Objectives. The aim of the current study was to assess whether calcaneal broadband ultrasound attenuation (BUA) can predict whole body and regional dual-energy x-ray absorptiometry (DXA)-derived bone mass in healthy, Australian children and adolescents at different stages of maturity. Methods. A total of 389 boys and girls across a wide age range (four to 18 years) volunteered to participate. The estimated age of peak height velocity (APHV) was used to classify children into pre-, peri-, and post-APHV groups. BUA was measured at the non-dominant heel with quantitative ultrasonometry (QUS) (Lunar Achilles Insight, GE), while bone mineral density (BMD) and bone mineral content (BMC) were examined at the femoral neck, lumbar spine and whole body (DXA, XR-800, Norland). Associations between BUA and DXA-derived measures were examined with Pearson correlations and linear regression. Participants were additionally ranked in quartiles for QUS and DXA measures in order to determine agreement in rankings. Results. For the whole sample, BUA predicted 29% of the study population variance in whole body BMC and BMD, 23% to 24% of the study population variance in lumbar spine BMC and BMD, and 21% to 24% of the variance in femoral neck BMC and BMD (p < 0.001). BUA predictions were strongest for the most mature participants (pre-APHV R. 2. = 0.03 to 0.19; peri-APHV R. 2. = 0.05 to 0.17; post-APHV R. 2. = 0.18 to 0.28) and marginally stronger for girls (R. 2. = 0.25-0.32, p < 0.001) than for boys (R. 2. = 0.21-0.27, p < 0.001). Agreement in quartile rankings between QUS and DXA measures of bone mass was generally poor (27.3% to 38.2%). Conclusion. Calcaneal BUA has a weak to moderate relationship with DXA measurements of bone mass in children, and has a tendency to misclassify children on the basis of quartile rankings. Cite this article: B. K. Weeks, R. Hirsch, R. C. Nogueira, B. R. Beck. Is calcaneal broadband ultrasound attenuation a valid index of dual-energy x-ray absorptiometry-derived bone mass in children? Bone Joint Res 2016;5:538–543. DOI: 10.1302/2046-3758.511.BJR-2016-0116.R1

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. Methods. In this study, 60 rats were included in a titanium rod implantation model and underwent subsequent guanylate cyclase treatment. Imaging, histology, and biomechanics were used to evaluate the osseointegration of rats in each group. First, the impact of VIT on bone integration in aged rats with iron overload was investigated. Subsequently, VIT was employed to modulate the differentiation of MC3T3-E1 cells and RAW264.7 cells under conditions of iron overload. Results. Utilizing an OVX rat model, we observed significant alterations in bone mass and osseointegration due to VIT administration in aged rats with iron overload. The observed effects were concomitant with reductions in bone metabolism, oxidative stress, and inflammation. To elucidate whether these effects are associated with osteoclast and osteoblast activity, we conducted in vitro experiments using MC3T3-E1 cells and RAW264.7 cells. Our findings indicate that iron accumulation suppressed the activity of MC3T3-E1 while enhancing RAW264.7 function. Furthermore, iron overload significantly decreased oxidative stress levels; however, these detrimental effects can be mitigated by VIT treatment. Conclusion. Collectively, our data provide compelling evidence that VIT has the potential to reverse the deleterious consequences of iron overload on osseointegration and bone mass during ageing. Cite this article: Bone Joint Res 2024;13(9):427–440

The metal on metal implants was introduced without the proper stepwise introduction. The ASR resurfacing hip arthroplasty (RHA) withdrawn due to high clinical failure rates and the large diameter head THA (LDH-THA) are also widely abandoned. Early (2 year) radiostereometry studies does not support early instability as cause of failure but more likely metal wear products. A possible advantage may be maintenance of bone mineral density (BMD).

We present 5 year prospective follow up from a randomized series, aiming to report changes from baseline and to investigate links between implant micromotion, Cr & Co ions and BMD.

Patients eligible for an artificial hip were randomized to RHA, Biomet LDH-THA or standard Biometric THA. 19, 17 and 15 patients completed 5 year follow-up. All followed with BMD of the femur, acetabulum and for RHA the collum. RHA and THA with whole blood Co and Co. LDH-THA only at 5 year. RHA had marker based RSA of both components, cup only for LDH-THA. Translations were compiled to total translation (TT= √(x²+y²+z²)). Data were collected at baseline, 8 weeks, 6 months, 1, 2 and 5 years.

Statistical tests: ANCOVA for TT movement, Spearman's correlation for BMD, Cr, Co and BMI to TT at 5 years

RSA: The 5 year median (25%to75%) RHA cup translations were X=-0.00(−0.49 to 0.19) Y=0.15(−0.03 to 0.20), z=0.24(−0.42 to 0.37) and TT 0.58 (0.16 to 1.82) mm. For the LDH-THA X=−0.33(−0.90 to 0.20) Y=0.28(0.02 to 0.54), z=0.43(−1.12 to −0.19) and TT 1.06 (0.97 to 1.72) mm. The TT was statistically different (p<0.05) for the two cups. The RHA femoral component moved X=0.37(0.21 to 0.56) Y=0.02(−0.07 to 0.11), z=-0.01(−0.07 to 0.26) and TT 0.48 (0.29 to 0.60) mm at 5 years. There was no TT movement from year 2.

