Bone Volume To Tissue Volume Research Articles

Gradient gyroid Ti6Al4V scaffolds with TiO2 surface modification: Promising approach for large bone defect repair

Large bone defects, particularly those exceeding the critical size, present a clinical challenge due to the limited regenerative capacity of bone tissue. Traditional treatments like autografts and allografts are constrained by donor availability, immune rejection, and mechanical performance. This study aimed to develop an effective solution by designing gradient gyroid scaffolds with titania (TiO2) surface modification for the repair of large segmental bone defects. The scaffolds were engineered to balance mechanical strength with the necessary internal space to promote new bone formation and nutrient exchange. A gradient design of the scaffold was optimized through Finite Element Analysis (FEA) and Computational Fluid Dynamics (CFD) simulations to enhance fluid flow and cell adhesion. In vivo studies in rabbits demonstrated that the G@TiO2 scaffold, featuring a gradient structure and TiO2 surface modification, exhibited superior healing capabilities compared to the homogeneous structure and TiO2 surface modification (H@TiO2) and gradient structure (G) scaffolds. At 12 weeks post-operation, in a bone defect representing nearly 30 % of the total length of the radius, the implantation of the G@TiO2 scaffold achieved a 27 % bone volume to tissue volume (BV/TV) ratio, demonstrating excellent osseointegration. The TiO2 surface modification provided photothermal antibacterial effects, enhancing the scaffold's biocompatibility and potential for infection prevention. These findings suggest that the gradient gyroid scaffold with TiO2 surface modification is a promising candidate for treating large segmental bone defects, offering a combination of mechanical strength, bioactivity, and infection resistance.

In situ fabrication of NIR-II responsive TiO2 bio-metasurface for photothermal antibacterial and enhanced osseointegration

Titanium implants, widely used in orthopedic and dental applications, often face challenges due to inadequate osseointegration and the risk of postoperative infections, which can potentially lead to implant failure. To address this issue, we developed a titanium implant with an in-situ fabricated anatase TiO2 metasurface, characterized by a subwavelength thickness and a preferential orientation of the (001) facets. This metasurface, which consists of uniformly distributed nano-crystallites of approximately 30 nm in size, aims to enhance both osseointegration and antibacterial properties. The addition of isopropanol (IPA) to the precursor solution used in the fabrication process played a crucial role in controlling the grain size and coating thickness of the metasurface. This process led to a redshift of the light absorption peak into the near-infrared (NIR)-II region, thereby increasing the penetration depth of photothermal therapy. The implants with TiO2 metasurface exhibited increased hydrophilicity, rapid apatite formation in simulated body fluid, and an effective photothermal response under NIR-II light, showing significant antibacterial activity against E. coli and S. aureus. In vivo experiments in rabbits indicated superior bone regeneration and osseointegration around the implants with TiO2 metasurface compared to the control titanium implants. At 4 weeks postoperatively, the bone volume to tissue volume (BV/TV) ratio within the implant was 53.94 %, and by 8 weeks, the implants were nearly entirely filled with new bone, with a BV/TV ratio of approximately 70 %. The findings suggest that the TiO2 metasurface, which combines antibacterial and bioactive features, has the potential to reduce the risk of postoperative infections and improve clinical outcomes.

Enhanced corrosion resistance, antibacterial properties and osteogenesis by Cu ion optimized MgAl-layered double hydroxide on Mg alloy

Magnesium (Mg) and its alloys have similar densities and elastic moduli to natural bone, making them an excellent choice for orthopedic implants. However, Mg alloys are prone to electrochemical corrosion, which often leads to implant failure and hinders the further development of Mg alloys due to bacterial infection around the implant. This work aims to enhance the corrosion resistance of Mg alloys, and provide theoretical guidance for solving the problem that Mg-based orthopedic implants are susceptible to bacterial infection and, thus, implant failure. In order to solve the corrosion problem, the Mg alloy AZ91D was used as the substrate, and a compact and uniform MgAlCu-layered double hydroxide (Mg(Cu)-LDH) was prepared on its surface using a hydrothermal method. The Mg(Cu)-LDH provides a barrier between the AZ91D and corrosive liquid, which effectively protects the Mg substrate from being corroded. The Mg(Cu)-LDH shows great cell viability for MC3T3-E1 cells. The Cu2+ and Mg2+ in the coating also endow the Mg(Cu)-LDH/AZ91D with antibacterial properties, showing strong antibacterial effects on both E. coli and S. aureus with antibacterial rates over 85%. Finally, in vivo results indicated that a LDH-coated implant had no systemic effects on the hearts, livers, spleens, lungs or kidneys. It was shown that 4 weeks after surgery the ratio of bone volume to tissue volume (BV/TV) of the LDH implant was 24%, which was 1.7 times that observed for AZ91D.

