Trabecular Microarchitecture Research Articles

Changes in Bone Quality after Treatment with Etelcalcetide.

Secondary hyperparathyroidism is associated with osteoporosis and fractures. Etelcalcetide is an intravenous calcimimetic for the control of hyperparathyroidism in patients on hemodialysis. Effects of etelcalcetide on the skeleton are unknown. In a single-arm, open-label, 36-week prospective trial, we hypothesized that etelcalcetide improves bone quality and strength without damaging bone-tissue quality. Participants were 18 years or older, on hemodialysis ≥1 year, without calcimimetic exposure within 12 weeks of enrollment. We measured pretreatment and post-treatment areal bone mineral density by dual-energy X-ray absorptiometry, central skeleton trabecular microarchitecture by trabecular bone score, and peripheral skeleton volumetric bone density, geometry, microarchitecture, and estimated strength by high-resolution peripheral quantitative computed tomography. Bone-tissue quality was assessed using quadruple-label bone biopsy in a subset of patients. Paired t tests were used in our analysis. Twenty-two participants were enrolled; 13 completed follow-up (mean±SD age 51±14 years, 53% male, and 15% White). Five underwent bone biopsy (mean±SD age 52±16 years and 80% female). Over 36 weeks, parathyroid hormone levels declined 67%±9% ( P < 0.001); areal bone mineral density at the spine, femoral neck, and total hip increased 3%±1%, 7%±2%, and 3%±1%, respectively ( P < 0.05); spine trabecular bone score increased 10%±2% ( P < 0.001); and radius stiffness and failure load trended to a 7%±4% ( P = 0.05) and 6%±4% increase ( P = 0.06), respectively. Bone biopsy demonstrated a decreased bone formation rate (mean difference -25±4 µ m 3 / µ m 2 per year; P < 0.01). Treatment with etelcalcetide for 36 weeks was associated with improvements in central skeleton areal bone mineral density and trabecular quality and lowered bone turnover without affecting bone material properties. The Effect of Etelcalcetide on CKD-MBD (Parsabiv-MBD), NCT03960437.

Distal Tibial Bone Properties and Bone Stress Injury Risk in Young Men Undergoing Arduous Physical Training

Trabecular microarchitecture contributes to bone strength, but its role in bone stress injury (BSI) risk in young healthy adults is unclear. Tibial volumetric BMD (vBMD), geometry, and microarchitecture, whole-body areal BMD, lean and fat mass, biochemical markers of bone metabolism, aerobic fitness, and muscle strength and power were measured in 201 British Army male infantry recruits (age 20.7 [4.3] years, BMI 24.0 ± 2.7 kg·m2) in week one of basic training. Tibial scans were performed at the ultra-distal site, 22.5 mm from the distal endplate of the non-dominant leg using High Resolution Peripheral Quantitative Computed Tomography (XtremeCT, Scanco Medical AG, Switzerland). Binary logistic regression analysis was performed to identify associations with lower body BSI confirmed by MRI. 20 recruits (10.0%) were diagnosed with a lower body BSI. Pre-injured participants had lower cortical area, stiffness and estimated failure load (p = 0.029, 0.012 and 0.011 respectively) but tibial vBMD, geometry, and microarchitecture were not associated with BSI incidence when controlling for age, total body mass, lean body mass, height, total 25(OH)D, 2.4-km run time, peak power output and maximum dynamic lift strength. Infantry Regiment (OR 9.3 [95%CI, 2.6, 33.4]) Parachute versus Line Infantry, (p ≤ 0.001) and 2.4-km best effort run time (1.06 [95%CI, 1.02, 1.10], p < 0.033) were significant predictors. Intrinsic risk factors, including ultradistal tibial density, geometry, and microarchitecture, were not associated with lower body BSI during arduous infantry training. The ninefold increased risk of BSI in the Parachute Regiment compared with Line Infantry suggests that injury propensity is primarily a function of training load and risk factors are population-specific.

Preventive effect of Total ethanolic extract of Butea monosperma on bone loss in osteopenic rats

