RANKL from bone marrow adipose lineage cells promotes osteoclast formation and bone loss.

Receptor activator of NF-κB ligand (RANKL) is essential for osteoclast formation and bone remodeling. Nevertheless, the cellular source of RANKL for osteoclastogenesis has not been fully uncovered. Different from peripheral adipose tissue, bone marrow (BM) adipose lineage cells originate from bone marrow mesenchymal stromal cells (BMSCs). Here, we demonstrate that adiponectin promoter-driven Cre expression (AdipoqCre ) can target bone marrow adipose lineage cells. We cross the AdipoqCre mice with ranklfl/fl mice to conditionally delete RANKL from BM adipose lineage cells. Conditional deletion of RANKL increases cancellous bone mass of long bones in mice by reducing the formation of trabecular osteoclasts and inhibiting bone resorption but does not affect cortical bone thickness or resorption of calcified cartilage. AdipoqCre ; ranklfl/fl mice exhibit resistance to estrogen deficiency and rosiglitazone (ROS)-induced trabecular bone loss but show bone loss induced by unloading. BM adipose lineage cells therefore represent an essential source of RANKL for the formation of trabecula osteoclasts and resorption of cancellous bone during remodeling under physiological and pathological conditions. Targeting bone marrow adiposity is a promising way of preventing pathological bone loss.

Development and validation of the geriatric trauma frailty index for geriatric trauma patients based on electronic hospital records.

BACKGROUND: Globally, geriatric patients are the dominant population requiring global medical care. We established a frailty index for geriatric trauma patients by retrospectively analysing electronic hospital records to identify patients with frailty characteristics and poor prognostic outcomes. METHOD: Data were obtained from 2016 US National Emergency Department Sample and Shanghai Trauma Emergency Medical Association (2015-18). Overall, 141,267 hospitalised geriatric trauma patients (age ≥ 65 years) were included. We used a three-step method to construct geriatric trauma frailty index (GTFI) based on the International Statistical Classification of Diseases and Related Health Problems, Tenth Revision diagnostic codes. Systematic cluster analysis was used. The accuracy of GTFI was verified in national validation cohort, and its applicability to Chinese patients was assessed in local validation cohort. RESULTS: In development cohort (n = 28,179), frail patients had longer lengths of stay and higher Charlson co-morbidity index than non-frail patients (18.2 ± 12.4 days, 5.59 ± 2.0 versus 5.3 ± 5.3 days, 5.33 ± 1.8, respectively). In national validation cohort (n = 113,089), frail patients had longer lengths of stay (8.5 ± 8.8 days versus 4.5 ± 3.1 days) and higher in-hospital mortality than non-frail patients (2,795, 11.69% versus 589, 0.66%). Areas under the curves for GTFI for length of stay (>14 days) and in-hospital mortality were 0.848 (0.841, 0.854) and 0.885 (0.880, 0.891) in national validation cohort, and were 0.791 (0.779, 0.804) and 0.903 (0.885, 0.922) in local validation cohort (n = 14,827). CONCLUSIONS: The GTFI helps hospitals and emergency departments to identify geriatric trauma patients with poor prognostic outcomes, and has been proven to be useful in China.

Guaiacol suppresses osteoclastogenesis by blocking interactions of RANK with TRAF6 and C-Src and inhibiting NF-κB, MAPK and AKT pathways.