The mean (SD) acetabular BMD was diminished to 93(90–97)% for RHA and 97(93–99.9)% for THA, but LDH-THA maintained 99(95–103)%. Overall femoral BMD was unchanged at 5 years for all interventions, but both stemmed implants lost 17% at the calcar.

Median (25%to75%) whole-blood Cr peaked in the LDH-THA group with 1.7 (0.9 to 3.1) followed by RHA 1.2 (0.8 to 5.0) and THA with 0.5 (0.4 to 0.7)ppb.

For Co the highest levels were found in RHA with 1.6(0.8 to 4.7) followed by LDH-THA 1.2 (0.7–1.7) and THA 0.2 (0.2 to 0.6) ppb.

The only correlations above +/−0.3 for TT were the RHA femoral component with a correlation of 0.47 to BMI, 0.30 to Co and Cr. The ASR cup conversely had a negative correlation of −0.60 to BMI and again, the LDH-THA cup had a negative correlation of −0.37 to Cr.

In contrast to registered revision rates, we found significantly larger movement for the Biomet cup than the ASR cup. The metal ion levels were similar. The LDH-THA cup maintained the acetabular BMD best at 5 years, but the difference was small, we are limited by small numbers and the correlations between TT and the covariates showed no clear pattern.

Obesity is correlated with the development of osteoporotic diseases. Gut microbiota-derived metabolite trimethylamine-n-oxide (TMAO) accelerates obesity-mediated tissue deterioration. This study was aimed to investigate what role TMAO may play in osteoporosis development during obesity. Mice were fed with high-fat diet (HFD; 60 kcal% fat) or chow diet (CD; 10 kcal% fat) or 0.2% TMAO in drinking water for 6 months. Body adiposis and bone microstructure were investigated using μCT imaging. Gut microbiome and serum metabolome were characterized using 16S rRNA sequencing and liquid chromatography-tandem mass spectrometry. Osteogenic differentiation of bone-marrow mesenchymal cells was quantified using RT-PCR and von Kossa staining. Cellular senescence was evaluated by key senescence markers p16, p21, p53, and senescence association β-galactosidase staining. HFD-fed mice developed hyperglycemia, body adiposis and osteoporosis signs, including low bone mineral density, sparse trabecular microarchitecture, and decreased biomechanical strength. HFD consumption induced gut microbiota dysbiosis, which revealed a high Firmicutes/Bacteroidetes ratio and decreased α-diversity and abundances of beneficial microorganisms Akkermansiaceae, Lactobacillaceae, and Bifidobacteriaceae. Serum metabolome uncovered increased serum L-carnitine and TMAO levels in HFD-fed mice. Of note, transplantation of fecal microbiota from CD-fed mice compromised HFD consumption-induced TMAO overproduction and attenuated loss in bone mass, trabecular microstructure, and bone formation rate. TMAO treatment inhibited trabecular and cortical bone mass and biomechanical characteristics; and repressed osteogenic differentiation capacity of bone-marrow mesenchymal cells. Mechanistically, TMAO accelerated mitochondrial dysfunction and senescence program, interrupted mineralized matrix production in osteoblasts. Gut microbial metabolite TMAO induced osteoblast dysfunction, accelerating the development of obesity-induced skeletal deterioration. This study, for the first time, conveys a productive insight into the catabolic role of gut microflora metabolite TMAO in regulating osteoblast activity and bone tissue integrity during obesity

Introduction. Osteoporosis accounts for a major risk factor of fracture-associated disability or premature death in the elderly. Enhancement of bone anabolism for slowing osteoporosis is highly demanding. Exerkine fibronectin type III domain containing 5 (FNDC5) regulates energy metabolism, inflammation, and aging. This study was aimed to investigate whether Fndc5 signaling in osteoblasts changed estrogen deficiency-mediated bone loss or microarchitecture deterioration. Method. Female osteoblast-specific Fndc5 transgenic mice (Fndc5Tg), which overexpressed Fndc5 under the control of key osteoblast marker osteocalcin promoter, were given bilateral ovariectomy to induce estrogen deficiency-mediated osteoporosis. Bone mass, microstructures, and biomechanical properties were quantified using μCT imaging and material testing. Dynamic bone formation was traced using fluorescence calcein. Osteogenic differentiation and adipocyte formation of bone-marrow mesenchymal cells were investigated using von Kossa staining and Nile red staining, respectively. Serum osteocalcin, CTX-1 and TRAP5b levels were quantified using designated ELISA kits. Mitochondrial respiration was investigated using Seahorse Extracellular Flux Analyzer. Result. Fndc5Tg mice developed relatively higher bone mass and microarchitecture than wild-type mice. Fndc5 overexpression attenuated the losses of bone mineral density and trabecular network, including trabecular volume, thickness, and trabecular number, and improved cortical thickness and porosity in ovariectomized mice. Gain of Fndc5 function preserved biomechanical characteristics (maximum load, breaking force, and energy), serum bone formation marker osteocalcin levels, and bone formation rate, whereas it reduced serum bone resorption makers CTX-1 and TRAP5b levels, osteoclast overburden, and marrow adiposis. In vitro, Fndc5 reversed the estrogen deficiency-mediated mineralized matrix underproduction and adipocyte formation of bone-marrow mesenchymal cells, and inhibited osteoclast formation in osteoporotic bone. Mechanistically, Fndc5 activated AMPK signaling, promoting mitochondrial respiration and ATP production to enhance osteoblastic activity. Conclusion. Fndc5 signaling exerted bone-protective actions delaying estrogen deficiency-mediated osteoporosis. This study highlighted a new molecular remedial option for osteoporosis development by manipulating Fndc5 functions

