Bone Characteristics Research Articles

Simulation of Microgravity and Coculturing with Hematopoietic Cells Oppositely Modulate Wnt Signaling in Mesenchymal Stromal Cells.

The osteogenic potential of mesenchymal stromal cells (MSCs) can determine bone homeostasis and the physical characteristics of bones. Microgravity reduces the ability of these cells to differentiate in osteogenic direction. It has been shown that the addition of hematopoietic stem and progenitor cells (HSPCs) to MSC culture in vitro can have the opposite effect. The aim of this study was to identify transcriptional changes in 84 genes associated with Wnt signaling in MSCs during microgravity simulation and interaction with HSPCs. The results indicate an increase in the non-canonical Wnt signaling activity during coculturing of MSCs and HSPCs, while simulated microgravity enhances the canonical component of this signaling pathway. These changes may underlie the modulation of osteogenic potential of MSCs in hematopoietic niche under microgravity.

Fetal ultrasonography of the distal limb: a new tool to assess equine fetal age and bone development

In Quarter Horses (QH), fetal age can be predicted within 2 weeks prior to 200 days of gestation via ultrasonography, but as pregnancy advances, accuracy decreases (Renaudin.et.al. Reprod Dom Anim. 2022;57: 743-753). Recently, fetal ultrasonographic measurement of the first phalanx (P1) length was introduced as a novel biometric parameter during late gestation, and the time of apparition and closure of P1’s epiphyses were found to be potential markers of bone maturation in utero (Renaudin.et.al. AAEP.2021;67:264-265). The aim of this study was to determine if bone characteristics of the second phalanx (P2), distal metacarpal 3 (MC3), proximal and distal sesamoid can predict fetal age. Ten healthy pregnant mares (9 QH and 1 Thoroughbred carrying a QH fetus) with known ovulation dates were used. Fetuses were examined by transrectal ultrasound every 2 weeks from 9 months of gestation until parturition. At each examination, the length of the ossified portion of P2’s diaphysis was measured, the presence or absence of P2’s and distal MC3’s epiphyses and the time of appearance of the proximal and distal sesamoid bones were documented. P2 length correlated strongly with days of gestation (P < 0.0001; r 2 = 0.75) and a correlation equation was established: y = 0.1413x -24.89 (y = predicted value of P2 length; x = fetal age). The P2 proximal epiphysis and MC3 distal epiphysis appeared on ultrasound between 285 and 306 days of gestation (mean: 294 days),and 260 and 294 days of gestation (mean: 268 days) respectively and did not close before parturition. P2 distal epiphysis was never imaged. Proximal and distal sesamoids were first observed between 286 and 306 days of gestation (mean: 295 days) and 300 and 329 days of gestation (mean: 317 days) respectively except for the smallest foal where they appeared at 331 and 335 days respectively. In conclusion, P2 length can be used in addition to P1 length as a biometric parameter in late gestation. Distal MC3’s, P1’s and P2’s epiphyses, and sesamoid bones diaphyses appear in a chronological order with MC3 distal epiphysis appearing first, P1’s second, P2’s third, proximal sesamoids fourth and distal sesamoid last. Distal limb ossification can be considered complete in QHs when the MC3 distal epiphysis, P1 and P2 proximal epiphysis and all sesamoid bones are present. Clinically, fetal ultrasonography of the distal limb may be used to assess fetal age and in the decision-making process of not inducing parturition if in utero bone development is not complete. This project was supported by the Center for Equine Health with funds provided by the State of California satellite wagering fund and contributions by private donors.

Automated Identification and Reconstruction of 3D Images on the Mastoid Air Cell System

The mastoid air cell system (MACS) protects the structures in the ear and regulates air pressure in the ear cavity. MACS segmentation is very difficult because of the many overlapping object characteristics in the temporal bone. This study aims to accurately identify and measure MACS areas from CT-scan images of mastoiditis patients. The data tested consisted of 128 CT images from 13 different patients. Images were taken using the Siemens SOMATOM Perspective CT Scanner model 10662260 axially. The extended Adaptive Threshold (eAT) method was developed to produce optimal threshold values for each test image. Furthermore, the eAT results are used to convert the test image into a binary image and then applied to the identification and extraction model automatically for reconstruction from 2D to 3D images. Smaller MACS sizes indicate inflammation of the mastoid bone and require intensive care. Thus, this research can be used to help doctors make the right decisions in carrying out further medical actions.

