Baicalein alleviates osteoarthritis by protecting subchondral bone, inhibiting angiogenesis and synovial proliferation.

Osteoarthritis (OA) is one of the most frequent chronic joint diseases with the increasing life expectancy. The main characteristics of the disease are loss of articular cartilage, subchondral bone sclerosis and synovium inflammation. Physical measures, drug therapy and surgery are the mainstay of treatments for OA, whereas drug therapies are mainly limited to analgesics, glucocorticoids, hyaluronic acids and some alternative therapies because of single therapeutic target of OA joints. Baicalein, a traditional Chinese medicine extracted from Scutellaria baicalensis Georgi, has been widely used in anti-inflammatory therapies. Previous studies revealed that baicalein could alleviate cartilage degeneration effectively by acting on articular chondrocytes. However, the mechanisms involved in baicalein-mediated protection of the OA are not completely understood in consideration of integrality of arthrosis. In this study, we found that intra-articular injection of baicalein ameliorated subchondral bone remodelling. Further studies showed that baicalein could decrease the number of differentiated osteoblasts by inhibiting pre-osteoblasts proliferation and promoting pre-osteoblasts apoptosis. In addition, baicalein impaired angiogenesis of endothelial cells and inhibited proliferation of synovial cells. Taken together, these results implicated that baicalein might be an effective medicine for treating OA by regulating multiple targets.

The effects of tranylcypromine on osteoclastogenesis in vitro and in vivo.

Identification of anti-osteoclastogenic agents is important for the treatment of bone loss diseases that feature excessive osteoclast (OC) activity and bone resorption. Tranylcypromine (TCP), an irreversible inhibitor of monoamine oxidase (MAO), has been used as an antidepressant and anxiolytic agent in the clinical treatment of mood and anxiety disorders. TCP has been discovered to exert anabolic effect on osteoblasts, and MAO-A has also been verified as an important mediator in prostate cancer cells to accelerate osteoclastogenesis. In current study, we were focused on TCP and MAO-A effects on osteoclastogenesis. As illustrated by tartrate-resistant acid phosphatase staining, TCP was capable of inhibiting osteoclastogenesis induced by receptor activators of the NF-κB ligand (RANKL) in bone marrow-derived macrophage cells without any cytotoxicity. It was also shown to effectively suppress bone resorption of OCs. The subsequent study revealed that TCP inhibited osteoclastogenesis-related genes in a time-dependent manner through protein kinase B (AKT)-mediated mechanism followed by the nuclear factor of activated T cells, cytoplasmic 1 (NFATc1)-c-fos pathway. And TCP could overcome the osteoclastogenic effects of AKT activator SC79. In addition, our results indicated that the expression and catalytic activity of MAO-A were up-regulated by RANKL stimulation and down-regulated by TCP in vitro and in vivo. Furthermore, the effects of MAO-A knockdown on OC differentiation indicated that MAO-A played an important role in osteoclastogenesis in vitro and might contribute to the inhibitory effects of TCP. And AKT, NFATc1, and c-fos were involved in the MAO-A pathway. Notably, our in vivo study reflected that TCPs were capable of restoring the bone loss in LPS-induced calvaria osteolysis and estrogen deficiency-induced osteoporosis models. Thus, our current work provided a potential option for the treatment of bone loss diseases and highlighted the important role of MAO-A in osteoclastogenesis as well.-Liu, Z., Yang, K., Yan, X., Wang, T., Jiang, T., Zhou, Q., Qi, J., Qian, N., Zhou, H., Chen, B., Huang, P., Guo, L., Zhang, X., Xu, X., Jiang, M., Deng, L. The effects of tranylcypromine on osteoclastogenesis in vitro and in vivo.

Small molecule nAS-E targeting cAMP response element binding protein (CREB) and CREB-binding protein interaction inhibits breast cancer bone metastasis.