Morinda officinalis polysaccharide enable suppression of osteoclastic differentiation by exosomes derived from rat mesenchymal stem cells

Context Morinda officinalis F.C. How. (MO) (Rubiaceae) can strengthen bone function. Objective To examine the functional mechanism and effect of MO polysaccharides (MOPs) in rats with glucocorticoid-induced osteoporosis (GIOP). Materials and methods Rats with GIOP were treated with 5, 15 or 45 mL/kg of MOP [n = 15 for each dose, intraperitoneal (i.p.) injection every other day for 8 weeks]. The body weight of rats and histomorphology of bone tissues were examined. Bone marrow mesenchymal stem cells (BMSCs)-derived exosomes (Exo) were collected and identified. Bone marrow-derived macrophages (BMMs) were induced to differentiate into osteoclasts and treated with BMSC-Exo for in vitro studies. Results MOP reduced the body weight (5, 15, or 45 mg/kg MOP vs. phosphate-buffered saline: 8%, 15% and 25%, p < 0.01), elevated the bone volume to tissue volume (BV/TV), mean trabecular thickness (Tb.Th), mean trabecular number (Tb.N) and mean connectivity density (Conn.D) (40–86%, p < 0.01), decreased the mean trabecular separation/spacing (Tb.Sp) (22–37%, p < 0.01), increased the cortical bone continuity (35–90%, p < 0.01) and elevated RUNX family transcription factor 2 and RANK levels (5–12%, p < 0.01), but suppressed matrix metallopeptidase 9 and cathepsin K levels (9–20%, p < 0.01) in femur tissues. BMSC-Exo from MOP-treated rats (MOP-Exo) suppressed osteoclastic differentiation and proliferation of BMMs. The downregulation of microRNA-101-3p (miR-101-3p) or the upregulation of prostaglandin-endoperoxide synthase 2 (PTGS2) blocked the functions of MOP-Exo. Discussion and conclusions MOP inhibits osteoclastic differentiation and could potentially be used for osteoporosis management. This suppression may be enhanced by the upregulation of miR-101-3p or the inhibition of PTGS2.

Craniofacial Bones and Teeth in Spacefarers: Systematic Review and Meta-analysis.

Estimating the risk of dental problems in long-duration space missions to the Moon and Mars is critical for avoiding dental emergencies in an environment that does not support proper treatment. Previous risk estimates were constructed based on the experience in short-duration space missions and isolated environments on Earth. However, previous estimates did not account for potential changes in dental structures due to space travel, even though bone loss is a known problem for long-duration spaceflights. The objective of this study was to systematically analyze the changes in hard tissues of the craniofacial complex during spaceflights. Comprehensive search of Medline, Embase, Scopus, the NASA Technical Report Server, and other sources identified 1,585 potentially relevant studies. After screening, 32 articles that presented quantitative data for skull in humans (6/32) and for calvariae, mandible, and lower incisors in rats (20/32) and mice (6/32) were selected. Skull bone mineral density showed a significant increase in spacefaring humans. In spacefaring rodents, calvariae bone volume to tissue volume (BV/TV) demonstrated a trend toward increasing that did not reach statistical significance, while in mandibles, there was a significant decrease in BV/TV. Dentin thickness and incisor volume of rodent incisors were not significantly different between spaceflight and ground controls. Our study demonstrates significant knowledge gaps regarding many structures of the craniofacial complex such as the maxilla, molar, premolar, and canine teeth, as well as small sample sizes for the studies of mandible and incisors. Understanding the effects of microgravity on craniofacial structures is important for estimating risks during long-duration spaceflight and for formulating proper protocols to prevent dental emergencies. Avoiding dental emergencies in long-duration spaceflights is critical since this environment does not support proper treatment. Prior risk estimates did not account for changes in dental structures due to space travel. We reviewed and synthesized the literature for changes in craniofacial complex associated with spaceflight. The results of our study will help clinicians and scientists to better prepare to mitigate potential oral health issues in space travelers on long-duration missions.