Correlations of cephalometric parameters of the upper respiratory tract in Ukrainian young men and young women with a wide face type

Annotation. Changes in the size of the upper respiratory tract can lead to the emergence or aggravation, complications of already existing pathologies. In this regard, there is a need to study their sizes both in normal and pathological conditions. Cephalometric analysis is one of the important tools that allows you to assess the location of the structures of the upper respiratory tract and their parameters. The purpose of the study is to establish the peculiarities of correlations between cephalometric parameters of the upper respiratory tract in Ukrainian young men and young women with an orthognathic bite with a wide face type. On primary lateral radiographs of Ukrainian young men (aged 17 to 21 years) and young women (aged 16 to 20 years) with a wide facial type, orthognathic bite and absence of upper respiratory tract pathology, using the licensed medical software OnyxCeph³™, version 3DPro (company Image Instruments GmbH, Germany) and the diagnostic program “UniqCeph” carried out a cephalometric analysis of the upper respiratory tract, soft palate, hyoid bone and tongue. Correlations were evaluated using the Statistica 6.0 license package using Spearman's non-parametric statistics. In young men and young women with a wide face type, multiple, mostly straight, medium-strength reliable (r= from 0.42 to 0.56) and strong (r= from 0.62 to 0.82) correlations were established between most of the cephalometric characteristics of the upper respiratory tract itself, and only in young women – multiple straight correlations of average strength reliable (r=0.44 and r=0.53) relationships between most of the cephalometric characteristics of the hyoid bone. In addition, in young men with a wide face type, multiple straight correlations of mostly medium strength, reliable (r= from 0.47 to 0.52) and unreliable (r= from 0.30 to 0.41) relationships of the AH-CV, AH-MP or VT distances and most of the cephalometric characteristics of the upper respiratory tract itself, mainly the inverse of the average strength of reliable (r=-0.44 in both cases) and unreliable (r=-0.32 and r=-0.38) correlations of the value of most of the cephalometric characteristics of the soft palate (with the exception of the PM-U distance) and the tongue, as well as mostly straight correlations of medium strength unreliable (r= from 0.34 to 0.38) relationships between the values of most of the cephalometric characteristics of the hyoid bone (with the exception of the AH-CV distance) and the tongue; and in young women, there are direct, reliable, medium-strength (r=0.45 and r=0.53) and strong (r=0.63 in both cases) relationships between the value of the AH-CV distance and almost all cephalometric characteristics of the upper respiratory tract itself, as well as mainly direct unreliable average strength (r= from 0.37 to 0.38) correlations between the size of the PM-U or AH-FH distance and most of the characteristics of the tongue. Thus, the most pronounced manifestations of sexual dimorphism correlations are established between the cephalometric characteristics of the upper respiratory tract itself and the hyoid bone or tongue, as well as between the cephalometric characteristics of the soft palate and the tongue.

Impact of dietary analyzed calcium to phosphorus ratios and standardized total tract digestible phosphorus to net energy ratios on growth performance, bone, and carcass characteristics of pigs.