Aim: The intent of the study was to assess the bone conserving effect of Butea monosperma total extract (BTE) prepared from the stem-bark, in ovariectomy (Ovx)-induced bone loss in Sprague Dawley (SD) rats.&#x0D; Methods: Sprague-Dawley rats were ovariectomized (Ovx) and BTE treatment with three different doses (100mg, 250mg and 500mg/kg body weight) commenced a day after Ovx and continued for 12 weeks. Skeletal parameters including trabecular and cortical bone microarchitecture, bone mineral density, bone mineral content, biomechanical strength, bone turnover markers (serum procollagen 1 N-terminal propeptide/ P1NP and cross-linked C-telopeptide of type I collagen/CTX-1), new bone formation rate (periosteal bone formation rate and mineral apposition rate), and expression of osteogenic genes were assessed. Estrogenicity of BTE was assessed by studying uterus at the end of the treatments.&#x0D; Results: Ovx rats treated with BTE prevented the alterations in trabecular and cortical microarchitecture, maintained bone mineral density, bone mineral content, and increased bone biomechanical strength in comparison with Ovx rats. Treatment of BTE also enhanced new bone formation rate, increased the serum bone formation marker (P1NP), decreased the serum bone resorption marker (CTX-1), and upregulated the osteogenic genes in bones. BTE was devoid of estrogen-like effect in uterus.&#x0D; Conclusion: BTE protects against Ovx-induced bone loss by inhibiting bone resorption and increasing new bone formation. The most effective bone conserving dose of BTE was 250mg/kg. This study demonstrates the potential of BTE in preventing/delaying osteoporosis development in postmenopausal women.&#x0D; Keywords: Butea total extract, ovariectomy, bone formation, bone mineral density.

Fractal dimension analysis of different mandibular regions in familial Mediterranean fever patients: A cross-sectional retrospective study.

Familial Mediterranean fever (FMF) is a genetic condition that may cause loss of bone mineral density (BMD) due to chronic inflammation. Previously, fractal dimension (FD) analysis values of mandibular cortical bone were shown to be lower in osteoporosis. Therefore, FD might be considered as an auxiliary tool to refer patients for dual-energy x-ray absorptiometry (DXA), which is the gold standard for BMD measurement. The purpose of this cross-sectional retrospective study was to evaluate trabecular and cortical microarchitecture of the mandible with FD analysis on panoramic radiographs in a subpopulation of FMF. Also, the effect of colchicine use was investigated. Forty-three FMF patients, aged between 10.8 and 71.2 years, and age- and gender-matched control group consisting of patients, who had no systemic diseases, were included. Demographic information such as age and gender, and colchicine use were recorded. In terms of age, the patients were classified as <30 and 30< years. On each panoramic radiographs five regions of interest were selected on the mandible as: 1- premolar, 2- molar, 3- angular, 4- condylar, and 5- basal cortical bone regions on right (R) and left (L) sides. Statistical significance was accepted at p<0.05 level. Intra- and inter-observer agreements demonstrated good to excellent consistency. In FMF patients, L3 and L4 values were higher, whereas L5 values were lower (p<0.05) than the control group. In terms of age, the difference between groups was insignificant in FMF patients (p>0.05), whereas in control group R3 and L4 values were higher in the 30< age group (p<0.05). Regarding gender and colchicine use, the difference between groups was insignificant (p>0.05). FMF disease might be a candidate for referral to DXA examination based on decreased bone density in the mandibular cortex detected by FD measurements on routine panoramic radiographs. Further studies are warranted to ascertain this relationship.

Germ-Free C57BL/6 Mice Have Increased Bone Mass and Altered Matrix Properties but Not Decreased Bone Fracture Resistance.

The gut microbiome impacts bone mass, which implies a disruption to bone homeostasis. However, it is not yet clear how the gut microbiome affects the regulation of bone mass and bone quality. We hypothesized that germ-free (GF) mice have increased bone mass and decreased bone toughness compared with conventionally housed mice. We tested this hypothesis using adult (20- to 21-week-old) C57BL/6J GF and conventionally raised female and male mice (n = 6-10/group). Trabecular microarchitecture and cortical geometry were measured from micro-CT of the femur distal metaphysis and cortical midshaft. Whole-femur strength and estimated material properties were measured using three-point bending and notched fracture toughness. Bone matrix properties were measured for the cortical femur by quantitative back-scattered electron imaging and nanoindentation, and, for the humerus, by Raman spectroscopy and fluorescent advanced glycation end product (fAGE) assay. Shifts in cortical tissue metabolism were measured from the contralateral humerus. GF mice had reduced bone resorption, increased trabecular bone microarchitecture, increased tissue strength and decreased whole-bone strengththat was not explained by differences in bone size, increased tissue mineralization and fAGEs, and altered collagen structure that did not decrease fracture toughness. We observed several sex differences in GF mice, most notably for bone tissue metabolism. Male GF mice had a greater signature of amino acid metabolism, and female GF mice had a greater signature of lipid metabolism, exceeding the metabolic sex differences of the conventional mice. Together, these data demonstrate that the GF state in C57BL/6J mice alters bone mass and matrix properties but does not decrease bone fracture resistance. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

#3641 DOES IBANDRONATE OR CALCIUM AND VITAMIN D MAINTAIN OR IMPROVE BONE MICROARCHITECTURE IN THE FIRST YEAR AFTER KIDNEY TRANSPLANTATION?