Angelica sinensis (AS; Dang Gui), a traditional Chinese herb, has for centuries been used for the treatment of bone diseases, including osteoporosis and osteonecrosis. However, the effective ingredient and underlying mechanisms remain elusive. Here, we identified guaiacol as the active component of AS by two-dimensional cell membrane chromatography/C18 column/time-of-flight mass spectrometry (2D CMC/C18 column/TOFMS). Guaiacol suppressed osteoclastogenesis and osteoclast function in bone marrow monocytes (BMMCs) and RAW264.7 cells in vitro in a dose-dependent manner. Co-immunoprecipitation indicated that guaiacol blocked RANK-TRAF6 association and RANK-C-Src association. Moreover, guaiacol prevented phosphorylation of p65, p50, IκB (NF-κB pathway), ERK, JNK, c-fos, p38 (MAPK pathway) and Akt (AKT pathway), and reduced the expression levels of Cathepsin K, CTR, MMP-9 and TRAP. Guaiacol also suppressed the expression of nuclear factor of activated T-cells cytoplasmic 1(NFATc1) and the RANKL-induced Ca2+ oscillation. In vivo, it ameliorated ovariectomy-induced bone loss by suppressing excessive osteoclastogenesis. Taken together, our findings suggest that guaiacol inhibits RANKL-induced osteoclastogenesis by blocking the interactions of RANK with TRAF6 and C-Src, and by suppressing the NF-κB, MAPK and AKT signalling pathways. Therefore, this compound shows therapeutic potential for osteoclastogenesis-related bone diseases, including postmenopausal osteoporosis.

Neobavaisoflavone inhibits osteoclastogenesis through blocking RANKL signalling-mediated TRAF6 and c-Src recruitment and NF-κB, MAPK and Akt pathways.

Psoralea corylifolia (P corylifolia) has been popularly applied in traditional Chinese medicine decoction for treating osteoporosis and promoting fracture healing since centuries ago. However, the bioactive natural components remain unknown. In this study, applying comprehensive two-dimensional cell membrane chromatographic/C18 column/time-of-flight mass spectrometry (2D CMC/C18 column/TOFMS) system, neobavaisoflavone (NBIF), for the first time, was identified for the bioaffinity with RAW 264.7 cells membranes from the extracts of P corylifolia. Here, we revealed that NBIF inhibited RANKL-mediated osteoclastogenesis in bone marrow monocytes (BMMCs) and RAW264.7 cells dose dependently at the early stage. Moreover, NBIF inhibited osteoclasts function demonstrated by actin ring formation assay and pit-formation assay. With regard to the underlying molecular mechanism, co-immunoprecipitation showed that both the interactions of RANK with TRAF6 and with c-Src were disrupted. In addition, NBIF inhibited the phosphorylation of P50, P65, IκB in NF-κB pathway, ERK, JNK, P38 in MAPKs pathway, AKT in Akt pathway, accompanied with a blockade of calcium oscillation and inactivation of nuclear translocation of nuclear factor of activated T cells cytoplasmic 1 (NFATc1). In vivo, NBIF inhibited osteoclastogenesis, promoted osteogenesis and ameliorated bone loss in ovariectomized mice. In summary, P corylifolia-derived NBIF inhibited RANKL-mediated osteoclastogenesis by suppressing the recruitment of TRAF6 and c-Src to RANK, inactivating NF-κB, MAPKs, and Akt signalling pathways and inhibiting calcium oscillation and NFATc1 translocation. NBIF might serve as a promising candidate for the treatment of osteoclast-associated osteopenic diseases.

l-tetrahydropalmatine suppresses osteoclastogenesis in vivo and in vitro via blocking RANK-TRAF6 interactions and inhibiting NF-κB and MAPK pathways.

Bone homeostasis is delicately orchestrated by osteoblasts and osteoclasts. Various pathological bone loss situations result from the overactivated osteoclastogenesis. Receptor activator of nuclear factor κB ligand (RANKL)-activated NF-κB and MAPK pathways is vital for osteoclastogenesis. Here, we for the first time explored the effects of l-tetrahydropalmatine (l-THP), an active alkaloid derived from corydalis, on the formation and function of osteoclasts in vitro and in vivo. In RAW264.7 cells and bone marrow monocytes cells (BMMCs), l-THP inhibited osteoclastic differentiation at the early stage, down-regulated transcription level of osteoclastogenesis-related genes and impaired osteoclasts functions. Mechanically, Western blot showed that l-THP inhibited the phosphorylation of P50, P65, IκB, ERK, JNK and P38, and the electrophoretic mobility shift assay (EMSA) revealed that DNA binding activity of NF-κB was suppressed, ultimately inhibiting the expression of nuclear factor of activated T cells (NFATc1). Besides, Co-immunoprecipitation indicated that l-THP blocked the interactions of RANK and TNF receptor associated factor 6 (TRAF6) at an upstream site. In vivo, l-THP significantly inhibited ovariectomy-induced bone loss and osteoclastogenesis in mice. Collectively, our study demonstrated that l-THP suppressed osteoclastogenesis by blocking RANK-TRAF6 interactions and inhibiting NF-κB and MAPK pathways. l-THP is a promising agent for treating osteoclastogenesis-related diseases such as post-menopausal osteoporosis.

