A novel therapeutic approach with Caviunin-based isoflavonoid that en routes bone marrow cells to bone formation via BMP2/Wnt-β-catenin signaling

Estrogenic flavonoids and their molecular mechanisms of action

Flavonoids are a major group of phytoestrogens associated with physiological effects, and ecological and social impacts. Although the estrogenic activity of flavonoids was reported by researchers in the fields of medical, environmental and food studies, their molecular mechanisms of action have not been comprehensively reviewed. The estrogenic activity of the respective classes of flavonoids, anthocyanidins/anthocyanins, 2-arylbenzofurans/3-arylcoumarins/α-methyldeoxybenzoins, aurones/chalcones/dihydrochalcones, coumaronochromones, coumestans, flavans/flavan-3-ols/flavan-4-ols, flavanones/dihydroflavonols, flavones/flavonols, homoisoflavonoids, isoflavans, isoflavanones, isoflavenes, isoflavones, neoflavonoids, oligoflavonoids, pterocarpans/pterocarpenes, and rotenone/rotenoids, was summarized through a comprehensive literature search, and their structure-activity relationship, biological activities, signaling pathways, and applications were discussed. Although the respective classes of flavonoids contained at least one chemical mimicking estrogen, the mechanisms varied, such as those with estrogenic, anti-estrogenic, non-estrogenic, and biphasic activities, and additional activities through crosstalk/bypassing, which exert biological activities through cell signaling pathways. Such mechanistic variations of estrogen action are not limited to flavonoids and are observed among other broad categories of chemicals, thus this group of chemicals can be termed as the "estrogenome". This review article focuses on the connection of estrogen action mainly between the outer and the inner environments, which represent variations of chemicals and biological activities/signaling pathways, respectively, and form the basis to understand their applications. The applications of chemicals will markedly progress due to emerging technologies, such as artificial intelligence for precision medicine, which is also true of the study of the estrogenome including estrogenic flavonoids.

Advent of phytobiologics and nano-interventions for bone remodeling: a comprehensive review

Bone metabolism constitutes the intricate processes of matrix deposition, mineralization, and resorption. Any imbalance in these processes leads to traumatic bone injuries and serious disease conditions. Therefore, bone remodeling plays a crucial role during the regeneration process maintaining the balance between osteoblastogenesis and osteoclastogenesis. Currently, numerous phytobiologics are emerging as the new therapeutics for the treatment of bone-related complications overcoming the synthetic drug-based side effects. They can either target osteoblasts, osteoclasts, or both through different mechanistic pathways for maintaining the bone remodeling process. Although phytobiologics have been widely used since tradition for the treatment of bone fractures recently, the research is accentuated toward the development of osteogenic phytobioactives, constituent-based drug designing models, and efficacious delivery of the phytobioactives. To achieve this, different plant extracts and successful isolation of their phytoconstituents are critical for osteogenic research. Hence, this review emphasizes the phytobioactives based research specifically enlisting the plants and their constituents used so far as bone therapeutics, their respective isolation procedures, and nanotechnological interventions in bone research. Also, the review enlists the vast array of folklore plants and the newly emerging nano-delivery systems in treating bone injuries as the future scope of research in the phytomedicinal orthopedic applications.

A novel BMP2 secretagogue ameliorates glucocorticoid induced oxidative stress in osteoblasts by activating NRF2 dependent survival while promoting Wnt/β-catenin mediated osteogenesis