A total of 2,184 pigs (337 × 1,050, PIC; initially 12.4 ± 0.17 kg) were used in a 143-d study to evaluate the effects of feeding varying analyzed calcium to phosphorus ratios (Ca:P) at two standardized total tract digestible (STTD) phosphorus to net energy ratios (STTD P:NE). Pens of pigs (26 pigs per pen) were assigned to 1 of the 6 dietary treatments in a 2 × 3 factorial with main effects of STTD P:NE and Ca:P ratio. Diets consisted of two levels of STTD P:NE; High (1.80, 1.62, 1.43, 1.25, 1.10, and 0.99 g STTD P/Mcal NE from 11 to 22, 22 to 40, 40 to 58, 58 to 81, 81 to 104, and 104 to 129 kg, respectively); or Low (75% of the High levels), and three analyzed Ca:P ratios (0.90:1, 1.30:1, and 1.75:1). There were 14 pens per treatment. Diets were corn-soybean meal-based and contained a constant phytase concentration within each dietary phase with levels decreasing throughout the trial (phases 1 through 3, 500 FTU/kg, assumed release of 0.13% STTD P; phase 4, 400 FTU/kg, assumed release of 0.11% STTD P; phase 5, 290 FTU/kg, assumed release of 0.09% STTD P; and phase 6, 210 FTU/kg, assumed release of 0.07% STTD P). Overall, there was a Ca:P × STTD P:NE interaction (P < 0.05) observed for average daily gain (ADG), feed efficiency (G:F), final body weight (BW), hot carcass weight (HCW), bone mineral density, bone mineral content, and bone-breaking strength. When feeding Low STTD P:NE levels, increasing the analyzed Ca:P ratio decreased (linear, P < 0.001) ADG final BW, HCW, and tended to worsen G:F, bone mineral density, and bone mineral content (linear, P < 0.10). However, when feeding High STTD P:NE levels, increasing the analyzed Ca:P ratio significantly improved bone mineral content and bone mineral density (linear, P < 0.05), and tended to improve ADG and final BW (linear, P < 0.10) and G:F (quadratic P < 0.10). Additionally, increasing the analyzed Ca:P ratio worsened ADG, G:F, and bone mineralization with Low STTD P:NE but had marginal impacts when adequate STTD P:NE was fed.

Biomechanical analysis of a novel Y-plate designed for the treatment of extraarticular distal humerus fractures

Adult distal humerus fractures are infrequent, yet they account for one-third of all humerus fractures. For the treatment of comminuted and osteoporotic fractures, locking plates are claimed to be biomechanically superior to alternative internal fixing techniques. Treatment remains difficult despite recent advancements and the use of locking plates due to frequent comminution, low bone quality, and limited healing ability in osteoporotic bone. An optimal design of the newly constructed plate and the control model were selected. The biomechanical characteristics of non-osteoporotic and osteoporotic synthetic bone were compared on six models. The biomechanical properties of the new plate were tested and compared on 54 osteoporotic synthetic humerus models. The control models were reconstructive and parallel LCPs. The tests were carried out under static and dynamic axial, lateral and bending loads. Fracture displacements were measured by optical measuring system Aramis. The test model is significantly stiffer for lateral load (p = 0.0007) and for bending load at the moment of model failure (p = 0.0002), while for axial load the LCP model showed greater stiffness (p = 0.0017). During lateral dynamic loading, all three LCP models broke and there was a significant difference compared to the test model (p = 0.0125). The LCP model is dynamically significantly more durable under axial load, while the largest displacements were recorded with the test model (p = 0.029). The displacements induced by all three loads are within the limits that fulfil the parameters of appropriate biomechanical stability. A novel locking plate for extra-articular distal humerus fractures may provide an alternative to the traditional two-plate.

Effects of more natural housing conditions on the muscular and skeletal characteristics of female C57BL/6J mice

BackgroundEnrichment of home cages in laboratory experiments offers clear advantages, but has been criticized in some respects. First, there is a lack of definition, which makes methodological uniformity difficult. Second, there is concern that the enrichment of home cages may increase the variance of results in experiments. Here, the influence of more natural housing conditions on physiological parameters of female C57BL/6J mice was investigated from an animal welfare point of view. For this purpose, the animals were kept in three different housing conditions: conventional cage housing, enriched housing and the semi naturalistic environment. The focus was on musculoskeletal changes after long-term environmental enrichment.ResultsThe housing conditions had a long-term effect on the body weight of the test animals. The more complex and natural the home cage, the heavier the animals. This was associated with increased adipose deposits in the animals. There were no significant changes in muscle and bone characteristics except for single clues (femur diameter, bone resorption marker CTX-1). Additionally, the animals in the semi naturalistic environment (SNE) were found to have the fewest bone anomalies. Housing in the SNE appears to have the least effect on stress hormone concentrations. The lowest oxygen uptake was observed in enriched cage housing.ConclusionsDespite increasing values, observed body weights were in the normal and strain-typical range. Overall, musculoskeletal parameters were slightly improved and age-related effects appear to have been attenuated. The variances in the results were not increased by more natural housing. This confirms the suitability of the applied housing conditions to ensure and increase animal welfare in laboratory experiments.