The adaptation of sport assessment-patella questionnaire into simplified Chinese version: cross-cultural adaptation, reliability and validity.

BACKGROUND: The original version of Victorian Institute of Sport Assessment-Patella Questionnaire (VISA-P) is developed in English, and aimed to assess the severity of patellar tendinopathy symptoms. Before used in China, it should be translated to Chinese version. OBJECTIVES: Our aim is to make a translation/cross-culturally adaption for the VISA-P into simplified Chinese version (VISA-PC). And primarily validate the VISA-PC in Chinese speaking population. METHODS: The translation process of VISA-P questionnaire into simplified Chinese version (VISP-PC) followed the International recognized guideline. Cross-cultural adaptation was carried out with a clinical measurement study. A total of 128 projects which consisted 33 healthy students, 39 patients with patellar tendinopathy and 56 military students (receive military training as at-risk population) were included into this study. Internal consistency was evaluated with Cronbach's alpha, and test-retest reliability was assessed with intraclass correlation coefficients (ICCs). Construct validity and floor and ceiling effects were also tested. RESULTS: The scores were 95.84 ± 5.97 of healthy group, 91.87 ± 9.03 of at-risk group, 62.49 ± 11.39 of pathological group. There is no ceiling and floor effect of VISA-PC. The Cronbach's alpha (0.895) and ICC (0.986) values showed good internal consistency and reliability. There were high correlations between VISA-PC and Kujala patellofemoral score (r = 0.721). VISA-PC score also had good correlation with the relevant SF-36 items. CONCLUSION: The VISA-PC was well translated into simplified Chinese version (VISA-PC), which is reliable and valid for Chinese-speaking patients with patellar tendinopathy. LEVEL OF EVIDENCE: II.

Reversal of Osteoporotic Activity by Endothelial Cell-Secreted Bone Targeting and Biocompatible Exosomes.

Exosomes, also known as extracellular vesicles, are naturally occurring, biocompatible, and bioacive nanoparticles ranging from 40 to 150 nm in diameter. Bone-secreted exosomes play important roles in bone homeostasis, the interruption of which can lead to diseases such as osteoporosis, rheumatoid arthritis, and osteopetrosis. Though the relationship between vascular and bone homeostasis has been recognized recently, the role of vascular endothelial cell (EC)-secreted exosomes (EC-Exos) in bone homeostasis is not well understood. Herein, we found that EC-Exos show more efficient bone targeting than osteoblast-derived exosomes or bone marrow mesenchymal stem cell-derived exosomes. We also found that EC-Exos can be internalized by bone marrow-derived macrophages (BMMs) to alter their morphology. EC-Exos can inhibit osteoclast activity in vitro and inhibit osteoporosis in an ovariectomized mouse model. Sequencing of exosome miRNA revealed that miR-155 was highly expressed in EC-Exos-treated BMMs. The miR-155 level in EC-Exos was much higher than that in BMMs and ECs, indicating that miR-155 was endogenous cargo of EC-derived vesicles. Blockage of BMMs miR-155 levels reversed the suppression by EC-Exos of osteoclast induction, confirming that exosomal miR-155 may have therapeutic potential against osteoporosis. Taken together, our findings suggest that EC-Exos may be utilized as a bone targeting and nontoxic nanomedicine for the treatment of bone resorption disorders.