In our previous study, a novel BMP2 secretagogue was synthesized belonging to a class of galloyl conjugates of flavanones, with remarkable osteogenic potential that promoted bone regeneration. We aimed to establish the protective effect of our compound against bone loss that co-exists with excess Glucocorticoid (GC) therapy. GC therapy induces osteoblast damage leading to apoptosis by increasing reactive oxygen species (ROS). Our results delineate that compound 5e (a BMP2 secretagogue) activates NRF2 signalling to counter the disturbed cellular redox homeostasis and escalate osteoblast survival as assessed by Western blot and immunocytochemistry. Depletion of NRF2 by siRNA blocked activation of the NRF2/HO-1 pathway, magnified oxidative stress, increased apoptosis and abrogated the protective effects of compound 5e. 5e, on the other hand, increased ALP, mineralization activity, and promoted osteoblast differentiation by activating WNT/β-catenin signalling in BMP2 dependent manner, validated by Western blot of WNT3A, SOST, GSK3-β and β-catenin nuclear translocation. Treatment of 5e in presence of BMP inhibitor noggin attenuated the osteogenic efficacy and minimized Wnt//β-catenin signalling in presence of dexamethasone. Our compound prevents GC challenged trabecular and cortical bone loss assessed by micro-CT and promotes bone formation and osteocyte survival determined by calcein labelling and TUNEL assay in GC treated animals. The osteogenic potential of the compound was authenticated by bone turnover markers. On a concluding note, compounds with BMP upregulation can be potential therapeutics for the prevention and treatment of glucocorticoid-induced osteoporosis.

Wnt signaling in colorectal cancer: pathogenic role and therapeutic target

Background

The Wnt signaling pathway is a complex network of protein interactions that functions most commonly in embryonic development and cancer, but is also involved in normal physiological processes in adults. The canonical Wnt signaling pathway regulates cell pluripotency and determines the differentiation fate of cells during development. The canonical Wnt signaling pathway (also known as the Wnt/β-catenin signaling pathway) is a recognized driver of colon cancer and one of the most representative signaling pathways. As a functional effector molecule of Wnt signaling, the modification and degradation of β-catenin are key events in the Wnt signaling pathway and the development and progression of colon cancer. Therefore, the Wnt signaling pathway plays an important role in the pathogenesis of diseases, especially the pathogenesis of colorectal cancer (CRC).

Objective

Inhibit the Wnt signaling pathway to explore the therapeutic targets of colorectal cancer.

Methods

Based on studying the Wnt pathway, master the biochemical processes related to the Wnt pathway, and analyze the relevant targets when drugs or inhibitors act on the Wnt pathway, to clarify the medication ideas of drugs or inhibitors for the treatment of diseases, especially colorectal cancer.

Results

Wnt signaling pathways include: Wnt/β-catenin or canonical Wnt signaling pathway, planar cell polarity (Wnt-PCP) pathway and Wnt-Ca²⁺ signaling pathway. The Wnt signaling pathway is closely related to cancer cell proliferation, stemness, apoptosis, autophagy, metabolism, inflammation and immunization, microenvironment, resistance, ion channel, heterogeneity, EMT/migration/invasion/metastasis. Drugs/phytochemicals and molecular preparations for the Wnt pathway of CRC treatment have now been developed. Wnt inhibitors are also commonly used clinically for the treatment of CRC.

Conclusion

The development of drugs/phytochemicals and molecular inhibitors targeting the Wnt pathway can effectively treat colorectal cancer clinically.

Assessment of the Therapeutic Potential of Melatonin for the Treatment of Osteoporosis Through a Narrative Review of Its Signaling and Preclinical and Clinical Studies

Melatonin is a bioamine produced primarily in the pineal gland, although peripheral sites, including the gut, may also be its minor source. Melatonin regulates various functions, including circadian rhythm, reproduction, temperature regulation, immune system, cardiovascular system, energy metabolism, and bone metabolism. Studies on cultured bone cells, preclinical disease models of bone loss, and clinical trials suggest favorable modulation of bone metabolism by melatonin. This narrative review gives a comprehensive account of the current understanding of melatonin at the cell/molecular to the systems levels. Melatonin predominantly acts through its cognate receptors, of which melatonin receptor 2 (MT2R) is expressed in mesenchymal stem cells (MSCs), osteoblasts (bone-forming), and osteoclasts (bone-resorbing). Melatonin favors the osteoblastic fate of MSCs, stimulates osteoblast survival and differentiation, and inhibits osteoclastogenic differentiation of hematopoietic stem cells. Produced from osteoblastic cells, osteoprotegerin (OPG) and receptor activator of nuclear factor kappa B ligand (RANKL) critically regulate osteoclastogenesis and melatonin by suppressing the osteoclastogenic RANKL, and upregulating the anti-osteoclastogenic OPG exerts a strong anti-resorptive effect. Although the anti-inflammatory role of melatonin favors osteogenic function and antagonizes the osteoclastogenic function with the participation of SIRT signaling, various miRNAs also mediate the effects of the hormone on bone cells. In rodent models of osteoporosis, melatonin has been unequivocally shown to have an anti-osteoporotic effect. Several clinical trials indicate the bone mass conserving effect of melatonin in aging/postmenopausal osteoporosis. This review aims to determine the possibility of melatonin as a novel class of anti-osteoporosis therapy through the critical assessment of the available literature.