Daidzein induces bone morphogenetic protein-2 and runt-related transcription 2 on periodontal ligament cells after experimental tooth movement

ABSTRACT Purpose To analysis, daidzein increases the expression of bone morphogenetic protein-2 (BMP-2) and runt-related transcription factor 2 (Runx2) after experimental tooth movement (EXTM). Materials and Methods 36 Wistar rats were randomly divided into the EXTM group and EXTM with daidzein group (EXTM+DZ group). After EXTM, the rats in the EXTM+DZ group were treated with daidzein (10 mg/kg/day). Micro-computed tomography (CT) analysis revealed the bone mineral density (BMD), ratio of bone volume to tissue volume (BV/TV), and ratio of relapse. Histopathological changes were examined by immunohistochemical staining for BMP-2 and Runx2. Human PDLCs were subjected to tension force and treated with 10 μg/mL daidzein. The expression of BMP-2 and Runx2 by daidzein was confirmed by real-time polymerase chain reaction and enzyme-linked immunosorbent assay. Results The EXTM+DZ group showed a significantly decreased ratio of relapse and increased BMD and BV/TV as compared to the EXTM group. The ratio of BMP-2 – and Runx-2 –positive cells in the EXTM+DZ group was higher than that in the EXTM group. Moreover, daidzein upregulated the mRNA expression and protein levels of BMP-2 and Runx2 in a time-dependent manner. Conclusion These results suggested that daidzein decreased the ratio of relapse through BMP-2 and Runx2 expression.

A Delphinidin-Enriched Maqui Berry Extract Improves Bone Metabolism and Protects against Bone Loss in Osteopenic Mouse Models.

In our previous investigation, delphinidin, one of the most abundant anthocyanins found in vegetables and berry fruits, had been shown to inhibit osteoclasts and prevent bone loss in mouse models of osteoporosis. In the present study, we investigated whether a delphinidin glycoside-enriched maqui berry extract (MBE, Delphinol®) exhibits beneficial effects on bone metabolism both in vitro and in vivo. MBE stimulated the osteoblastic differentiation of MC3T3-E1 cells, as indicated by enhanced mineralized nodule formation, and increased alkaline phosphatase activity, through the upregulation of bone morphogenetic protein 2 (Bmp2), runt-related transcription factor 2 (Runx2), osterix (Osx), osteocalcin (Ocn), and matrix extracellular phosphoglycoprotein (Mepe) mRNA expression. Immunostaining and immunoprecipitation assays demonstrated that MBE suppressed NF-κB transnucleation through acting as a superoxide anion/peroxynitrite scavenger in MC3T3-E1 cells. Simultaneously, MBE inhibited both osteoclastogenesis in primary bone marrow macrophages and pit formation by maturated osteoclasts on dentine slices. Microcomputed tomography (micro-CT) and bone histomorphometry analyses of femurs demonstrated that the daily ingestion of MBE significantly increased BV/TV (ratio of bone volume to tissue volume), Tb.Th (trabecular thickness), Tb.N (trabecular number), N.Nd/N.Tm (node to terminus ratio), OV/TV (ratio of osteoid volume to tissue volume), BFR/TV (bone formation rate per tissue volume), and significantly decreased Tb.Sp (trabecular separation), ES/BS (ratio of eroded surface to bone surface) and N.Oc/BS (number of osteoclast per unit of bone surface), compared to vehicle controls in osteopenic mouse models. These findings suggest that MBE can be a promising natural agent for the prevention of bone loss in osteopenic conditions by not only inhibiting bone resorption, but also stimulating bone formation.