Inhalation of Hydrogen of Different Concentrations Ameliorates Spinal Cord Injury in Mice by Protecting Spinal Cord Neurons from Apoptosis, Oxidative Injury and Mitochondrial Structure Damages.

BACKGROUND/AIMS: Hydrogen selectively neutralizes reactive oxygen species (ROS) and ameliorates various ROS-induced injuries. Spinal cord injury (SCI) is a serious injury to the central nervous system, and secondary SCI is closely related to excessive ROS generation. We hypothesized that hydrogen inhalation ameliorates SCI, and the mechanism of action may be related to the protective effects of hydrogen against oxidative stress, apoptosis, and mitochondrial damage. METHODS: Mechanically injured spinal cord neurons were incubated with different concentrations of hydrogen in vitro. Immunofluorescence staining and transmission electron microscopy were used to confirm the protective effects of hydrogen. ROS and related proteins were detected with dihydroethidium fluorescence staining, enzyme-linked immunosorbent assays, and western blotting. Terminal deoxynucleotidyl transferase dUTP nick end labeling assays, flow cytometry, and western blotting were used to detect neuronal apoptosis. ATP concentrations, Janus Green B staining, and mitochondrial permeability transition pore (mPTP) status were assessed to investigate mitochondrial damage. RNA sequencing was performed to screen potential target genes of hydrogen application. Hydrogen was administered to mice after spinal cord contusion injury was established for 42 days. The Basso Mouse Scale (BMS) and footprint analyses were used to assess locomotor functions, and immunofluorescence staining of the injured spinal cord segments was performed to detect oxidative stress status. RESULTS: Spinal cord neurons were preserved by hydrogen administration after mechanical injury in a dose-dependent manner. ROS generation, oxidative stress injury-related markers, and the number of apoptotic neurons were significantly reduced after hydrogen treatment. The ATP production and mPTP function in injured neurons were preserved by hydrogen incubation. The expression levels of Cox8b, Cox6a2, Cox7a1, Hspb7, and Atp2a1 were inhibited by hydrogen treatment. BMS scores and the footprint assessment of mice with SCI were improved by hydrogen inhalation. CONCLUSIONS: Hydrogen inhalation (75%) ameliorated SCI in vivo and attenuated neuronal mechanical injuries in vitro, and its protective effect on spinal cord neurons was exerted in a dose-dependent manner. The underlying mechanisms included reducing ROS generation and oxidative stress, inhibiting neuronal apoptosis, and restoring mitochondrial construction and function. Cox8b, Cox6a2, Cox7a1, Hspb7, and Atp2a1 were identified as potential target genes of hydrogen treatment.

Matrine prevents bone loss in ovariectomized mice by inhibiting RANKL-induced osteoclastogenesis.

Osteoporosis is a metabolic bone disease characterized by decreased bone density and strength due to excessive loss of bone protein and mineral content. The imbalance between osteogenesis by osteoblasts and osteoclastogenesis by osteoclasts contributes to the pathogenesis of postmenopausal osteoporosis. Estrogen withdrawal leads to increased levels of proinflammatory cytokines. Overactivated osteoclasts by inflammation play a vital role in the imbalance. Matrine is an alkaloid found in plants from the Sophora genus with various pharmacological effects, including anti-inflammatory activity. Here we demonstrate that matrine significantly prevented ovariectomy-induced bone loss and inhibited osteoclastogenesis in vivo with decreased serum levels of TRAcp5b, TNF-α, and IL-6. In vitro matrine significantly inhibited osteoclast differentiation induced by receptor activator for NF-κB ligand (RANKL) and M-CSF in bone marrow monocytes and RAW264.7 cells as demonstrated by tartrate-resistant acid phosphatase (TRAP) staining and actin-ring formation as well as bone resorption through pit formation assays. For molecular mechanisms, matrine abrogated RANKL-induced activation of NF-κB, AKT, and MAPK pathways and suppressed osteoclastogenesis-related marker expression, including matrix metalloproteinase 9, NFATc1, TRAP, C-Src, and cathepsin K. Our study demonstrates that matrine inhibits osteoclastogenesis through modulation of multiple pathways and that matrine is a promising agent in the treatment of osteoclast-related diseases such as osteoporosis.-Chen, X., Zhi, X., Pan, P., Cui, J., Cao, L., Weng, W., Zhou, Q., Wang, L., Zhai, X. Zhao, Q., Hu, H., Huang, B., Su, J. Matrine prevents bone loss in ovariectomized mice by inhibiting RANKL-induced osteoclastogenesis.

