Trabecular Bone Volume Fraction Research Articles

Trabecular bone volume fraction in Holocene and Late Pleistocene humans

Research suggests that recent modern humans have gracile skeletons in having low trabecular bone volume fraction (BV/TV) and that gracilization of the skeleton occurred in the last 10,000 years. This has been attributed to a reduction in physical activity in the Holocene. However, there has been no thorough sampling of BV/TV in Pleistocene humans due to limited access to high resolution images of fossil specimens. Therefore, our study investigates the gracilization of BV/TV in Late Pleistocene humans and recent (Holocene) modern humans to improve our understanding of the emergence of gracility. We used microcomputed tomography to measure BV/TV in the femora, humeri and metacarpals of a sample of Late Pleistocene humans from Dolní Věstonice (Czech Republic, ∼26 ka, n = 6) and Ohalo II (Israel, ∼19 ka, n = 1), and a sample of recent humans including farming groups (n = 39) and hunter-gatherers (n = 6). We predicted that 1) Late Pleistocene humans would exhibit greater femoral and humeral head BV/TV compared with recent humans and 2) among recent humans, metacarpal head BV/TV would be greater in hunter-gatherers compared with farmers. Late Pleistocene humans had higher BV/TV compared with recent humans in both the femur and humerus, supporting our first prediction, and consistent with previous findings that Late Pleistocene humans are robust as compared to recent humans. However, among recent humans, there was no significant difference in BV/TV in the metacarpals between the two subsistence groups. The results highlight the similarity in BV/TV in the hand of two human groups from different geographic locales and subsistence patterns and raise questions about assumptions of activity levels in archaeological populations and their relationships to trabecular BV/TV.

Halofuginone Inhibits Osteoclastogenesis and Enhances Osteoblastogenesis by Regulating Th17/Treg Cell Balance in Multiple Myeloma Mice with Bone Lesions

Evidences shows that T helper 17 (Th17) and regulatory T (Treg) cells imbalance plays a critical role in bone lesions of MM patients. Therefore, regulating the Th17/Treg imbalance may be beneficial for bone lesions in MM. Ten MM mice complicated with bone lesions were established and divided into the halofuginone (HF) group and the PBS group. After treatment, tibia and fibula from both groups were scanned by micro-CT. Osteoclasts and osteoblasts were validated by histochemical staining and ELISA. Th17 and Treg cells were tested by flow cytometry. The correlations between Th17/Treg cell ratio and osteoclasts, osteoblasts and bone remodeling were analyzed using the Spearman relative analysis. After treatment, mice in the HF group had an increase in trabecular bone volume fraction and thickened cortex, but a decrease in trabecular separation compared to mice in the PBS group.Tartrate-resistant acid phosphase (TRAP) + osteoclasts and its biomarker TRACP5b in serum were reduced, while alkaline phosphatase (ALP) + osteoblasts and its biomarker N-terminal propeptide of type 1precollagen (P1NP) in serum were accreted in the HF group. Th17/Treg cell ratio in halofuginone-treated mice was 0.85 ± 0.05, and was significantly lower than that in PBS-treated mice, which was 1.51 ± 0.03. In addition, it showed that the Th17/Treg cell ratio was significantly and positively associated with osteoclasts, but was significantly and negatively associated with osteoblasts and bone remodeling. Halofuginone plays a critical role in the amelioration bone lesions in MM, as it can inhibit osteoclastogenesis and enhance osteoblastogenesis by regulating the Th17/Treg cell balance.

Bioactive peptide relieves glucocorticoid-induced osteoporosis by giant macrocyclic encapsulation

Bioactive peptides play a crucial role in the field of regenerative medicine and tissue engineering. However, their application in vivo and clinic is hindered by their poor stability, short half-life, and low retention rate. Herein, we propose a novel strategy for encapsulating bioactive peptides using giant macrocycles. Platelet-derived growth factor (PDGF) bioactive mimicking peptide Nap-FFGVRKKP (P) was selected as the representative of a bioactive peptide. Quaterphen[4]arene (4) exhibited extensive host-guest complexation with P, and the binding constant was (1.16 ± 0.10) × 107 M−1. In vitro cell experiments confirmed that P + 4 could promote the proliferation of BMSCs by 2.27 times. Even with the addition of the inhibitor dexamethasone (Dex), P + 4 was still able to save 76.94% of the cells in the control group. Compared to the Dex group, the bone mass of the mice with osteoporosis in the P + 4 group was significantly increased. The mean trabecular thickness (Tb.Th) increased by 17.03%, and the trabecular bone volume fraction (BV/TV) values increased by 40.55%. This supramolecular bioactive peptide delivery strategy provides a general approach for delivering bioactive peptides and opens up new opportunities for the development of peptide-based drugs.

