Objectives. Cellular movement and relocalisation are important for many physiologic properties. Local mesenchymal stem cells (MSCs) from injured tissues and circulating MSCs aid in fracture healing. Cytokines and chemokines such as Stromal cell-derived factor 1(SDF-1) and its receptor chemokine receptor type 4 (CXCR4) play important roles in maintaining mobilisation, trafficking and homing of stem cells from bone marrow to the site of injury. We investigated the differences in migration of MSCs from the femurs of young, adult and ovariectomised (OVX) rats and the effect of CXCR4 over-expression on their migration. Methods. MSCs from young, adult and OVX rats were put in a Boyden chamber to establish their migration towards SDF-1. This was compared with MSCs transfected with CXCR4, as well as MSCs differentiated to osteoblasts. Results. MSCs from OVX rats migrate significantly (p < 0.05) less towards SDF-1 (9%, . sd. 5%) compared with MSCs from adult (15%, . sd. 3%) and young rats (25%, . sd. 4%). Cells transfected with CXCR4 migrated significantly more towards SDF-1 compared with non-transfected cells, irrespective of whether these cells were from OVX (26.5%, . sd. 4%), young (47%, . sd. 17%) or adult (21%, . sd. 4%) rats. Transfected MSCs differentiated to osteoblasts express CXCR4 but do not migrate towards SDF-1. Conclusions. MSC migration is impaired by age and osteoporosis in rats, and this may be associated with a significant reduction in bone formation in osteoporotic patients. The migration of stem cells can be ameliorated by upregulating CXCR4 levels which could possibly enhance fracture healing in osteoporotic patients. Cite this article: A. Sanghani-Kerai, M. Coathup, S. Samazideh, P. Kalia, L. Di Silvio, B. Idowu, G. Blunn.
To assess the sensitivity and specificity of self-reported osteoporosis
compared with dual energy X-ray absorptiometry (DXA) defined osteoporosis,
and to describe medication use among participants with the condition. Data were obtained from a population-based longitudinal study
and assessed for the prevalence of osteoporosis, falls, fractures
and medication use. DXA scans were also undertaken.Objectives
Methods
Abstract. Objectives. Osteoporotic fractures tend to be more challenging than fractures in healthy bone and the efficacy of metal screw fixation decreases with decreasing bone mineral density making it more difficult for such screws to gain purchase. This leads to increased complication rates such as malunion, non-union and implant failure (1). Bioresorbable polymer devices have seen clinical success in fracture fixation and are a promising alternative for metallic devices but are rarely used in the osteoporotic population. To address this, we are developing a system that may allow osteoporotic patients to avail of bioresorbable devices (2) but it is important to establish if patients have any reservations about having a plastic resorbable device instead of a metal one. Therefore the aim of this study was to explore the acceptability of bioresorbable fracture fixation devices to people with osteoporosis. Methods. A cross sectional descriptive study was conducted in a UK wide population using convenience sampling. An online survey comprising nine survey questions and nine demographic questions was developed in Microsoft Teams and tested for face validity in a small pilot study (n=6). Following amendments and ethical approval, the survey was distributed by the Royal
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.
Summary.
As a part of the European Union BIOMED I study “Assessment of Bone Quality in
Background.