Varying degrees of spontaneous osteogenesis of Masquelet’s induced membrane: experimental and clinical observations

BackgroundMasquelet’s induced membrane (IM) has osteogenesis activity, but IM spontaneous osteogenesis (SO) has not been described previously.ObjectivesTo report on varying degrees of IMSO and analyze its possible causes.MethodsTwelve eight-week-old male Sprague-Dawley rats with 10 mm right femoral bone defects who received the first stage of IM technique (IMT) were used to observe the SO. In addition, clinical data from patients with bone defects who received the first stage of IMT with an interval of > 2 months post-operatively and exhibited SO between January 2012 and June 2020 were retrospectively analyzed. The SO was divided into four grades according to the amount and characteristics of the new bone formation.ResultsAt twelve weeks, grade II SO was observed in all rats, and more new bone was formed in the IM near the bone end forming an uneven margin. Histology revealed bone and cartilage foci in the new bone. Four of the 98 patients treated with the first stage of IMT exhibited IMSO, including one female and three males with a median age of 40.5 years (range 29–52 years). The bone defects were caused by severe fractures and infection in two cases and by infection or tumor in one case each. Partial or segmental defects occurred in two cases. The time interval between inserting a cement spacer and diagnosis of SO ranged from six months to nine years. Two cases were grade I, and one case each of grades III and IV.ConclusionVarying degrees of SO confirm the existence of the IMSO phenomenon. Bioactive bone tissue or local inflammation and a long time interval are the primary reasons underlying enhancement of the osteogenic activity of IM and leading to SO, which tends to take place as endochondral osteogenesis.

Primary Stability Assessment of Conical Implants in Under-Prepared Sites: An In Vitro Study in Low-Density Polyurethane Foams

Bone characteristics, the implant macrogeometry, and the drilling technique are considered the main important factors to obtain a good implant primary stability (PS). Indeed, although it is known that implant placement in poor bone sites increases the possibility of implant failure, several surgical procedures have been proposed to improve PS, such as site under-preparation. Hence, this in vitro study aimed to evaluate the insertion torque (IT), removal torque (RT), and resonance frequency analysis (RFA) of conical implants (3.3 and 4 × 13 mm) placed in under-prepared sites on 10 and 20 pounds per cubic foot (PCF) density polyurethane sheets (simulating a D3 and D2 bone, respectively) with and without a cortical sheet of 30 PCF in density (corresponding to a D1 bone). After using ANOVA or Kolmogorov–Smirnov test to elaborate data, the resulting IT and RT values were directly proportional to the polyurethane block densities (e.g., the lowest and highest IT values were 8.36 ± 0.52 Ncm in the 10 PCF density sheet and 46.21 ± 0.79 Ncm in the 20 PCF density sheet + cortical for 4 × 13 mm implants) and increased with the increasing amount of site under-preparation (the highest results for both implants were found with a 2.2 mm under-preparation, showing a significantly higher IT with a p &lt; 0.05 compared with others, especially in the highest-density sheets). Both implants inserted in the 20 PCF density block + cortical with all under-preparation protocols exhibited significantly higher RFA values (p &lt; 0.05–0.0001) compared with the corresponding ones in the 10 PCF block. Moreover, 3.3 × 13 mm implants showed the same results comparing the 20 PCF block and the 10 PCF block + cortical. In conclusion, in this in vitro study using low-density polyurethane blocks, the under-preparation of the implant insertion sites was shown to be effective in increasing implants’ PS.

Microstructural Changes of Bone after Soft Tissue Removal: ATR-FTIR and XRD Spectroscopies

The structural alterations that may arise in boiled and nonboiled bones are often overlooked despite their critical importance in the development of defleshing techniques across various scientific disciplines. To elucidate the microstructural characteristics of bones following the removal of soft tissue through conventional methods, attenuated total reflectance Fourier-transform infrared (ATR-FTIR) and X-ray diffraction (XRD) spectroscopies were employed. Our findings indicate that the boiled water method resulted in higher crystallinity, as evidenced by the FTIR data, whereas the XRD data revealed the opposite. This underscores the notion that a direct comparison between these two techniques is unfeasible as they measure distinct crystallinity parameters. In addition, the cold water maceration method caused a significant reduction in collagen crosslinking, as evidenced by the lower index observed.