11\u03b2-HSD1 plays a critical role in trabecular bone loss associated with systemic glucocorticoid therapy

BackgroundDespite their efficacy in the treatment of chronic inflammation, the prolonged application of therapeutic glucocorticoids (GCs) is limited by significant systemic side effects including glucocorticoid-induced osteoporosis (GIOP). 11β-Hydroxysteroid dehydrogenase type 1 (11β-HSD1) is a bi-directional enzyme that primarily activates GCs in vivo, regulating tissue-specific exposure to active GC. We aimed to determine the contribution of 11β-HSD1 to GIOP.MethodsWild type (WT) and 11β-HSD1 knockout (KO) mice were treated with corticosterone (100 μg/ml, 0.66% ethanol) or vehicle (0.66% ethanol) in drinking water over 4 weeks (six animals per group). Bone parameters were assessed by micro-CT, sub-micron absorption tomography and serum markers of bone metabolism. Osteoblast and osteoclast gene expression was assessed by quantitative RT-PCR.ResultsWild type mice receiving corticosterone developed marked trabecular bone loss with reduced bone volume to tissue volume (BV/TV), trabecular thickness (Tb.Th) and trabecular number (Tb.N). Histomorphometric analysis revealed a dramatic reduction in osteoblast numbers. This was matched by a significant reduction in the serum marker of osteoblast bone formation P1NP and gene expression of the osteoblast markers Alp and Bglap. In contrast, 11β-HSD1 KO mice receiving corticosterone demonstrated almost complete protection from trabecular bone loss, with partial protection from the decrease in osteoblast numbers and markers of bone formation relative to WT counterparts receiving corticosterone.ConclusionsThis study demonstrates that 11β-HSD1 plays a critical role in GIOP, mediating GC suppression of anabolic bone formation and reduced bone volume secondary to a decrease in osteoblast numbers. This raises the intriguing possibility that therapeutic inhibitors of 11β-HSD1 may be effective in preventing GIOP in patients receiving therapeutic steroids.

Petunidin, a B-ring 5'-O-Methylated Derivative of Delphinidin, Stimulates Osteoblastogenesis and Reduces sRANKL-Induced Bone Loss.

Several lines of evidence suggest that oxidative stress is one of the key pathogenic mechanisms of osteoporosis. We aimed to elucidate the bone protective effects of petunidin, one of the most common anthocyanidins, considering its potent antioxidative activity. Petunidin (>5 μg/mL) significantly inhibited osteoclastogenesis and downregulated c-fos, Nfatc1, Mmp9, Ctsk, and Dc-stamp mRNA expression in RAW264.7 cells. Conversely, petunidin (>16 μg/mL) stimulated mineralized matrix formation and gene expression of Bmp2 and Ocn, whereas it suppressed Mmp13, Mmp2, and Mmp9 mRNA expression and proteolytic activities of MMP13 and MMP9 in MC3T3-E1 cells. Micro-CT and bone histomorphometry analyses of sRANKL-induced osteopenic C57BL/6J mice showed that daily oral administration of petunidin (7.5 mg/kg/day) increased bone volume to tissue volume (BV/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N), the ratio of osteoid volume to tissue volume (OV/TV), osteoid thickness (O.Th), the ratio of osteoid surface to bone surface (OS/BS), the ratio of osteoblast surface to bone surface (Ob.S/BS), and the number of osteoblast per unit of bone surface (N.Ob/BS), and decreased trabecular separation (Tb.Sp), the ratio of eroded surface to bone surface (ES/BS), the ratio of osteoclast surface to bone surface (Oc.S/BS), and number of osteoclast per unit of bone surface (N.Oc/BS), compared to untreated mice. Furthermore, histological sections of the femurs showed that oral administration of petunidin to sRANKL-induced osteopenic mice increased the size of osteoblasts located along the bone surface and the volume of osteoid was consistent with the in vitro osteoblast differentiation and MMP inhibition. These results suggest that petunidin is a promising natural agent to improve sRANKL-induced osteopenia in mice through increased osteoid formation, reflecting accelerated osteoblastogenesis, concomitant with suppressed bone resorption.