The chinese version of achilles tendon total rupture score: cross-cultural adaptation, reliability and validity.

BACKGROUND: The Achilles tendon Total Rupture Score (ATRS), which is originally developed in 2007 in Swedish, is the only patient-reported outcome measure (PROM) for specific outcome assessment of an Achilles tendon rupture.Purpose of this study is to translate and cross-culturally adapt Achilles tendon Total Rupture Score (ATRS) into simplified Chinese, and primarily evaluate the responsiveness, reliability and validity. METHODS: International recognized guideline which was designed by Beaton was followed to make the translation of ATRS from English into simplified Chinese version (CH-ATRS). A prospective cohort study was carried out for the cross-cultural adaptation. There were 112 participants included into the study. Psychometric properties including floor and ceiling effects, Cronbach's alpha, intraclass correlation coefficient, effect size, standard response mean, and construct validity were tested. RESULTS: The mean scores of CH-ATRS are 57.42 ± 13.70. No sign of floor or ceiling effect was found of CH-ATRS. High level of internal consistency was supported by the value of Cronbach's alpha (0.893). ICC (0.979, 95%CI: 0.984-0.993) was high to indicate the high test-retest reliability. Great responsive ness was proved with the high absolute value of ES and SRM (0.84 and 8.98, respectively). The total CH-ATRS score had very good correlation with physical function and body pain subscales of SF-36 (r = -0.758 and r = -0.694, respectively, p < 0.001), while poor correlation with vitality and role physical subscales of SF-36 (r = -0.033 and r = -0.025, respectively, p ≥ 0.05), which supported construct validity of CH-ATRS. CONCLUSION: This Chinese version of Achilles tendon Total Rupture Score (CH-ATRS) can be used as a reliable and valid instrument for Achilles tendon rupture assessing in Chinese-speaking population. Level of evidence II.

Surgical treatment of calcaneal fractures of Sanders type II and III by a minimally invasive technique using a locking plate.

The aim of the present study was to investigate the outcomes of surgical treatment of calcaneal fractures of Sanders type II and III using a minimally invasive technique and a locking plate. We reviewed 33 feet in 33 consecutive patients with Sanders type II and III calcaneal fractures who had undergone a minimally invasive technique using percutaneous reduction and locking plates. All operations were performed by the same surgeons. The postoperative evaluation included radiographs, determination of restoration of Böhler's angle and Gissane's angle, and administration of the American Orthopaedic Foot and Ankle Society ankle-hind foot scale, Maryland Foot Score, and visual analog scale of pain. The mean visual analog scale score was 1.6 ± 1.4 when radiographic fracture healing was observed. The median functional score of the 33 patients (33 feet) reached 82 (interquartile range 80 to 99) at the last follow-up evaluation according to the American Orthopaedic Foot and Ankle Society ankle-hind foot scale and 89 (interquartile range 80 to 99) according to Maryland Foot Score. All cases achieved restoration of a normal Böhler's angle and Gissane's angle. Postoperative superficial infections occurred in 2 patients, subtalar arthritis developed in 2, and no soft tissue necrosis was observed. For Sanders type II and III fractures of the calcaneus bone, treatment with a minimally invasive technique combining percutaneous reduction and locking plate fixation provided satisfactory clinical results, with a lower incidence of complications. However, longer term studies with a larger sample size and more randomized controlled trials are required to define the superiority of our minimally invasive technique compared with conventional surgical treatment of calcaneal fractures.

