The Characteristics of Gut Microbiota and Its Relation with Diet in Postmenopausal Osteoporosis.

The gut microbiome is linked to osteoporosis. Previous clinical studies showed inconsistent results. This study aimed to characterize the gut microbiota feature and reveal its relation with diet in postmenopausal osteoporosis. Fifty-five postmenopausal women with osteoporosis (Op group) and forty-four age-matched postmenopausal women (normal bone mineral density, Con group) were included in this study. Fecal microbiota was collected and analyzed by shallow shotgun sequencing. Food frequency questionnaires were collected from both groups, and Spearman analysis was used to clarify its correlation with gut microbiota. A total of 2671 species from 29 phyla, 292 families, 152 orders, 80 classes were detected in the study. The two groups had no significant difference in the α and ß diversity (p > 0.05). At the genus level, Anaerostipes was enriched in Op group (p < 0.05). At species level, Methanobrevibacter smithii, Bifidobacterium animalis, Rhodococcus defluvii, Lactobacillus plantarum, and Carnobacterium mobile were enriched in the Op group, while Bacillus luciferensis, Acetivibrio cellulolyticus, Citrobacter amalonaticus, and Bifidobacterium breve were differentially enriched in the Con group. Food frequency questionnaire showed that postmenopausal women with osteoporosis intaked more red meat, beer, white and red wine (p < 0.05), and the Con group had more yogurt, fruit, and tea consumption. Red meat consumption had a significant negative correlation with Streptosporangiales (p < 0.01) and Actinomadura (p < 0.05). Fruits intake negatively correlated with Nocardiaceae, Rhodococcus, and Rhodococcus defluvii (p < 0.05). More yogurt intake was consistently correlated with a greater abundance of Streptosporangiales. This study suggests that gut microbiota is significantly altered in the postmenopausal osteoporosis population at genus and species levels, and specific dietary intake might relate to these changes.

Integrating model explanations and hybrid priors into deep stacked networks for the "safe zone" prediction of acetabular cup.

BACKGROUND: Existing state-of-the-art "safe zone" prediction methods are statistics-based methods, image-matching techniques, and machine learning methods. Yet, those methods bring a tension between accuracy and interpretability. PURPOSE: To explore the model explanations and estimator consensus for "safe zone" prediction. MATERIAL AND METHODS: We collected the pelvic datasets from Orthopaedic Hospital, and a novel acetabular cup detection method is proposed for automatic ROI segmentation. Hybrid priors comprising both specific priors from data and general priors from experts are constructed. Specifically, specific priors are constructed based on the fine-tuned ResNet-101 convolutional neural networks (CNN) model, and general priors are constructed based on expert knowledge. Our method considers the model explanations and dynamic consensus through appending a SHapley Additive exPlanations (SHAP) module and a dynamic estimator stacking. RESULTS: The proposed method achieves an accuracy of 99.40% and an area under the curve of 0.9998. Experimental results show that our model achieves superior results to the state-of-the-art conventional ensemble classifiers and deep CNN models. CONCLUSION: This new screening model provides a new option for the "safe zone" prediction of acetabular cup.

Photogenerated reactive oxygen species and hyperthermia by Cu3SnS4 nanoflakes for advanced photocatalytic and photothermal antibacterial therapy.

BACKGROUND: The rapid spread of infectious bacteria has brought great challenges to public health. It is imperative to explore effective and environment-friendly antibacterial modality to defeat antibiotic-resistant bacteria with high biosafety and broad-spectrum antibacterial property. RESULTS: Herein, biocompatible Cu3SnS4 nanoflakes (NFs) were prepared by a facile and low-cost fabrication procedure. These Cu3SnS4 NFs could be activated by visible light, leading to visible light-mediated photocatalytic generation of a myriad of reactive oxygen species (ROS). Besides, the plasmonic Cu3SnS4 NFs exhibit strong near infrared (NIR) absorption and a high photothermal conversion efficiency of 55.7%. The ROS mediated cellular oxidative damage and the NIR mediated photothermal disruption of bacterial membranes collaboratively contributed to the advanced antibacterial therapy, which has been validated by the efficient eradication of both Gram-negative Escherichia coli and Gram-positive methicillin-resistant Staphylococcus aureus strains in vitro and in vivo. Meanwhile, the exogenous copper ions metabolism from the Cu3SnS4 NFs facilitated the endothelial cell angiogenesis and collagen deposition, thus expediting the wound healing. Importantly, the inherent localized surface plasmon resonance effect of Cu3SnS4 NFs empowered them as an active substrate for surface-enhanced Raman scattering (SERS) imaging and SERS-labeled bacteria detection. CONCLUSIONS: The low cost and biocompatibility together with the solar-driven broad-spectrum photocatalytic/photothermal antibacterial property of Cu3SnS4 NFs make them a candidate for sensitive bacteria detection and effective antibacterial treatment.