Introduction. Promoting bone mass homeostasis keeps skeleton away from osteoporosis. a-Ketoglutarate (a-KG) is an indispensable intermediate of tricarboxylic acid cycle (TCA) process for cellular energy production. a-KG mitigates cellular senescence, tissue degeneration, and oxidative stress. We investigated whether a-KG affected osteoblast activity or osteoporosis development. Method. Serum and bone specimens were biopsied from 26 patients with osteoporosis or 24 patients without osteoporosis who required spinal surgery. Ovariectomized or aged mice were fed 0.25% or 0.75% a-KG in drinking water for 8 – 12 weeks ad libitum. Bone mineral density, trabecular/cortical bone microarchitecture, mechanical strength, bone formation, and osteoclastic erosion were investigated using mCT, material testing device, in vivo calcein labelling, and TRAP histochemical staining. Serum a-KG, osteocalcin, and TRAP5b levels were quantified using ELISA kits. Bone-marrow mesenchymal cells and macrophages were incubated osteogenic and osteoclastogenic media. Histone H3K27me3 levels and enrichment were investigated using immunoblotting and chromatin precipitation-PCR. Result. Serum a-KG levels in patients with osteoporosis were less than controls; and were correlated with T-scores of hips (R2 = 0.6471, P < 0.0001) and lumbar spine (R2 = 0.7235, P < 0.001) in osteoporosis (AUC = 0.9941, P < 0.001). a-KG supplement compromised a plethora of osteoporosis signs in ovariectomized or aged mice, including bone mass loss, trabecular bone microarchitecture deterioration, and mechanical strength loss. It elevated serum osteocalcin levels and decreased serum TRAP5b. a-KG preserved caclein-labelling bone formation and repressed osteoclast resorption. It reversed osteogenic differentiation of bone-marrow stromal cells and reduced osteoclast formation in ovariectomized mice. Mechanically, a-KG attenuated H3K27 hypermethylation and Runx2 transcription repression, improving mineralized matrix production in osteogenic cells. Conclusion. Decreased serum a-KG is correlated with human and murine osteoporosis. a-KG reverses bone loss by repressing histone methylation in osteoblasts. This study highlighted a-KG supplement as a new biochemical option for protecting osteoporosis

To analyze the effect of tooth extraction site preservation on bone mineral density 6 months after surgery. From 2020 to 2021, two adjacent teeth (37, 38) of the same patient were extracted at the same time, and then 37 were selected for site preservation, implanted with Bio-oss bone powder, covered with double Bio-gide membrane, reduce tension and sutured. After 6 months of self-healing, 38 was taken CBCT, and the gray value measurement tool in the software was used to measure the bone mineral density of 37 bone graft areas and 38 extraction sockets. Bone density was high in the center of the bone graft area after the extraction site, and the density decreased in the adjacent alveolar socket, but the gray value was still higher than 38 for natural healing. Extraction site surgery can improve bone mass and quality at the extraction site. It is good for implanting

Osteoporosis is a progressive, chronic disease of bone metabolism, characterized by decreased bone mass and mineral density, predisposing individuals to an increased risk of fractures. The use of animal models, which is the gold standard for the screening of anti-osteoporosis drugs, raises numerous ethical concerns and is highly debated because the composition and structure of animal bones is very different from human bones. In addition, there is currently a poor translation of pre-clinical efficacy in animal models to human trials, meaning that there is a need for an alternative method of screening and evaluating new therapeutics for metabolic bone disorders, in vitro. The aim of this project is to develop a 3D Bone-On-A-Chip that summarizes the spatial orientation and mutual influences of the key cellular components of bone tissue, in a citrate and hydroxyapatite-enriched 3D matrix, acting as a 3D model of osteoporosis. To this purpose, a polydimethylsiloxane microfluidic device was developed by CAD modelling, stereolithography and replica molding. The device is composed by two layers: (i) a bottom layer for a 3D culture of osteocytes embedded in an osteomimetic collagen-enriched matrigel matrix with citrate-doped hydroxyapatite nanocrystals, and (ii) a upper layer for a 2D perfused co-culture of osteoblasts and osteoclasts seeded on a microporous PET membrane. Cell vitality was evaluated via live/dead assay. Bone deposition and bone resorption was analysed respectively with ALP, Alizarin RED and TRACP staining. Osteocytes dendrite expression was evaluated via immunofluorescence. Subsequently, the model was validated as drug screening platform inducing osteocytes apoptosis and administrating standard anti-osteoporotic drugs. This device has the potential to substitute or minimize animal models in pre-clinical studies of osteoporosis, contributing to pave the way for a more precise and punctual personalized treatment

