Bone Microstructure Parameters Research Articles

PASSIVE BICYCLE TRAINING STIMULATES EPIPHYSEAL BONE FORMATION AND RESTORES BONE INTEGRITY INDEPENDENT OF LOCOMOTOR RECOVERY IN A RAT SPINAL CORD INJURY MODEL.

It is unknown whether activity-based physical therapy (ABPT) modalities that mobilize the paralyzed limbs improve bone integrity at the highly fracture-prone epiphyseal regions of the distal femur and proximal tibia following severe spinal cord injury (SCI). In this study, four-months-old skeletally-mature littermate-matched male Sprague-Dawley rats received SHAM surgery or severe contusion SCI. At 1-week post-surgery, SCI rats were stratified to undergo no-ABPT or two 20-minute bouts/day of quadrupedal bodyweight-supported treadmill training (qBWSTT) or hindlimb passive-isokinetic bicycle (Cycle) training, 5-days/week for another 3-weeks. We assessed locomotor recovery and plantar flexor muscle mass, tracked cancellous and cortical bone microstructure at the distal femoral and proximal tibial epiphyses using in vivo microCT, and evaluated bone turnover at the tibial epiphysis with histomorphometry. All SCI animals displayed persistent hindlimb paralysis and pervasive muscle atrophy. Over the initial 2-weeks, which included 1-week of no exercise and 1-week of ABPT acclimation, a similar magnitude of bone loss developed in all SCI groups. Thereafter, cancellous bone loss and cortical bone decrements increased in the SCI no-ABPT group. qBWSTT attenuated this trabecular bone loss but did not prevent the ongoing cortical bone deficits. In comparison, twice-daily Cycle training increased the number and activity of osteoblasts vs other SCI groups and restored all bone microstructural parameters to SHAM levels at both epiphyseal sites. These data indicate that a novel passive-isokinetic Cycle training regimen reversed cancellous and cortical bone deterioration at key epiphyseal sites after experimental SCI, via osteoblast-mediated bone anabolic mechanisms, independent of locomotor recovery or increased muscle mass.

Effect of Xanthohumol from Humulus lupulus L. Against Gouty Bone Damage in Arthritis of Rats Induced by Mono-sodium Urate.

Xanthohumol (XAN) is an isoprenyl flavonoid from Humulus lupulus L. known for beer brewing, and an osteoprotective agent due to its active improvement in bone loss of osteoporosis. This study was first time to investigate its effects on anti-gouty bone injury in rats of gouty arthritis (GA) induced by monosodium urate (MSU). Results showed that XAN could significantly exert anti-inflammatory activity by alleviating swelling degree of joints, reducing serum level of inflammatory factors, improving inflammatory injury and degrading the Markin's score in lesion joint. Meanwhile, XAN could also fight against gouty bone damage by improving pathological changes of bone tissue and parameters of bone micro-structure. Moreover, XAN could even promote bone formation by effectively enhancing expression of Runx2 and OPG, while inhibit bone resorption with depressing matrix metalloproteinase-9 (MMP-9), MMP-13 and CTSK expression, reducing RANKL secretion, and abating the ratio of RANKL/OPG. Therefore, it was the first time to reveal the mechanism of XAN against gouty bone injury via inhibiting RANKL/OPG/RANK signaling pathway. Above all, this study provided potential strategy for the treatment of GA, and further contributed to research and resource development for hops.

Total Flavonoids Isolated from the Leaves of Eucommia ulmoides Augment Peak Bone Mass in Female Rats and Show no Side Effects in Other Organs.