Associations of global biomarkers of oxidative stress with osteoporosis, bone microstructure and bone turnover: Evidence from human and animal studies

PurposeHuman evidence on the association between oxidative stress and osteoporosis is inconsistent. Fluorescent Oxidation Products (FlOPs) are global biomarkers of oxidative stress. We examined the associations of FlOPs (excitation/emission wavelengths 320/420 nm for FlOP_320, 360/420 nm for FlOP_360, and 400/475 nm for FlOP_400) with osteoporosis, bone microstructure, and bone turnover markers in humans and rats. MethodsIn humans, we conducted a 1:2 age, sex, hospital, and specimen-matched case-control study to test the association between FlOPs and osteoporosis diagnosed from dual-energy X-ray absorptiometry. In eight-week-old male Wistar rats, we administrated D-galactose and 0.9 % saline for 90 days in treatment and control groups (n = 8/group); micro-CT was used to determine bone microstructure. ResultsIn humans, higher levels of FlOP_320 (OR for per 1 SD increase = 1.49, 95 % CI: 1.01–2.20) and FlOP_360 (OR for per 1 SD increase = 1.59, 95 % CI: 1.07–2.37) were associated with increased odds of osteoporosis. FlOP_400 were not associated with osteoporosis. D-galactose treated rats, as compared with control rats, showed higher levels of FlOP_320 and MDA, and lower P1NP levels during 90 days of experiment (all P < 0.05). The D-galactose group had lower trabecular bone volume fraction (0.07 ± 0.03 vs. 0.13 ± 0.05; P = 0.008) and volumetric BMD (225.4 ± 13.8 vs. 279.1 ± 33.2 mg HA/cm3; P = 0.001) than the control group. ConclusionIn conclusion, higher FlOP_320 levels were associated with increased odds of osteoporosis, impaired bone microstructure and decreased bone formation.

Three-Dimensional Osseointegration Patterns of Cementless Femoral Stems: An ex Vivo Study with High-Resolution Imaging and Histological Evaluation.

Osseointegration is essential for the long-term survival of cementless femoral stems and is dependent on periprosthetic bone quality and correct implantation technique. The aim of this study was to evaluate the 3-dimensional long-term fixation patterns of, and bone microarchitecture around, cementless hip stems. Four specimens with varying degrees of bone quality and fixation characteristics from body donors who had received Alloclassic Zweymüller hip stems during their lifetime (mean time in situ at the time of death: 12.73 years) were evaluated with use of radiographs, high-resolution computed tomography (CT) scans, and hard-tissue histology. The CT voxel size was 85 µm, and the following parameters were calculated: total bone volume, total bone volume fraction, trabecular bone volume, trabecular bone volume fraction, cortical bone volume, cortical bone volume fraction, and cortical thickness. Bone-implant contact and canal fill index values for each Gruen zone of the specimens were calculated with use of histological samples. Femoral stems with apparently good cortical contact on clinical radiographs showed higher values for cortical bone volume, trabecular bone volume, and cortical thickness in the high-resolution CT analysis than femoral stems with apparently weak cortical contact on clinical radiographs. Based on the histological evaluation, the mean bone-implant contact ranged from 22.94% to 57.24% and the mean canal fill index ranged from 52.33% to 69.67% among the specimens. This study demonstrated different osseointegration patterns of cementless femoral stems on the basis of radiographs, high-resolution CT scans, and histological evaluation. Femora with high cortical bone volume and cortical thickness were associated with higher canal fill indices, whereas femora with low cortical bone volume and cortical thickness had lower canal fill indices and showed a characteristic corner-anchorage pattern. Osseointegration patterns and thus the long-term survival of cementless femoral stems are dependent on cortical bone volume and cortical thickness.