Introduction and Objective. Senescent bone cell overburden accelerates osteoporosis. Epigenetic alteration, including microRNA signalling and DND methylation, is one of prominent features of cellular senescence. This study aimed to investigate what role microRNA-29a signalling may play in the development of senile osteoporosis. Materials and Methods. Bone biopsy and serum were harvested from 13 young patients and 15 senior patients who required spine surgery. Bone mass, microstructure, and biomechanics of miR-29a knockout mice (miR-29aKO) and miR-29a transgenic mice (miR-29aTg) were probed using mCT imaging and three-point bending material test. Senescent cells were probed using senescence-associated b-galactosidase (SA-b-gal) staining. Transcriptomic landscapes of osteoblasts were characterized using whole genome microarray and KEGG bioinformatics. miR-29a and senescence markers p16. INK4a. , p21. Waf/cipl. and inflammatory cytokines were quantified using RT-PCR. DNA methylome was probed using methylation-specific PCR and 5-methylcytosine immunoblotting. Results. Senescent osteoblast overburden, DNA hypermethylation and oxidative damage together with significant decreases in serum miR-29a levels were present in bone specimens of aged patients. miR-29aKO mice showed a phenotype of skeletal underdevelopment, low bone mineral density and weak biomechanics. miR-29a knockout worsened age-induced bone mass and microstructure deterioration. Of note, aged miR-29aTg mice showed less bone loss and fatty marrow than aged wild-type mice. Transgenic overexpression of miR-29s compromised age-dysregulated osteogenic differentiation capacity of bone-marrow mesenchymal cells. In vitro, miR-29a promoted transcriptomic landscapes of antioxidant proteins in osteoblasts. The microRNA interrupted DNA methyltransferase (Dnmt3b)-mediated DNA methylation, inhibiting reactive oxygen radicals burst, IL-6 and RANKL production, and a plethora of senescent activity, including increased p16. INK4a. , p21. Waf/cipl. signalling and SA-b-gal activity. Conclusions. miR-29a loss is correlated with human age-mediated osteoporosis. miR-29a signalling is indispensable in bone mase homeostasis and microstructure integrity. Gain of miR-29a function is advantageous to delay age-induced bone loss through promoting antioxidant proteins to inhibit DNA hypermethylation-mediated osteoblast senescence. Collective investigations shine light onto the anabolic effects miR-29a signalling to bone integrity and highlight a new epigenetic protection strategy through controlling microRNA signalling to delay osteoblast senescence and senile osteoporosis development

It is known that Osteoporosis is the pathology of bone mass and tissue loss resulting in an increase of fragility, risk of fracture occurrence, and risk of fracture recurrence. We noted there was no definitive pathway in our last audit, therefore recommended: availability of the Osteoporosis clinic referral form in an accessible place, the form be filled by the doctor reviewing the patient in the first fracture clinic, and a liaison nurse to ensure these forms were filled and sent to the Osteoporosis clinic. This second audit analyses our Trust's response to these recommendations and effect achieved in Osteoporosis care. We reviewed our local data base from the 7/27/2020 – 10/2/2021 retrospectively for distal radius fractures who were seen in fracture clinic. We analysed a sample size of 59 patients, excluding patients who had already commenced bone protection medications. 67.7% of our patients had neither been on bone protection medications nor recorded referrals and 13.5% were already on bone protection medications when they sustained the fragility fracture. Ten out of the 51 patients were offered referral to the osteoporosis clinic, and one refused. This makes 20% (10 out of 50) of the patients had completed referrals. In comparison, in our first audit, 11% had already been on bone protection medications and 18% had completed referrals. The second cycle showed a slight increase in compliance. Majority of the referrals were completed by Orthopaedic Consultants in both audits and ana awareness increase noted among non-consultants in starting the referral process. Based on our analysis, our Trust has a slight improvement in commencing bone protection medications, associated with slight improvement in completing referrals to the Osteoporosis clinic. Despite our recommendations in the first audit, there is still no easily accessible definitive pathway to ensure our Trust's patients have timely access to bone protection and continued care at the Osteoporosis clinic. We recommend streamlining our recommendations to have a more effective approach in ensuring our Trust meets national guidelines. We will implement a Yes or No question assessment for patients visiting clinic in our electronic database which should assist in referral completions