Eucommia ulmoides is a unique monophyletic and tertiary relict in China and is listed as a national second-class precious protected tree species. Eucommia ulmoides, recognized as a traditional Chinese medicine, can tonify the liver and kidneys and strengthen bones and muscles. Modern pharmacological research has proved that Eucommia ulmoides has multiple osteoprotective effects, including prohibiting the occurrence of osteoporosis and arthritis and enhancing the healing of bone fractures and bone defects. To check its osteotropic effects, which may provide ideas for its potential use for the development of novel drugs to treat osteoporosis, this study evaluated the effect of total flavonoids from Eucommia ulmoides leaves (TFEL) on the acquisition of Peak Bone Mass (PBM) in young female rats. TFEL was isolated, and its purity was confirmed by using a UV spectrophotometer. TFEL with a purity of 85.09% was administered to 6-week-old female rats by oral gavage at a low (50), mid (100), or high (200 mg/kg/d) dose, and the control group was administrated only with the same volume of water. After 13 weeks of treatment, the rats were sacrificed, and serum, different organs, and limb bones (femurs and tibias) were harvested, and the bone turnover markers, organ index, Bone Mineral Density (BMD), biomechanical property, and microstructure parameters were assayed. Furthermore, molecular targets were screened, and network pharmacology analyses were conducted to reveal the potential mechanisms of action of TFEL. Oral administration of TFEL for 13 weeks decreased the serum level of bone resorption marker TRACP-5b. As revealed by micro-computer tomography analysis, it elevated BMD even at a low dose (50 mg/kg/d) and improved the microstructural parameters, which were also confirmed by H&E histological staining. However, TFEL showed no effects on body weights, organ index, and micromorphology in the uterus. In our network pharmacology study, an intersection analysis screened out 64 shared targets, with quercetin, kaempferol, naringenin, and apigenin regulating the greatest number of targets associated with osteoporosis. Flavonoids in Eucommia ulmoides inhibited the occurrence of osteoporosis potentially through targeting signaling pathways for calcium, VEGF, IL-17, and NF-κB. Furthermore, AKT1, EGFR, PTGS2, VEGFA, and CALM were found to be potentially important target genes for the osteoprotective effects of flavonoids in Eucommia ulmoides. The above results suggested that TFEL can be used to elevate the peak bone mass in adolescence in female individuals, which may prevent the occurrence of postmenopausal osteoporosis, and the good safety of TFEL also suggests that it can be used as a food additive for daily life to improve the bone health.

Evaluation of Bone Microstructure Parameters by Using Tomographic Methods and Compressive Strength Estimation

Objective: The aim of this study was to evaluate the microstructure of the mandible by micro computed tomography (µCT), cone beam computed tomography (CBCT) and computed tomography (CT) and to estimate the compressive strength of the bone based on the values obtained by these methods. Methods: Thirty specimens obtained from ex-vivo sheep mandible were scanned by µCT cone beam computed tomography and computed tomography. These specimens were also subjected to compression testing and compression strength values were calculated. Morphometric parameters were evaluated using ImageJ software Bland-Altman lower upper bound agreement and ICC coefficient were used to evaluate the agreement between the tomography methods used and the gold standard. Linear and multivariate stepwise regression analysis was performed to calculate the compression strength value based on the radiomorphometric parameters. Statistical significance level was accepted as .05. Results: Bone Surface/Total Volume, Bone Volume/Total Volume and Degree of Anistoropy parameters evaluated by CBCT and Fractal Dimension parameter evaluated by CT showed a statistically significant agreement with the gold standard method µCT. Bone Volume/Total Volume and Degree of Anistoropy parameters obtained with µCT (R2:0.75), Bone Volume/Total Volume, Degree of Anistoropy , Connectivity Density parameters (R2:0.62), and the Structure Model Index parameter (R2:0.13) obtained by CT can be used to predict the compression strength value. Conclusion: Bone compression strength can be estimated by CBCT and µCT methods in a desired level. Bone Volume/Total Volume and Degree of Anistoropy parameters are significant determinants of bone mechanical property in not only µCT but also CBCT method.

TBS correlates with bone density and microstructure at trabecular and cortical bone evaluated by HR-pQCT.

Trabecular bone score (TBS) estimates bone microstructure, which is directly measured by high-resolution peripheral quantitative computed tomography (HRpQCT). We evaluated the correlation between these methods and TBS influence on fracture risk assessed by FRAX. We evaluated 129 individuals (82 women, 43 postmenopausal) 20 to 82.3 years without prevalent clinical or non-clinical morphometric vertebral fractures, using DXA (spine and hip), HR-pQCT at distal radius (R) and tibia (T) and TBS which classifies bone microarchitecture as normal (TBS ≥ 1.350), partially degraded (1.200 < TBS < 1.350), or degraded (TBS ≤ 1.200). Spine and hip BMD and HR-pQCT parameters at cortical bone: area (T), density (R,T) thickness (T) and trabecular bone: density (R,T), number (T) and thickness (R) were significantly better in the 78 individuals with normal TBS (group 1) versus the 51 classified as partially degraded (n = 42) or degraded microarchitecture (n = 9) altogether (group 2). TBS values correlated with age (r = -0.55), positively with spine and hip BMD and all cortical and trabecular bone density and microstructure parameters evaluated, p < 0.05 all tests. Binary logistic regression defined age (p = 0.008) and cortical thickness (p = 0.018) as main influences on TBS, while ANCOVA demonstrated that HR-pQCT data corrected for age were not different between TBS groups 1 and 2. TBS adjustment increased FRAX risk for major osteoporotic fractures and hip fractures. We describe significant association between TBS and both trabecular and cortical bone parameters measured by HR-pQCT, consistent with TBS influence on fracture risk estimation by FRAX, including hip fractures, where cortical bone predominates.