Bone is the most common metastatic site for breast cancer. The excessive osteoclast activity in the metastatic bone lesions often produces osteolysis. The cyclic-AMP (cAMP)-response element binding protein (CREB) serves a variety of biological functions including the transformation and immortalization of breast cancer cells. In addition, evidence has shown that CREB plays a key role in osteoclastgenesis and bone resorption. Small organic molecules with good pharmacokinetic properties and specificity, targeting CREB-CBP (CREB-binding protein) interaction to inhibit CREB-mediated gene transcription have attracted more considerations as cancer therapeutics. We recently identified naphthol AS-E (nAS-E) as a cell-permeable inhibitor of CREB-mediated gene transcription through inhibiting CREB-CBP interaction. In this study, we tested the effect of nAS-E on breast cancer cell proliferation, survival, migration as well as osteoclast formation and bone resorption in vitro for the first time. Our results demonstrated that nAS-E inhibited breast cancer cell proliferation, migration, survival and suppressed osteoclast differentiation as well as bone resorption through inhibiting CREB-CBP interaction. In addition, the in vivo effect of nAS-E in protecting against breast cancer-induced osteolysis was evaluated. Our results indicated that nAS-E could reverse bone loss induced by MDA-MB-231 tumour. These results suggest that small molecules targeting CREB-CBP interaction to inhibit CREB-mediated gene transcription might be a potential approach for the treatment of breast cancer bone metastasis.

Estrogen inhibits osteoclasts formation and bone resorption via microRNA-27a targeting PPARγ and APC.

Inhibition of osteoclasts formation and bone resorption by estrogen is very important in the etiology of postmenopausal osteoporosis. The mechanisms of this process are still not fully understood. Recent studies implicated an important role of microRNAs in estrogen-mediated responses in various cellular processes, including cell differentiation and proliferation. Thus, we hypothesized that these regulatory molecules might be implicated in the process of estrogen-decreased osteoclasts formation and bone resorption. Western blot, quantitative real-time polymerase chain reaction, tartrate-resistant acid phosphatase staining, pit formation assay and luciferase assay were used to investigate the role of microRNAs in estrogen-inhibited osteoclast differentiation and bone resorption. We found that estrogen could directly suppress receptor activator of nuclear factor B ligand/macrophage colony-stimulating factor-induced differentiation of bone marrow-derived macrophages into osteoclasts in the absence of stromal cell. MicroRNA-27a was significantly increased during the process of estrogen-decreased osteoclast differentiation. Overexpressing of microRNA-27a remarkably enhanced the inhibitory effect of estrogen on osteoclast differentiation and bone resorption, whereas which were alleviated by microRNA-27a depletion. Mechanistic studies showed that microRNA-27a inhibited peroxisome proliferator-activated receptor gamma (PPARγ) and adenomatous polyposis coli (APC) expression in osteoclasts through a microRNA-27a binding site within the 3'-untranslational region of PPARγ and APC. PPARγ and APC respectively contributed to microRNA-27a-decreased osteoclast differentiation and bone resorption. Taken together, these results showed that microRNA-27a may play a significant role in the process of estrogen-inhibited osteoclast differentiation and function.

The prevention of latanoprost on osteoclastgenesis in vitro and lipopolysaccharide-induced murine calvaria osteolysis in vivo.

Identification of agents that inhibit osteoclast formation and function is important for the treatment of osteolytic diseases which feature excessive osteoclast formation and bone resorption. Latanoprost (LTP), an analog of prostaglandin F2α, is a medication which works to lower pressure inside the eyes. Prostaglandin F2α was reported to regulate bone metabolism, however, the effect of LTP in osteoclastogenesis is still unknown. Here, we found that LTP suppressed RANKL-induced osteoclastogenesis in a dose-dependent manner as illustrated by TRAP activity and TRAP staining. In addition, the osteoclast function was also reduced by LTP treatment, as indicated in less osteoclastic resorption pit areas. Furthermore, LTP inhibited the mRNA expressions of osteoclast marker genes such as TRAP and cathepsin K. In order to illustrate its molecular mechanism, we examined the changing of mRNA and protein levels of NFATc1 and c-fos by LTP treatment, as well as the phosphorylation of ERK, AKT, JNK, and p38. The results suggested that LTP inhibited RANKL-induced osteoclastgenesis and function by inhibiting ERK, AKT, JNK, and p38 cascade, following by the c-fos/NFATc1 pathway. In agreement with in vitro results, using an in vivo lipopolysaccharide-induced murine calvaria osteolysis mouse model, we found that administration of LTP was able to reverse the lipopolysaccharide-induced bone loss. Together, these data demonstrated that LTP attenuated the bone loss in lipopolysaccharide-induced murine calvaria osteolysis mice through inhibiting osteoclast formation and function. Our study thus provided the evidences that LTP was a potential treatment option against osteolytic bone diseases.