Three-dimensional printing-based personalized limb salvage and reconstruction treatment of pelvic tumors.

BACKGROUND AND OBJECTIVES: The treatment of pelvic tumors is widely recognized to be challenging. The purpose of this study was to evaluate the efficacy of personalized three-dimensional (3D) printing-based limb salvage and reconstruction treatment for pelvic tumors. METHODS: Twenty-eight pelvic tumor patients were enrolled. 3D printing lesion models and osteotomy templates were prepared for surgery planning, prosthesis design, and osteotomy assistance during surgery. 3D printing-based personalized pelvic prostheses were manufactured and used in all 28 patients. Follow-up of postoperative survival, prosthesis survival, imaging examinations, and Musculoskeletal Tumor Society (MSTS) lower limb functional scores were carried out. RESULTS: The mean follow-up period was 32.2 months, during which 16 patients had disease-free survival, 3 survived with the disease, and 9 died. The prostheses were stable, and the mean offset of the center of rotation was 5.48 mm. The prosthesis-bone interface showed good integration. For the 19 surviving patients, the mean MSTS lower limb functional score was 23.2. Postoperative complications included superficial infection in six patients and hip dislocation in three patients. CONCLUSIONS: Personalized 3D printing-based limb salvage and reconstruction was an effective treatment for pelvic tumors. Our patients achieved good early postoperative efficacy and functional recovery.

A clinical study on bone defect reconstruction and functional recovery in benign bone tumors of the lower extremity, treated by bone marrow mesenchymal stem cell rapid screening-enrichment-composite system.

BACKGROUND: With the development of medical technology, credible options for defect reconstructions after the resection of benign bone tumors of the lower extremities have become a high priority. As the current reconstructive methods commonly used in clinical practice have some flaws, new methods of reconstruction need to be explored. We aimed to prepare a new kind of bioactive scaffold for the repair of bone defects through a stem cell rapid screening-enrichment-composite technology system developed by our team. Furthermore, we aimed to investigate the curative effects of these bioactive scaffolds. METHODS: Firstly, cell count, trypan blue exclusion rate, and ALP staining were used to evaluate changes in enrichment efficiency, cell activity, and osteogenic ability before and after enrichment. Then, the scaffolds were placed under the skin of nude mice to verify their osteogenic effects in vivo. Finally, the scaffolds were used for the reconstruction of bone defects after operations for benign bone tumors in a patient's lower limb. The healing status of the defect site at 1 and 3 months was assessed by X-ray, and the Musculoskeletal Tumor Society (MSTS) score was applied to reflect the recovery of patient limb function. RESULTS: The system effectively enriched stem cells without affecting the activity and osteogenic abilities of the bone marrow mesenchymal stem cells (BMSCs). Meanwhile, the bioactive scaffolds obtained better osteogenic effects. In patients, the active scaffolds showed better bone integration and healing status, and the patients also obtained higher MSTS scores at 1 and 3 months after surgery. CONCLUSION: As a new technique, the rapid screening-enrichment-composite technology of stem cells demonstrates a better therapeutic effect in the reconstruction of bone defects after surgery for benign bone tumors of the lower extremities, which will further improve patient prognosis.

Effect of strontium-containing on the properties of Mg-doped wollastonite bioceramic scaffolds.