Introduction and Objective. Klinefelter Syndrome (KS, karyotype 47,XXY) is the most frequent chromosomal aneuploidy in males, as well as the most common cause of infertility in men. Patients suffer from a lack of testosterone, i.e. hypergonadotropic hypogonadism provoking infertility, but KS men also show an increased predisposition to osteoporosis and a higher risk of bone fracture. In a mouse model for human KS, bone analysis of adult mice revealed a decrease in bone mass that could not be rescued by testosterone replacement, suggesting a gene dosage effect originating from the supernumerary X-chromosome on bone metabolism. Usually, X chromosome inactivation (XCI) compensates for the dosage imbalance of X-chromosomal genes between sexes. Some studies suggested that expression of genes that escape silencing of the supernumerary X-chromosome (e.g. androgen receptor) has an impact on sex differences, but may also cause pathological changes in males. As a promising new such candidate for a musculoskeletal escape gene, we identified the integral membrane protein (ITM) 2a, which is encoded on the X-chromosome and related to enchondral ossification. The aim of the project was to characterize systemic bone loss in the course of aging in our KS mouse model, and whether the supernumerary X-chromosome causes differences in expression of genes related to bone development. Materials and Methods. Bone structure of 24 month (=aged) old male wild type (WT) and 41, XXY mice (B6Ei.Lt-Y) were analysed by μCT. Afterwards bones were paraffin embedded and cut. In addition, tissue of brain, liver, kidney, lung and heart were also isolated and embedded for IHC staining. Using an anti-ITM2a antibody, expression and cellular localization of ITM2a was evaluated. IHC was also performed on musculoskeletal tissue of WT embryos (E18.5) and neonatal mice to determine possible age-related differences. Results. In 24 month old mice, the analysis of the lumbar vertebrae revealed a significantly lower BV/TV, trabecular bone volume and trabecular number in the XXY- group compared to WT. Trabecular thickness appeared lower but did not reach significance, with the cortical thickness being significantly higher in the XXY- group. High expression of ITM2a was detected in bone slices of both karyotypes in the chondrocytes inside the growth plate, as well as in megakaryocytes and leucocytes as well as endothelial cells of blood vessels inside the bone marrow. Osteocytes, along with erythrocytes and erythropoetic stem cells were negative for ITM2a. Other organs that showed ITM2a positive staining were kidney (blood vessels), heart (muscle) and brain (different structures). Liver and lung tissue were negative for ITM2a. No obvious difference in the intensity of the ITM2a-expression was observed between the WT and the XXY-karyotype. Analyses of embryotic bone tissue (WT) showed high expression of ITM2a in proliferating, hypertrophic and resting chondrocytes in the growth plates of tibia and femur. In comparison, the neonatal animals (WT) did not show any protein-expression in chondrocytes. Furthermore, within the metaphysis of both, embryotic and neonatal bones, endothelial cells and osteoblasts were ITM2a-positive. Further analyses of bones and tissues from young mice (4–6 month) are ongoing. Conclusions. Bone analyses revealed a significant reduction in trabecular bone mass along with fewer and thinner trabeculae in XXY mice compared to the WT, especially in the spine. ITM2a expression was visible in different cell types inside the bone, and in addition, different expression patterns at different stages of development (embryonic/neonatal) were observed. However, we have not found a significant difference in the quantity of ITM2a between tissues of XXY-karyotypes and WT. Further analyses of X-chromosomal encoded and therefore dysregulated modulators in XXY-karyotype mice and patients may reveal new sex chromosomal effector proteins in bone metabolism

Osteoporosis is a common disorder characterized by low bone mass and reduced bone quality that affects the bone strength negatively and leads to increased risk of fracture. Bone mineral density (BMD) has been the standard instrument for the diagnosis of osteoporosis and the determination of fracture risk. Despite the approximation of the bone mass, BMD does not provide information about the bone structure. Trabecular bone score (TBS), which provides an indirect evaluation of skeletal microarchitecture, is calculated from dual X-ray absorptiometry and a simple and noninvasive method that may contribute to the prediction of osteoporotic fractures in addition to the measure of bone density. The goal of this study was to determine the mean TBS values in healthy postmenopausal women and the overall association between TBS and demographic features, bone mineral density of the lumbar spine and femoral neck and bone mineral density to body mass index ratio (BMD/BMI) of the lumbar spine. Fifty-three postmenopausal healthy women participated. The bone mineral density of the lumbar spine and femoral neck were measured dual X-ray absorptiometry. Anteroposterior lumbar spine acquisitions were used to calculate TBS for L1-L4. Age, height, weight, BMI and the ratio of BMD to BMI, which was considered to be a simple tool for assessing fracture risk in especially obese individuals, were calculated. The relationship between TBS and other variables was examined using Spearman's rank correlation coefficients. Mean BMD of the lumbar spine and the femoral neck were 0.945 ± 0.133 and 0.785 ± 0.112 g/cm2, respectively (Table 1). Mean TBS was 1.354 ± 0.107. There was a significant positive moderate correlation between TBS and total lumbar BMD/BMI ratio (r=0.595, pTBS values of postmenopausal women were negatively correlated with age and BMI and positively with bone mineral density and BMD/BMI ratio. The ratio between lumbar BMD and BMI presented a stronger correlation with TBS than that of BMD with TBS. Because of the better correlation, the BMD/BMI ratio may be used as a simple tool for the assessment of the risk of fractures. Further investigation may be needed to evaluate the factors influencing exercise intervention on TBS on this population of patients

Cigarette smoking has a negative impact on the skeletal system by reducing bone mass and increasing the risk of fractures through its direct or indirect effects on bone remodeling. Recent evidence shows that smoking causes an imbalance in bone turnover, making bone vulnerable to osteoporosis and fragility fractures. In addition, cigarette smoking is known to have deleterious effects on fracture healing, as a positive correlation has been shown between the daily number of cigarettes smoked and years of exposure to smoking, although the underlying mechanisms are not fully understood. Smoking is also known to cause several medical and surgical complications responsible for longer hospital stays and a consequent increase in resource consumption. Smoking cessation is, therefore, highly advisable to prevent the onset of metabolic bone disease. However, some of the consequences appear to continue for decades. Based on this evidence, the aim of our work was to assess the impact of smoking on the skeletal system, particularly bone fractures, and to identify the pathophysiological mechanisms responsible for the impairment of fracture healing. Because smoking represents a major public health problem, understanding the association between cigarette smoking and the occurrence of bone disease is necessary in order to identify potential new targets for intervention