Benzofuran pyran hybrid prevents glucocorticoid induced osteoporosis in mice via modulation of canonical Wnt/β-catenin signaling

Glucocorticoid induced osteoporosis (GIOP) is the second most leading cause of osteoporosis. We have identified a compound, a benzofuran pyran hybrid compound 4e that has osteogenic potential and we wanted to assess its efficacy in GIOP in male mice. We assessed the effect of dexamethasone and compound 4e on primary osteoblasts using various cell based and immunofluorescence assays. For in vivo studies we administered methylprednisolone and compound 4e as a prophylactic measure in male Balb/c mice for 28 days and then evaluated the effect on bone microarchitecture by microCT, bone formation by histology along with clinically relevant bone markers. Compound 4e preserved osteoblast differentiation as evident by higher ALP positive cells and mineralization in compound treated groups. Compound 4e also increased the expression of osteogenic genes. This compound guarded β-catenin expression both in vitro and in vivo as confirmed by western blot and immunofluorescence assays. This led to the preservation of bone microarchitecture and cortical thickness at 2.5 mg kg⁻¹ and 5 mg kg⁻¹ doses. Further compound 4e enhanced bone formation rate and regulated osteocyte death. The osteogenic potential of compound 4e was reflected by an increased level of serum marker osteocalcin and decreased levels of SOST and CTX-I. Overall, Compound 4e is able to overcome the catabolic effect of dexamethasone on bone by targeting the canonical WNT/β-catenin signaling as evidenced by both in vitro and in vivo studies.

Caviunin glycoside (CAFG) from Dalbergia sissoo attenuates osteoarthritis by modulating chondrogenic and matrix regulating proteins

ETHNOPHARMACOLOGICAL RELEVANCE

Dalbergia sissoo DC. (Indian rosewood or Sheesham) is a traditional medicinal plant, reported since time immemorial for its analgesic, anti-nociceptive, anti-inflammatory, and immuno-modulatory properties. D. sissoo DC (DS). is being used traditionally to cure joint inflammation and joint pain.

AIM

To study the potential of DS leaves and its derived novel compound CAFG to treat the clinical symptoms of osteoarthritis (OA) and its underlying mechanism.

METHODS

The chemical profile of DS extract (DSE) with isoflavonoids and isoflvaonoid glycosides from the DS was established by UHPLC-PDA and UHPLC-MS/MS. Monosodium iodoacetate (MIA) was injected into the knee joint to develop the OA model in rats. DSE was given orally for 28 days daily at 250 and 500 mg.kg^-1day^-1. For in-vitro experiments, chondrocytes isolated from joint articular cartilage were negatively induced with interleukin-1β (IL-1β) and CAFG was given to the cells as a co-treatment.

RESULTS

Chondrocytes undergo apoptosis following inflammation and proteoglycan synthesis affected in MIA injected knees. DSE administration prevented these effects as assessed by H&E and Toluidine blue staining. Micro-CT analysis showed that subchondral bone loss was restored. DSE decreased elevated serum levels of cartilage-bone degradation (CTX-I, CTX-II, and COMP), inflammation markers IL-1β, and matrix-degrading MMP-3 and 13. The effects of IL-1β on gene expression of chondrocytes were reversed by CAFG treatment at 1 μM.