A comparative study of image quality and diagnostic confidence in diagnosis and follow-up of scaphoid fractures using photon-counting detector CT and energy-integrating detector CT

PurposeScaphoid fractures in patients and assessment of healing using PCD-CT have, as far as we know, not yet been studied. Therefore, the aim was to compare photon counting detector CT (PCD-CT) with energy integrating detector CT (EID-CT) in terms of fracture visibility and evaluation of fracture healing. MethodEight patients with scaphoid fracture were examined with EID-CT and PCD-CT within the first week post-trauma, and with additional scans at 4, 6 and 8 weeks. Our clinical protocol for wrist examination with EID-CT was used (CTDIvol 3.1 ± 0.1 mGy, UHR kernel Ur77). For PCD-CT matched radiation dose, reconstruction kernel Br89. Quantitative analyses of noise, CNR, trabecular and cortical sharpness, and bone volume fraction were conducted. Five radiologists evaluated the images for fracture visibility, fracture gap consolidation and image quality, and rated their confidence in the diagnosis. ResultsThe trabecular and cortical sharpness were superior in images obtained with PCD-CT compared with EID-CT. A successive reduction in trabecular bone volume fraction during the immobilized periods was found with both systems. Despite higher noise and lower CNR with PCD-CT, radiologists rated the image quality of PCD-CT as superior. The visibility of the fracture line within 1-week post-trauma was rated higher with PCD-CT as was diagnostic confidence, but the subsequent assessments of fracture gap consolidation during healing process and the confidence in diagnosis were found equivalent between both systems. ConclusionPCD-CT offers superior visibility of bone microstructure compared with EID-CT. The evaluation of fracture healing and confidence in diagnosis were rated equally with both systems, but the radiologists found primary fracture visibility and overall image quality superior with PCD-CT.

Glucocorticoid-induced osteoporosis is prevented by dietary prune in female mice.

Glucocorticoid-induced osteoporosis (GIO) is a significant side effect of prolonged glucocorticoid (GC) treatment. Chronic GC treatment also leads to trabecular bone loss and gut microbiota dysbiosis in mice. The gut dysbiosis is mechanistically linked to GIO, which indicates that the microbiota can be targeted to prevent GIO. Prunes, a dried fruit and prebiotic, have emerged in the literature as an effective treatment for sex-steroid deficiency induced osteoporosis (primary osteoporosis). Prunes also significantly alter the composition of the gut microbiota in both rodent models and human studies. Therefore, we tested if dietary prune (DP) supplementation could prevent GC-induced bone loss and affect microbiota composition in an established model of GIO. Sixteen-week-old, skeletally mature, female C57BL/6J mice were treated with a subcutaneous 5mg placebo or prednisolone pellet for 8weeks and fed an AIN-93M control diet or a diet modified to include 5, 15, or 25% (w/w) dried California prune powder. As expected, GC treated mice developed significant trabecular bone loss in the distal femur. More importantly, as little as 5% DP supplementation effectively prevented trabecular bone loss. Further, dose dependent increases in trabecular bone volume fraction were observed in GC + 15% and GC + 25% DP mice. Amazingly, in the placebo (non-GC treated) groups, 25% DP supplementation caused a ∼3-fold increase in distal femur trabecular bone volume fraction; this sizable bone response has not been previously observed in healthy mice with gut targeted natural treatments. Along with the striking effect on bone health, GC treatment and 25% DP supplementation led to drastic shifts in gut microbiota composition and several specific changes are strongly associated with bone health. Taken together, these results are the first to demonstrate that DP supplementation effectively prevents the negative effects of prolonged GC therapy on trabecular bone health and strongly associates with shifts in the composition of the gut microbiota.