The inhibition of RANKL expression in fibroblasts attenuate CoCr particles induced aseptic prosthesis loosening via the MyD88-independent TLR signaling pathway.

Periprosthetic osteolysis and aseptic loosening are mainly caused by wear particles (Ps) that are generated from friction interfaces. However, the mechanisms underlying the development of aseptic loosening remain unclear. Therefore, we aimed toclarify how the myeloid differentiation factor 88 (MyD88)-independent Toll-like receptor (TLR) signaling pathway mediates cobalt and chromium (CoCr)-Ps-induced osteolysis. We quantified the expression levels of TLRs, MyD88, RANKL, and inflammatory factors in patients experiencing aseptic loosening after primary total hip arthroplasty (THA) with metal-on-metal (MoM) bearings and hip osteoarthritis (hOA). We observed the in vitro and in vivo levels of RANKL, TLRs, and MyD88 in fibroblasts challenged with CoCr Ps by applying shMyD88 interference lentivirus vectors to block the MyD88-independent TLR pathway. The levels of TLRs, MyD88, RANKL, and inflammatory factors in the revision THA (rTHA) with MoM group were higher than those in the hOA group. Our data collectively revealed that inhibiting MyD88 expression could reduce osteoclastogenesis in vitro and CoCr-Ps-induced osteolysis in vivo. Our findings suggested that osteoclastogenesis is promoted by the CoCr-Ps-induced expression of RANKL in fibroblasts and that MyD88 is a potential target in the treatment of wear Ps-induced osteolysis.

The effects of different amounts of drug microspheres on the vivo and vitro performance of the PLGA/ß-TCP scaffold.

OIC-A006 (BMPs osteogenesis compounds), can stimulate bone marrow mesenchymal stem cells ALP, OPN, OC, Cbfal expression. To stimulate new bone formation in the body. We postulate different amounts of drug microspheres on the PLGA/ß-CPT scaffold can produce the effects on performance and sustained release characteristics. In this paper, through adding different amount of carrier drug microsphere, three concentrations scaffolds which are 12.5, 18.75 and 25 µmol/L are prepared by adding different amounts of drug-loaded microspheres. Hereafter called OICM/CPT-200, OICM/CPT-300, OICM/CPT-400. We implant them in rat femur diameter 3 mm depth of 3 mm hole for eight weeks. The degradation, microsphere, delivery properties, with X-ray, micro-CT and histology are tested. Results show that the contain carrier drug microsphere scaffolds become radiopaque, and the gaps between the scaffold and radial cut ends are often invisible. This preliminary study reveals that different carrier drug microsphere has a corresponding effect the performance of stent body, OICM/CPT - 200 scaffolds induction effect is best. Illustrates that the low concentration load OIC-A006 microspheres can promote bone healing, and high concentration of OIC-A006 micro ball is played a inhibitory effect on bone healing process.

MicroRNA-17-92a upregulation by estrogen leads to Bim targeting and inhibition of osteoblast apoptosis.