CONCLUSION

Data showed that DSE protected joint cartilage and deterioration in subchondral bone in vivo while in in-vitro, its active ingredient CAFG prevented interleukin-1β induced effects and inhibited OA. This finding suggest that DSE and CAFG could be used as a possible therapeutic to treat osteoarthritis.

Dickkopf-1 promotes Vascular Smooth Muscle Cell proliferation and migration through upregulating UHRF1 during Cyclic Stretch application

Dickkopf-1 (DKK1) was recently shown to play an important role in cardiovascular disease. The aim of this work was to assess the role of DKK1 in the regulation of smooth muscle cell function by mechanical stretch and the mechanisms underlying this process.

Methods: Wild-type C57BL/6J mice were subjected to sham or abdominal aortic constriction (AAC) surgery. The expression level of DKK1 was examined by immunohistochemical staining and Western blotting. Analyses of DKK1 function in vascular smooth muscle cell (VSMC) proliferation and migration were performed. Transcriptome sequencing analysis was performed to identify the differentially expressed genes and pathways regulated by DKK1. Smooth muscle-specific Dkk1 knockout mice were used to confirm the function of DKK1 in vivo. Chromatin immunoprecipitation (ChIP) was used to confirm DNA-protein interactions. Promoter luciferase analysis was used to detect transcription factor activity.

Results: We found that AAC significantly increased DKK1 protein levels in the thoracic aorta and coronary artery in vivo. In vitro, high-level stretch (18%) induced the expression of DKK1 in VSMCs. Knocking down DKK1 inhibited VSMC proliferation and migration under high-level stretch (18%). We identified ubiquitin-like containing PHD and RING finger domains 1 (UHRF1) as a target gene of DKK1. Knockdown of UHRF1 with small interfering RNAs partially reversed the regulatory effect of recombinant DKK1 on VSMCs. Specific deletion of DKK1 in VSMCs was sufficient to attenuate the AAC-induced upregulation of UHRF1, thickening of arterial media and increase in VSMC proliferation. Furthermore, we found that DKK1 regulated UHRF1 expression through the YAP-TEAD pathway. TEAD1 and TEAD4 bound directly to the promoter of UHRF1, and blocking the YAP-TEAD interaction inhibited UHRF1 upregulation due to DKK1.

Conclusions: This study reveals that DKK1 mediates the mechanical stretch regulation of smooth muscle cell function by modulating UHRF1 expression through the YAP-TEAD pathway.

Bone Lining Cells Could Be Sources of Bone Marrow Adipocytes

BACKGROUND

Recently, lineage-tracing studies demonstrated that parathyroid hormone and anti-sclerostin antibody (Scl-Ab) can convert bone lining cells (BLCs) into active osteoblasts. However, BLCs might also be differentiated into other lineages. Here we investigated whether BLCs could differentiate into bone marrow adipocytes (BMAds) and whether Scl-Ab could suppress this process.

METHODS

Dmp1-CreERt2:mTmG mice were injected with 0.5 mg of 4-hydroxytamoxifen once weekly from postnatal week 4 to week 8. The mice were treated with either vehicle or rosiglitazone for 8 weeks (weeks 12-20). Moreover, they were administered either vehicle or Scl-Ab (50 mg/kg) twice weekly for 4 weeks (weeks 16-20, N = 4-6/group). We chased the GFP+ cells from the endosteal surface to the bone marrow (BM) of the femur. Using immunohistochemical staining, the numbers of perilipin+ or GFP+/perilipin double+ cells in the BM were quantified. In addition, serum N-terminal propeptide of type I procollagen (P1NP) levels were measured at each time point, and bone mass was analyzed at 20 weeks using micro-computed tomography.

