium control, although in a low range. PEGylation and/or clodronate®-injection revealed no significant differences regarding nanoparticle accumulation at the implantation site. PEGylation increases circulation time, but MNPSNP accumulation at the implant site was still insufficient for treatment of infections. Additional efforts have to further increase circulation time and local accumulation. Acknowledgements: This work is funded by the German Research Foundation (DFG, project number 280642759)

Chronic low back pain (cLBP) is a complex, multifaceted disorder where biological, psychological, and social factors affect its onset and trajectory. Consequently, cLBP encompasses many different disease variants, with multiple patient-specific mechanisms. The goal of NIH Back Pain Consortium (BACPAC) Research Program is to develop understanding of cLBP mechanisms and to develop algorithms that optimally match specific treatments to individual patients. To accomplish this, one research activity of BACPAC is to develop theoretical models for chronic low back pain based on the current state of knowledge in the scientific community, and to interrogate the relationships implied by the theoretical models using data generated by or available to BACPAC. The models consider biopsychosocial perspectives, and encompass both peripheral (i.e. low back) and central (i.e. spinal and supra-spinal) factors as well as proposed mechanisms of action of cLBP treatments. However, absent explanations, models/algorithms may fall short of regulatory requirements and clinician expectations, and ultimately may not be embraced by physicians and patients. To address this, BACPAC is developing a clinical utility roadmap (CUR) to clarify how models will be used in practice for selecting optimal treatments, monitoring response to treatment, and reducing health care utilization. This presentation will review the goals of BACPAC and how theoretical models and CUR are being used to support computational knowledge networks to integrate data from deeply phenotyped cLBP patients

Objectives. Given the function of adiponectin (ADIPOQ) on the inflammatory condition of obesity and osteoarthritis (OA), we hypothesized that the ADIPOQ gene might be a candidate gene for a marker of susceptibility to OA. Methods. We systematically screened three tagging polymorphisms (rs182052, rs2082940 and rs6773957) in the ADIPOQ gene, and evaluated the association between the genetic variants and OA risk in a case-controlled study that included 196 OA patients and 442 controls in a northern Chinese population. Genotyping was performed using the Sequenom MassARRAY iPLEX platform. Results. The single nucleotide polymorphism (SNP) rs182052 was found to be potentially associated with knee OA risk (additive model: odds ratio = 1.38; 95% confidence interval 1.07 to 1.76; p = 0.012). Furthermore, a non-significant association was observed for rs182052 and body mass index with regard to OA risk in interaction analyses (p = 0.063). Similarly, no significant interaction was detected for rs182052 and age with regard to OA risk (p = 0.614). Conclusion. These findings suggest that the SNP rs182052 in the ADIPOQ gene may potentially modify individual susceptibility to knee OA in the Chinese population. Further studies are warranted to investigate our findings in more depth. Cite this article: L. Jiang, X. Zhu, J. Rong, B. Xing, S. Wang, A. Liu, M. Chu, G. Huang. Obesity, osteoarthritis and genetic risk: The rs182052 polymorphism in the ADIPOQ gene is potentially associated with risk of knee osteoarthritis. Bone Joint Res 2018;7:494–500. DOI: 10.1302/2046-3758.77.BJR-2017-0274.R1