Lactobacillus plantarum attenuates glucocorticoid-induced osteoporosis by altering the composition of rat gut microbiota and serum metabolic profile.

Osteoporosis, one of the most common non-communicable human diseases worldwide, is one of the most prevalent disease of the adult skeleton. Glucocorticoid-induced osteoporosis(GIOP) is the foremost form of secondary osteoporosis, extensively researched due to its prevalence.Probiotics constitute a primary bioactive component within numerous foods, offering promise as a potential biological intervention for preventing and treating osteoporosis. This study aimed to evaluate the beneficial effects of the probiotic Lactobacillus plantarum on bone health and its underlying mechanisms in a rat model of glucocorticoid dexamethasone-induced osteoporosis, using the osteoporosis treatment drug alendronate as a reference. We examined the bone microstructure (Micro-CT and HE staining) and analyzed the gut microbiome and serum metabolome in rats. The results revealed that L. plantarum treatment significantly restored parameters of bone microstructure, with elevated bone density, increased number and thickness of trabeculae, and decreased Tb.Sp. Gut microbiota sequencing results showed that probiotic treatment increased gut microbial diversity and the ratio of Firmicutes to Bacteroidota decreased. Beneficial bacteria abundance was significantly increased (Lachnospiraceae_NK4A136_group, Ruminococcus, UCG_005, Romboutsia, and Christensenellaceae_R_7_group), and harmful bacteria abundance was significantly decreased (Desulfovibrionaceae). According to the results of serum metabolomics, significant changes in serum metabolites occurred in different groups. These differential metabolites were predominantly enriched within the pathways of Pentose and Glucuronate Interconversions, as well as Propanoate Metabolism. Furthermore, treatment of L. plantarum significantly increased serum levels of Pyrazine and gamma-Glutamylcysteine, which were associated with inhibition of osteoclast formation and promoting osteoblast formation. Lactobacillus plantarum can protect rats from DEX-induced GIOP by mediating the "gut microbial-bone axis" promoting the production of beneficial bacteria and metabolites. Therefore L. plantarum is a potential candidate for the treatment of GIOP.

Catalpol attenuates osteoporosis in ovariectomized rats through promoting osteoclast apoptosis via the Sirt6-ERα-FasL axis

BackgroundCatalpol, a major active component of the Chinese herb Rehmannia glutinosa, possesses various pharmacological benefits, including anti-inflammatory, antidiabetic, and antitumor properties. Recent studies have reported that catalpol can attenuate bone loss and enhance bone formation. Nevertheless, the molecular mechanisms underlying its effects on osteoporosis pathogenesis remain unclear. PurposeWe investigated whether catalpol had a protective effect against postmenopausal osteoporosis (PMOP) and explored its exact mechanism of action. MethodsSeventy-two rats were randomly divided into six groups: sham, model, low-dose catalpol (5 mg/kg/day), medium-dose catalpol (10 mg/kg/day), high-dose catalpol (20 mg/kg/day), and positive control (alendronate, 2.5 mg/kg). In this experiment, a ovariectomy was performed to establish a female rat model of PMOP. After 12 weeks of gavage, micro-computed tomography (micro-CT) and histochemical staining were performed to evaluate bone mass, bone microstructure and histological parameters. Furthermore, RAW 264.7 cells were induced by RANKL to form mature osteoclasts to investigate the effect of catalpol on osteoclast differentiation and apoptosis in vitro. Additionally, the osteoclast apoptosis-related proteins of Sirt6, ERα, FasL, NFATc1, cleaved-caspase 8, cleaved-caspase 3, and Bax were assessed using western blotting. The expressions of NFATc1, Ctsk, Oscar, and Trap were quantified using RT-qPCR. The apoptotic rate of the osteoclasts was determined using flow cytometry. Sirt6 knockdown was performed using siRNA gene silencing in experiments to investigate its role in catalpol-mediated osteoclast apoptosis. The deacetylation of ERα in osteoclasts was tested via co-immunoprecipitation. ResultsCatalpol (10 and 20 mg/kg) and alendronate (2.5 mg/kg) could significantly improve bone mineral density (BMD) and microstructure and decrease osteoclast density in ovariectomized (OVX) rats. In addition, catalpol (10 and 20 mg/kg) upregulated the expression of Sirt6, ERα, FasL, cleaved-caspase 8, cleaved-caspase 3, Bax, and downregulated the expression of NFATc1, Ctsk, Oscar, Trap both in vivo and in vitro. Catalpol also promoted ERα deacetylation and stabilized ERα protein to enhance the expression of FasL. In addition, Sirt6 knockdown by siRNA prevented ERα deacetylation and eliminated catalpol-mediated osteoclast apoptosis. ConclusionsThe present study demonstrated that catalpol prevents estrogen deficiency-induced osteoporosis by promoting osteoclast apoptosis via the Sirt6-ERα-FasL axis. These findings revealed a novel molecular mechanism underpinning the impact of catalpol in the progression of osteoporosis and provided novel insights into the treatment of osteoporosis.