Menopause-Associated Changes in Mandibular Bone Microarchitecture Are Site-Specific

BackgroundThere are conflicting reports on the effects of decreased estrogen levels on mandibular bone microarchitecture, and whether these effects are consistent throughout the mandible is unclear and may have important implications for treatment planning. PurposeThe goal of this study was to evaluate trabecular and cortical bone microstructure in the mandibular condyle and the mandibular basal bone and compare these sites between premenopausal and postmenopausal women. Study Design, Setting, SampleParticipants were recruited for a cross-sectional cohort study at Columbia University Irving Medical Center. Each participant had CBCT taken of their mandibular condyles and of the basal bone. Exclusion criteria for the population included a) current chemo- or immunotherapy; b) history of bisphosphonate or other osteoporosis therapy; and c) currently pregnant, nursing, or on hormonal birth control. Independent VariableThe predictor variables are menopausal status (before or after menopause) and mandibular region of interest (condyle/basal bone). Outcome VariableParameters of interest included the following indicators of bone quality: trabecular bone volume fraction (BVF), trabecular thickness, trabecular number, trabecular separation, cortical BVF, cortical thickness, and cortical porosity. CovariatesCovariates included demographic variables such as age, estrogen levels, and ethnicity. AnalysesQuantitative microstructure analyses were conducted on CBCT images, and differences between groups for continuous measures (including age) were assessed with unpaired t-test, and demographic variables were assessed by Chi-square. Statistical significance was recorded at p<0.05. ResultsThe premenopausal and postmenopausal groups each had 31 participants, with the following average age: premenopausal= 43.9±6.9 vs. postmenopausal = 57.5±7.6 years old; p<0.001, and estrogen levels: premenopausal =91.77±80.13 pg/ml vs. postmenopausal= 41.44±61.62 pg/ml; p <0.01). Postmenopausal women had significantly greater condylar trabecular separation (0.61±0.18 vs 0.47±0.11 mm; p<0.001) and lower trabecular number (1.03±0.18 vs 1.21±0.19 1/mm; p<0.001) compared to premenopausal women. There were no significant differences in the basal bone microarchitectural parameters between the menopausal groups. Conclusion and RelevanceMenopause is associated with mandibular condylar trabecular bone loss but has minimal effects on the mandibular basal bone. This may have important ramifications for treatment planning in advanced age individuals.

Comparison of the ability of exosomes and ectosomes derived from adipose-derived stromal cells to promote cartilage regeneration in a rat osteochondral defect model

BackgroundExtracellular vesicles (EVs) derived from mesenchymal stromal cells (MSCs) offer promising prospects for stimulating cartilage regeneration. The different formation mechanisms suggest that exosomes and ectosomes possess different biological functions. However, little attention has been paid to the differential effects of EV subsets on cartilage regeneration.MethodsOur study compared the effects of the two EVs isolated from adipose-derived MSCs (ASCs) on chondrocytes and bone marrow–derived MSCs (BMSCs) in vitro. Additionally, we loaded the two EVs into type I collagen hydrogels to optimize their application for the treatment of osteochondral defects in vivo.ResultsIn vitro experiments demonstrate that ASC-derived exosomes (ASC-Exos) significantly promoted the proliferation and migration of both cells more effectively than ASC-derived ectosomes (ASC-Ectos). Furthermore, ASC-Exos facilitated a stronger differentiation of BMSCs into chondrogenic cells than ASC-Ectos, but both inhibited chondrocyte apoptosis to a similar extent. In the osteochondral defect model of rats, ASC-Exos promoted cartilage regeneration in situ better than ASC-Ectos. At 8 weeks, the hydrogel containing exosomes group (Gel + Exo group) had higher macroscopic and histological scores, a higher value of trabecular bone volume fraction (BV/TV), a lower value of trabecular thickness (Tb.Sp), and a better remodeling of extracellular matrix than the hydrogel containing ectosomes group (Gel + Ecto group). At 4 and 8 weeks, the expression of CD206 and Arginase-1 in the Gel + Exo group was significantly higher than that in the Gel + Ecto group.ConclusionOur findings indicate that administering ASC-Exos may be a more effective EV strategy for cartilage regeneration than the administration of ASC-Ectos.