Abstract Background and Aims Modern immunosuppressive protocols are associated with less loss of bone mass immediately after kidney transplantation, as compared with previous eras. Even so, bone microarchitecture may still be disturbed due to long-standing uremia, leading to bone fragility and fracture susceptibility. Trabecular bone score (TBS) is a new tool to assess trabecular bone microarchitecture based on standard dual energy X-ray absorptiometry (DXA) of lumbar spine images. TBS reflects bone quality rather than quantity. Studies on the effect of common anti-fracture strategies on TBS in kidney transplant recipients (KTR) are scarce. Our aim was to investigate different treatments on bone microarchitecture by TBS in KTR. Method We analyzed TBS changes and potential treatment effects in 179 de novo KTR, 118 of whom had participated in a randomized controlled trial[1] evaluating the effect of ibandronate (active/placebo) on top of calcium and vitamin D in the first year after kidney transplantation. Trial participants were compared to 61 patients transplanted in the same time-period, meeting the same study inclusion criteria, but receiving no specific bone-directed treatment. Correlations between changes in TBS and lumbar spine BMD were investigated. We used ANOVA and ANCOVA with adjustment for baseline TBS values to evaluate the potential effects of calcium and vitamin D with/without concomitant ibandronate on TBS 12 months after transplantation, as compared to no treatment. Results Mean TBS increased in all groups from baseline to 12 months after transplantation (2.1% for ibandronate/calcium/vitamin D, 2.7% for calcium/vitamin D, and 3.4% for no treatment). Adjusting for baseline TBS, there were no significant differences in TBS at 12 months, neither with overall comparison (p = 0.377) nor when comparing the groups pairwise. The correlation between TBS and BMD was weak (r = 0.170, p = 0.02) at baseline, and change in TBS was not significantly correlated with change in lumbar spine BMD in any of the groups. Conclusion In a group of de novo KTR with reasonably well-preserved bone mass, it does not appear that one year of treatment with ibandronate or calcium and vitamin D significantly affects bone quality as measured by TBS. We found surprisingly weak correlation between changes in TBS and BMD over the study period, indicating that these measurements reflect different aspects of bone integrity and metabolism. This study strengthens the view that focus should be on identifying KTR at high risk of fracture at time of transplantation, as these patients could benefit from anti-resorptive therapy.

#4051 FGF-23 IN CHRONIC KIDNEY DISEASE: CORRELATION WITH BONE AND CARDIOVASCULAR PARAMETERS – A PRELIMINARY STUDY

Abstract Background and Aims The FGF-23/Klotho ratio increases from early stages of chronic kidney disease (CKD) in parallel with kidney function declined. In some cases, serum FGF-23 levels increase is unbalanced, causing organ damage and increasing cardiovascular risk. The aim of our study was to evaluate the intact FGF-23 (iFGF-23) levels in a cohort of CKD patients and to establish its correlation with cardiovascular and bone mineral metabolism parameters. Method A prospective observational study in 59 adult normophosphatemic patients with CKD stage 2-4, was performed. Clinical and analytical variables (serum calcium, phosporus, intact parathyroid hormone (iPTH), iFGF-23, calcidiol and calcitriol) were evaluated. Basal transthoracic echocardiogram, bone densitometry (Lunar prodigy, GE iDXA), software trabecular bone score (TBS), iNsight clinical data analyzer and carotid Doppler ultrasound were performed. We excluded patients with background of primary hyperparathyroidism, hepatorenal polycystic disease, kidney transplant, tumoral nephrectomy, active neoplasm, tubulopathies or treatment with active vitamin D or calcimimetics. For statistical analysis, we use SPSS software (T Student, Xi2, Fisher test, ANOVA test, U-Mann Whitney test and correlations of Pearson and Spearman) Results Mean age was 62,7±10,5 years, 82,5% were men; 17,7% have CKD stage 2, 28,8% stage 3a, 42,3% stage 3b and 9,6% stage 4. The main CKD etiology was vascular (25%) and diabetes (22%). Previous cardiovascular disease was observed in 11% (ischemic heart disease 6,3%, cerebrovascular disease 3,2% and descompensated heart failure with hospitalization 1,6%). Mean iFGF-23 levels in CKD stage 2 were 80,4±38 ng/l (38-170, median 71 ng/l), in CKD stage 3a 95,5±39,7 ng/l (46-178,9 ng/l, median 85,5 ng/l), in CKD stage 3b 118,8±55,06 (35,5-285 ng/l, median 124,6 ng/l) and in stage 4 134,8±50,9 ng/l (65,25-216,5 ng/l, median 136,1 ng/l). We found correlation between iFGF-23 levels and glomerular filtration rate (Rho:-0,390, p: 0,003), as well as with CKD stages (ANOVA test, p: 0,057). We performed 48 carotid doppler ultrasound and observed mild carotid atheromatosis in 58,7%, mainly bilateral, and intima-media thickness &amp;gt;0,9 mm in 7,9%. In patients with atheromatosis, 38,9% showed iFGF-23 levels in second tertil and 36% in the third. We observed left ventricular hypertrophy (LVH) in 46% of patients, mostly mild degree. In bone densitometry, we found mean femoral neck T-Score of -1±1,1 and lumbar spine T-Score of -0,07±1,5, mean mineral bone density (DMO) in femoral neck of 0,89±0,25 g/cm2 and 1,17±0,20 g/cm2 in lumbar spine. Only 40% of patients had normal TBS score. We found correlation between serum iFGF-23 levels and phosphorus tubular reabsorption (r:-0,396, p: 0,002), calcidiol (Rho: 0,264, p:0,047), calcitriol (r: -0,412, p:0,002), iPTH (Rho: 0,296, p:0,025), lumbar T-Score (r: -0,320 p:0,022), lumbar DMO (r:-0,267, p:0,049) and TBS (r: -0,396, p:0,005). Conclusion We confirm an association between a glomerular filtration rate decline and an increase in serum iFGF-23 levels. The inverse correlation observed between iFGF-23 serum levels and lumbar T-Score, lumbar DMO and trabecular microarchitecture suggests a negative effect of iFGF-23 in bone mineralization.