Association of TNF-α, IGF-1, and IGFBP-1 levels with the severity of osteopenia in mice with nonalcoholic fatty liver disease

BackgroundsNonalcoholic fatty liver disease (NAFLD) exhibits a close association with osteoporosis. This work aims to assess the potential effects of NAFLD on the progression of osteopenia in animal models.MethodsForty-eight C57BL/6 female mice were randomly divided to wild-type (WT) group and high-fat diet (HFD) group. The corresponding detections were performed after sacrifice at 16, 24 and 32 weeks, respectively.ResultsAt 16 weeks, an remarkable increase in body weight and lipid aggregation in the hepatocytes of HFD group was observed compared to the WT group, while the bone structure parameters showed no significant difference. At 24 weeks, the levels of TNF-α and IL-6 in NAFLD mice were significantly increased, while the level of osteoprotegerin mRNA in bone tissue was decreased, and the level of receptor activator of nuclear factor Kappa-B ligand mRNA was increased. Meanwhile, the function of osteoclasts was increased, and the bone microstructure parameters showed significant changes. At 32 weeks, in the HFD mice, the mRNA levels of insulin-like growth factor-1 (IGF-1), runt-related transcription factor 2, and osterix mRNA were reduced, while the insulin-like growth factor binding protein-1 (IGFBP-1) level was increased. Simultaneously, the osteoblast function was decreased, and the differences of bone structure parameters were more significant, showing obvious osteoporosis.ConclusionsThe bone loss in HFD mice is pronounced as NAFLD progresses, and the changes of the TNF-α, IL-6, IGF-1, and IGFBP-1 levels may play critical roles at the different stages of NAFLD in HFD.

Total Flavonoids from Rhizoma Drynariae (Gusuibu) Alleviates Diabetic Osteoporosis by Activating BMP2/Smad Signaling Pathway.

Diabetic osteoporosis (DOP) is a widespread public health problem. The flavonoids of Rhizoma Drynariae (RDF) have a clear preventive and therapeutic effect on osteoporosis (OP), but it is not yet clear whether RDF has an anti-DOP and whether its mechanism is related to the activation of the BMP2/Smad signaling pathway. The current study aimed to study this effect of RDF in DOP rats and the possible involvement of the BMP2/Smad signaling pathway activation. Following intragastric administration of RDF for 12 weeks, the body weight, blood glucose, and the bone histopathological changes detected by hematoxylin-eosin (H&E) and calcein staining were monitored, while bone parameters were regularly assessed from observations made by micro-CT. At the end of the experiment, the expression of Bmp2, Bmpr1a, Runx2, and Smad4/5 genes was detected by real-time PCR (RT-PCR). Meanwhile, western blotting or immunohistochemical staining monitored the protein expressions of BMP2, RUNX2, and SMAD5 in the bone. The results firstly indicated that RDF significantly alleviated the signs and symptoms of DOP, which manifested as improved body weight and blood glucose. As obtained from the results of histopathology and micro-CT, RDF could promote the formation of bone trabeculae and alter several the bone microstructure parameters, including an increase in the bone volume/total volume (BV/TV), connective density (Conn-Dens), and trabecular bone number (Tb.N), as well as a decrease in the trabecular spacing (Tb.Sp). The western blotting analysis and RT-PCR results also confirmed that RDF could markedly increase the mRNA expression levels of Bmp2, Bmpr1α, Smad4, Runx2, and Smad5 in the bone, as well as the corresponding protein expression levels of BMP2, RUNX2, and SMAD5. These results reveal that RDF can activate the BMP2/Smad signaling pathway, thus promoting bone remodeling in DOP rats. RDF can increase bone trabeculae and bone mineral density by promoting bone formation and inhibiting bone absorption, thereby playing a role in improving DOP. This effect is related to the regulation of the BMP2/Smad signaling pathway.

Arctiin attenuates iron overload‑induced osteoporosis by regulating the PI3K/Akt pathway.