ScRNA-Seq Reveals a Distinct Osteogenic Progenitor of Alveolar Bone

The metabolism and remodeling of alveolar bone are the most active among the whole skeletal system, which is related to the biological characteristics and heterogeneity of the bone mesenchymal stromal cells (MSCs). However, there is a lack of systematic description of the heterogeneity of MSC-derived osteoblastic lineage cells as well as their distinct osteogenic differentiation trajectory of alveolar bone. In this study, we constructed a single-cell atlas of the mouse alveolar bone cells through single-cell RNA sequencing (scRNA-seq). Remarkably, by comparing the cell compositions between the alveolar bone and long bone, we uncovered a previously undescribed cell population that exhibits a high expression of protocadherin Fat4 (Fat4+ cells) and is specifically enriched around alveolar bone marrow cavities. ScRNA-seq analysis indicated that Fat4+ cells may initiate a distinct osteogenic differentiation trajectory in the alveolar bone. By isolating and cultivating Fat4+ cells in vitro, we demonstrated that they possess colony-forming, osteogenic, and adipogenic capabilities. Moreover, FAT4 knockdown could significantly inhibit the osteogenic differentiation of alveolar bone MSCs. Furthermore, we revealed that the Fat4+ cells exhibit a core transcriptional signature consisting of several key transcription factors, such as SOX6, which are involved in osteogenesis, and further demonstrated that SOX6 is required for the efficient osteogenic differentiation of the Fat4+ cells. Collectively, our high-resolution single-cell atlas of the alveolar bone reveals a distinct osteogenic progenitor that may contribute to the unique physiological characteristics of alveolar bone.

Effects on Bone and Muscle upon Treadmill Interval Training in Hypogonadal Male Rats.

Testosterone deficiency in males is linked to various pathological conditions, including muscle and bone loss. This study evaluated the potential of different training modalities to counteract these losses in hypogonadal male rats. A total of 54 male Wistar rats underwent either castration (ORX, n = 18) or sham castration (n = 18), with 18 castrated rats engaging in uphill, level, or downhill interval treadmill training. Analyses were conducted at 4, 8, and 12 weeks postsurgery. Muscle force of the soleus muscle, muscle tissue samples, and bone characteristics were analyzed. No significant differences were observed in cortical bone characteristics. Castrated rats experienced decreased trabecular bone mineral density compared to sham-operated rats. However, 12 weeks of training increased trabecular bone mineral density, with no significant differences among groups. Muscle force measurements revealed decreased tetanic force in castrated rats at week 12, while uphill and downhill interval training restored force to sham group levels and led to muscle hypertrophy compared to ORX animals. Linear regression analyses showed a positive correlation between bone biomechanical characteristics and muscle force. The findings suggest that running exercise can prevent bone loss in osteoporosis, with similar bone restoration effects observed across different training modalities.

Increased 18F-FAPI uptake in bones and joints of lung cancer patients: characteristics and distributions.

This study investigated the distribution and characteristics of various bone and joint lesions on 18F-FAPI PET/CT in lung cancer patients. Seventy-four lung cancer patients who underwent 18F-FAPI PET/CT were reviewed. Bone and joint lesions with elevated 18F-FAPI uptake were recorded and analyzed. The distribution and maximum uptake value (SUVmax) of different benign lesions or bone metastases were presented. In addition, the SUVmax of bone metastases on 18F-FDG and 18F-FAPI-04 PET/CT were also compared. In 53 patients, a total of 262 lesions presented 18F-FAPI accumulation. Bone metastases were mainly in vertebrae, pelvis, and ribs, while benign lesions were in vertebral margins, alveolar bone, and shoulder joints. The SUVmax of bone metastases was significantly higher than that of benign lesions ([Formula: see text] vs. [Formula: see text], [Formula: see text]), with NSCLC cases having higher SUVmax values than SCLC cases ([Formula: see text] vs. [Formula: see text], [Formula: see text]). Among benign lesions, arthritis and periodontitis demonstrated higher SUVmax than degenerative lesions (arthritis: [Formula: see text]; periodontitis: [Formula: see text]; degenerative diseases: [Formula: see text]; [Formula: see text] and [Formula: see text], respectively). The SUVmax of bone metastases was comparable between 18F-FDG and 18F-FAPI PET/CT. However, 18F-FAPI PET/CT was found to be superior in identifying cranial metastases compared to 18F-FDG PET/CT (TBRmet/brain: [Formula: see text] vs. [Formula: see text], [Formula: see text]). This study demonstrated that 18F-FAPI PET/CT is a valuable imaging modality for detecting bone and joint lesions in lung cancer patients. The SUVmax of malignant lesions was higher than that of benign lesions, but cannot accurately distinguish benign and malignant lesions. The uptake of FAPI differs among lesions with different pathological types.