Effect on Bone Architecture of Marginal Grooves in Dental Implants Under Occlusal Loaded Conditions in Beagle Dogs.

The aim of this study was to clarify whether marginal grooves on dental implants affect osseointegration, bone structure, and the alignment of collagen fibers to determine bone quality under loaded conditions. Anodized Ti-6Al-4V alloy dental implants, with and without marginal grooves (test and control implants, respectively), were used (3.7 × 8.0 mm). Fourth premolars and first molars of 6 beagle mandibles were extracted. Two control and test implants were placed in randomly selected healed sites at 12 weeks after tooth extraction. Screw-retained single crowns for first molars were fabricated. Euthanasia was performed at 8 weeks after the application of occlusal forces. Implant marginal bone level, bone to implant contact (BIC), bone structure around dental implants, and the alignment of collagen fibers determining bone quality were analyzed. The marginal bone level in test implants was significantly higher than that in control implants. Occlusal forces significantly increased BIC in test implants ( P = .007), whereas BIC did not change in control implants, irrespective of occlusal forces ( P = .303). Moreover, occlusal forces significantly increased BIC in test implants compared with control implants ( P = .032). Additionally, occlusal forces preferentially aligned collagen fibers in test implants, but not control implants. Hence, marginal grooves on dental implants have positive effects on increased osseointegration and adapted bone quality based on the preferential alignment of collagen fibers around dental implants under loaded conditions.

Spinacia oleracea extract attenuates disease progression and sub-chondral bone changes in monosodium iodoacetate-induced osteoarthritis in rats

BackgroundSpinacia oleracea is an important dietary vegetable in India and throughout the world and has many beneficial effects. It is cultivated globally. However, its effect on osteoarthritis that mainly targets the cartilage cells remains unknown. In this study we aimed to evaluate the anti-osteoarthritic and chondro-protective effects of SOE on chemically induced osteoarthritis (OA).MethodsOA was induced by intra-patellar injection of monosodium iodoacetate (MIA) at the knee joint in rats. SOE was then given orally at 250 and 500 mg.kg− 1 day− 1 doses for 28 days to these rats. Anti-osteoarthritic potential of SOE was evaluated by micro-CT, mRNA and protein expression of pro-inflammatory and chondrogenic genes, clinically relevant biomarker’s and behavioural experiments.ResultsIn vitro cell free and cell based assays indicated that SOE acts as a strong anti-oxidant and an anti-inflammatory agent. Histological analysis of knee joints at the end of the experiment by safranin-o and toluidine blue staining established its protective effect. Radiological data corroborated the findings with improvement in the joint space and irregularity of the articular and atrophied femoral condyles and tibial plateau. Micro-CT analysis of sub-chondral bone indicated that SOE had the ability to mitigate OA effects by increasing bone volume to tissue volume (BV/TV) which resulted in decrease of trabecular pattern factor (Tb.Pf) by more than 200%. SOE stimulated chondrogenic marker gene expression with reduction in pro-inflammatory markers. Purified compounds isolated from SOE exhibited increased Sox-9 and Col-II protein expression in articular chondrocytes. Serum and urine analysis indicated that SOE had the potential to down-regulate glutathione S-transferase (GST) activity, clinical markers of osteoarthritis like cartilage oligometric matrix protein (COMP) and CTX-II. Overall, this led to a significant improvement in locomotion and balancing activity in rats as assessed by Open-field and Rota rod test.ConclusionOn the basis of in vitro and in vivo experiments performed with Spinacea oleracea extract we can deduce that SOE has the ability to alleviate the MIA induced deleterious effects.

Application of Plasma Sprayed Zirconia Coating in Dental Implant: Study in Implant.