Anti-apoptotic effects of estrogen on osteoblasts are very important in the etiology of estrogen protection of the adult skeleton against bone loss. The mechanisms of this process are still not fully understood. Recent studies implicated an important role of microRNAs in estrogen-mediated responses in various cellular processes, including cell apoptosis and proliferation. Therefore, we hypothesized that these regulatory molecules might be involved with estrogen in protecting osteoblasts from apoptosis. Western blotting, quantitative real-time PCR, flow cytometry and luciferase assays were employed to investigate the role of microRNAs in this process. The microRNA cluster miR-17-92a, a post-transcriptional regulator, was significantly reduced during dexamethasone, etoposide and tumor necrosis factor alpha (TNF-α)-induced osteoblasts apoptosis. The repression of miR-17-92a was significantly attenuated by estrogen. To delineate the role of miR-17-92a in apoptosis, we silenced and overexpressed miR-17-92a in osteoblasts. We found that miR-17-92a depletion significantly enhanced dexamethasone-induced apoptosis and overexpressing miR-17-92a remarkably increased the anti-apoptotic effects of estrogen on osteoblasts. Mechanistic studies showed that miR-17-92a inhibited Bim expression through a microRNA-17-92a-binding site within the 3'-untranslated region of Bim. The post-transcriptional repression of Bim was further confirmed by a luciferase reporter assay. These results showed that miR-17-92a, plays a significant role in the process of estrogen protection of osteoblasts against apoptosis, by regulating Bim expression.

Bone selective protective effect of a novel bone-seeking estrogen on trabecular bone in ovariectomized rats.

The drawbacks of estrogen restrict the clinical use of hormone replacement therapy, and it would be most helpful to explore new estrogenic substances that could prevent bone loss and be free from any adverse effects. We synthesized a new compound named bone-seeking estrogen (SE2) by combining 17ß-estradiol (E2) with iminodiacetic acid through the Mannich reaction. E2 and SE2 were labeled with isotope (3)H, and the tissue distribution tests of E2-(3)H and SE2-(3)H were analyzed by the radioactivity. The specific nuclear binding of E2 and SE2 in osteoblasts was measured. SE2 exhibited significantly greater affinity for bone but lower affinity for ovary and uterus than did E2, and SE2 maintained a high affinity for the estrogen receptor alpha similar to that of E2. SE2 administration did not induce uterine hypertrophy. Body weight increase was significantly suppressed by treatment with E2 but not by SE2 after ovariectomy (OVX). SE2 decreased bone turnover as E2 after OVX detected by serum biochemical markers. Bone histology and micro-CT analysis revealed that SE2 administration, similar to E2, could improve bone mass and trabecular architecture after OVX. Biomechanical analyses showed that SE2 treatment effectively increased mechanical properties after OVX. The results suggested that SE2 was effective in preventing OVX-induced bone loss and exhibited few side effects on body weight and uterine hypertrophy, which was beneficial in reducing the adverse effects caused by E2. SE2 may be a better choice than E2 for the prevention of postmenopausal osteoporosis.

OIC-A006-loaded true bone ceramic heals rabbit critical-sized segmental radial defect.

It has been reported that OIC-A006, an osteogenically inducible compound, is able to promote osteogenesis in vitro and in vivo. In this study, we used a rabbit critical-sized segmental radial defect model (CSD) (15 mm) to analyse the osteogenic activity of OIC-A006 in non-cell-seeded tissue engineering bone substitutes. The scaffold carrier was bovine sintered bone "true bone ceramic (TBC)". OIC-A006 was delivered by PLGA (D,L-lactide-co-glycolide acid) microspheres. Drug-free PLGA microspheres and rhBMP-2-loaded PLGA microspheres were used as negative and positive control groups, respectively. Three kinds of composite were fabricated by coupling TBC, type-I collagen and the corresponding microspheres. The animals were randomly divided into 4 groups: (1) Group A: defect only, (2) group B:TBC/Collagen/drug-free-microspheres, (3) group C:TBC/Collagen/ OIC-A006-microspheres, (4) group D: TBC/Collagen/rhBMP-2-microspheres. The samples were analysed by histology, X-ray,microcomputed tomography (micro-CT), and biomechanical analyses. The results showed that OIC-A006 promoted bone regeneration to a remarkable extent. It is suggested that the application of OIC-A006 might be a valuable method in bone tissue engineering for healing large segmental defects of long bones. However, the biomechanical strength was a little inferior to that of BMPs.