Closed reduction and internal fixation versus total hip arthroplasty for displaced femoral neck fracture.

OBJECTIVE: To compare the clinical effects between closed reduction and internal fixation (CRIF) and total hip arthroplasty (THA) for displaced femoral neck fracture. METHODS: In this prospective randomized study, 285 patients aged above 65 years with hip fractures (Garden III or IV) were included from January 2001 to December 2005. The cases were randomly allocated to either the CRIF group or THA group. Patients with pathological fractures (bone tumors or metabolic bone disease), preoperative avascular necrosis of the femoral head, osteoarthritis, rheumatoid arthritis, hemiplegia, long-term bed rest and complications affecting hip functions were excluded. RESULTS: During the 5-year follow-up, CRIF group had significantly higher rates of complication in hip joint, general complication and reoperation than THA group (38.3% vs. 12.7%, P<0.01; 45.3% vs. 21.7%, P<0.01; 33.6% vs. 10.2%, P<0.05 respectively). There was no difference in mortality between the two groups. Postoperative function of the hip joint in THA group recovered favorably with higher Harris scores. CONCLUSION: For displaced fractures of the femoral neck in elderly patients, THA can achieve a lower rate of complication and reoperation, as well as better postoperative recovery of hip joint function compared with CRIF.

Linking the relationship between dietary folic acid intake and risk of osteoporosis among middle-aged and older people: A nationwide population-based study.

Among middle-aged and older people, balanced and nutritious diets are the foundation for maintaining bone health and preventing osteoporosis. This study is aimed at investigating the link between dietary folic acid intake and the risk of osteoporosis among middle-aged and older people. A total of 20,686 people from the National Health and Nutritional Examination Survey (NHANES) 2007-2010 are screened and included, and 5312 people aged ≥45 years with integral data are ultimately enrolled in evaluation. Demographics and dietary intake-related data are gathered and analyzed, and the odds ratio (OR) and 95% confidence interval (CI) of each tertile category of dietary folic acid intake and each unit increase in folic acid are assessed via multivariate logistic regression models. On this basis, the receiver operating characteristic (ROC) curve is used to identify the optimal cutoff value of dietary folic acid intake for indicating the risk of osteoporosis. Of 5312 people with a mean age of 62.4 ± 11.0 years old, a total of 513 people with osteoporosis are screened, and the dietary folic acid intake amount of the osteoporosis group is significantly lower than that of the non-osteoporosis group (p < .001). The lowest tertile category is then used to act as a reference category, and a higher dietary folic acid intake amount is observed to be positively related to lower odds for risk of osteoporosis. This trend is also not changed in adjustments for combinations of different covariates (p all < .05). Based on this, a dietary folic acid intake of 475.5 µg/day is identified as an optimal cutoff value for revealing osteoporosis. Collectively, this nationwide population-based study reveals that a higher daily dietary folic acid intake has potential protective effects on osteoporosis in middle-aged and older people.

Synthetic biology-based bacterial extracellular vesicles displaying BMP-2 and CXCR4 to ameliorate osteoporosis.

Osteoporosis (OP) is a systematic bone disease characterized by low bone mass and fragile bone microarchitecture. Conventional treatment for OP has limited efficacy and long-term toxicity. Synthetic biology makes bacterial extracellular vesicle (BEVs)-based therapeutic strategies a promising alternative for the treatment of OP. Here, we constructed a recombinant probiotics Escherichia coli Nissle 1917-pET28a-ClyA-BMP-2-CXCR4 (ECN-pClyA-BMP-2-CXCR4), in which BMP-2 and CXCR4 were overexpressed in fusion with BEVs surface protein ClyA. Subsequently, we isolated engineered BEVs-BMP-2-CXCR4 (BEVs-BC) for OP therapy. The engineered BEVs-BC exhibited great bone targeting in vivo. In addition, BEVs-BC had good biocompatibility and remarkable ability to promote osteogenic differentiation of BMSCs. Finally, the synthetic biology-based BEVs-BC significantly prevented the OP in an ovariectomized (OVX) mouse model. In conclusion, we constructed BEVs-BC with both bone-targeting and bone-forming in one-step using synthetic biology, which provides an effective strategy for OP and has great potential for industrialization.