BACKGROUND: Bone scaffold is one of the most effective methods to treat bone defect. The ideal scaffold of bone tissue should not only provide space for bone tissue growth, but also have sufficient mechanical strength to support the bone defect area. Moreover, the scaffold should provide a customized size or shape for the patient's bone defect. METHODS: In this study, strontium-containing Mg-doped wollastonite (Sr-CSM) bioceramic scaffolds with controllable pore size and pore structure were manufactured by direct ink writing 3D printing. Biological properties of Sr-CSM scaffolds were evaluated by apatite formation ability, in vitro proliferation ability of rabbit bone-marrow stem cells (rBMSCs), and alkaline phosphatase (ALP) activity using ß-TCP and Mg-doped wollastonite (CSM) scaffolds as control. The compression strength of three scaffold specimens was probed after completely drying them while been submerged in Tris-HCl solution for 0, 2,4 and 6 weeks. RESULTS: The mechanical test results showed that strontium-containing Mg-doped wollastonite (Sr-CSM) scaffolds had acceptable initial compression strength (56 MPa) and maintained good mechanical stability during degradation in vitro. Biological experiments showed that Sr-CSM scaffolds had a better apatite formation ability. Cell experiments showed that Sr-CSM scaffold had a higher cell proliferation ability compared with ß-TCP and CSM scaffold. The higher ALP activity of Sr-CSM scaffold indicates that it can better stimulate osteoblastic differentiation and bone mineralization. CONCLUSIONS: Therefore, Sr-CSM scaffolds not only have acceptable compression strength, but also have higher osteogenesis bioactivity, which can be used in bone tissue engineering scaffolds.

Partially Melted Ti6Al4V Particles Increase Bacterial Adhesion and Inhibit Osteogenic Activity on 3D-printed Implants: An In Vitro Study.

BACKGROUND: A porous Ti6Al4V implant that is manufactured using selective laser melting (SLM) has broad potential applications in the field of orthopaedic implants. The pore structure of the SLM porous Ti6Al4V implant allows for cell migration and osteogenic differentiation, which is favorable for bone ingrowth and osseointegration. However, it is unclear whether the pore structure and partially melted Ti6Al4V particles on a SLM porous Ti6Al4V implant will increase bacterial adhesion and, perhaps, the risk of implant-related infection. QUESTIONS/PURPOSES: (1) Is there more bacterial adhesion and colonization on SLM porous Ti6Al4V implants than on polished orthopaedic implants? (2) Do partially melted Ti6Al4V particles on SLM porous Ti6Al4V implants reduce human bone mesenchymal stem cells (hBMSCs) adhesion, viability, and activity? METHODS: To determine bacterial adhesion and biofilm formation, we incubated five different Ti6Al4V discs (polished, grit-blasted, plasma-sprayed, particle SLM porous, and nonparticle SLM porous discs) with methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli. Bacterial coverage on the surface of the five different Ti6Al4V discs were evaluated based on scanning electron microscopy (SEM) images quantitatively. In addition, a spread-plate method was used to quantitatively evaluate the bacterial adhesion on those implants. The biofilm formation was stained with crystal violet and semi-quantitatively determined with a microplate reader. The morphology and adhesion of hBMSCs on the five Ti6Al4V discs were observed with SEM. The cell viability was quantitatively evaluated with a Cell Counting Kit-8 assay. In addition, the osteogenic activity was determined in vitro with a quantitatively alkaline phosphatase activity assay and alizarin-red staining. For semiquantitative analysis, the alizarin-red stained mineralized nodules were dissolved and determined with a microplate reader. RESULTS: The polished discs had the lowest MRSA adhesion (8.3% ± 2.6%) compared with grit-blasted (19.1% ± 3.9%; p = 0.006), plasma-sprayed (38.5% ± 5.3%; p < 0.001), particle (23.1% ± 2.8%; p < 0.001), and nonparticle discs (15.7% ± 2.5%; p = 0.003). Additionally, when comparing the two SLM discs, we found that particle discs had higher bacterial coverage than nonparticle discs (23.1% ± 2.8% versus 15.7% ± 2.5%; p = 0.020). An E. coli analysis showed similar results, with the higher adhesion to particle SLM discs than to nonparticle discs (20.7% ± 4.2% versus 14.4% ± 3.6%; p = 0.011). In addition, on particle SLM porous discs, bacterial colonies were localized around the partially melted Ti6Al4V particles, based on SEM images. After a 7-day incubation period, the cell viability in the particle group (optical density value 0.72 ± 0.05) was lower than that in the nonparticle groups (optical density value: 0.87 ± 0.08; p = 0.003). Alkaline phosphatase activity, as a marker of osteogenic differentiation, was lower in the particle group than in the nonparticle group (1.32 ± 0.12 U/mL versus 1.58 ± 0.09 U/mL; p = 0.012). CONCLUSION: Higher bacterial adhesion was observed on SLM porous discs than on polished discs. The partially melted Ti6Al4V particles on SLM porous discs not only enhanced bacterial adhesion but also inhibited the osteogenic activity of hBMSCs. Postprocessing treatment is necessary to remove partially melted Ti6Al4V particles on an SLM implant before further use. Additional studies are needed to determine whether an SLM porous Ti6Al4V implant increases the risk of implant-related infection in vivo. CLINICAL RELEVANCE: As implants with porous Ti6Al4V made using SLM are being designed, our preliminary findings suggest that postprocessing treatment is needed to remove partially melted Ti6Al4V particles before further use. In addition, the depth of the porous structure of the SLM implant should not exceed the maximum depth of bone ingrowth because the host immune defense cannot prevent bacterial adhesion without integration.