The aim was to investigate the osseointegration of a novel coating-plasma-sprayed nanostructured zirconia (NSZ) in dental implant. Nanostructured zirconia coating on non-thread titanium implant was prepared by plasma spraying, the implant surface morphology, surface roughness and wettability were measured. In vivo, nanostructured zirconia-coated implants were inserted in rabbit tibia and animals were respectively sacrificed at 2, 4, 8 and 12 weeks after implantation. The bond strength between implant and bone was measured by removal torque (RTQ) test. The osseointegration was observed by scanning electron microscopy (SEM), micro computed tomography (Micro CT) and histological analyses. Quantified parameters were calculated, including removal torque, Bone Volume to Tissue Volume (BV/TV), Trabecular Thickness (Tb. Th), Trabecular Number (Tb. N), Trabecular Separation/Spacing (Tb. Sp), and Bone-Implant contact (BIC) percentage. The statistical differences were detected by two-tail Mann-Whitney U test (SPSS 20.0). The surface roughness (1.58µm) and wettability (54.61°) of nanostructured zirconia coated implant was more suitable than those of titanium implant (0.598µm and 74.38°) for osseointegration and hierarchical surface morphology could be seen on zirconia coating. The histological analyses showed that zirconia coated implant induced earlier and more condensed bone formation than titanium implant at 2 and 4 weeks. Quantified parameters showed the significant differences between these two groups at early healing period, but the differences between these two groups decreased with the increase of healing period. All these results demonstrated that plasma sprayed zirconia coated implant induced better bone formation than titanium implant at early stage.

Bone formation mediated by local administration of thymosin β4 in distraction osteogenesis

Objective To explore the effect and mechanism of local administration of thymosin β4 (Tβ4) on bone regeneration in a distraction osteogenesis model of rat femur. Methods Sixty Sprague-Dawley rats were randomly divided into groups A, B and C in this study. A distraction osteogenesis model was established in the left femur after osteotomy. At the end of distraction period, the bone regeneration area in group A was subjected to no treatment, that in group B to injection of phosphate buffer saline (PBS), and that in group C to injection of Tβ4. On days 22, 29 and 43 postoperatively, the rats from each group were randomly sacrificed and processed for observation of bone regeneration in the distraction osteogenesis area using radiography, Micro-CT, histology and immunohistochemical staining. RT-PCR was used to detect the ex-pression of related genes as well. Results Radiography revealed that the bone regeneration in group C was superior to that in groups A and B on days 22, 29 and 43 postoperatively. Micro-CT examination showed significantly increased bone volume (BV), bone mineral density (BMD) and ratio of bone volume to tissue volume (BV/TV) in group C on days 22, 29 and 43 postoperatively, and significantly decreased ratio of bone surface area to bone volume on postoperative day 43 in comparison with groups A and B(P<0.05). HE staining indicated that local capillary density was significantly higher in group C than in groups A and B after local administration of Tβ4 in the distraction osteogenesis. Immunohistochemical staining showed that the capillary density and osteoblasts in group C were higher than in groups A and B. RT-PCR results revealed significantly higher expression of eNOS and Osterix mRNA in the local callus in group C on postoperative day 22 than in groups A and group B (P<0.05). Conclusion Local administration of thymosin β4 may promote bone formation, which is probably related to the increased expression of eNOS and Osterix. Key words: Thymosin; Bone lengthening; Osteogenesis, distraction; External fixators

Assessment of articular cartilage and subchondral bone using EPIC-microCT in Labrador retrievers with incipient medial coronoid disease

The aetiopathogenesis of medial coronoid disease (MCD) remains obscure, despite its high prevalence. The role of changes to subchondral bone or articular cartilage is much debated. Although there is evidence of micro-damage to subchondral bone, it is not known whether this is a cause or a consequence of MCD, nor is it known whether articular cartilage is modified in the early stages of the disease. The aim of the present study was to use equilibrium partitioning of an ionic contrast agent with micro-computed tomography (microCT) to investigate changes to both the articular cartilage and the subchondral bone of the medial coronoid processes (MCP) of growing Labrador retrievers at an early stage of the disease and at different bodyweights.Of 14 purpose-bred Labrador retrievers (15–27weeks), six were diagnosed with bilateral MCD and one was diagnosed with unilateral MCD on the basis of microCT studies. The mean X-ray attenuation of articular cartilage was significantly higher in dogs with MCD than in dogs without MCD (P<0.01). In all dogs, the mean X-ray attenuation of articular cartilage was significantly higher at the lateral (P<0.001) than at the proximal aspect of the MCP, indicating decreased glycosaminoglycan content. Changes in parameters of subchondral bone micro-architecture, namely the ratio of bone volume to tissue volume (BV/TV), bone surface density (BS/TV), bone surface to volume ratio (BS/BV), trabecular thickness (Tb.Th; mm), size of marrow cavities described by trabecular spacing (Tb.Sp; mm), and structural model index (SMI), differed significantly by litter (P<0.05) due to the difference in age and weight, but not by the presence/absence of MCD (P>0.05), indicating that subchondral bone density is not affected in early MCD. This study demonstrated that cartilage matrix and not subchondral bone density is affected in the early stages of MCD.