Background. Fractures of the femoral neck occurring outside the capsule of the hip joint are assumed to have an intact blood supply and hence their conventional management is by fixation rather than arthroplasty. The dynamic hip screw and its variants have been used over many years to fix such fractures but have inherent vulnerabilities; they require an intact lateral femoral cortex, confer a relatively long moment arm to the redistribution of body weight and may cause a stress riser due to the plate with which they are fixed to the femur. Intramedullary devices for fixation of proximal femoral fractures have a shorter moment arm, can be distally locked with reduced perforation of the femoral cortex and are believed to be inherently more stable. For these reasons, a number of surgeons believe them to be superior to the DHS for all extracapsular fractures and their use is now widespread. In this study, we present the usage trends of both devices in extracapsular fractures over the last five years and set these results in the context of patient demographics. Methods. Our departmental electronic patient management system was used to identify all patients undergoing surgery coded as either DHS or its variants or intramedullary fixation of hip fracture. The patients’ age, sex and American Society of Anaesthesiologists grading were recorded. Comparison between groups was made using appropriate tests in SPSS. Results. Our unit has seen a steady move towards the use of intramedullary fixation of extracapsular fractures over five years, from 28.2% to 45.2% of operations, without a change in demographics of the population or a change in surgical outcomes at the most basic level. Conclusion. The move towards intramedullary fixation without evidence of improved outcomes, given the significantly higher cost, requires urgent research. Level of Evidence. IV

Dupuytren Disease (DD), the most common connective tissue disease in man, presents as a benign fibromatosis of the hands and fingers resulting in the formation of nodules and cords and often leading to flexion contractures in association with keloids or Peyronie disease. Surgical resection of the fibrotic nodules, and more recently intra-lesional collagenase injection are the main therapeutic options for these patients. While the exact cause of DD is still unknown, linkage and Genome Wide Association Studies (GWAS) showed molecular heterogeneity with at least 10 different susceptibility loci 6 of which are close to genes encoding proteins in the Wnt-signaling pathway. We aim to identify the molecular basis of Dupuytren Disease (DD). Twenty patients with Dupuytren disease (including 3 patients with autosomal dominant inheritance, 1 with keloids and congenital torticollis, 2 with Peronie disease), were included in this study. Chromosome Microarray Analysis (CMA), Whole Exome Sequencing (WES) of gDNA and proteomic analysis by LC-Tandem Mass Spectrometry (LC-MSMS) studies were performed. Expression and Network analysis of LCMSMS results was performed using Principal Component Analysis (PCA), ANOVA and Ingenuity Pathway Analysis (IPA). No pathogenic copy number variants (CNVs) were found in CMA (n = 3). WES showed potentially pathogenic variants in POSTN, WNT11, MMP1 and COL3A1. PCA showed three differentially expressed clusters and network-IPA identified ACTB, BAX, COL3A1, FBN1, FN1, MMP1 as potential biomarkers. Comprehensive multi-OMIC analysis of gDNA and tissue proteins in patients with DD identified several connective tissue biomarkers potentially important in the pathogenesis of DD

Cartilage injuries often represent irreversible tissue damage because cartilage has only a low ability to regenerate. Thus, cartilage loss results in permanent damage, which can become the starting point for osteoarthritis. In the past, bioactive glass scaffolds have been developed for bone replacement and some of these variants have also been colonized with chondrocytes. However, the hydroxylapaptite phase that is usually formed in bioglass scaffolds is not very suitable for cartilage formation (chondrogenesis). This interdisciplinary project was undertaken to develop a novel slowly degrading bioactive glass scaffold tailored for cartilage repair by resembling the native extracellular cartilage matrix (ECM) in structure and surface properties. When colonized with articular chondrocytes, the composition and topology of the scaffolds should support cell adherence, proliferation and ECM synthesis as a prerequisite for chondrogenesis in the scaffold. To study cell growth in the scaffold, the scaffolds were colonized with human mesenchymal stromal cells (hMSCs) and primary porcine articular chondrocytes (pACs) (27,777.8 cells per mm. 3. ) for 7 – 35 d in a rotatory device. Cell survival in the scaffold was determined by vitality assay. Scanning electron microscopy (SEM) visualized cell ultramorphology and direct interaction of hMSCs and pACs with the bioglass surface. Cell proliferation was detected by CyQuant assay. Subsequently, the production of sulphated glycosaminoglycans (sGAGs) typical for chondrogenic differentiation was depicted by Alcian blue staining and quantified by dimethylmethylene blue assay assay. Quantitative real-time polymerase chain reaction (QPCR) revealed gene expression of cartilage-specific aggrecan, Sox9, collagen type II and dedifferentiation-associated collagen type I. To demonstrate the ECM-protein synthesis of the cells, the production of collagen type II and type I was determined by immunolabelling. The bioactive glass scaffold remained stable over the whole observation time and allowed the survival of hMSCs and pACs for 35 days in culture. The SEM analyses revealed an intimate cell-biomaterial interaction for both cell types showing cell spreading, formation of numerous filopodia and ECM deposition. Both cell types revealed initial proliferation, decreasing after 14 days and becoming elevated again after 21 days. hMSCs formed cell clusters, whereas pACs showed an even distribution. Both cell types filled more and more the pores of the scaffold. The relative gene expression of cartilage-specific markers could be proven for hMSCs and pACs. Cell associated sGAGs deposition could be demonstrated by Alcian blue staining and sGAGs were elevated in the beginning and end of the culturing period. While the production of collagen type II could be observed with both cell types, the synthesis of aggrecan could not be detected in scaffolds seeded with hMSCs. hMSCs and pACs adhered, spread and survived on the novel bioactive glass scaffolds and exhibited a chondrocytic phenotype