Anlotinib induces hepatocellular carcinoma apoptosis and inhibits proliferation via Erk and Akt pathway.

Although anlotinib, a multi-targeted receptor tyrosine kinase inhibitor has been reported have antitumor effects in many preclinical and clinical trials, little is known about its effect on hepatocellular carcinoma (HCC). Here, we have shown the antitumor effects of anlotinib on HCC. Data indicated that anlotinib application significantly inhibited HCC cell viability, proliferation, colony formation, and prompted apoptosis in vitro. Furthermore, animal experiments also illustrated that anlotinib alleviated HCC progression. Mechanically, we demonstrated that anlotinib treatment downregulated the anti-apoptotic protein Bcl-2 and Survivin, but upregulated pro-apoptotic molecule Bax, which accounts for its therapeutic effect on HCC. Pathway analysis has shown decreased phosphorylation levels of Erk and Akt. Together, this study suggests that anlotinib may have a direct antitumor progression effect on HCC by inhibiting Bcl-2 and Survivin expression, promoting Bax expression via inactivating Erk and Akt pathways and could be a promising agent treating HCC.

Calcifediol (25-hydroxyvitamin D) improvement and calcium-phosphate metabolism of alendronate sodium/vitamin D3 combination in Chinese women with postmenopausal osteoporosis: a post hoc efficacy analysis and safety reappraisal.

BACKGROUND: Vitamin D (VD) insufficiency or deficiency is a frequent comorbidity in Chinese women with postmenopausal osteoporosis (PMO). The present study aimed to investigate 25-hydroxyvitamin D [25(OH) D] improvement and calcium-phosphate metabolism in Chinese PMO patients treated with 70 mg of alendronate sodium and 5600 IU of vitamin D3 (ALN/D5600). METHODS: Chinese PMO women (n = 219) were treated with 12-month ALN/D5600 (n = 111) or calcitriol (n = 108). Changes in 25(OH) D at month 12 were post hoc analyzed by the baseline 25 (OH) D status using the longitudinal analysis. The main safety outcome measures included serum calcium and phosphate and 24-h urine calcium, and the repeated measures mixed model was used to assess the frequencies of the calcium-phosphate metabolic disorders. RESULTS: Absolute change in mean serum 25(OH) D level was the greatest in VD-deficient patients and least in VD-sufficient patients at months six and 12 (both, P < 0.01). Serum calcium level remained significantly lower in the ALN/D5600 treatment group than in the calcitriol treatment group throughout the 12 months. Mean 24-h urine calcium slightly increased in the ALN/D5600 treatment group and significantly increased in the calcitriol treatment group (+ 1.1 and + 0.9 mmol/L at months six and 12; both, P < 0.05). Calcitriol treatment was associated with more frequent hypercalciuria at month six (9.4% vs. 18.5%, P = 0.05), but not at month 12 (12.3% vs. 13.0%). CONCLUSION: Baseline VD status predicted 25(OH) D improvement in PMO patients on 12-month ALN/D5600 treatment. The daily use of 0.25 µg of calcitriol was associated with more frequent hypercalciuria at month six, compared to ALN/5600 treatment, necessitating the safety re-evaluation of calcitriol at a higher dosage.