Micro-scale vertebral features in postmenopausal women with alcohol-associated and metabolic-associated fatty liver disease: ex vivo bone quality analyses.

Although epidemiological studies indicate increased fracture risk in women with alcohol-associated liver disease (AALD) and metabolic-associated fatty liver disease (MAFLD), data about their micro-scale bone features are still limited. We aimed to characterize bone quality changes in the anterior mid-transverse part of the first lumbar vertebral body collected from 32 adult postmenopausal females. Based on pathohistological assessment of the liver tissue, individuals were divided into AALD (n = 13), MAFLD (n = 9), and control group (n = 10). We analyzed trabecular and cortical micro-architecture (using micro-computed tomography), bone mechanical properties (using Vickers microhardness tester), osteocyte lacunar network and bone marrow adiposity morphology (using optic microscopy). Data were adjusted to elude the covariant effects of advanced age and body mass index on our results. Our data indicated a minor trend toward deteriorated bone quality in MAFLD women, presented in impaired trabecular and cortical micro-architectural integrity, which could be associated with bone marrow adiposity alterations noted in these women. Additionally, we observed a significant decline in micro-architectural, mechanical, and osteocyte lacunar features in lumbar vertebrae collected from the AALD group. Lastly, our data indicated that vertebral bone deterioration was more prominent in the AALD group than in the MAFLD group. Our data suggested that MAFLD and AALD are factors that could play a part in compromised vertebral strength of postmenopausal women. Also, our data contribute to understanding the multifactorial nature of bone fragility in these patients and highlight the necessity for developing more effective patient-specific diagnostic, preventive, and therapeutic strategies.

Evaluation of mandibular cortical and trabecular radiomorphometry in familial Mediterranean fever patients

The objective of this retrospective study was to evaluate the mandibular cortical and trabecular morphology and microarchitecture of patients with familial Mediterranean fever (FMF) and compare them to those of healthy individuals by examining radiomorphometric indices on panoramic radiographs. We examined a group of 56 FMF patients aged 5 to 71 years and an age- and sex-matched control group of individuals with no systemic diseases. We classified the FMF and control groups according to age and sex and the FMF group according to colchicine use. We evaluated the quantitative radiomorphometic indices of gonial index, antegonial index, molar cortical thickness, mental index, panoramic mandibular index, and lacunarity, and the qualitative mandibular cortical index on all panoramic radiographs and performed between and within group analysis. Mean gonial index, antegonial index, and molar cortical thickness values of the FMF group were significantly smaller than those of the control group. Significantly fewer patients in the FMF group were classified as mandibular cortical index type 1 compared to the control group. There were no significant differences in quantitative index values according to colchicine use in the FMF group or regarding the categorical parameters of age, sex, and mandibular cortical index classification. Radiomorphometric values of the mandibular basal cortex posterior to the mental foramen differ significantly in FMF patients compared to healthy counterparts. Dentists should note mandibular morphologic changes indicative of low bone density when examining panoramic images of patients with this disease.

Is There a Causal Relationship between Physical Activity and Bone Microarchitecture? A Study of Adult Female Twin Pairs.