Summary Statement. Corin has developed bone conserving prosthesis (MiniHip™) to better replicate the physiological load distribution in the femur. This study assessed whether the MiniHip™ prosthesis can better match the pre-osteoarthritic head centre for patient demographics when compared to contemporary long stem devices. Introduction. Leg length and offset discrepancy resulting from Total Hip Replacement (THR) is a major cause of concern for the orthopaedic community. The inability to substitute the proximal portion of the native femur with a device that suitably mimics the pre-operative offset and head height can lead to loss of abductor power, instability, lower back pain and the need for orthodoses. Contemporary devices are manufactured based on predicate studies to cater for the variations within the patient demographic. Stem variants, modular necks and heads are often provided to meet this requirement. The number of components and instruments that manufacturers are prepared to supply however is limited by cost and an unwillingness to introduce unnecessary complexity. This can restrict the ability to achieve the pre-osteoarthritic head centre for all patient morphologies. Corin has developed MiniHip™ to better replicate the physiological load distribution in the femur. This study assessed whether the MiniHip™ prosthesis can better match the pre-osteoarthritic head centre for patient demographics when compared to contemporary long stem devices. Methods. The Dorr classification is a well accepted clinical method for defining femoral endosteal morphology. This is often used by the surgeon to select the appropriate type and size of stem for the individual patient. It is accepted that a strong correlation exists between Flare Index (FI), characterising the thinning of cortical walls and development of ‘stove-pipe’ morphology, and age, in particular for females. A statistical model of the proximal femur was built from 30 full length femoral scans (Imorphics, UK). Minimum and maximum intramedullary measurements calculated from the statistical model were applied to relationships produced by combining Corins work with that of prior authors. This data was then used to generate 2D CAD models into which implants were inserted to compare the head centres achievable with the MiniHip™ compared to those of a contemporary long stem. Results. Results for the CAD overlay indicated the MiniHip prosthesis is better suited to restoring head centre for a range of morphological variations. In contrast, the long stem prosthesis requires a larger size range and increased inventory in terms of stem variants and modular components to achieve the same array of head centres. The disparity between the Corin FI and that of prior authors can be accounted for by the methods employed; the greyscale-based edge detection (Imorphics) compared to a manual identification method. Discussion/Conclusion. By overlaying the Corin MiniHip™ over the CAD representation of anticipated flare index, it is evident that the MiniHip™ stem is more suitable for the anticipated range of morphologies. The versatility of this design enables the restoration of head height and offset regardless of canal geometry, degree of offset and or CCD angle. This is not the case for contemporary long stem devices which rely on a more diaphyseal region for anchorage and stability and therefore depend on stem variants and modularity to cater for morphology changes