Development of musculoskeletal deficits in children with cystic fibrosis in later childhood.

Cystic fibrosis (CF) is a genetic condition primarily affecting the respiratory system, with the associated progressive lung damage and loss of function resulting in reduced lifespan. Bone health is also impaired in individuals with CF, leading to much higher fracture risk even in adolescence. However, the development of these deficits during growth and the relative contributions of puberty, body size and muscular loading remain somewhat unexplored. We therefore recruited 25 children with CF (10 girls, mean age 11.3±2.9y) and 147 children without CF (75 girls, mean age 12.4±2.6y). Bone characteristics were assessed using peripheral quantitative computed tomography (pQCT) at 4% and 66% distal-proximal tibia. Muscle cross-sectional area (CSA) and density (an indicator of muscle quality) were also assessed at the latter site. Tibial bone microstructure was assessed using high-resolution pQCT (HR-pQCT) at 8% distal-proximal tibial length. In addition, peak jump power and hop force were measured using jumping mechanography. Group-by-age interactions and group differences in bone and muscle characteristics were examined using multiple linear regression, adjusted for age, sex and pubertal status and in additional models, height and muscle force. In initial models group-by-age interactions were evident for distal tibial total bone mineral content (BMC) and trabecular volumetric bone mineral density (vBMD), with a lower rate of age-related accrual evident in children with CF. In assessments of distal tibial microstructure, similar patterns were observed for trabecular number and thickness, and cortical CSA. In the tibial shaft, group-by-age interactions indicating slower growth in CF were evident for total BMC and cortical CSA, whilst age-independent deficits in CF were observed for several other variables. Peak jump power and hop force also exhibited similar interactions. Group-by-age interactions for bone were partially attenuated at the distal tibia and fully attenuated at the tibial shaft by adjustment for muscle force. These results suggest that bone and muscle deficits in children with CF develop throughout later childhood, independent of differences in pubertal stage and body size. These diverging growth patterns appear to be mediated by differences in muscle function, particularly for bone characteristics in the tibial shaft. Given the high fracture risk in this population from childhood onwards, development of interventions to improve bone health would be of substantial clinical value.

The many facets of micropetrosis - Magnesium whitlockite deposition in bisphosphonate-exposed human alveolar bone with osteolytic metastasis.

The lacuno-canalicular space of apoptotic osteocytes eventually becomes mineralised in vivo. This condition is known as micropetrosis and is a fundamental characteristic of ageing bone. Increased prevalence of such hypermineralised osteocyte lacunae is viewed as a structural marker of impaired bone function - both mechanical and biological. Within the lacuno-canalicular space, mineralised apoptotic debris typically occurs as micrometre-sized, spherical nodules of magnesium-rich, carbonated apatite. Moreover, characteristically facetted, rhomboidal nodules of magnesium whitlockite [Mg-whitlockite; Ca18Mg2(HPO4)2(PO4)12] have been reported in human alveolar bone exposed to the bisphosphonate alendronate. This work provides supporting evidence for Mg-whitlockite formation in the alveolar bone of a 70-year-old male exposed to the bisphosphonate zoledronic acid to suppress osteolytic changes in skeletal metastasis. Backscattered electron scanning electron microscopy (BSE-SEM) revealed spherical and rhomboidal nodules within the lacuno-canalicular space. A variant of spherical nodules exhibited a fuzzy surface layer comprising radially extending acicular crystallites. The rhomboidal nodules ranged between ∼200nm to ∼2.4µm across the widest dimension (652±331nm). Micro-Raman spectroscopy and energy dispersive X-ray spectroscopy confirmed that rhomboidal nodules are compositionally distinct from spherical nodules, exhibiting higher Mg content and lower Ca/P ratio. Formation of Mg-whitlockite within osteocyte lacunae is multifactorial in nature and suggests altered bone biomineralisation. Nevertheless, the underlying mechanism(s) and sequence of events remain poorly understood and warrant further investigation. The possibility to discriminate between carbonated apatite and Mg-whitlockite nodules within osteocyte lacunae, based on particle morphology, attests to the diagnostic potential of BSE-SEM with or without additional analyses of material composition.