The reasons for the association between physical activity (PA) and bone microarchitecture traits are unclear. We examined whether these associations were consistent with causation and/or with shared familial factors using a cross-sectional study of 47 dizygotic and 93 monozygotic female twin pairs aged 31-77 years. Images of the nondominant distal tibia were obtained using high-resolutionperipheral quantitative computed tomography. The bone microarchitecture was assessed using StrAx1.0 software. Based on a self-completed questionnaire, a PA index was calculated as a weighted sum of weekly hours of light (walking, light gardening), moderate (social tennis, golf, hiking), and vigorous activity (competitive active sports) = light + 2 * moderate + 3 * vigorous. We applied Inference about Causation through Examination of FAmiliaL CONfounding (ICE FALCON) to test whether cross-pair cross-trait associations changed after adjustment for within-individual associations. Within-individual distal tibia cortical cross-sectional area (CSA) and cortical thickness were positively associated with PA (regression coefficients [β] = 0.20 and 0.22), while the porosity of the inner transitional zone was negatively associated with PA (β = -0.17), all p < 0.05. Trabecular volumetric bone mineral density (vBMD) and trabecular thickness were positively associated with PA (β = 0.13 and 0.14), and medullary CSA was negatively associated with PA (β = -0.22), all p ≤ 0.01. Cross-pair cross-trait associations of cortical thickness, cortical CSA, and medullary CSA with PA attenuated after adjustment for the within-individual association (p = 0.048, p = 0.062, and p = 0.028 for changes). In conclusion, increasing PA was associated with thicker cortices, larger cortical area, lower porosity of the inner transitional zone, thicker trabeculae, and smaller medullary cavities. The attenuation of cross-pair cross-trait associations after accounting for the within-individual associations was consistent with PA having a causal effect on the improved cortical and trabecular microarchitecture of adult females, in addition to shared familial factors. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Sesamol improves bone mass in ovary intact growing and adult rats but accelerates bone deterioration in the ovariectomized rats

Sesamol, an active component in sesame seeds, is known for its health benefits. However, its effect on bone metabolism remains unexplored. The present study aims to investigate the effect of sesamol on growing, adult and osteoporotic skeleton and its mechanism of action. Sesamol at various doses were administered orally to growing, ovariectomized, and ovary-intact rats. Alterations in bone parameters were examined using micro-CT and histological studies. Western blot and mRNA expression from long bones were performed. We further evaluated the effect of sesamol on osteoblast and osteoclast function and its mode of action in the cell culture system. These data showed that sesamol was able to promote peak bone mass in growing rats. However, sesamol had the opposite effect in ovariectomized rats, evident from gross deterioration of trabecular and cortical microarchitecture. Concurrently, it improved the bone mass in adult rats. In vitro results revealed that sesamol enhances the bone formation by stimulating osteoblast differentiation through MAPK, AKT, and BMP-2 signaling. In contrast, it enhances osteoclast differentiation and expression of osteoclast-specific genes in osteoclast differentiation medium. Interestingly, in presence of estrogen, the effect reversed and sesamol decreased osteoclast differentiation, in vitro. Sesamol improves bone microarchitecture in growing and ovary-intact rats, whereas it enhances the bone deterioration in ovariectomized rats. While sesamol promotes bone formation, its opposing effect on the skeleton can be attributed to its dual effect on osteoclastogenesis in presence and absence of estrogen. These preclinical findings suggest a special attention towards the detrimental effect of sesamol in postmenopausal women.

Tailoring the Microarchitectures of 3D Printed Bone-like Scaffolds for Tissue Engineering Applications.

Material extrusion (MEX), commonly referred to as fused deposition modeling (FDM) or fused filament fabrication (FFF), is a versatile and cost-effective technique to fabricate suitable scaffolds for tissue engineering. Driven by a computer-aided design input, specific patterns can be easily collected in an extremely reproducible and repeatable process. Referring to possible skeletal affections, 3D-printed scaffolds can support tissue regeneration of large bone defects with complex geometries, an open major clinical challenge. In this study, polylactic acid scaffolds were printed resembling trabecular bone microarchitecture in order to deal with morphologically biomimetic features to potentially enhance the biological outcome. Three models with different pore sizes (i.e., 500, 600, and 700 µm) were prepared and evaluated by means of micro-computed tomography. The biological assessment was carried out seeding SAOS-2 cells, a bone-like cell model, on the scaffolds, which showed excellent biocompatibility, bioactivity, and osteoinductivity. The model with larger pores, characterized by improved osteoconductive properties and protein adsorption rate, was further investigated as a potential platform for bone-tissue engineering, evaluating the paracrine activity of human mesenchymal stem cells. The reported findings demonstrate that the designed microarchitecture, better mimicking the natural bone extracellular matrix, favors a greater bioactivity and can be thus regarded as an interesting option for bone-tissue engineering.

Whole-Body Metabolism and the Musculoskeletal Impacts of Targeting Activin A and Myostatin in Severe Osteogenesis Imperfecta.