Computer-aided designed, three dimensional-printed hemipelvic prosthesis for peri-acetabular malignant bone tumour.

BACKGROUND: Prosthetic reconstruction may be a promising treatment for peri-acetabular malignant bone tumour; however, it is associated with a high complication rate. Therefore, prosthetic design and approach of prosthetic reconstruction after tumour resection warrant study. METHODS: We retrospectively analyzed 11 patients with peri-acetabular malignant bone tumours treated by personalized 3D-printed hemipelvic prostheses after en bloc resection between 2015 and 2016. Pre-operative and post-operative pain at rest was assessed according to a 10-cm VAS score. The results of functional improvement were evaluated using the MSTS-93 score at the final follow-up. We also analyzed tumour recurrence, metastases, and complications associated with the reconstruction procedure. RESULTS: All patients were observed for six to 24 months with an average follow-up of 15.5 months. One patient had occasional pain of the involved hip at the final follow-up (VAS, pre vs. post 8 months: 3 vs. 2). The mean MSTS-93 score was 19.2 (range, 13-25). Hip dislocation was detected in two patients, while delayed wound healing occurred in one patient. One patient with mesenchymal chondrosarcoma had a left iliac bone metastasis. Local tumour recurrence was not observed. CONCLUSIONS: Reconstruction of bony defect after tumour resection using personalized 3D-printed hemipelvic prostheses can obtain acceptable functional results without severe complications. Based on previous reports and our results, we believe that reconstruction arthroplasty using 3D-printed hemipelvic prostheses will provide a promising alternative for those patients with peri-acetabular malignant bone tumours. LEVEL OF EVIDENCE: Level IV, therapeutic study.

Upregulation of Akt signaling enhances femoral fracture healing by accelerating atrophic quadriceps recovery.

Muscle damage and disuse muscular atrophy are detrimental for fracture healing. It has been reported that the Akt signaling pathway plays a role in skeletal muscle hypertrophy and atrophy. The aim of this study was to further investigate whether promoting local muscle function through regulating Akt signaling affects fracture healing. For this purpose, we combined a rat model of short-term atrophy of the quadriceps with a femoral fracture model. In brief, botulinum toxin-A (BTX) were administered locally into the quadriceps one week before femur osteotomy to induce muscle atrophy. For the following weeks after BTX treatment, animals received injection of the Akt activator SC79 (20mg/kg/week) or the Akt inhibitor MK2206 (100mg/kg/week). We found that SC79 significantly accelerated the recovery of quadriceps weight and fiber size after BTX treatment. Moreover, animals that received SC79 injection showed greater bone callus volumes and superior femur mechanical properties. Immunological analysis revealed that the expression levels of the muscle-specific marker myosin heavy chain (MHC) were increased while expression of a negative regulator of muscle mass and function, myostatin, was decreased after SC79 treatment. Furthermore, SC79 increased the mRNA levels of the myogenic regulatory factors MyoD, MRF4 and Myf5 and promoted myotube formation in vitro. Taken together, these findings reveal that SC79 could accelerate the recovery of reversible muscular atrophy induced by BTX and subsequently promote fracture healing through activation of the Akt signaling pathway, which suggests its therapeutic potential in orthopedics.

Targeting Notch1 signaling pathway positively affects the sensitivity of osteosarcoma to cisplatin by regulating the expression and/or activity of Caspase family.

BACKGROUND: The introduction of cisplatin has improved the long-term survival rate in osteosarcoma patients. However, some patients are intrinsically resistant to cisplatin. This study reported that the activation of Notch1 is positively correlated with cisplatin sensitivity, evidenced by both clinical and in vitro data. RESULTS: In this study, a total 8 osteosarcoma specimens were enrolled and divided into two groups according to their cancer chemotherapeutic drugs sensitivity examination results. The relationship between Notch1 expression and cisplatin sensitivity of osteosarcoma patients was detected by immunohistochemistry and semi-quantitative analysis. Subsequently, two typical osteosarcoma cell lines, Saos-2 and MG63, were selected to study the changes of cisplatin sensitivity by up-regulating (NICD1 plasmid transfeciton) or decreasing (gamma-secretase complex inhibitor DAPT) the activation state of Notch1 signaling pathway. Our results showed a significant correlation between the expression of Notch1 and cisplatin sensitivity in patient specimens. In vitro, Saos-2 with higher expression of Notch1 had significantly better cisplatin sensitivity than MG63 whose Notch1 level was relatively lower. By targeting regulation in vitro, the cisplatin sensitivity of Saos-2 and MG63 had significantly increased after the activation of Notch1 signaling pathway, and vice versa. Further mechanism investigation revealed that activation/inhibition of Notch1 sensitized/desensitized cisplatin-induced apoptosis, which probably depended on the changes in the activity of Caspase family, including Caspase 3, Caspase 8 and Caspase 9 in these cells. CONCLUSIONS: Our data clearly demonstrated that Notch1 is critical for cisplatin sensitivity in osteosarcoma. It can be used as a molecular marker and regulator for cisplatin sensitivity in osteosarcoma patients.