α-Asarone Attenuates Osteoclastogenesis and Prevents Against Oestrogen-Deficiency Induced Osteoporosis.

Osteoporosis (OP) is defined as low bone mineral density which features over activated osteoclasts (OCs) and bone resorption. Targeting excessive OCs activity is thought to be an effective therapeutic approach for OP treatment. α-asarone (ASA), a compound from the traditional Chinese medicinal herb Acorus tatarinowii, has been widely used as a therapeutic agent against several diseases such as epilepsy, cough, bronchitis and asthma for many years. Recently, it was reported that ASA-derived lignins which were purified from Acorus tatarinowii root tissues effectively suppressed both RANKL-induced osteoclastogenesis and bone resorption. Besides, a classic Chinese formulation Bajitianwan (BJTW) which consisted of root and rhizome of Acorus tatarinowii Schott also showed positive effects on age-related bone loss. In the present study, we aimed to study the effects of ASA on osteoclastogenesis in vitro and in vivo. As illustrated by TRAP staining, ASA was capable of inhibiting RANKL-induced osteoclastogenesis in a dose-dependent manner, not only at an early-stage, but also in the late-stage. Besides, it also effectively suppressed bone resorption of mature OCs in a pit resorption assay. The formation of F-actin ring during osteoclastogenesis, which was important in OCs bone-resorption, was impaired as well. Subsequent mechanism experiments exposed that ASA inhibited osteoclastogenesis related genes in a time-dependent manner through AKT, p38 and NF-κB, followed by NFATc1/c-fos signaling pathway. Notably, our in vivo study uncovered that ASA was capable of improving the bone microstructure in oestrogen-deficiency induced OP models. Thus, our current work highlighted the important role of an old drug ASA in bone metabolism especially in OCs differentiation. ASA may find its potential as a lead compound to treat excessive OCs activity-induced bone loss diseases and more structure optimization is further needed.

High Mineralization Capacity of IDG-SW3 Cells in 3D Collagen Hydrogel for Bone Healing in Estrogen-Deficient Mice.

Tissue engineering with 3D scaffold is a simple and effective method for bone healing after large-scale bone loss. So far, bone marrow-derived mesenchymal stem cells (BMSCs) are mostly used in the treatment of bone healing in animal models due to their self-renewal capability and osteogenic potential. Due to the fact that the main functional cells in promoting osteoid mineralization and bone remodeling were osteocytes, we chose an osteoblast-to-osteocyte transition cell line, IDG-SW3, which are not proliferative under physiological conditions, and compared the healing capability of these cells to that of BMSCs in bone defect. In vitro, IDG-SW3 cells revealed a stronger mineralization capacity when grown in 3D collagen gel, compared to that of BMSCs. Although both BMSC and IDG-SW3 can generate stable calcium-phosphate crystal similar to hydroxyapatite (HA), the content was much more enriched in IDG-SW3-mixed collagen gel. Moreover, the osteoclasts co-cultured with IDG-SW3-mixed collagen gel were easier to be activated, indicating that the IDG-SW3 grafting could promote the bone remodeling more efficiently in vivo. Last, in order to reduce the self-healing capability, we assessed the healing capability between the IDG-SW3 cells and BMSCs in osteoporotic mice. We found that the collagen hydrogel mixed with IDG-SW3 cells has a better healing pattern than what was seen in hydrogel mixed with BMSCs. Therefore, these results demonstrated that by promoting osteoblast-to-osteocyte transition, the therapeutic effect of BMSCs in bone defect repair could be improved.

Histone demethylase LSD1 is critical for endochondral ossification during bone fracture healing.