The accurate positioning of the total knee arthroplasty affects the survival of the implants(1). Alignment of the femoral component in relation to the native knee is best determined using pre- and post-operative 3D-CT reconstruction(2). Currently, the scans are visualised on separate displays. There is a high inter- and intra-observer variability in measurements of implant rotation and translation(3). Correct alignment is required to allow a direct comparison of the pre- and post-operative surfaces. This is prevented by the presence of the prostheses, the bone shape alteration around the implant, associated metal artefacts, and possibly a segmentation noise. The aim is to create a novel method to automatically register pre- and post-operative femora for the direct comparison of the implant and the native bone. The concept is to use post-operative femoral shaft segments free of metal noise and of surgical alteration for alignment with the pre-operative scan. It involves three steps. Firstly, using principal component analysis, the femoral shafts are re-oriented to match the X axis. Secondly, variants of the post-operative scan are created by subtracting 1mm increments from the distal femoral end. Thirdly, an iterative closest point algorithm is applied to align the variants with the pre-operative scan. For exploratory validation, this algorithm was applied to a mesh representing the distal half of a 3D scanned femur. The mesh of a prosthesis was blended with the femur to create a post-operative model. To simulate a realistic environment, segmentation and metal artefact noise were added. For segmentation noise, each femoral vertex was translated randomly within +−1mm,+−2mm,+−3mm along its normal vector. To create metal artefact random noise was added within 50 mm of the implant points in the planes orthogonal to the shaft. The alignment error was considered as the average distance between corresponding points which are identical in pre- and post-operative femora. These preliminary results obtained within a simulated environment show that by using only the native parts of the femur, the algorithm was able to automatically register the pre- and post-operative scans even in presence of the implant. Its application will allow visualisation of the scans on the same display for the direct comparison of the perioperative scans. This method requires further validation with more realistic noise models and with patient data. Future studies will have to determine if correct alignment has any effect on inter- and intra-observer variability

Introduction. Achilles tendinopathy (AT) is a highly prevalent injury in athletes and non-athletes with an unknown aetiology. Genetic risk factors have been a recent focus of investigation. The aim of this systematic review was to determine which loci have been linked with mid-portion AT and could potentially be used as biomarkers in tendinopathy risk models or as preventative or therapeutic targets. Materials and Methods. Eight electronic bibliographic databases were searched from inception to April 2015 for cross-sectional, prospective cohort and case-control studies that included empirical research investigating genes associated with mid-portion AT. Potential publications were assessed by two independent reviewers (AAC and PRJ) for inclusion and quality. Quality was evaluated using a validated scale. Results. Twelve candidate gene studies and three pathway-based genetic association studies that investigated genetic risk factors for AT were identified. According to Ariëns's criteria, there was strong evidence for the COL5A1 gene. There was some evidence for 6 of the other genes investigated: COL5A3, TNC, CASP8, MIR608, GDF5, MMP3 and TIMP2 genes. There was inconclusive evidence for the following genes: COL3A1, COL5A2, COL11A1, COL11A2, COL12A1, COL1A1, COL27A1, COL14A1, COMP, THBS2, ADAMTS2, ADAMTS5, ADAMTS14, ADAM12, TGFβ1, IL-1β, IL-1RN, IL-6, NOS2 and NOS3. There was some evidence for combinations of functional variants of different genes and pseudohaplotypes constructed from many functional variants. The quality of included studies varied (3/9 to 7/9), and the average quality assessment score was 5.5/9 (61%). Discussion. There are genetic differences between subjects with and without AT. To further elucidate these findings, prospective studies are needed to investigate the increased risk associated with specific genetic findings. Modifying training loads or preventative exercise may be used to mitigate increased risk, although it needs to be highlighted that a genetic association does not necessarily mean an individual will develop Achilles tendinopathy. Gene therapy may have a role in tendon healing, but further research is necessary to develop risk models and establish the most advantageous genes to transfer