Entangled titanium fibre balls combined with nano strontium hydroxyapatite in repairing bone defects.

OBJECTIVE: To investigate the effect of entangled titanium fibre balls (ETFBs) combined with nano strontium hydroxyapatite (nano-Sr-HAP) on the repair of bone defects in vivo. MATERIALS AND METHODS: Twenty-four 6-month-old, specific pathogen-free, male Sprague-Dawley rats were used. Drill defects were created in bilateral femoral condyles. ETFBs combined with nano-Sr-HAP were selected randomly from 72 samples and implanted into the femoral bone defects of left legs, which served as the experimental group, while ETFBs without nano-Sr-HAP were implanted into right legs for comparison. The bone defects on both sides were X-rayed. The anteroposterior positions and histological procedures and evaluations of each sample were performed at 1, 2, 4 and 8 weeks post-surgery. RESULTS: Histological results showed that the ETBs allowed new bone to grow within their structure. Additionally, an increase in new bone was seen on the nano-Sr-HAP side compared to the control side. The results of histomorphometric analysis confirmed that the new bone formation on the left side gradually increased with time. There was a statistical increase in new bone at 2, 4 and 8 weeks, and the differences between the two sides were statistically significant at weeks 4 and 8 (p < 0.05 for all comparisons). CONCLUSION: The results showed that ETFBs possess a unique 3-dimensional interconnective porous structure and have excellent biocompatibility, cell affinity and osteoconductivity, which makes them useful as scaffold materials for repairing bone defects. On the other hand, nano-Sr-HAP improved the bone defect-repairing capacity of the ETFBs, which showed osteoinductive properties.

Hydrogen Therapy Reverses Cancer-Associated Fibroblasts Phenotypes and Remodels Stromal Microenvironment to Stimulate Systematic Anti-Tumor Immunity.

Tumor microenvironment (TME) plays an important role in the tumor progression. Among TME components, cancer-associated fibroblasts (CAFs) show multiple tumor-promoting effects and can induce tumor immune evasion and drug-resistance. Regulating CAFs can be a potential strategy to augment systemic anti-tumor immunity. Here, the study observes that hydrogen treatment can alleviate intracellular reactive oxygen species of CAFs and reshape CAFs' tumor-promoting and immune-suppressive phenotypes. Accordingly, a controllable and TME-responsive hydrogen therapy based on a CaCO3 nanoparticles-coated magnesium system (Mg-CaCO3) is developed. The hydrogen therapy by Mg-CaCO3 can not only directly kill tumor cells, but also inhibit pro-tumor and immune suppressive factors in CAFs, and thus augment immune activities of CD4+ T cells. As implanted in situ, Mg-CaCO3 can significantly suppress tumor growth, turn the "cold" primary tumor into "hot", and stimulate systematic anti-tumor immunity, which is confirmed by the bilateral tumor transplantation models of "cold tumor" (4T1 cells) and "hot tumor" (MC38 cells). This hydrogen therapy system reverses immune suppressive phenotypes of CAFs, thus providing a systematic anti-tumor immune stimulating strategy by remodeling tumor stromal microenvironment.

An osteosarcoma-on-a-chip model for studying osteosarcoma matrix-cell interactions and drug responses.