Lacticaseibacillus rhamnosus GG Improves Periodontal Bone Repair via Gut–Blood Axis in Hyperlipidemia

Periodontal bone regeneration remains a clinical challenge, and hyperlipidemia can aggravate alveolar bone resorption. Probiotics have recently been reported to improve bone mass. We aimed to determine the role of Lacticaseibacillus rhamnosus GG (LGG) in periodontal bone regeneration improvement within the context of periodontitis with hyperlipidemia. A Sprague Dawley rat model for periodontitis, hyperlipidemia, and periodontal fenestration defect was constructed (n = 36) and administered LGG gavage for 6 wk (the rats were subsequently sacrificed). Fecal microbiota from donor rats 3 wk after LGG gavage was transplanted into recipient rats to evaluate the role of LGG-modulated gut microbiota in periodontal bone regeneration. Regenerated bone mass was detected using micro–computerized tomography and hematoxylin and eosin stain. Gut microbiota was analyzed using 16S ribosomal RNA sequencing. Serum metabolites were detected by liquid chromatography–mass spectrometry (6 wk after LGG gavage). The pro-osteogenic effects of screened serum metabolite were verified in vitro on bone marrow mesenchymal stem cells (BMMSCs). We found that the bone mineral density, bone volume (BV), trabecular bone volume fraction (BV/TV), and trabecular thickness of the regenerated periodontal bone increased after LGG gavage (P < 0.05) but had little effect on oral flora. After LGG gavage, Staphylococcus, Corynebacterium, and Collinsella in the gut of donors were significantly changed, and these differences were maintained in recipients, who also showed increased trabecular thickness of the regenerated periodontal bone (P < 0.05). These key genera were correlated with BV/TV and BV (P < 0.05). In addition, LGG gavage significantly regulated bone-related blood metabolites, of which selenomethionine promoted BMMSC osteogenesis. Notably, selenomethionine was associated with key gut genera (P < 0.05). Collectively, LGG improved periodontal bone regeneration in the context of periodontitis with hyperlipidemia by modulating gut microbiota and increasing pro-osteogenic metabolites in the blood. These results reveal new insights into the use of probiotics to promote periodontal bone regeneration via the gut–blood–bone axis.

Predicting Non-traumatic Incident Fractures on Rheumatic Disease Patients on Long-term Glucocorticoids

Background: To identify contributors to non-traumatic incident fractures on rheumatic disease patients who are on long term glucocorticoids (LTGC) Methods: Two hundred and twenty patients on LTGC (110 with vertebral fracture and 110 without vertebral fracture) who participated in a cross-sectional study in 2014-2015 were invited to have repeated assessments on 1) aBMD using dual-energy X-ray absorptiometry (DXA), 2) volumetric BMD (vBMD), microstructure and bone strength assessment of the wrist and tibia using high-resolution peripheral quantitative computed tomography (HR-pQCT) and 3) spine radiographs in the 5th year. Clinical covariates were recorded on questionnaires, and Fracture Risk Assessment Tool (FRAX) score was calculated accordingly. Non-traumatic incident fracture over the 5-year were documented. Receiver operating characteristic curve (ROC) analysis was performed to compare the strength of fracture prediction tools. Results: Out of the 140 patients who completed the 5th year assessments, 47 (33.6%) developed incident fractures. History of previous fracture, aBMD at hip and lumbar spine, T-score, trabecular vBMD, trabecular bone volume fraction and estimated bone strength at the tibia at baseline remained significantly different after adjusting for age between the group with and without incident fractures. The area under curve (AUC) of a prediction model comprised of age, history of previous fracture and average trabecular vBMD at tibia was comparable with that of the FRAX score (0.710 vs 0.679-0.702), and slightly outperformed than the AUC of DXA aBMD at hip and lumbar spine (0.628-0.668) under ROC analysis. Conclusion: Age, history of previous fracture and average trabecular vBMD at tibia could be the main contributors in building a prediction model for non-traumatic incident fracture in rheumatic disease patients on LTGC.

Adaptational Response of Individual Trabeculae Morphology to Loading at Different Directions

Trabecular bone undergoes changes in its morphology when subjected to external loading. This paper analyses changes in morphological parameters of individual trabeculae (trabecular thickness and bone volume fraction) in response to loadings at different directions: 0°, 20°, 45°, 70° and 90°. It was found that increase in the load incline caused increase in trabecular thickness and bone volume fraction. In addition, the equilibrium-state trabeculae obtained from adaptation to load at 90° (shear loading) had the highest axial and lateral stiffnesses, as compared to trabecular geometries obtained from other loading scenarios.

The effects of preosteoblast-derived exosomes on macrophages and bone in mice.