Iron overload is a prevalent pathological factor observed among elderly individuals and those with specific hematological disorders, and is frequently associated with an elevated incidence of osteoporosis. Although arctiin (ARC) has been shown to possess antioxidant properties and the ability to mitigate bone degeneration, its mechanism of action in the treatment of iron overload‑induced osteoporosis (IOOP) remains incompletely understood. To explore the potential molecular mechanisms underlying the effects of ARC, the MC3T3‑E1 cell osteoblast cell line was used. Cell Counting Kit was used to assess MC3T3‑E1 cell viability. Alkaline phosphatase staining and alizarin red staining were assessed for osteogenic differentiation. Calcein AM assay was used to assess intracellular iron concentration. In addition, intracellular levels of reactive oxygen species (ROS), lipid peroxides, mitochondrial ROS, apoptosis rate and mitochondrial membrane potential changes in MC3T3‑E1 cells were examined using flow cytometry and corresponding fluorescent dyes. The relationship between ARC and the PI3K/Akt pathway was then explored by western blotting and immunofluorescence. In addition, the effects of ARC on IOOP was verified using an iron overload mouse model. Immunohistochemistry was performed to evaluate expression of osteogenesis‑related proteins. Micro-CT and H&E were used to analyze bone microstructural parameters and histomorphometric indices in the bone tissue. Notably, ARC treatment reversed the decreased viability and increased apoptosis in MC3T3‑E1 cells originally induced by ferric ammonium citrate, whilst promoting the formation of mineralized bone nodules in MC3T3‑E1 cells. Furthermore, iron overload induced a decrease in the mitochondrial membrane potential, augmented lipid peroxidation and increased the accumulation of ROS in MC3T3‑E1 cells. ARC not only positively regulated the anti‑apoptotic and osteogenic capabilities of these cells via modulation of the PI3K/Akt pathway, but also exhibited antioxidant properties by reducing oxidative stress. Invivo experiments confirmed that ARC improved bone microarchitecture and biochemical parameters in a mouse model of iron overload. In conclusion, ARC exhibits potential as a therapeutic agent for IOOP by modulating the PI3K/Akt pathway, and via its anti‑apoptotic, antioxidant and osteogenic properties.

The orthodontic implant site-switching technique: a preliminary study in dogs

BackgroundTo evaluate the quantity and quality of bone in the newly formed edentulous area produced by the orthodontic implant site-switching technique.MethodsThe bilateral maxillary first premolars of five beagle dogs were extracted and bone defects were created. The right and left sides of the maxilla were randomly divided into control and experimental sides. On the experimental side, the maxillary second premolar was mesially moved into the position of the missing first premolar. On the control side, the second maxillary premolar was extracted. Six months later, the beagles were euthanized. Microcomputer tomography was used to analyze bone microstructure parameters, alveolar bone height and alveolar bone width of the regenerated bone. Histological analysis was performed by staining tissue sections with toluidine blue.ResultsMedian BV/TV values in the experimental group (81.78%) were significantly larger than those in the control group (35.67%; p = 0.04). Median Tb.Sp values in the experimental group (0.14 mm) were significantly lower than those in the control group (0.54 mm; p = 0.04). Median Tb.Th values in the experimental group (0.48 mm) were significantly higher than those in the control group (0.21 mm; p = 0.04). Median Tb.Pf values in the experimental group (0.65/mm) were significantly lower than those in the control group (3.15/mm; p = 0.04). There was no significant difference in the trabecular number (Tb.N) between the two groups (p = 0.23). The median alveolar bone height values in the experimental group (-0.81 mm) were significantly higher than those in the control group (-2.11 mm; p = 0.04) at a distance 5 mm from the mesial CEJ of the third premolar. The median alveolar bone height values in the experimental group (0.45 mm) were significantly higher than those in the control group (-1.70 mm; p = 0.04) at a distance 6 mm from the mesial CEJ of the third premolar. There was no significant difference in alveolar bone width when compared between the two groups (p > 0.05).ConclusionsThe newly formed edentulous area created by orthodontic treatment had more compact and thicker trabeculae than the extraction socket. Furthermore, the newly formed edentulous area had a greater alveolar bone height available for the placement of implants.

Nifedipine attenuates alveolar bone destruction and improves trabecular microarchitectures in mice with experimental periodontitis.

Studies have shown that nifedipine exerts anti-inflammatory and immunosuppressive actions in addition to being a calcium channel blocker. The present study was performed to explore the influence of nifedipine on alveolar bone destruction in mice with experimental periodontitis by evaluating morphological information acquired from micro-computed tomography analysis. BALB/c mice were randomly assigned into four groups: control (C) group; experimental periodontitis (E) group; experimental periodontitis + 10mg/kg dose of nifedipine (EN10) group; and experimental periodontitis + 50mg/kg dose of nifedipine (EN50) group. Periodontitis was induced by oral inoculation with Porphyromonas gingivalis over a 3-week time period. Nifedipine significantly mitigated the loss of alveolar bone height as well as increase of root surface exposure induced by experimental periodontitis. Additionally, the reduction in the bone volume fraction associated with P. gingivalis infection was significantly recovered upon nifedipine treatment. Further, nifedipine attenuated P. gingivalis-induced deteriorations in the trabeculae-associated parameters. Significant difference was evident between Groups EN10 and EN50 in both the extent of alveolar bone loss and microstructural parameters assessed, except trabecular separation and trabecular number. Nifedipine appeared to have good performance in ameliorating bone loss in mice with induced periodontitis. Nifedipine may be utilized in the clinical management of periodontitis, though further research is indicated to verify the therapeutic effect.