Marrow niches in osteosarcoma (OS) are a specialized microenvironment that is essential for the maintenance and regulation of OS cells. However, existing animal xenograft models are plagued by variability, complexity, and high cost. Herein, we used a decellularized osteosarcoma extracellular matrix (dOsEM) loaded with extracellular vesicles from human bone marrow-derived stem cells (hBMSC-EVs) and OS cells as a bioink to construct a micro-osteosarcoma (micro-OS) through 3D printing. The micro-OS was further combined with a microfluidic system to develop into an OS-on-a-chip (OOC) with a built-in recirculating perfusion system. The OOC system successfully integrated bone marrow niches, cell‒cell and cell-matrix crosstalk, and circulation, allowing a more accurate representation of OS characteristics in vivo. Moreover, the OOC system may serve as a valuable research platform for studying OS biological mechanisms compared with traditional xenograft models and is expected to enable precise and rapid evaluation and consequently more effective and comprehensive treatments for OS.

Nerve Growth Factor-Preconditioned Mesenchymal Stem Cell-Derived Exosome-Functionalized 3D-Printed Hierarchical Porous Scaffolds with Neuro-Promotive Properties for Enhancing Innervated Bone Regeneration.

The essential role of the neural network in enhancing bone regeneration has often been overlooked in biomaterial design, leading to delayed or compromised bone healing. Engineered mesenchymal stem cells (MSCs)-derived exosomes are becoming increasingly recognized as potent cell-free agents for manipulating cellular behavior and improving therapeutic effectiveness. Herein, MSCs are stimulated with nerve growth factor (NGF) to regulate exosomal cargoes to improve neuro-promotive potential and facilitate innervated bone regeneration. In vitro cell experiments showed that the NGF-stimulated MSCs-derived exosomes (N-Exos) obviously improved the cellular function and neurotrophic effects of the neural cells, and consequently, the osteogenic potential of the osteo-reparative cells. Bioinformatic analysis by miRNA sequencing and pathway enrichment revealed that the beneficial effects of N-Exos may partly be ascribed to the NGF-elicited multicomponent exosomal miRNAs and the subsequent regulation and activation of the MAPK and PI3K-Akt signaling pathways. On this basis, N-Exos were delivered on the micropores of the 3D-printed hierarchical porous scaffold to accomplish the sustained release profile and extended bioavailability. In a rat model with a distal femoral defect, the N-Exos-functionalized hierarchical porous scaffold significantly induced neurovascular structure formation and innervated bone regeneration. This study provided a feasible strategy to modulate the functional cargoes of MSCs-derived exosomes to acquire desirable neuro-promotive and osteogenic potential. Furthermore, the developed N-Exos-functionalized hierarchical porous scaffold may represent a promising neurovascular-promotive bone reparative scaffold for clinical translation.

Bone mineral density and risk of breast cancer in postmenopausal women.

High bone mineral density (BMD) has been associated with increased breast cancer in prospective studies of postmenopausal women, but the real relationship is still controversial. Therefore, we undertook a meta-analysis to evaluate the association between BMD and the risk of breast cancer in postmenopausal women. We performed systematic searches on MEDLINE, EMBASE, and OVID. Data extraction was performed independently by two reviewers. For each study, we extracted the relative risks (RRs) and 95 % confidence intervals (CIs) for categorical variables and per standard deviation (SD) increases in BMD. Heterogeneity, publication bias, and subgroup analysis were performed. The analysis included 70,878 postmenopausal women from 10 studies with 1,889 breast cancers during a mean follow-up of 6 years (range 3.2-8.4 years). The summary RRs for the highest versus lowest categorical variable showed that higher BMD in the hip (RR 1.62; 95 % CI: 1.17-2.06) and in the spine (RR 1.82; 95 % CI: 1.07-2.57) were associated with a 62 and 82 % increased risk of breast cancer. Per SD, increase in hip BMD and spine BMD were also associated with a higher risk of breast cancer (RR for hip BMD 1.20; 95 % CI: 1.09-1.31 and RR for spine BMD 1.26; 95 % CI: 1.10-1.41). In this meta-analysis, a higher BMD was found to be associated with a significantly higher risk of breast cancer in postmenopausal women.

Poor osteoinductive potential of subcutaneous bone cement-induced membranes for tissue engineered bone.