Mutations in the COL1A1 and COL1A2 genes, which encode type I collagen, are present in around 85%-90% of osteogenesis imperfecta (OI) patients. Because type I collagen is the principal protein composition of bones, any changes in its gene sequences or synthesis can severely affect bone structure. As a result, skeletal deformity and bone frailty are defining characteristics of OI. Homozygous oim/oim mice are utilized as models of severe progressive type III OI. Bone adapts to external forces by altering its mass and architecture. Previous attempts to leverage the relationship between muscle and bone involved using a soluble activin receptor type IIB-mFc (sActRIIB-mFc) fusion protein to lower circulating concentrations of activin A and myostatin. These two proteins are part of the TGF-β superfamily that regulate muscle and bone function. While this approach resulted in increased muscle masses and enhanced bone properties, adverse effects emerged due to ligand promiscuity, limiting clinical efficacy and obscuring the precise contributions of myostatin and activin A. In this study, we investigated the musculoskeletal and whole-body metabolism effect of treating 5-week-old wildtype (Wt) and oim/oim mice for 11 weeks with either control antibody (Ctrl-Ab) or monoclonal anti-activin A antibody (ActA-Ab), anti-myostatin antibody (Mstn-Ab), or a combination of ActA-Ab and Mstn-Ab (Combo). We demonstrated that ActA-Ab treatment minimally impacts muscle mass in oim/oim mice, whereas Mstn-Ab and Combo treatments substantially increased muscle mass and overall lean mass regardless of genotype and sex. Further, while no improvements in cortical bone microarchitecture were observed with all treatments, minimal improvements in trabecular bone microarchitecture were observed with the Combo treatment in oim/oim mice. Our findings suggest that individual or combinatorial inhibition of myostatin and activin A alone is insufficient to robustly improve femoral biomechanical and microarchitectural properties in severely affected OI mice. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Bone mineral density and microarchitecture change during skeletal growth in harbor seals (Phoca vitulina) from the German coast

Across species, the skeletal system shares mutual functions, including the protection of inner organs, structural basis for locomotion, and acting as an endocrine organ, thus being of pivotal importance for survival. However, insights into skeletal characteristics of marine mammals are limited, especially in the growing skeleton. Harbor seals (Phoca vitulina) are common marine mammals in the North and Baltic Seas and are suitable indicators of the condition of their ecosystem. Here, we analyzed whole-body areal bone mineral density (aBMD) by dual-energy X-ray absorptiometry (DXA) and lumbar vertebrae by high-resolution peripheral quantitative computed tomography (HR-pQCT) in neonate, juvenile, and adult harbor seals. Along skeletal growth, an increase in two-dimensional aBMD by DXA was paralleled by three-dimensional volumetric BMD by HR-pQCT, which could be attributed to an increasing trabecular thickness while trabecular number remained constant. Strong associations were observed between body dimensions (weight and length) and aBMD and trabecular microarchitecture (R2 = 0.71–0.92, all p < 0.001). To validate the results of the DXA measurement (i.e., the standard method used worldwide to diagnose osteoporosis in humans), we performed linear regression analyses with the three-dimensional measurements from the HR-pQCT method, which revealed strong associations between the two imaging techniques (e.g., aBMD and Tb.Th: R2 = 0.96, p < 0.0001). Taken together, our findings highlight the importance of systematic skeletal investigations in marine mammals during growth, illustrating the high accuracy of DXA in this context. Regardless of the limited sample size, the observed trabecular thickening is likely to represent a distinct pattern of vertebral bone maturation. As differences in nutritional status, among other factors, are likely to affect skeletal health, it appears essential to routinely perform skeletal assessments in marine mammals. Placing the results in the context of environmental exposures may allow effective measures to protect their populations.

Regional variations in the intra- and intervertebral trabecular microarchitecture of the osteoporotic axial skeleton.

Trabecular structures in vertebral bodies are unequally distributed in the cervical, thoracic and lumbar spine, and also within individual vertebrae. Knowledge of the microstructure of these entities could influence our comprehension and treatment of osteoporotic fractures, and even surgical procedures. Appropriate investigations may clarify the pathomechanisms of various osteoporotic fractures (fish, wedge-shaped, and flat vertebrae). We obtained three cancellous bone cylinders from the centers and margins of cervical vertebra 3 to lumbar vertebra 5, and investigated these in regard of bone volume fraction, trabecular thickness, separation, trabecular number, trabecular bone pattern factor, connectivity density, and degree of anisotropy. Using a Jamshidi needle®, we obtained samples from three quadrants (QI: right-sided edge, QII: central, QIII: left-sided edge) of 242 prepared vertebrae, and investigated these on a micro-CT device. In all, 726 bone samples were taken from eleven body donors. Bone volume fraction, trabecular thickness, and the degree of anisotropy were significantly lower in QII than in QI and QIII. Trabecular pattern factor, however, was significantly higher in QII than in QI and QIII. The results helped to explain fish vertebrae. Wedge fractures and flat vertebrae are most likely caused by the complex destruction of trabecular and cortical structures. The higher bone volume fraction in the cervical spine compared to the thoracic and lumbar spine accounts for the small number of fractures in the cervical spine. The marked trabecular pattern factor in the center of thoracic and lumbar vertebrae could be a reason for the surgeon to use different screw designs for individual vertebrae.