The effect of preosteoblast-derived exosomes on bone marrow macrophages (BMMΦ) and calvarial osteoblasts (cOB) was evaluated invitro, and bone formation studies were performed invivo in mice. Preosteoblastic MC3T3-E1 clone 4 (MC4) cell-derived exosomes (MC4exo) were characterized with particle tracking, transmission electron microscopy and western blot analysis to validate size, number, shape and phenotypic exosome markers. Exosomes pre-labelled with PKH67 were incubated with BMMΦ and phagocytosis of exosomes was confirmed. To examine the effect of MC4exo on macrophage polarization, BMMΦ were treated with MC4exo and the expression of pro- and anti-inflammatory cytokines was determined by qPCR. MC4exo treatment upregulated mRNA expression of Cd86, Il1β, Ccl2, Rankl and Nos, and downregulated Cd206, Il10 and Tnfα, suggesting a shift towards pro-inflammatory 'M1-like' macrophage polarization. Combination of RANKL and MC4exo increased osteoclast differentiation of BMMΦ in comparison to RANKL alone as analysed by TRAP staining. MC4exo treatment showed no significant effect on calvarial osteoblast mineralization. For invivo studies, intratibial inoculation of MC4exo (2 × 109 particles in PBS, n = 12) and vehicle control (PBS only, n = 12) was performed in C57Bl/6 mice (8 weeks, male). Micro-CT analyses of the trabecular and cortical bone compartments were assessed at 4 weeks post-injection. Tibial sections were stained for TRAP activity to determine osteoclast presence and immunofluorescence staining was performed to detect osteocalcin (Ocn), osterix (Osx) and F4/80 expression. Intratibial inoculation of MC4exo increased the diaphyseal bone mineral density and trabecular bone volume fraction due to increased trabecular number. This increase in bone was accompanied by a reduction in bone marrow macrophages and osteoclasts at the experimental endpoint. Together, these findings suggest that preosteoblast-derived exosomes enhanced bone formation by influencing macrophage responses.

The Study of the Caudal Vertebrae of Thick-Toed Geckos after a Prolonged Space Flight by X-ray Phase-Contrast Micro-CT.

The proximal caudal vertebrae and notochord in thick-toed geckos (TG) (Chondrodactylus turneri, Gray, 1864) were investigated after a 30-day space flight onboard the biosatellite Bion-M1. This region has not been explored in previous studies. Our research focused on finding sites most affected by demineralization caused by microgravity (G0). We used X-ray phase-contrast tomography to study TG samples without invasive prior preparation to clarify our previous findings on the resistance of TG's bones to demineralization in G0. The results of the present study confirmed that geckos are capable of preserving bone mass after flight, as neither cortical nor trabecular bone volume fraction showed statistically significant changes after flight. On the other hand, we observed a clear decrease in the mineralization of the notochordal septum and a substantial rise in intercentrum volume following the flight. To monitor TG's mineral metabolism in G0, we propose to measure the volume of mineralized tissue in the notochordal septum. This technique holds promise as a sensitive approach to track the demineralization process in G0, given that the volume of calcification within the septum is limited, making it easy to detect even slight changes in mineral content.

Age-at-death estimation based on micro-CT assessment of pubic symphysis: Potentially new methodological approach

BackgroundAlthough various methods for age-at-death estimation of skeletal remains are available, this is still an unsolved issue in forensic anthropology, especially concerning elderly individuals. Moreover, the lack of population-specific methods often made age-at-death estimation unreliable in other populations. AimOur study aimed to examine whether micro-computed tomography (micro-CT) analysis of pubic bone samples obtained from the contemporary Serbian population could be used in anthropological and forensic practice for age-at-death estimation. MethodologyThis study encompassed 62 pubic samples obtained from 26 adult male and 36 adult female cadaveric donors (age range: 22–91 years). Initially, staging according to the Suchey–Brooks phases was performed by two experienced investigators, followed by micro-CT assessment of pubic bone trabecular and cortical compartments (spatial resolution of the scans was 10 µm). ResultsOur results revealed an age-associated decline in trabecular and cortical micro-architecture of elderly male and female individuals, with the most prominent changes present in trabecular bone volume fraction and total porosity of the anterior and posterior cortical surface of the pubic bone. Those parameters were used to generate age-at-death estimation equations. One sample t-test did not reveal a significant difference between estimated age-at-death and real (known) age-at-death in the overall sample (mean absolute error [MAE] of 4.76 years), female (MAE of 9.66 years) and male cadaveric donors (MAE of 6.10 years, p > 0.05). ConclusionOur data indicated that micro-architectural features of trabecular and cortical compartments of pubic bone could potentially be applied as an additional reliable method for age-at-death estimation in the Serbian population.