BACKGROUND: Large segmental bone defects remain a challenge for reconstructive surgeons. A two-stage repair strategy may offer a potential solution. Here, we sought to evaluate the osteoinductive potential of bone cement-induced membranes in an ectopic site. METHODS: First, bone cements were inserted into the subcutaneous tissues of 16 rabbits to induce membrane formation. After 2, 4, 6 and 8 weeks, the induced membranes were harvested to assess their vascularization and osteoinductive potential. Next, bone cements were subcutaneously inserted into 12 rabbits for 4 weeks. These bone cements were then harvested from the newly formed membranes and replaced with granular porous ß-TCP, with or without bone mesenchymal stem cells. New bone formation was then evaluated after 3, 6 and 9 weeks. RESULTS: The highest level of blood vessel formation and bone morphogenetic protein-2 expression in the membranes were found at 4 weeks (p < 0.05). In addition, vascular endothelial growth factor concentration was highest after 2 weeks (p < 0.001), persisting until 8 weeks. However, the results showed little ectopic bone formation at these time points. CONCLUSION: While bone cement-induced membranes appear to provide a suitable environment for bone formation, they fail to drive osteoinduction in non-osseous sites for the purposes of bone tissue engineering.

Long-term effects of alendronate on fracture healing and bone remodeling of femoral shaft in ovariectomized rats.

AIM: To investigate the long-term effects of alendronate (Aln), a widely used oral bisphosphonate, on fracture healing and bone remodeling in ovariectomized rats. METHODS: Adult female SD rats underwent ovariectomy, and then bilateral femoral osteotomy at 12 weeks post-ovariectomy. From d 2 post-ovariectomy, the animals were divided into 3 groups, and treated with Aln (3 mg·kg(-1)·d(-1), po) for 28 weeks (Aln/Aln), Aln for 12 weeks and saline for 16 weeks (Aln/Saline) or saline for 28 weeks (Saline/Saline). At 6 and 16 weeks post-fracture, the fracture calluses were examined with X-ray radiography, and biomechanical testing and histological analysis were performed. The calluses were labeled with tetracycline and calcein to evaluate the mineral apposition rate (MAR). RESULTS: The fracture line was less distinct in the 2 Aln-treated groups at 6 weeks post-fracture, and disappeared in all the 3 groups at 16 weeks post-fracture. The size of the callus and radiographic density of the femora in the Aln/Aln group were the highest among the 3 groups at 6 and 16 weeks post-fracture. Similar results were observed in the ultimate load at failure and energy absorption. However, the treatment with Aln delayed endochondral ossification of the callus, and significantly increased the total sagittal-sectional area, percentage callus area and callus thickness, and decreased the MAR at 6 and 16 weeks post-fracture. CONCLUSION: In the ovariectomized rat model, Aln is beneficial for the mechanical properties of the callus, but delays callus remodeling by suppressing the remodeling of woven bone into lamellar bone.

Analysis of trabecular distribution of the proximal femur in patients with fragility fractures.

BACKGROUND: Multi-detector computed tomography (MDCT) was used in order to assess the trabecular distribution of proximal femur and its relationship with hip fragility fractures. METHODS: A total of 99 elderly women were scanned by MDCT including: 27 trochanteric hip fractures (group A), 40 femoral neck fractures (group B), and 32 non-fractures (group C). A mid-coronal MPR image of the proximal femur was reconstructed for every patient by e-Film95 software. Four regions of interest (ROI) were chosen in the images including compressive trabecula (ComT), tensile trabecula (TenT), trochanteric trabecula (TroT) and Ward's triangle (WT) region. The mean CT values were measured by the software. RESULTS: The mean age was 81.44, 74.10 and 69.25 years for groups A, B and C, respectively. There was significant inter-group differences based on one-way ANOVA (P<0.05). The CT values in the four ROIs had significant differences in the groups except for TenT between group A and B (P>0.05). After the age adjustment with ANCOVA, the mean CT values of TroT and WT were significantly lower in group A as compared to that of the group B (P<0.05). However, there were no significant differences for ComT and TenT between groups A and B (P>0.05). CONCLUSIONS: The occurrence of femoral neck fracture was closely related to the degeneration of ComT and TenT. Trochanteric hip fractures were associated with a more severe degeneration in TroT as well as an enlargement of WT region besides the ComT and TenT degeneration. We concluded that the hip fragility fractures might be predicted by the measurement of the mean CT values in ComT, TenT, TroT and WT region.