Abstract. Objectives. Osteocytes function as critical regulators of bone homeostasis by sensing mechanical signals. Stimulation of the mechanosensitive ion channel, Piezo1 promotes bone anabolism and deletion of Piezo1 in osteoblasts and osteocytes decreases bone mass and bone strength in mice. This study determined whether loading of osteocytes in vitro results in upregulation of the Piezo1 pathway. Methods. Human MSC cells (Y201), embedded in type I collagen gels and differentiated to osteocytes in osteogenic media for 7-days, were subjected to pathophysiological load (5000 µstrain, 10Hz, 5 mins; n=6) with unloaded cells as controls (n=4). RNA was extracted 1-hr post load and Piezo1 activation assessed by RNAseq analysis (NovaSeq S1 flow cell 2 × 100bp PE reads). To mimic mechanical load and activate Piezo1, Y201s were differentiated to osteocytes in 3D gels for 13 days and treated, with Yoda1 (5µM, 2 hours, n=4); vehicle treated cells served as controls (n=4). Extracted RNA was subjected to RT-qPCR and data analysed by Minitab. Results. Low mRNA expression of PIEZO1 in unloaded cells was upregulated 5-fold following 1-hr of mechanical load (p=0.003). In addition, the transcription factor NFATc1, a known regulator of Piezo1 mechanotransduction, was also upregulated by load (2.4-fold; p=0.03). Y201 cells differentiated in gels expressed the osteocyte marker, SOST. Yoda1 upregulated PIEZO1 (1.7-fold; p=0.057), the early mechanical response gene, cFOS (4-fold; p=0.006), COL1A1 (3.9-fold; p=0.052), and IL-6 expression (7.7-fold; p=0.001). Discussion. This study reveals PIEZO1 as an important mechanosenser in osteocytes. Piezo 1 mediated increases in the bone matrix protein, type I collagen, and IL-6, a cytokine that drives inflammation and bone resorption. This provides a direct link between mechanical activation of Piezo 1, bone remodelling and inflammation, which may contribute to mechanically-induced joint degeneration in osteoarthritis. Mechanistically, we hypothesise this may occur through promoting Ca2+ influx and activation of the NFAT1 signalling pathway

Introduction and Objective. Global prevalence of obesity has risen almost three-fold between 1975 and 2016. Alongside the more well-known health implications of obesity such as cardiovascular disease, cancer and type II diabetes, is the effect of male obesity on testosterone depletion and hypogonadism. Hypogonadism is a well-known contributor to the acceleration of bone loss during aging, and obesity is the single biggest risk factor for testosterone deficiency in men. Understanding the micro and macro structural changes to bone in response to testosterone depletion in combination with a high fat ‘Western’ diet, will advance our understanding of the relationship between obesity and bone metabolism. This study investigated the impact of surgically induced testosterone depletion and subsequent testosterone treatment upon bone remodelling in mice fed a high fat diet. Materials and Methods. Male ApoE. −/−. mice were split into 3 groups at 7 weeks of age and fed a high fat diet: Sham surgery with placebo treatment, orchiectomy surgery with placebo treatment, and orchiectomy surgery with testosterone treatment. Surgeries were performed at 8 weeks of age, followed by fortnightly testosterone treatment via injection. Mice were sacrificed at 25 weeks of age. Tibiae were collected and scanned ex-vivo at 4.3μm on a SkyScan 1272 Micro-CT scanner (Bruker). Left tibiae were used for assessment of trabecular and cortical Volumes of Interest (VOIs) 0.2mm and 1.0mm respectively from the growth-plate bridge break. Tibiae were subsequently paraffin embedded and sectioned at 4μm prior to immunohistochemical evaluation of alkaline phosphatase. Results. Trabecular bone volume and mineral density were significantly reduced in orchiectomised mice compared to sham-operated controls; and these parameters were normalised to control levels in orchiectomised mice treated with testosterone. In contrast, Trabecular thickness was significantly higher in testosterone depleted animals. Cortical bone parameters and body weights did not significantly differ between groups. Levels of alkaline phosphatase did not differ significantly in cortical or trabecular osteoblasts between groups. Conclusions. Findings suggest that testosterone deficiency significantly reduces trabecular bone parameters, and testosterone therapy may be a useful intervention for the loss of bone mass in testosterone deficient males. These results indicate that testosterone therapy may be useful for the treatment of trabecular bone frailty in testosterone deficient males. Observed changes in trabecular bone do not appear to be due to decreased mineralisation caused by osteoblast alkaline phosphatase. Ongoing work includes histology analysis to elucidate the mechanisms underpinning the changes seen in the bones of testosterone deficient animals