Bacterial extracellular vesicles as bioactive nanocarriers for drug delivery: Advances and perspectives.

Nanosized extracellular vesicles derived from bacteria contain diverse cargo and transfer intercellular bioactive molecules to cells. Due to their favorable intercellular interactions, cell membrane-derived bacterial extracellular vesicles (BEVs) have great potential to become novel drug delivery platforms. In this review, we summarize the biogenesis mechanism and compositions of various BEVs. In addition, an overview of effective isolation and purification techniques of BEVs is provided. In particular, we focus on the application of BEVs as bioactive nanocarriers for drug delivery. Finally, we summarize the advances and challenges of BEVs after providing a comprehensive discussion in each section. We believe that a deeper understanding of BEVs will open new avenues for their exploitation in drug delivery applications.

Reactive Oxygen Species (ROS)-Responsive Biomaterials for the Treatment of Bone-Related Diseases.

Reactive oxygen species (ROS) are the key signaling molecules in many physiological signs of progress and are associated with almost all diseases, such as atherosclerosis, aging, and cancer. Bone is a specific connective tissue consisting of cells, fibers, and mineralized extracellular components, and its quality changes with aging and disease. Growing evidence indicated that overproduced ROS accumulation may disrupt cellular homeostasis in the progress of bone modeling and remodeling, leading to bone metabolic disease. Thus, ROS-responsive biomaterials have attracted great interest from many researchers as promising strategies to realize drug release or targeted therapy for bone-related diseases. Herein, we endeavor to introduce the role of ROS in the bone microenvironment, summarize the mechanism and development of ROS-responsive biomaterials, and their completion and potential for future therapy of bone-related diseases.

One-Step Preparation of an AgNP-nHA@RGO Three-Dimensional Porous Scaffold and Its Application in Infected Bone Defect Treatment.

BACKGROUND: Bactericidal capacity, durable inhibition of biofilm formation, and a three-dimensional (3D) porous structure are the emphases of infected bone defect (IBD) treatment via local scaffold implantation strategy. PURPOSE: In this study, silver nanoparticle (AgNP)-loaded nano-hydroxyapatite (nHA)@ reduced graphene oxide (RGO) 3D scaffolds (AHRG scaffolds) were designed to alleviate bone infection, inhibit biofilm formation, and promote bone repair through the synergistic effects of AgNPs, RGO, and nHA. MATERIALS AND METHODS: AHRGs were prepared using a one-step preparation method, to create a 3D porous scaffold to facilitate a uniform distribution of AgNPs and nHA. Methicillin-resistant Staphylococcus aureus (MRSA) was used as a model-resistant bacterium, and the effects of different silver loadings on the antimicrobial activity and cytocompatibility of materials were evaluated. Finally, a rabbit IBD model was used to evaluate the therapeutic effect of the AHRG scaffold in vivo. RESULTS: The results showed successful synthesis of the AHRG scaffold. The ideal 3D porous structure was verified using scanning electron microscopy and transmission electron microscopy, and X-ray photoelectron spectroscopy and selected area electron diffraction measurements revealed uniform distributions of AgNP and nHA. In vitro antibacterial and cytocompatibility indicated that the 4% AHRG scaffolds possessed the most favorable balance of bactericidal properties and cytocompatibility. In vivo evaluation of the IBD model showed promising treatment efficacy of AHRG scaffolds. CONCLUSION: The as-fabricated AHRG scaffolds effectively eliminated infection and inhibited biofilm formation. IBD repair was facilitated by the bactericidal properties and 3D porous structure of the AHRG scaffold, suggesting its potential in the treatment of IBDs.