The Effects of Prolonged Treatment with Cemtirestat on Bone Parameters Reflecting Bone Quality in Non-Diabetic and Streptozotocin-Induced Diabetic Rats.

Cemtirestat, a bifunctional drug acting as an aldose reductase inhibitor with antioxidant ability, is considered a promising candidate for the treatment of diabetic neuropathy. Our study firstly examined the effects of prolonged cemtirestat treatment on bone parameters reflecting bone quality in non-diabetic rats and rats with streptozotocin (STZ)-induced diabetes. Experimental animals were assigned to four groups: non-diabetic rats, non-diabetic rats treated with cemtirestat, diabetic rats, and diabetic rats treated with cemtirestat. Higher levels of plasma glucose, triglycerides, cholesterol, glycated hemoglobin, magnesium, reduced femoral weight and length, bone mineral density and content, parameters characterizing trabecular bone mass and microarchitecture, cortical microarchitecture and geometry, and bone mechanical properties were determined in STZ-induced diabetic versus non-diabetic rats. Treatment with cemtirestat did not affect all aforementioned parameters in non-diabetic animals, suggesting that this drug is safe. In diabetic rats, cemtirestat supplementation reduced plasma triglyceride levels, increased the Haversian canal area and slightly, but insignificantly, improved bone mineral content. Nevertheless, the insufficient effect of cemtirestat treatment on diabetic bone disease does not support its use in the therapy of this complication of type 1 diabetes mellitus.

AN EXPERIMENTAL INVESTIGATION OF THE MICROARCHITECTURE AND FRACTURE MECHANICS OF FEMURS OF ZUCKER DIABETIC FATTY (ZDF) RATS USING A SIDEWAYS FALL TEST

This study aims to assess the fracture mechanics of type-2 diabetic (T2D) femoral bone using innovative site-specific tests, whilst also examining the cortical and trabecular bone microarchitecture from various regions using micro-computed tomography (CT) of the femur as the disease progresses.Male [Zucker Diabetic Fatty (ZDF: fa/fa) (T2D) and Zucker Lean (ZL: fa/+) (Control)] rats were euthanized at 12-weeks of age, thereafter, right and left femora were dissected (Right femora: n = 6, per age, per condition; Left femora: n=8-9, per age, per condition). Right femurs were notched in the posterior of the midshaft. Micro-CT was used to scan the proximal femur, notched and unnotched femoral midshaft (cortical) of the right femur and the distal metaphysis (trabecular) of the left femur to investigate microarchitecture and composition. Right femurs were fracture toughness tested to measure the stress intensity factor (Kic) followed by a sideways fall test using a custom-made rig to investigate femoral neck mechanical properties.There was no difference in trabecular and cortical tissue material density (TMD) between T2D and control rats. Cortical thickness was unchanged, but trabeculae were thinner (p&lt;0.01) in T2D rats versus controls. However, T2D rats had a greater number of trabeculae (p&lt;0.05) although trabecular spacing was not different to controls. T2D rats had a higher connectivity distribution (p&lt;0.05) and degree of anisotropy (p&lt;0.05) in comparison to controls. There was no difference in the mechanical properties between strains.At 12-weeks of age, rats are experiencing early-stage T2Ds and the disease impact is currently not very clear. Structural and material properties are unchanged between strains, but the trabecular morphology shows that T2D rats have more trabecular struts present in order to account for the thinner trabeculae.

Trabecular bone remodeling in the aging mouse: A micro-multiphysics agent-based in silico model using single-cell mechanomics.