Bone fracture is repaired predominantly through endochondral ossification. However, the regulation of endochondral ossification by key factors during fracture healing remains largely enigmatic. Here, we identify histone modification enzyme LSD1 as a critical factor regulating endochondral ossification during bone regeneration. Loss of LSD1 in Prx1 lineage cells severely impaired bone fracture healing. Mechanistically, LSD1 tightly controls retinoic acid signaling through regulation of Aldh1a2 expression level. The increased retinoic acid signaling in LSD1-deficient mice suppressed SOX9 expression and impeded the cartilaginous callus formation during fracture repair. The discovery that LSD1 can regulate endochondral ossification during fracture healing will benefit the understanding of bone regeneration and have implications for regenerative medicine.

Development of Small-Molecules Targeting Receptor Activator of Nuclear Factor-κB Ligand (RANKL)-Receptor Activator of Nuclear Factor-κB (RANK) Protein-Protein Interaction by Structure-Based Virtual Screening and Hit Optimization.

Targeting RANKL/RANK offers the possibility of developing novel therapeutic approaches to treat bone metabolic diseases. Multiple efforts have been made to inhibit RANKL. For example, marketed monoclonal antibody drug Denosumab could inhibit the maturation of osteoclasts by binding to RANKL. This study is an original approach aimed at discovering small-molecule inhibitors impeding RANKL/RANK protein interaction. We identified compound 34 as a potent and selective RANKL/RANK inhibitor by performing structure-based virtual screening and hit optimization. Disruption of the RANKL/RANK interaction by 34 effectively inhibits RANKL-induced osteoclastogenesis and bone resorption. The expression of osteoclast marker genes was also suppressed by treatment of 34. Furthermore, 34 markedly blocked the NFATc1/c-fos pathway. Thus, our current work demonstrates that the chemical tractability of the difficult PPI (RANKL/RANK) target by a small-molecule compound 34 offers a potential lead compound to facilitate the development of new medications for bone-related diseases.

Vascularized 3D printed scaffolds for promoting bone regeneration.

3D printed scaffolds hold promising perspective for bone tissue regeneration. Inspired by process of bone development stage, 3D printed scaffolds with rapid internal vascularization ability and robust osteoinduction bioactivity will be an ideal bone substitute for clinical use. Here, we fabricated a 3D printed biodegradable scaffold that can control release deferoxamine, via surface aminolysis and layer-by-layer assembly technique, which is essential for angiogenesis and osteogenesis and match to bone development and reconstruction. Our in vitro studies show that the scaffold significantly accelerates the vascular pattern formation of human umbilical endothelial cells, boosts the mineralized matrix production, and the expression of osteogenesis-related genes during osteogenic differentiation of mesenchymal stem cells. In vivo results show that deferoxamine promotes the vascular ingrowth and enhances the bone regeneration at the defect site in a rat large bone defect model. Moreover, this 3D-printed scaffold has excellent biocompatibility that is suitable for mesenchymal stem cells grow and differentiate and possess the appropriate mechanical property that is similar to natural cancellous bone. In summary, this 3D-printed scaffold holds huge potential for clinical translation in the treatment of segmental bone defect, due to its flexibility, economical friendly and practicality.

A Novel Rhein Derivative Modulates Bone Formation and Resorption and Ameliorates Estrogen-Dependent Bone Loss.