Low Circulating Valine Associate With High Risk of Hip Fractures.

Hip fractures constitute a major health concern. An adequate supply of amino acids is crucial to ensure optimal acquisition and remodeling of bone. Circulating amino acid levels have been proposed as markers of bone mineral density, but data on their ability to predict incident fractures are scarce. To investigate the associations between circulating amino acids and incident fractures. We used UK Biobank (n = 111 257; 901 hip fracture cases) as a discovery cohort and the Umeå Fracture and Osteoporosis (UFO) hip fracture study (hip fracture cases n = 2225; controls n = 2225) for replication. Associations with bone microstructure parameters were tested in a subsample of Osteoporotic Fractures in Men Sweden (n = 449). Circulating valine was robustly associated with hip fractures in the UK Biobank (HR per SD increase 0.79, 95% CI 0.73-0.84), and this finding was replicated in the UFO study (combined meta-analysis including 3126 incident hip fracture cases, odds ratio per SD increase 0.84, 95% CI 0.80-0.88). Detailed bone microstructure analyses showed that high circulating valine was associated with high cortical bone area and trabecular thickness. Low circulating valine is a robust predictor of incident hip fractures. We propose that circulating valine may add information for hip fracture prediction. Future studies are warranted to determine whether low valine is causally associated with hip fractures.

CARTILAGE AND SUBCHONDRAL BONE CHANGES IN OSTEOARTHRITIS CAN BE DETECTED QUANTITATIVELY USING IN VIVO IMAGING

Cartilage diseases have a significant impact on the patient's quality of life and are a heavy burden for the healthcare system. Better understanding, early detection and proper follow-up could improve quality of life and reduce healthcare related costs. Therefore, the aim of this study was to evaluate if difference between osteoarthritic (OA) and non-osteoarthritic (non-OA) knees can be detected quantitatively on cartilage and subchondral bone levels with advanced but clinical available imaging techniques.Two OA (mean age = 88.3 years) and three non-OA (mean age = 51.0 years) human cadaveric knees were scanned two times. A high-resolution peripheral quantitative computed tomography (HR-pQCT) scan (XtremeCT, Scanco Medical AG, Switzerland) was performed to quantify the bone microstructure. A contrast-enhanced clinical CT scan (GE Revolution Evo, GE Medical Systems AG, Switzerland) was acquired with the contrast agent Visipaque 320 (60 ml) to measure cartilage. Subregions dividing the condyle in four parts were identified semi-automatically and the images were segmented using adaptive thresholding. Microstructural parameters of subchondral bone and cartilage thickness were quantified.The overall cartilage thickness was reduced by 0.27 mm between the OA and non-OA knees and the subchondral bone quality decreased accordingly (reduction of 33.52 % in BV/TV in the layer from 3 to 8 mm below the cartilage) for the femoral medial condyle. The largest differences were observed at the medial part of the femoral medial condyle both for cartilage and for bone parameters, corresponding to clinical observations.Subchondral bone microstructural parameters and cartilage thickness were quantified using in vivo available imaging and apparent differences between the OA and non-OA knees were detected. Those results may improve OA follow-up and diagnosis and could lead to a better understanding of OA. However, further in vivo studies are needed to validate these methods in clinical practice.

Diosgenin reduces bone loss through the regulation of gut microbiota in ovariectomized rats