Periprosthetic joint infections (PJI) are increasing in prevalence and are recognised as one of the most common modes of failure of joint replacements. Osteomyelitis arising from PJI is challenging to treat, difficult to cure and increases patient mortality 5-fold. PJI can have subtle symptoms and lie dormant or go undiagnosed for many years, suggesting persistent bacterial infection. Staphylococcus aureus is the most common pathogen causing PJI. Osteocytes are the most numerous and long-lived cell type in hard bone tissue. Our recent work has shown that S. aureus can infect and reside in human osteocytes without causing cell death, both experimentally and in bone samples from patients with PJI. Osteocytes respond to infection by the differential regulation of a large number of genes, suggesting previously unknown immune functions of this important cell type. S. aureus adapts during intracellular infection of osteocytes by adopting a quasi-dormant, small colony variant (SCV) phenotype, a property of several bacterial species known to cause PJI, which could contribute to persistent or silent infection. These findings shed new light on the aetiology of PJI and osteomyelitis in general. Further elucidation of the role of osteocytes in bone infection will hopefully lead to improved disease detection and management

Mechanical loading is a potent stimulator of bone formation. A screen for genes associated with mechanically-induced osteogenesis implicated the glutamate transporter GLAST-1 (1), in the mechanoresponse. We are investigating whether modulation of glutamate transporters represents a potential anabolic therapy in bone. Bone cells express functional components from each stage of the glutamate signalling pathway and activation of ionotropic glutamate receptors on osteoblasts can increase bone forming activity (2). Five high affinity Na+-dependant excitatory amino acid transporters (EAATs 1-5) regulate glutamatergic signalling. EAAT1 (GLAST-1) is expressed by osteocytes and bone-forming osteoblasts in vivo. We quantified transcripts for EAATs 1-3 and two splice variants (EAAT1a and EAAT1ex9skip) in human osteoblasts (MG63, SaOS-2 and primary) using real time-PCR. EAAT1a expression was very low whilst levels of the dominant negative EAAT1ex9skip were much higher in all cell types. EAAT1 and EAAT3 proteins were detected by immunofluorescence. We also demonstrated that glutamate transporters function in human osteoblasts. Sodium-dependent 14C-labelled glutamate uptake, sensitive to pharmacological EAAT inhibitors (t-PDC, TBOA) and extracellular glutamate concentration (10-500μM) was detected in MG63 and SaOS-2 cells. To determine whether modulation of EAATs can influence bone formation, we used pharmacological inhibitors of EAATs 1-5 (t-PDC and TBOA) and also over-expressed EAAT1exon9skip using antisense oligonucleotides (AONs) targeted to splice donor sequence of exon 9. Experiments were performed in 0-500μM glutamate. Pharmacological inhibition of EAATs over 5-21 days increased alkaline phosphatase activity and mineralisation of SaOS-2 cells and human primary osteoblasts. Over-expression of EAAT1ex9skip significantly increased cell number and decreased cell death as well as significantly increasing PCNA, Osteonectin and Type I collagen mRNAs in MG63 cells. Furthermore, over-expression of EAAT1ex9skip increased mean alkaline phosphatase activity over 48hrs in SaOS-2 cells. These data show that EAATs are expressed and functional in osteoblasts and that pharmaceutical and genetic inhibition of their activity increases bone formation. These mechanically regulated glutamate transporters are important in regulating bone homeostasis and their manipulation may represent a new anabolic therapy for the treatment of disorders such as osteoporosis or non-union fractures

Objectives

Several genome-wide association studies (GWAS) of bone mineral density (BMD) have successfully identified multiple susceptibility genes, yet isolated susceptibility genes are often difficult to interpret biologically. The aim of this study was to unravel the genetic background of BMD at pathway level, by integrating BMD GWAS data with genome-wide expression quantitative trait loci (eQTLs) and methylation quantitative trait loci (meQTLs) data

Objectives

Osteoporosis is a chronic disease. The aim of this study was to identify key genes in osteoporosis.

Objectives

This study looked to analyse the expression levels of microRNA-140-3p and microRNA-140-5p in synovial fluid, and their correlations to the severity of disease regarding knee osteoarthritis (OA).