Improved femoral micro-architecture in adult male individuals with overweight: fracture resistance due to regional specificities.

It is still unclear whether femoral fracture risk is positively or negatively altered in individuals with overweight. Considering the lack of studies including men with overweight, this study aimed to analyze regional specificities in mechano-structural femoral properties (femoral neck and intertrochanteric region) in adult male cadavers with overweight compared to their normal-weight age-matched counterparts. Ex-vivo osteodensitometry, micro-computed tomography, and Vickers micro-indentation testing were performed on femoral samples taken from 30 adult male cadavers, divided into the group with overweight (BMI between 25 and 30 kg/m2; n = 14; age:55 ± 16 years) and control group (BMI between 18.5 and 25 kg/m2; n = 16; age:51 ± 18 years). Better quality of trabecular and cortical microstructure in the inferomedial (higher trabecular bone volume fraction, trabecular thickness, and cortical thickness, coupled with reduced cortical pore diameter, p < 0.05) and superolateral femoral neck (higher trabecular number and tendency to lower cortical porosity, p = 0.043, p = 0.053, respectively) was noted in men with overweight compared to controls. Additionally, the intertrochanteric region of men with overweight had more numerous and denser trabeculae, coupled with a thicker and less porous cortex (p < 0.05). Still, substantial overweight-induced change in femoral osteodensitometry parameters and Vickers micro-hardness was not demonstrated in assessed femoral subregions (p > 0.05). Despite the absence of significant changes in femoral osteodensitometry, individuals with overweight had better trabecular and cortical femoral micro-architecture implying higher femoral fracture resistance. However, the microhardness was not significantly favorable in the individuals who were overweight, indicating the necessity for further research.

Trabecular bone morphology in big cats reflects the complex diversity of limb use but not home range size or daily travel distance.

A relationship exists between mechanical loading and bone morphology. Although studies show a relationship between trabecular bone morphology and locomotor strategy in mammals, none of them have studied trabecular bone morphology in felid species occupying disparate and overlapping habitats. We investigate trabecular bone volume fraction (BVF) in the femoral and humeral heads, and distal tibia of four felid species (mountain lions, jaguars, cheetahs, and leopards) to identify whether there is a relationship between BVF and locomotor behavior. This study's goals are to identify whether felid species with high daily travel distance or large home range size have greater BVF compared with those with small daily travel distance or home range size, and whether BVF is correlated among the three elements of the fore and hindlimb studied. We quantified BVF in micro- and peripheral computed tomography images and found no significant differences across species in the femoral and humeral head (p > 0.05). However, in the distal tibia, results showed that leopards, mountain lions, and cheetahs have significantly greater (p < 0.05) BVF than jaguars. Despite differences in home range size and daily travel distance, the proximal elements did not reflect differences in BVF; however, the distal-most element did, suggesting decreased loading among jaguars. These findings suggest that the observed pattern of trabecular bone morphology is potentially due to the diversity in locomotor strategy of the forelimb. Additionally, these results imply that neither home range size nor daily travel distance are clear indicators of activity levels. A cautious approach is warranted in studying how loading influences trabecular morphology.

Radiation-induced changes in load-sharing and structure-function behavior in murine lumbar vertebrae