Diosgenin (DIO) is an aglycone of steroid saponins acquired from plants, including Dioscorea alata, Smilax China, and Trigonella foenum graecum, acting as an anti-osteoporosis, anti-diabetic, anti-hyperlipidemic, anti-inflammatory. Recent studies have demonstrated that DIO reduces bone loss. This study aimed to investigate the effects of DIO on the gut microbiota (GM) of ovariectomized (OVX) osteoporotic rats. Female Sprague-Dawley rats were randomly divided into sham operation (sham + vehicle group) or ovariectomy. For 12 weeks, OVX rats were treated using a vehicle (OVX + vehicle group) and DIO (OVX + DIO group). Subsequently, ELISA was conducted to determine serum estradiol levels, micro-CT scanning was performed to evaluate bone quality, and feces were collected for metagenomics sequencing to examine the structure and function of GM. Raw reads were filtered to remove chimera sequences. Operational taxonomic units (OTUs) were clustered in the filtered reads. A Venn diagram analysis was conducted to study the common and unique OTUs in the sham + vehicle, OVX + vehicle, and OVX + DIO groups. LEfSe analysis was conducted to evaluate the specific GM of the three groups. The GM functions were analyzed using the KEGG and CAZy databases. After a 12-week treatment, DIO administration prevented OVX-induced weight gain and increased the estradiol levels. DIO treatment improved the bone microstructure and structural parameters of rat tibias. Metagenomics sequencing results identified 1139, 1207, and 1235 operational taxonomic units (OTUs) in the sham + vehicle, OVX + vehicle, and OVX + DIO groups, respectively. The percentage of common OTUs was 41.2%. Treatment with DIO restored the composition of GM in OVX rats by increasing the abundance of Coriobacteriia Adlercreutzia, Romboutsia, and Romboutsia_idealis and reducing the abundance of Betaproteobacteria, Gammaproteobacteria, Methanobacteria, Bacteroides, Phocaeicola, Alistipes, Bacteroids_uniformis, Bacteroids_xylanisolvens. The anti-osteoporosis effect of DIO can be regulated through environmental information processing, organismal Systems, Cellular Processes, human diseases, metabolism, and genetic information processing. Meanwhile, treatment with DIO improved GM homeostasis by increasing the metabolism of carbohydrates, other amino acids, and glycans and reducing translation, energy metabolism, and nucleotide metabolism. DIO can reduce bone loss by regulating the structural composition and function of GM, a novel strategy for preventing osteoporosis.

Bone metastases do not affect the measurement uncertainties of a global digital volume correlation algorithm.

Introduction: Measurement uncertainties of Digital Volume Correlation (DVC) are influenced by several factors, like input images quality, correlation algorithm, bone type, etc. However, it is still unknown if highly heterogeneous trabecular microstructures, typical of lytic and blastic metastases, affect the precision of DVC measurements. Methods: Fifteen metastatic and nine healthy vertebral bodies were scanned twice in zero-strain conditions with a micro-computed tomography (isotropic voxel size = 39 μm). The bone microstructural parameters (Bone Volume Fraction, Structure Thickness, Structure Separation, Structure Number) were calculated. Displacements and strains were evaluated through a global DVC approach (BoneDVC). The relationship between the standard deviation of the error (SDER) and the microstructural parameters was investigated in the entire vertebrae. To evaluate to what extent the measurement uncertainty is influenced by the microstructure, similar relationships were assessed within sub-regions of interest. Results: Higher variability in the SDER was found for metastatic vertebrae compared to the healthy ones (range 91-1030 με versus 222-599 με). A weak correlation was found between the SDER and the Structure Separation in metastatic vertebrae and in the sub-regions of interest, highlighting that the heterogenous trabecular microstructure only weakly affects the measurement uncertainties of BoneDVC. No correlation was found for the other microstructural parameters. The spatial distribution of the strain measurement uncertainties seemed to be associated with regions with reduced greyscale gradient variation in the microCT images. Discussion: Measurement uncertainties cannot be taken for granted but need to be assessed in each single application of the DVC to consider the minimum unavoidable measurement uncertainty when interpreting the results.

Differential toxicity profile of secreted and processed α-Klotho expression over mineral metabolism and bone microstructure

The aging-protective gene α-Klotho (KL) produces two main transcripts. The full-length mRNA generates a transmembrane protein that after proteolytic ectodomain shedding can be detected in serum as processed Klotho (p-KL), and a shorter transcript which codes for a putatively secreted protein (s-KL). Both isoforms exhibit potent pleiotropic beneficial properties, although previous reports showed negative side effects on mineral homeostasis after increasing p-KL concentration exogenously. Here, we expressed independently both isoforms using gene transfer vectors, to assess s-KL effects on mineral metabolism. While mice treated with p-KL presented altered expression of several kidney ion channels, as well as altered levels of Pi and Ca2+ in blood, s-KL treated mice had levels comparable to Null-treated control mice. Besides, bone gene expression of Fgf23 showed a fourfold increase after p-KL treatment, effects not observed with the s-KL isoform. Similarly, bone microstructure parameters of p-KL-treated mice were significantly worse than in control animals, while this was not observed for s-KL, which showed an unexpected increase in trabecular thickness and cortical mineral density. As a conclusion, s-KL (but not p-KL) is a safe therapeutic strategy to exploit KL anti-aging protective effects, presenting no apparent negative effects over mineral metabolism and bone microstructure.

Identification of key miRNAs in unilateral mastication-induced disruption of cartilage homeostasis.