The pain-related behavior changes correlate with the bone damage in a rat model of rheumatoid arthritis

ObjectiveIn view of the extensive bone damage in rheumatoid arthritis, we used a commonly utilized animal model to detect behavioral changes in pain-related and the bone damage during the early disease, and to explore the correlation between bone damage and pain-related behavioral changes. MethodsArthritis were induced in Sprague-Dawley (SD) male rats by injecting complete Freund's adjuvant (CFA) into the tails. Pain-related behavior changes were studied using the Hargreaves, VonFrey, and acetone tests on the 0, 7, 14, day and 28 day after CFA injection. The rats were sacrificed according the same schedule. The bone damage of the right proximal tibia was studied by microCT scan and bone histological slices. ResultsAnimals developed soft tissue inflammation and polyarthritis on 7 days after CFA injection, and arthritic score proved obvious arthritis were established within the study period. Mechanical hyperalgesia and cold allodynia were present in the affected hind paw from the 7 day through the 28 day, but the heat hyperalgesia and the mechanical allodynia lasted a short time after CFA injection. Trabecular bone number (Tb.N), Tissue Mineral Content (TMC) and Bone Volume to Tissue Volume (BV/TV) in the proximal tibia by microCT scan were also reduced after induction, especial 14 days after CFA injection. The bone histological slices showed the trabecular bone and proteoglycan diminished, the bone damage severity scores became more severely on the 7 day after CFA injection. Using analysis of covariance, these changes had statistical significance compared with baseline. By linear regression analysis demonstrated mechanical hyperalgesia and cold allodynia correlated well with arthritic score, bone damage parameters and bone damage severity scores. ConclusionAdjuvant-induced arthritis (AA) were observed after CFA injection and lasted within the later experimental period. Pain-related behavioral changes were observed in the early time of AA. Bone damage was also occurred with arthritis development. Pain-related behavioral change correlated well with arthritic score and bone damage parameters.

Skeletal muscle mass is associated with bone geometry and microstructure and serum insulin-like growth factor binding protein-2 levels in adult women and men.

Skeletal muscle and bone form highly-integrated systems that undergo significant age-related changes, but the relationships between muscle mass and trabecular versus cortical bone or trabecular microarchitecture have not been systematically investigated. Thus, we examined the association between appendicular skeletal muscle mass (ASM) relative to height squared (relative ASM) and bone parameters at several sites assessed by conventional as well as high-resolution peripheral QCT in a cohort of 272 women and 317 men aged 20 to 97 years. In women, relative ASM was associated with cortical thickness (CtTh) at the femoral neck, lumbar spine, radius, and tibia (age-and physical activity adjusted r = 0.19-0.32; all p < 0.01). Relative ASM was also associated with trabecular volumetric bone mineral density (vBMD) at the femoral neck and spine (all p < 0.05), and trabecular bone volume to tissue volume (BV/TV), number (TbN), thickness (TbTh), and separation (TbSp) at the radius (all p ≤ 0.05). In all men, relative ASM was associated with CtTh at all sites (age- and physical activity-adjusted r = 0.17-0.28; all p < 0.01). Associations between relative ASM and trabecular vBMD at the spine in men were lost after adjusting for age; however, relative ASM was associated with trabecular vBMD at the femoral neck and TbN and TbSp at the radius (all p < 0.01). We also investigated circulating factors associated with bone health that may be indicative of relative ASM and found that serum insulin-like growth factor (IGF) binding protein-2 (IGFBP-2) levels were the most robust negative predictors of relative ASM in both sexes. Collectively, these data add to the growing body of evidence supporting the highly-integrated nature of skeletal muscle and bone, and provide new insights into potential biomarkers that reflect the health of the musculoskeletal system.