In this study, we used micro-CT-based finite element analysis to investigate the biomechanical effects of radiation on the microstructure and mechanical function of murine lumbar vertebrae. Specifically, we evaluated vertebral microstructure, whole-bone stiffness, and cortical-trabecular load sharing in the L5 vertebral body of mice exposed to ionizing radiation 11 days post exposure (5 Gy total dose; n = 13) and controls (n = 14). Our findings revealed the irradiated group exhibited reduced trabecular bone volume and microstructure (p < 0.001) compared to controls, while cortical bone volume remained unchanged (p = 0.91). Axially compressive loads in the irradiated group were diverted from the trabecular centrum and into the vertebral cortex, as evidenced by a higher cortical load-fraction (p = 0.02) and a higher proportion of cortical tissue at risk of initial failure (p < 0.01). Whole-bone stiffness was lower in the irradiated group compared to the controls, though the difference was small and non-significant (2045 ± 142 vs. 2185 ± 225 vs. N/mm, irradiated vs. control, p = 0.07). Additionally, the structure-function relationship between trabecular bone volume and trabecular load fraction differed between groups (p = 0.03), indicating a less biomechanically efficient trabecular network in the irradiated group. We conclude that radiation can decrease trabecular bone volume and result in a less biomechanically efficient trabecular structure, leading to increased reliance on the vertebral cortex to resist axially compressive loads. These findings offer biomechanical insight into the effects of radiation on structure-function behavior in murine lumbar vertebrae independent of possible tissue-level material effects.

Bone-Derived IGF-I Regulates Radial Bone Growth in Adult Male Mice.

Insulin-like growth factor-I (IGF-I) levels, which are reduced by age, and cortical bone dimensions are major determinants of fracture risk in elderly subjects. Inactivation of liver-derived circulating IGF-I results in reduced periosteal bone expansion in young and older mice. In mice with lifelong depletion of IGF-I in osteoblast lineage cells, the long bones display reduced cortical bone width. However, it has not previously been investigated whether inducible inactivation of IGF-I locally in bone in adult/old mice affects the bone phenotype. Adult tamoxifen-inducible inactivation of IGF-I using a CAGG-CreER mouse model (inducible IGF-IKO mice) substantially reduced IGF-I expression in bone (-55%) but not in liver. Serum IGF-I and body weight were unchanged. We used this inducible mouse model to assess the effect of local IGF-I on the skeleton in adult male mice, avoiding confounding developmental effects. After tamoxifen-induced inactivation of the IGF-I gene at 9 months of age, the skeletal phenotype was determined at 14 months of age. Computed tomography analyses of tibia revealed that the mid-diaphyseal cortical periosteal and endosteal circumferences and calculated bone strength parameters were decreased in inducible IGF-IKO mice compared with controls. Furthermore, 3-point bending showed reduced tibia cortical bone stiffness in inducible IGF-IKO mice. In contrast, the tibia and vertebral trabecular bone volume fraction was unchanged. In conclusion, inactivation of IGF-I in cortical bone with unchanged liver-derived IGF-I in older male mice resulted in reduced radial growth of cortical bone. This suggests that not only circulating IGF-I but also locally derived IGF-I regulates the cortical bone phenotype in older mice.

Preptin Deficiency Does Not Protect against High-Fat Diet-Induced Metabolic Dysfunction or Bone Loss in Mice.

Preptin is derived from the cleavage of the E-peptide of pro-insulin-like growth factor (IGF)-II and is an insulin secretagogue. Observational studies have linked elevated circulating preptin to metabolic dysfunction in humans; however, a causal role for preptin in metabolic dysfunction has not been established. Additionally, preptin can promote osteoblast proliferation and differentiation, suggesting a link with skeletal health. We previously described a global preptin knockout (KO) model. In this study, we sought to uncover the impact of preptin KO in mice on the response to a moderately high-fat diet (HFD) and low-fat diet (LFD). HFD groups had higher weight and fat mass gain, lower trabecular and cortical bone volume and fracture load, and higher liver triglycerides. In males, preptin deficiency led to lower blood glucose than wild-type (WT) mice under LFD conditions. This was accompanied by differences in bone microarchitecture, including lower trabecular bone volume fraction, trabecular number, and lower cortical thickness. These differences were absent in female mice, although KO females had a HFD-driven increase in fat mass and liver triglycerides that was absent in WT mice. Female WT mice had increased glucose-stimulated insulin secretion under HFD conditions that was absent in female KO mice. Overall, preptin may have a detrimental impact on metabolism and a positive impact on bone health in male mice and may protect against liver fat storage in females while enabling islet compensation under HFD conditions. When we consider that serum preptin levels are elevated in humans of both sexes in pathological states in which insulin levels are elevated, the impact of preptin on comorbidity risk needs to be better understood. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.