Introduction. Excessive bone mass and microarchitecture loss exacerbate the risk of osteoporotic fracture, a skeletal disorder attributable to disability in the elder. Excessive marrow adipose development at the expense of osteoblastic bone acquisition is a prominent feature of aging-induced osteoporotic skeletons. MicroRNA-29a (miR-29a) modulates osteogenic and adipogenic commitment of mesenchymal progenitor cells. The purposes of this study were to test if miR-29a overexpression changed bone mass or microstructure in aged skeletal tissues. Materials/Methods. Transgenic mice that overexpressed miR-29a in osteoblasts driven by osteocalcin promoter (miR-29aTg) were generated. Littermates without carrying construct of interest were used as wild-type mice (WT). 3- and 12-month-old mice were designated into young and aged groups respectively. Bone mineral density (BMD), cortical, trabecular microarchitecture and morphometric profiles were quantified with ultrahigh resolution μCT system. Primary bone-marrow mesenchymal stem cells (BMMSCs) were incubated in osteogenic and adipogenic conditions. Expressions of osteogenic and adipogenic marker were quantified with RT-PCR. Results. Skeletons in the aged WT group showed 65% decrease in BMD in association with 72% reduction in miR-29a expression and 2.3-fold elevation in marrow fat volume as compared with those in young WT group. The young miR-29aTg mice showed 35–48% increases in serum osteocalcin and bone alkaline phosphatase levels concomitant with 22–35% increases in BMD, trabecular BV/TV, Tb.Th, Tb.N, and cortical morphology than those of young WT mice. Intriguing analyses are that miR-29aTg mice exhibited mild responses to the aging provocation of BMD loss, trabecular, cortical microstructure deterioration, and fatty marrow histopathology. In vitro, primary BMMSCs in miR-29aTg mice showed significant increases in osteogenic gene expression and mineralized matrices as probed with von Kossa staining, whereas adipogenic gene expression and adipocyte formation were evidently reduced as evidenced by fluorescence Nile Red. Conclusion. miR-29a overexpression in osteoblasts facilitates skeletal tissue anabolism. High osteogenic lineage commitment of bone-marrow mesenchymal progenitor cells contributes to high bone mass and microstructure phenotypes promoted by miR-29a signaling. Analyses shed a new light on the miR-29a signaling protection against the aging escalation of osteoporosis pathogenesis

Introduction and Objective. Individuals with type 2 diabetes (T2D) have a 3-fold increased risk of bone fracture compared to non-diabetics, with the majority of fractures occurring in the hip, vertebrae and wrists. However, unlike osteoporosis, in T2D, increased bone fragility is generally not accompanied by a reduction in bone mineral density (BMD). This implies that T2D is explained by poorer bone quality, whereby the intrinsic properties of the bone tissue itself are impaired, rather than bone mass. Yet, the mechanics remain unclear. The objective of this study is to (1) assess the fracture mechanics of bone at the structural and tissue level; and (2) investigate for changes in the composition of bone tissue along with measuring total fluorescent advanced glycation end products (fAGEs) from the skin, as T2D progresses with age in Zucker diabetic fatty (ZDF (fa/fa)) and lean Zucker (ZL (fa/+)) rats. Materials and Methods. Right ulnae and skin sections were harvested from ZDF (fa/fa) (T2D) and ZL (fa/+) (Control) rats at 12 and 46 weeks (wks) of age (n = 8, per strain and age) and frozen. Right ulnae were thawed for 12 hrs before micro-CT (μCT) scanning to assess the microstructure and measure BMD. After scanning, ulnae were loaded until failure via three-point bending. Fourier transform-infrared microspectroscopy (FTIR) was used to measure various bone mineral- and collagen-related parameters such as, mineral-to-matrix ratio and nonenzymatic cross-link ratio. Finally, fAGEs were measured from skin sections using fluorescence spectrometry and an absorbance assay, reported in units of ng quinine/ mg collagen. Results. At 12 and 46 wks bone size was significantly smaller in length (p < 0.01), cortical area (p < 0.001) and cross-sectional moment of inertia (p < 0.001) in T2D rats compared to age-matched controls. A slight reduction in BMD was observed in T2D rats compared to controls at both ages, however, this was not significant. Structural properties of T2D bone were significantly altered at 12 and 46 wks, with bending rigidity increasing approximately 2.5-fold and 1.5-fold in control and T2D rats with age, respectively (p < 0.0001). Similarly, yield and ultimate moment significantly reduced in T2D rats with age in comparison to controls (p < 0.0001). Energy absorbed to failure was significantly reduced in T2D rats at 46 weeks of age compared to controls (p < 0.01). The amount of energy absorbed to failure increased approximately 1.4-fold from 12 to 46 wks in control rats, however, in T2D rats a reduction was seen with age, although not significant. At 12 wks, there was no significant deficits in tissue material properties, whereas, at 46 wks a significant reduction in yield stress, yield strain and ultimate stress was observed for T2D rats in comparison to controls (p < 0.05). Conclusions. These findings show that longitudinal growth is impaired as early as 12 wks of age and by 46 wks bone size is significantly reduced in T2D rats compared to controls. The reduction in T2D structural properties is likely attributed to the bone geometry deficits. At 12 wks of age, the tissue material properties are not altered in T2D bone versus controls. However, at 46 wks, bone strength is reduced in T2D, leading to the conclusion that tissue properties are altered as the disease progresses