Nuclear factor erythroid 2–related factor 2 (Nrf2) is a crucial transcription factor to maintain cellular redox homeostasis, but is also affecting bone metabolism. As the association between Nrf2 and osteoporosis in elderly females is not fully elucidated, our aim was to shed light on the potential contribution of Nrf2 to the development of age-dependent osteoporosis using a mouse model. Female wild-type (WT, n=18) and Nrf2-knockout (KO, n=12) mice were sacrificed at different ages (12 weeks=young mature adult, and 90 weeks=old), morphological cortical and trabecular properties of femoral bone analyzed by micro-computed tomography (µCT), and compared to histochemistry. Mechanical properties were derived from quasi-static compression tests and digital image correlation (DIC) used to analyze full-field strain distribution. Bone resorbing cells and aromatase expression by osteocytes were evaluated immunohistochemically and empty osteocyte lacunae counted in cortical bone. Wilcoxon rank sum test was used for data comparison and differences considered statistically significant at p<0.05. When compared to old WT mice, old Nrf2-KO mice revealed a significantly reduced trabecular bone mineral density (BMD), cortical thickness (Ct.Th), cortical area (Ct.Ar), and cortical bone fraction (Ct.Ar/Tt.Ar). Surprisingly, these parameters were not different in skeletally mature young adult mice. Metaphyseal trabeculae were thin but present in all old WT mice, while no trabecular bone was detectable in 60% of old KO mice. Occurrence of empty osteocyte lacunae did not differ between both groups, but a significantly higher number of osteoclast-like cells and fewer aromatase-positive osteocytes were found in old KO mice. Furthermore, female Nrf2-KO mice showed an age-dependently reduced fracture resilience when compared to age-matched WT mice. Our results confirmed lower bone quantity and quality as well as an increased number of bone resorbing cells in old female Nrf2-KO mice. Additionally, aromatase expression in osteocytes of old Nrf2-KO mice was compromised, which may indicate a chronic lack of estrogen in bones of old Nrf2-deficient mice. Thus, chronic Nrf2 loss seems to contribute to age-dependent progression of female osteoporosis.
Summary Statement. The structure of bone inside a
Summary Statement. A population based finite element study that accounts for subject-specific morphology, density and load variations, suggests that osteoporosis does not markedly lower the mechanical compliance of the proximal femur to routine loads. Introduction.
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.
Current therapies for osteoporosis are limited to generalised antiresorptive or anabolic interventions, which do not target specific regions to improve skeletal health. Moreover, the adaptive changes of separate and combined pharmacological and biomechanical treatments in the ovariectomised (OVX) mouse tibia has not been studied yet. Therefore, this study combines micro- computed tomography (micro-CT) imaging and computational modelling to evaluate the efficacies of treatments in reducing bone loss. In vivo micro-CT (10.4µm/voxel) images of the right tibiae of N=18 female OVX C57BL/6 mice were acquired at weeks 14, 16, 18, 20 and 22 of age for 3 groups: mechanical loading (ML), parathyroid hormone (PTH) or combined therapies (PTHML). All mice received either injection of PTH (100μg/kg/day, 5days/week) or vehicle from week 18. The right tibiae were mechanically loaded in vivo at week 19 and 21 with a 12N peak load, 40 cycles/day and 3 days/week. Bone adaptation was quantified through spatial changes in bone mineral density (BMD) and strain distribution was obtained from micro-CT-based finite element models.Abstract
Objectives
Methodology
Bioabsorbable metals hold a lot of potential as orthopaedic implant materials. Three metal families are currently being investigated: iron (Fe), magnesium (Mg) and zinc (Zn). Currently, however, biodegradation of such implants is poorly predictable. We thus used Direct Metal Printing to additively manufacture porous implants of a standardized bone-mimetic design and evaluated their mechanical properties and degradation behaviour, respectively, under Atomized powder was manufactured to porous implants of repetitive diamond unit cells, using a ProX DMP 320 (Layerwise, Belgium) or a custom-modified ReaLizer SLM50 metal printer. Degradation behaviour was characterized under static and dynamic conditions in a custom-built bioreactor system (37ºC, 5% CO2 and 20% O2) for up of 28 days. Implants were characterized by micro-CT before and after Micro-CT analyses confirmed average strut sizes (420 ± 4 μm), and porosity (64%), to be close to design values. After 28 days of In summary, DMP allows to accurately control interconnectivity and topology of implants from all three families and micro-structured design holds potential to optimize their degradation speed. This first systematic report sheds light into how design influences degradation behaviour under
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.
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. 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 p16INK4a, p21Waf/cipl and inflammatory cytokines were quantified using RT-PCR. DNA methylome was probed using methylation-specific PCR and 5-methylcytosine immunoblotting.Introduction and Objective
Materials and Methods