Manipulation of the anabolic and catabolic responses with BMP-2 and zoledronic acid in a rat femoral fracture model

Bone repair involves a complex set of regulated signaling pathways that control the formation of new bone matrix and the resorption of damaged bone matrix at the fracture site. It has been reported that the optimal time point for single-dose zoledronic acid (ZA) administration systemically increased the strength of bone morphogenetic protein (BMP)-7-mediated callus. However, its repair mechanism during bone fracture healing remains unknown. We aimed to investigate the synergic effect of recombinant human (rh) BMP-2 and ZA in a rat femoral fracture model. Fifty-eight rats were divided into 4 groups. Group I (n=14) animals were implanted with a carrier alone. Group II (n=15) animals were implanted with a carrier containing 1-μg rhBMP-2. Group III (n=14) animals were implanted with a carrier and a subcutaneous systemic ZA injection 2 weeks after surgery. Group IV (n=15) animals were implanted with a carrier containing 1-μg rhBMP-2 and ZA subcutaneous injection 2 weeks after surgery. The rats were euthanized after 6 weeks and their fractured femurs were explanted and assessed by manual palpation, radiographs, and high-resolution micro-computerized tomography (micro-CT) and were subjected to biomechanical and histological analysis. The fusion rates in Group IV (93.3%) were considerably higher than those in Groups I (28.6%), II (53.3%), and III (57.1%). Additionally, the radiographic scores of Group IV were higher than those in Groups I, II, and III. In micro-CT analysis, the tissue volume (TV) of the callus was higher in Group IV than in Groups I and II (p<0.05). New bone volume (BV) and trabecular spacing (Tb.Sp) also showed essentially the same trend as that of TV. The ratio of BV to TV (BV/TV), the trabecular number (Tb.N), and the trabecular thickness (Tb.Th) was higher in Groups III and IV than in Groups I and II (p<0.05). In biomechanical analysis, the ultimate loads at failure and stiffness in Groups III and IV were on average higher than those in Groups I and II (p<0.05), while the energy absorption of Group IV was higher than those of Groups I and II (p<0.05). The synergic effect of rhBMP-2 and ZA given systemically as a single dose at the optimal time was efficacious for fracture repair and significantly enhanced bone fusion. Our results suggest that this combination facilitates bone healing and has potential clinical application.

Botox induced muscle paralysis rapidly degrades bone

The means by which muscle function modulates bone homeostasis is poorly understood. To begin to address this issue, we have developed a novel murine model of unilateral transient hindlimb muscle paralysis using botulinum toxin A (Botox). Female C57BL/6 mice (16 weeks) received IM injections of either saline or Botox ( n = 10 each) in both the quadriceps and calf muscles of the right hindleg. Gait dysfunction was assessed by multi-observer inventory, muscle alterations were determined by wet mass, and bone alterations were assessed by micro-CT imaging at the distal femur, proximal tibia, and tibia mid-diaphysis. Profound degradation of both muscle and bone was observed within 21 days despite significant restoration of weight bearing function by 14 days. The muscle mass of the injected quadriceps and calf muscles was diminished −47.3% and −59.7%, respectively, vs. saline mice (both P < 0.001). The ratio of bone volume to tissue volume (BV/TV) within the distal femoral epiphysis and proximal tibial metaphysis of Botox injected limbs was reduced −43.2% and −54.3%, respectively, while tibia cortical bone volume was reduced −14.6% (all P < 0.001). Comparison of the contralateral non-injected limbs indicated the presence of moderate systemic effects in the model that were most probably associated with diminished activity following muscle paralysis. Taken as a whole, the micro-CT data implied that trabecular and cortical bone loss was primarily achieved by bone resorption. These data confirm the decisive role of neuromuscular function in mediating bone homeostasis and establish a model with unique potential to explore the mechanisms underlying this relation. Given the rapidly expanding use of neuromuscular inhibitors for indications such as pain reduction, these data also raise the critical need to monitor bone loss in these patients.