Myostatin Promotes Osteoclastogenesis by Regulating Ccdc50 Gene Expression and RANKL-Induced NF-κB and MAPK Pathways.

Myostatin is a crucial cytokine that is widely present in skeletal muscle and that negatively regulates the growth and development of muscle cells. Recent research has shown that myostatin might play an essential role in bone metabolism. In RAW264.7 cells and bone marrow monocytes (BMMCs), myostatin activates the expression of the II type receptor ActR II B. Here, we report that myostatin significantly promoted RANKL/M-CSF-induced osteoclastogenesis and activated NF-κB and MAPK pathways in vitro via the Ccdc50 gene. Overexpression of myostatin promoted osteoclastogenesis and osteoclastogenesis-related markers including c-Src, MMP9, CTR, CK, and NFATc1. Specifically, myostatin increased the phosphorylation of Smad2, which led to the activation of NF-κB and MAPK pathways to activate osteoclastogenesis. Ccdc50 was identified as a gene whose expression was highly decreased in osteoclastogenesis upon myostatin treatment, and it could inhibit the function of myostatin in osteoclastogenesis by blocking NF-κB and MAPKs pathways. Our study indicates that myostatin is a promising candidate target for inhibiting RANKL-mediated osteoclastogenesis and might participate in therapy for osteoporosis, and that the Ccdc50 gene plays a significant role in the regulatory process.

Targeting actin-bundling protein L-plastin as an anabolic therapy for bone loss.

The actin-bundling protein L-plastin (LPL) mediates the resorption activity of osteoclasts, but its therapeutic potential in pathological bone loss remains unexplored. Here, we report that LPL knockout mice show increased bone mass and cortical thickness with more mononuclear tartrate-resistant acid phosphatase-positive cells, osteoblasts, CD31hiEmcnhi endothelial vessels, and fewer multinuclear osteoclasts in the bone marrow and periosteum. LPL deletion impeded preosteoclasts fusion by inhibiting filopodia formation and increased the number of preosteoclasts, which release platelet-derived growth factor-BB to promote CD31hiEmcnhi vessel growth and bone formation. LPL expression is regulated by the phosphatidylinositol 3-kinase/AKT/specific protein 1 axis in response to receptor activator of nuclear factor-κB ligand. Furthermore, we identified an LPL inhibitor, oroxylin A, that could maintain bone mass in ovariectomy-induced osteoporosis and accelerate bone fracture healing in mice. In conclusion, we showed that LPL regulates osteoclasts fusion, and targeting LPL serves as a novel anabolic therapy for pathological bone loss.

Structure-based development of an osteoprotegerin-like glycopeptide that blocks RANKL/RANK interactions and reduces ovariectomy-induced bone loss in mice.

Osteoporosis is a metabolic bone disease characterized by low bone mass and micro-architectural deterioration of bone, for which the underlying mechanism is an imbalance between bone resorption and bone remodeling. The protein-protein interactions between receptor activator of nuclear factor-κB ligand (RANKL), RANK (its receptor), and osteoprotegerin (OPG), are known to mediate the development and activation of osteoclasts in bone remodeling, and are regarded as a pivotal therapeutic target for the treatment of osteoporosis. Herein, we disclose the successful development of a novel glycopeptide (OM-2), the structure of which is based on the key interacting sites of the reported RANKL and OPG crystal structure. OM-2 exhibited potent binding affinity with RANKL and resistance to degradation by protease enzymes. It also blocked RANKL/RANK interactions, and inhibited osteoclastogenesis in vitro. In vivo studies confirmed that OM-2 could effectively reduce bone loss and inhibit osteoclast activation in ovariectomized (OVX) mice at a dosage of 20.0 mg/kg/day. Accordingly, OM-2 is suggested as a therapeutic candidate for postmenopausal osteoporosis (PMOP) and osteoclastogenesis-related diseases like rheumatoid arthritis (RA). More importantly, its identification validates our structure-based strategy for the development of drugs that target the RANKL/RANK/OPG system.