Bone remodeling is regulated by the interaction between different cells and tissues across many spatial and temporal scales. Notably, in silico models are regarded as powerful tools to further understand the signaling pathways that regulate this intricate spatial cellular interplay. To this end, we have established a 3D multiscale micro-multiphysics agent-based (micro-MPA) in silico model of trabecular bone remodeling using longitudinal in vivo data from the sixth caudal vertebra (CV6) of PolgA(D257A/D257A) mice, a mouse model of premature aging. Our in silico model includes a variety of cells as single agents and receptor-ligand kinetics, mechanomics, diffusion and decay of cytokines which regulate the cells' behavior. We highlighted its capabilities by simulating trabecular bone remodeling in the CV6 of five mice over 4weeks and we evaluated the static and dynamic morphometry of the trabecular bone microarchitecture. Based on the progression of the average trabecular bone volume fraction (BV/TV), we identified a configuration of the model parameters to simulate homeostatic trabecular bone remodeling, here named basal. Crucially, we also produced anabolic, anti-anabolic, catabolic and anti-catabolic responses with an increase or decrease by one standard deviation in the levels of osteoprotegerin (OPG), receptor activator of nuclear factor kB ligand (RANKL), and sclerostin (Scl) produced by the osteocytes. Our results showed that changes in the levels of OPG and RANKL were positively and negatively correlated with the BV/TV values after 4weeks in comparison to basal levels, respectively. Conversely, changes in Scl levels produced small fluctuations in BV/TV in comparison to the basal state. From these results, Scl was deemed to be the main driver of equilibrium while RANKL and OPG were shown to be involved in changes in bone volume fraction with potential relevance for age-related bone features. Ultimately, this micro-MPA model provides valuable insights into how cells respond to their local mechanical environment and can help to identify critical pathways affected by degenerative conditions and ageing.

Bone Marrow Adipose Tissue Is Increased in Postmenopausal Women With Postsurgical Hypoparathyroidism.

Suppression of bone turnover, greater trabecular volume, and normal-high normal all-site bone mineral density (BMD) are hallmarks of postsurgical hypoparathyroidism (HypoPT). Impairment in the trabecular microarchitecture with possible higher risk of vertebral fractures (VF) in women with postmenopausal HypoPT has also been described. Currently, no data on bone marrow adipose tissue (BMAT) are available in HypoPT. To assess BMAT by magnetic resonance imaging (MRI) and proton magnetic resonance spectroscopy (1H-MRS) in postmenopausal women with chronic postsurgical HypoPT. This cross-sectional pilot study, conducted at an ambulatory referral center, included 29 postmenopausal women (mean age 66 ± 8.4 years) with postsurgical HypoPT and 31 healthy postmenopausal women (mean age 63 ± 8.5). Lumbar spine MRI was performed and BMAT was measured by applying PRESS sequences on the L3 body. Lumbar spine, femoral neck, and total hip BMD were measured by dual x-ray absorptiometry (DXA); site-matched spine trabecular bone score (TBS) was calculated by TBS iNsight (Medimaps, Switzerland); VF assessment was performed with lateral thoracic and lumbar spine DXA. Fat content (FC) and saturation level (SL%) were higher (P <.0001 and P <.001), while water content (W) was lower in HypoPT compared to controls (P <.0001). FC significantly correlated with years since menopause and body weight (P <.05) in HypoPT, while TBS negatively correlated with FC and SL% (P <.05) and positively with residual lipids (RL) and W (P <.05). We demonstrate for the first time that BMAT is increased in postmenopausal women with postsurgical hypoparathyroidism and negatively associated with trabecular microarchitecture.

Opportunistic Evaluation of Trabecular Bone Texture by MRI Reflects Bone Mineral Density and Microarchitecture.

Many individuals at high risk for fracture are never evaluated for osteoporosis and subsequently do not receive necessary treatment. Utilization of magnetic resonance imaging (MRI) is burgeoning, providing an ideal opportunity to use MRI to identify individuals with skeletal deficits. We previously reported that MRI-based bone texture was more heterogeneous in postmenopausal women with a history of fracture compared to controls. The present study aimed to identify the microstructural characteristics that underlie trabecular texture features. In a prospective cohort, we measured spine volumetric bone mineral density (vBMD) by quantitative computed tomography (QCT), peripheral vBMD and microarchitecture by high-resolution peripheral QCT (HRpQCT), and areal BMD (aBMD) by dual-energy x-ray absorptiometry. Vertebral trabecular bone texture was analyzed using T1-weighted MRIs. A gray level co-occurrence matrix was used to characterize the distribution and spatial organization of voxelar intensities and derive the following texture features: contrast (variability), entropy (disorder), angular second moment (ASM; uniformity), and inverse difference moment (IDM; local homogeneity). Among 46 patients (mean age 64, 54% women), lower peripheral vBMD and worse trabecular microarchitecture by HRpQCT were associated with greater texture heterogeneity by MRI-higher contrast and entropy (r ∼ -0.3 to 0.4, P < .05), lower ASM and IDM (r ∼ +0.3 to 0.4, P < .05). Lower spine vBMD by QCT was associated with higher contrast and entropy (r ∼ -0.5, P < .001), lower ASM and IDM (r ∼ +0.5, P < .001). Relationships with aBMD were less pronounced. MRI-based measurements of trabecular bone texture relate to vBMD and microarchitecture, suggesting that this method reflects underlying microstructural properties of trabecular bone. Further investigation is required to validate this methodology, which could greatly improve identification of patients with skeletal fragility.