Osteoporosis, an osteolytic disease that affects millions of people worldwide, features a bone remodeling imbalance between bone resorption by osteoclasts and bone formation by osteoblasts. Identifying dual target-directed agents that inhibit excessive bone resorption and increase bone formation is considered an efficient strategy for developing new osteoporosis treatments. Rhein, a natural anthraquinone, can be isolated from various Asian herbal medicines. Rhein and its derivatives have been reported to have various beneficial pharmacological effects, especially their bone-targeting ability and anti-osteoclastogenesis activity. Moreover, hydrogen sulfide (H2 S) was reported to prevent ovariectomy- (OVX-) induced bone loss by enhancing bone formation, and sulfur replacement therapy has been considered a novel and plausible therapeutic option. Based on this information, we synthesized a rhein-derived thioamide (RT) and investigated its effects on bone resorption and bone formation in vitro and in vivo. It has been found that the RT-inhibited receptor activator of the nuclear factor-κB (NF-κB) ligand- (RANKL-) induced osteoclastogenesis and bone resorption in a dose-dependent manner. The expression of osteoclast marker genes was also suppressed by RT treatment. Furthermore, exploration of signal transduction pathways indicated that RT markedly blocked RANKL-induced osteoclastogenesis by attenuating MAPK pathways. However, RT treatment in an osteoblastic cell line, MC3TE-E1, indicated that RT led to an increase in the deposition of minerals and the expression of osteoblast marker genes, as demonstrated by Alizarin Red staining and alkaline phosphatase activity. Importantly, an OVX mouse model showed that RT could attenuate the bone loss in estrogen deficiency-induced osteoporosis in vivo with a smart H2 S-releasing property and that there was a considerable improvement in the biomechanical properties of bone. Accordingly, our current work highlights the dual regulation of bone remodeling by the rhein-derived molecule RT. This may be a highly promising approach for a new type of anti-osteoporosis agent. © 2018 American Society for Bone and Mineral Research.

SF-deferoxamine, a bone-seeking angiogenic drug, prevents bone loss in estrogen-deficient mice.

Deferoxamine (DFO) possesses a good chelating capability and is therefore used for the clinical treatment of ion deposition diseases. Increasing evidence shows that DFO can inhibit the activity of proline hydroxylase (PHD) by chelating iron, resulting in hypoxia-induced factor (HIF) signaling activation and angiogenesis promotion. However, clinical evidence indicates that a high concentration of DFO could be biotoxic due to its enrichment in related organs. Thus, we established a new compound by conjugating DFO with the bone-seeking agent iminodiacetic acid (IDA); the new agent is called SF-DFO, and we verified its promotion of HIF activation and tube formation in vivo. After confirming the bone-seeking property of SF-DFO in the femur and vertebra of both male and female mice and comparing it to that of DFO, we analyzed the protective effect of DFO and SF-DFO in an ovariectomized (OVX) mouse model. The serum CTX-I level revealed no influence of DFO and SF-DFO on osteoclast activity, but the blood vessels and osteoblasts in the metaphysis were more abundant after SF-DFO treatment, which resulted in a greater protective effect against trabecular bone loss compared to the DFO group. Additionally, the cortical parameters and bone strength performance were identical between the DFO and SF-DFO groups. However, the diffuse inflammatory response in the liver and spleen that occurred after DFO injection was not observed in the SF-DFO group. Thus, with reduced biotoxicity and an equivalent bone-seeking capability, SF-DFO may be a better choice for the prevention of vascular degradation-induced osteoporosis.

Early effects of parathyroid hormone on vascularized bone regeneration and implant osseointegration in aged rats.

The decreased bone mass and impaired osteogenesis capacities that occur with aging may influence the outcome of dental implants. Parathyroid hormone (PTH) (1-34) is an anabolic agent for the treatment of osteoporosis. However, little is known about its effects and mechanisms on vascularized bone regeneration and implant osseointegration in aging. In current study, we adopted both in vivo and in vitro approaches to explore the mechanisms of early actions of PTH (1-34) on the angiogenic and osteogenic microenvironment to enhance implant osseointegration in aged rats. Daily subcutaneous injections of 30 µg/kg PTH (1-34) were given to female rats aged 20 months beginning on next day of implantation and lasting for 5 weeks. Radiological and histological analysis confirmed that PTH (1-34) improved new bone formation, angiogenesis and implant osseointegration in aged rats in the early stage. The osteogenic potential of aged bone mesenchymal stem cells (BMSCs) was enhanced, while their adipogenesis capacity was attenuated. Furthermore, PTH (1-34) was shown to promote angiogenesis directly via endothelial cell migration and blood vessel formation in vitro. Meanwhile, PTH (1-34) stimulated more osteoclasts participation in bone remodeling by secreting angiogenic and osteogenic growth factors to induce early vascularization and stimulate the migration or differentiation of BMSCs indirectly. Together, these results demonstrate mechanistic insight into how PTH (1-34) regulates the angiogenic and osteogenic microenvironment to result in more active bone remodeling and new bone formation, making it an excellent potential therapeutic agent for rapid vascularized bone regeneration and implant osseointegration in the aged population.