This longitudinal microCT study revealed the osteolytic response to a Staphylococcus epidermidis-infected implant in vivoand also demonstrates how antibiotics and/or a low bone mass state influence the morphological changes in bone and the course of the infection. Colonisation of orthopaedic implants with Staphylococcus aureusor S. epidermidisis a major clinical concern, since infection-induced osteolysis can drastically impair implant fixation or integration within bone. High fracture incidence in post-menopausal osteoporosis patients means that this patient group are at risk of implant infection. The low bone mass in these patients may exacerbate infection-induced osteolysis, or alter antibiotic efficacy. Therefore, the aims of this study were to examine the bone changes resulting from a S. epidermidisimplant infection in vivousing microCT imaging, and to determine if a low bone mass stateinfluences the course of the infection and the efficacy of antibiotic therapy. An in vivomodel system using microCT scanning [1], involving the implantation of either a sterile or a S. epidermidis-colonised PEEK screw into the proximal tibia of 24 week-old female Wistar rats, was used to investigate the morphological changes in bone following infection over a 28 day period. In addition, the efficacy of a combination antibiotic therapy (rifampin and cefazolin: administered twice daily from days 7–21 post-screw implantation) for affecting osteolysis was also assessed. A subgroup of animals was subjected to ovariectomy (OVX) at 12 weeks of age, allowing for a 12 week period for bone loss prior to screw implantation at 24 weeks. Bone resorption and formation rates, bone-implant contact and peri-implant bone volume in the proximity of the screw were assessed by microCT scanning at days 0, 3, 6, 9, 14, 20 and 28 days post-surgery. Following euthanasia at day 28, the implanted screw, bone and soft tissues were subjected to quantitative bacteriology as a measure of the efficacy of the antibiotic regimen. In non-OVX animals S. epidermidisinfection induced marked osteolysis, which peaked between 9 and 14 days post-screw implantation. Peak bone resorption was detected at day 6, before recovering to baseline levels at day 14. Infection also resulted in extensive deposition of mineralised tissue, initially within the periosteal region (day 9–14), then subsequently in the osteolytic region at day 20–28. Quantitative bacteriology indicated all non-OVX animals remained infected. Rifampin and cefazolin successfully cleared the infection in 5/6 non-OVX animals group although there was no difference observed in CT-derived bone parameters. OVX resulted in extensive loss of trabecular bone but this did not alter the temporal pattern of infection-induced osteolysis, or mineralised tissue deposition, which was similar to that observed in the non-OVX animals. Similarly, there was no difference in bacterial counts between non-OVX and OVX animals (39,005 colony-forming units (CFU) [range: 3,675–156,800] vs 37,665 CFU [range 3,250–84,000], respectively). Interestingly, antibiotic treatment was less effective in the OVX animals (3/5 remained infected), suggesting that antibiotics have reduced efficacy in OVX animals. This study demonstrates S. epidermidis-induced osteolysis displays a similar temporal pattern in both normal and low bone mass states, with comparable bacterial loads present within the localised infection site

Chronic glucocorticoid use causes osteogenesis loss, accelerating the progression of osteoporosis. Histone methylation is shown to epigenetically increase repressive transcription, altering lineage programming of mesenchymal stem cells (MSC). This study is undertaken to characterize the action of histone demethylase UTX to osteogenic lineage specification of bone-marrow MSC and bone integrity upon glucocorticoid treatment. Bone-marrow MSC were incubated in osteogenic medium containing supraphysiological dexamethasone. Osteogenic gene expression and mineralized nodule formation were probed using RT-PCR and von Kossa staining. The enrichment of trimethylated lysine 27 at histone 3 (H3K27me3) in Dkk1 promoter was quantified using chromatin immunoprecipitation-PCR. Bone mass and trabecular morphometry in methylprednisolone-treated skeletons were quantified using microCT analysis. Supraphysiological dexamethasone decreased osteogenic genes Runx2 and osteocalcin expression and mineralized matrix production along with reduced UTX expression in MSC. Forced UTX expression attenuated the glucocorticoid-mediated loss of osteogenic differentiation, whereas UTX knockdown provoked osteogenesis loss and cytoplasmic oil overproduction. UTX demethylated H3K27 and reduced the glucocorticoid-mediated the H3K27 enrichment in Dkk1 promoter, reversing beta-catenin signal, but downregulating Dkk1 production by MSC. In vivo, treatment with UTX inhibitor GSK-J4 significantly suppressed bone mineral density, trabecular volume, and thickness along with porous trabecular, fatty marrow and disturbed beta-catenin/Dkk1 histopathology comparable with glucocorticoid-induced osteoporosis condition. This study offers a productive insight into how UTX protects MSC from methylated histone-mediated osteogenesis repression in the development of glucocorticoid-induced osteoporosis

Although osteoporosis reduces overall bone mass causing bone fragility, our recent studies have shown that bone tissue composition is altered at the microscopic level, which is undetectable by conventional diagnostic techniques (DEXA) but may contribute to bone fracture. However, the time sequence of changes in bone microarchitecture, mechanical environment and mineral distribution are not yet fully understood. This study quantified the longitudinal effects of estrogen deficiency on the trabecular microarchitecture and mineral distribution in the tibia of Female Wistar rats (6 months) that underwent ovariectomy (OVX, n=10) or sham surgery (SHAM, n=10). Weekly micro-CT scans of the proximal tibia were conducted at 15µm resolution for the first month of estrogen deficiency. Morphometric analysis was conducted to characterise the trabecular bone microarchitecture. The bone mineral composition was characterised with analysis of bone mineral density distributions (BMDD). There was significantly reduced trabecular bone volume fraction at 2 weeks in OVX rats compared to controls (p<0.01). There was no difference in mineral distribution between the OVX and control animals. This study provides the first evidence in uncovering the temporal nature of changes in bone microarchitecture and mineral distribution, showing that structure changes before composition. In-vivo µCT analysis for later time points (week 8, 14 and 34) is ongoing to comprehensively examine these longitudinal compositional changes. Moreover, we are conducting ex-vivo mechanical analysis (nanoindentation), and together these will uncover the time-sequence and respective contribution of changes in bone mass and composition to the integrity of the bone tissue at these stages of estrogen deficiency