The present study identified potentially pivotal miRNAs contributing to chondrogenic differentiation in temporomandibular joint suffering abnormal stress. Sprague-Dawley rats were randomly divided into control and experimental unilateral mastication (EUM) group. Bone micro-structure parameters was detected by micro-CT, and FGF-1 and MMP-1 expression was examined by immunohistochemistry. Differentially expressed miRNAs of bilateral condyle cartilage were screened via miRNA microarray at 4- and 8-week EUM, then further verified using quantitative reverse-transcription PCR. Over-expression of five differentially expressed miRNAs in chondrocytes was triggered by transfecting miRNA mimics. The expression of MMP-13, Col-II, OPN, and Runx2 was verified by western blotting. Expressions of FGF-1 and MMP-1 in right condyles gradually increased from 2 to 6 weeks after EUM. A total of 20 differentially expressed miRNAs were regulated by EUM, which related to cell proliferation, invasion, and osteoblast differentiation pathways. The over-expression of miR-148a-3p and miR-1-3p led to down-regulation of Col-II, while MMP-13 and Runx2 were up-regulated by induction of hypotrophic differentiation or IL-1β stimulation. These findings suggested that miR-148a-3p and miR-1-3p promote chondrogenic differentiation. Several pivotal miRNAs were found to be related to chondrogenic differentiation, which provides novel insight into pathogenic mechanisms of cartilage homeostasis.

Associations between cortical bone-to-implant contact and microstructure derived from CBCT and implant primary stability.

To evaluate the associations between the cortical bone-to-implant contact (CBIC), bone microstructure derived from cone-beam computed tomography (CBCT), and the primary stability of the implant. Twenty-two patients with 65 implants were enrolled in this study. The peak insertion torque values (ITVs) were measured during implant insertion, and the implant stability quotient (ISQ) values were measured immediately after implant placement and 3months after surgery. The profiles of the peri-implant bone structure were outlined using the volumetric reconstruction of the CBCTs and superimposition of the virtual models, and the features of CBIC and bone microstructure parameters were measured. The linear mixed effects model and generalized estimating equation were used to explore the predictors for implant primary stability. The average ITV, baseline, and secondary ISQ values were 31.44 ± 6.54 N·cm, 73.34 ± 7.39, and 80.32 ± 4.58, respectively. Statistically significant correlations were found between ITV and surface area of CBIC (r= .340, p= .006), bone volume fraction (r= .294, p= .017), and bone surface fraction (r= -.278, p= .039). Implants with buccolingual CBIC had a higher ITV than implants without CBIC (p= .016). None of the parameters were associated with baseline and secondary ISQ values in generalized estimating equation analysis (all p> .05). Within the limitations of the study, preoperative CBCT measurements might enable the prediction of ITV and therefore of implant primary stability values.

Open-source pipeline for automatic segmentation and microstructural analysis of murine knee subchondral bone.

A segmented dataset of μCT scans from 62 knees (healthy and arthritic) from 10-week male C57BL/6 mice was used to train a U-Net type architecture to automate segmentation of the subchondral trabecular bone. These segmentations were used in tandem with the original scans as input for microstructural analysis along with thresholded trabecular bone. Manually and U-Net segmented ROIs were fed into two available pipelines for microstructural analysis: the ITKBoneMorphometry library and CTan (SKYSCAN). Outcome parameters were compared between pipelines, including: bone volume (BV), total volume (TV), BV/TV, trabecular number (TbN), trabecular thickness (TbTh), trabecular separation (TbSp), and bone surface density (BSBV). There was good agreement for all bone measures comparing the manual and U-Net pipelines utilizing ITK (R = 0.88-0.98) and CTAn (R = 0.91-0.98). ITK and CTAn showed good agreement for BV, TV, BV/TV, TbTh and BSBV (R = 0.9-0.98). However, limited agreement was seen between TbN (R = 0.73) and TbSb (R = 0.59) due to methodological differences in how spacing is evaluated. Microstructural parameters generated from manual and automatic segmentations showed high correlation across all measures. Using the CTAn pipeline yielded strong R2 values (0.83-0.96) and very strong agreement based on ICC (0.90-0.98). The ITK pipeline yielded similarly high R2 values (0.91-0.96, except for TbN (0.77)), and ICC values (0.88-0.98). The automated segmentations yield lower average values for BV, TV and BV/TV (ranging from 14 % to 6.3 %), but differences were not found to be influenced by the mean ROI values. This integrated pipeline seamlessly automated both segmentation and quantification of the proximal tibia subchondral bone microstructure. This automated pipeline allows the analysis of large volumes of data, and its open-source nature may enable the standardization of microstructural analysis of trabecular bone across different research groups.