Plumbagin Ameliorates Collagen-Induced Arthritis by Regulating Treg/Th17 Cell Imbalances and Suppressing Osteoclastogenesis.

Objective: Plumbago zeylanica L. (with plumbagin as its active ingredients) has been used for centuries to treat conditions such as joint swelling, fractures, and bacterial infections, suggesting that it possesses anti-inflammatory and immunosuppressive properties. In the present study, we evaluated the potential anti-arthritic activity and related mechanisms of plumbagin. Methods: Collagen-induced arthritis (CIA) was initiated in Wistar rats with collagen type II. Plumbagin (2 and 6 mg/kg) was orally administered to rats with CIA from day 12 to day 32 post immunization. The effects of plumbagin on arthritis progression were assessed by paw swelling, clinical scoring, and histologic analysis. The percentage of Treg and Th17 were defined by flow cytometry or immunofluorescence (IF) staining. Bone erosion and resorption were assessed by micro-CT and histomorphometric analysis. Osteoclast differentiation was further determined by in vitro osteoclastogenesis assay. The molecular docking assay was used to determine the potential binding site of plumbagin. Results: Treatment with plumbagin significantly inhibited arthritis development, as well as suppressed the local and systemic inflammation. Plumbagin reciprocally regulated pro-inflammatory Th17 cell and immunosuppressive Treg cell populations. In addition, plumbagin protected inflammation-induced bone loss by inhibiting osteoclast formation and activity. Plumbagin markedly suppressed RANKL-stimulated osteoclast-specific gene expression by repressing NF-κB signaling activation and MAP kinase phosphorylation. Further study via molecular docking assay demonstrated that plumbagin bound to MET169 of JNK kinase and LYS138 and SER183 of p38 kinase. Conclusion: Plumbagin not only attenuates the immune-induced arthritis by inhibiting inflammation, but also protects bone erosion by directly inhibiting osteoclast formation and activity. These data suggest plumbagin is a promising new candidate drug for treating inflammatory joint diseases.

Increased 15-lipoxygenase-1 expression in chondrocytes contributes to the pathogenesis of osteoarthritis.

15-Lipoxygenase-1 (15-LO-1) is involved in many pathological processes. The purpose of this study was to determine the potential role of 15-LO-1 in osteoarthritis (OA). The levels of 15-LO-1 expression were measured by western blotting and quantitative real-time PCR in articular cartilage from the OA rat models and OA patients. To further investigate the effects of 15-LO-1 on chondrocyte functions, such as extracellular matrix (ECM) secretion, the release of matrix-degrading enzymes, the production of reactive oxygen species (ROS), cell proliferation and apoptosis, we decreased or increased 15-LO-1 expression in chondrocytes by means of transfecting with siRNA targeting 15-LO-1 and plasmid encoding 15-LO-1, respectively. The results showed that 15-LO-1 expression was obviously increased in articular cartilage from OA rats and OA patients. It was also found that many factor-related OA, such as mechanical loading, ROS, SNP and inflammatory factor, significantly promoted 15-LO-1 expression and activity in chondrocytes. Silencing 15-LO-1 was able to markedly alleviate mechanical loading-induced cartilage ECM secretion, cartilage-degrading enzyme secretion and ROS production. Overexpression of 15-LO-1 could inhibit chondrocyte proliferation and induce chondrocyte apoptosis. In addition, reduction of 15-LO-1 in vivo significantly alleviated OA. Taken together, these results indicate that 15-LO-1 has an important role in the disease progression of OA. Thus 15-LO-1 may be a good target for developing drugs in the treatment of OA.