SIMULATED MICROGRAVITY AND COCULTURING WITH HEMATOPOIETIIC CELLS OPPOSITELY MODULATE WNT SIGNALING IN MESENCHYMAL STROMAL CELLS

The osteogenic potential of mesenchymal stromal cells (MSCs) can determine the bone homeostasis and the physical characteristics of bones. Microgravity reduces the ability of these cells to differentiate in osteogenic direction. It has been shown that the addition of hematopoietic stem and progenitor cells (HSPCs) to MSC culture in vitro can have the opposite effect. The aim of this study was to identify transcriptional changes in 84 genes associated with Wnt signaling in MSCs during microgravity simulation and interaction with HSPCs. The results indicate an increase in the non-canonical Wnt signaling activity during MSCs and HSPCs cocultivation, while simulated microgravity enhances the canonical component of this signaling pathway. These changes may underlie the modulation of osteogenic potential of MSCs in hematopoietic niche under microgravity.

Relationship between Football-Specific Training Characteristics and Tibial Bone Adaptation in Male Academy Football Players.

We examined the relationship between football-specific training and changes in bone structural properties across a 12-week period in 15 male football players aged 16 years (Mean ± 1 SD = 16.6 ± 0.3 years) that belonged to a professional football academy. Tibial scans were performed at 4%, 14% and 38% sites using peripheral quantitative computed tomography immediately before and 12 weeks after increased football-specific training. Training was analysed using GPS to quantify peak speed, average speed, total distance and high-speed distance. Analyses were conducted with bias-corrected and accelerated bootstrapped 95% confidence intervals (BCa 95% CI). There were increases in bone mass at the 4% (mean ∆ = 0.15 g, BCa 95% CI = 0.07, 0.26 g, g = 0.72), 14% (mean ∆ = 0.04 g, BCa 95% CI = 0.02, 0.06 g, g = 1.20), and 38% sites (mean ∆ = 0.03 g, BCa 95% CI = 0.01, 0.05 g, g = 0.61). There were increases in trabecular density (4%), (mean ∆ = 3.57 mg·cm-3, BCa 95% CI = 0.38, 7.05 mg·cm-3, g = 0.53), cortical dentsity (14%) (mean ∆ = 5.08 mg·cm-3, BCa 95% CI = 0.19, 9.92 mg·cm-3, g = 0.49), and cortical density (38%) (mean ∆ = 6.32 mg·cm-3, BCa 95% CI = 4.31, 8.90 mg·cm-3, g = 1.22). Polar stress strain index (mean ∆ = 50.56 mm3, BCa 95% CI = 10.52, 109.95 mm3, g = 0.41), cortical area (mean ∆ = 2.12 mm2, BCa 95% CI = 0.09, 4.37 mm2, g = 0.48) and thickness (mean ∆ = 0.06 mm, BCa 95% CI = 0.01, 0.13 mm, g = 0.45) increased at the 38% site. Correlations revealed positive relationships between total distance and increased cortical density (38%) (r = 0.39, BCa 95% CI = 0.02, 0.66), and between peak speed and increased trabecular density (4%) (r = 0.43, BCa 95% CI = 0.03, 0.73). There were negative correlations between total (r = -0.21, BCa 95% CI = -0.65, -0.12) and high-speed distance (r = -0.29, BCa 95% CI = -0.57, -0.24) with increased polar stress strain index (38%). Results suggest that despite football training relating to increases in bone characteristics in male academy footballers, the specific training variables promoting adaptation over a 12-week period may vary. Further studies conducted over a longer period are required to fully elucidate the time-course of how certain football-specific training characteristics influence bone structural properties.

Evaluation of sagittal root position and labial alveolar bone concavity in the maxillary anterior tooth area for immediate implant placement.

The anatomical characteristics of the maxillary labial alveolar bone play a crucial role in the treatment planning of immediate implant placement. The sagittal root position (SRP) and alveolar bone concavity are closely related to anatomical characteristics in determining the ideal implant position. This study evaluated the SRP and labial alveolar bone concavity in the maxillary anterior teeth area. Cone-beam computed tomography images of 120 samples involving 720 teeth were uploaded to the medical imaging software. The SRP was classified as Class I, II, III, or IV, and the concavity of labial alveolar bone was measured. A T test was performed to compare measurements between the central and lateral incisors, between the central incisors and canines, and between the lateral incisors and canine. The majority of the SRPs of the maxillary anterior teeth were class I (engaging the labial cortical plate) with frequencies of 98.3%, 85.8%, and 81.7% for the canines, lateral incisors, and central incisors, respectively. In terms of concavity of labial alveolar bone in maxillary tooth area, canines also had the largest mean value (139.5°), followed by lateral incisors, whereas central incisors has the smallest mean value (131.7°). The results of the T test revealed a significant difference ( p < 0.001) in labial alveolar bone concavity between central and lateral incisors, between central incisors and canines, and between lateral incisors and canines. Most maxillary anterior teeth were classified as Class I SRP, Class III SRP was the least prevalent, and the concavity of the labial alveolar bone significantly differed between the central and lateral incisors, between the central incisors and canines, and between the lateral incisors and canines. In addition, the canines had the highest mean alveolar bone concavity angle, indicating that less concavity in the canines area.

Flow channel performance in 3D printed hydroxyapatite scaffolds to improve metabolism and tissue ingrowth in flat bone repair

The regeneration of flat bone present great challenges owing to the unique metabolic orientation and the great demand for nutrient transport. Reasonable structural design can effectively improve the performance of tissue regeneration of the scaffolds. In this study, bioactive hydroxyapatite scaffolds with various flow channel designs were precisely produced by 3D printing. The mechanical properties, permeability, substance transport and tissue ingrowth capacity brought by flow channel were investigated. Theoretical simulations and experimental results showed that the mechanical properties were highly correlated with the porosity of the scaffolds rather than the flow channel configurations. Curved channel showed a higher permeability for its better ability of omnidirectional diffusion, enhancing the substance transport and cell settlement by forming vortex flow. The flow channel scaffolds had better tissue ingrowth capability due to the abundant blood supply and cells/nutrients enrichment. Especially, the curved flow channel coupling with the annular one showed the best comprehensive performance in all the configurations designed, leading to the efficiency improvement of tissue ingrowth and bone regeneration. This study proposed preliminary principles for the design of planar two-dimensional flow channel based on the characteristics of flat bone, which provided a potential feasible strategy for large-scale flat bone regeneration and repair.

CRACK RESISTANCE CHARACTERISTICS OF MICROSTRUCTURE OF HAVERSIAN CORTICAL BONE

Background: The current research on crack propagation resistance characteristics of osteons is based on the single osteon model, which cannot reflect the interaction among osteons and the influence of material-property changes on the crack propagation. Moreover, the Haversian canal and the cement line were not included in the model, which could not reflect the influence of the true structural characteristics of the cortical bone on the microcracks. Objective: To investigate the effects of osteons, cement line and its material parameters on the stress intensity factor at the crack-tip based on theoretical formula calculation and finite element calculation. Results: The single osteon model, multi-osteon model and Haversian cortical bone model were established according to the microstructural characteristics of Haversian cortical bone. The calculation results of the first two models show that the “soft” osteon accelerates the crack propagation and the “hard” osteon hinders crack propagation, and the effect of multi-osteon model on a microcrack is significantly larger than that of single bone model. The calculation results of Haversian cortical bone model show that the stress intensity factors at both ends of the microcrack decreased when the distance from the “soft” osteon was within a certain range ([Formula: see text]). The stress intensity factor of endpoint ‘a’ in the crack-tip increases sharply when the microcrack is close to the osteon. Conclusions: The analysis results of the three models present that the microcrack propagation is affected by the material properties as well as the quantity of osteon, and the cement line is conductive to enhance the fracture toughness of the cortical bone.