RESULTS

Scl-Ab administration significantly reversed the decreases in bone parameters induced by rosiglitazone. Plump GFP+ cells, presumably active osteoblasts, and extremely flat GFP+ cells, presumably BLCs, were present on the endosteal surface of the femur at 8 and 12 weeks, respectively, in line with prior findings. When we chased the GFP+ cells, rosiglitazone significantly increased the number of GFP/perilipin double+ BMAds compared to the effects of the vehicle (P < 0.001), and overlapping Scl-Ab administration decreased the number of GFP/perilipin double + BMAd compared to rosiglitazone alone (P < 0.001). In addition, we found that osteoblast lineage cells such as BLCs might express PPARγ on immunohistochemical staining. When rosiglitazone was administered to Rip-Cre:mTmG mice, GFP+ cells were not present on the endosteal surface or in the BM of the femur; however, they were present in the pancreas.

CONCLUSION

BLCs could be sources of BMAds, and rosiglitazone could stimulate the differentiation of osteoblast lineage cells into BMAds. Suppression of the differentiation of osteoblast lineage cells into BMAds might contribute to anabolic effects resulting from the pharmacologic inhibition of sclerostin.

Polydatin improves osteogenic differentiation of human bone mesenchymal stem cells by stimulating TAZ expression via BMP2-Wnt/β-catenin signaling pathway

OBJECTIVES

Polydatin (PD), extracted from Polygonum cuspidatum, has shown potential therapeutic applications due to its antiosteoporotic and anti-inflammatory activities. Our previous study suggested that PD promotes the osteogenesis of human bone marrow stromal cells (hBMSCs) via the BMP2-Wnt/β-catenin pathway. The aim of our present study was to further explore the role of PD-mediated regulation of Tafazzin (TAZ), a transcriptional coactivator with a PDZ-binding motif, in osteogenesis.

MATERIALS AND METHODS

hBMSCs were isolated and treated with PD at various concentrations. Alizarin red staining and RT-qPCR were performed to identify calcium complex deposition in hBMSCs as well as the expression of specific osteoblast-related markers, respectively, in each group. Next, TAZ-silenced hBMSCs were generated by lentivirus-produced TAZ shRNA. After treatment with PD, the osteogenic abilities of the TAZ-silenced and control hBMSCs were estimated by ALP activity assay, and expression of the TAZ protein was detected by Western blot analysis and immunofluorescence staining. In vitro, an ovariectomized (OVX) mouse model was established and used to evaluate the effect of PD on bone destruction by micro-CT, immunohistochemistry, and ELISA.

RESULTS

In vitro, 30 μM PD significantly improved the proliferation and calcium deposition of hBMSCs and markedly stimulated the expression of the mRNAs RUNX2, Osteopontin, DLX5, β-catenin, TAZ, and Osteocalcin (OCN). Osteogenic differentiation induced by PD was blocked by lentivirus-mediated TAZ shRNA. Furthermore, Noggin (a regulator of bone morphogenic protein 2 (BMP2)) and DKK1 (an inhibitor of the Wnt/β-catenin pathway) were found to inhibit the increase in TAZ expression induced by PD. In vivo, PD prevented estrogen deficiency-induced bone loss in the OVX mouse model.

CONCLUSION

Taken together, our findings suggest that PD improved the osteogenic differentiation of hBMSCs and maintained the bone matrix in the OVX mouse model through the activation of TAZ, a potential target gene of the BMP2-Wnt/β-catenin pathway.

Aberrant canonical Wnt signaling: Phytochemical based modulation

BACKGROUND

Wnt signaling pathway plays a major role during development like gastrulation, axis formation, organ development and organization of body plan development. Wnt signaling aberration has been linked with various disease conditions like osteoporosis, colon cancer, hair follicle tumor, Leukemia, and Alzheimer's disease. Phytochemicals like flavonoid, glycosides, polyphenols, have been reported to directly target the markers of Wnt signaling in different disease models.

PURPOSE

The study deals in detail about the different phytochemical targeting key players of Wnt signaling pathway in diseases like Cancer, Osteoporosis, and Alzheimer's disease. We have focused on the Pharmacological basis of disease alleviation by phytochemical specifically targeting the Wnt signaling markers in this study.

METHODS

The study focused on the published articles from the preclinical rodent and invitro cell line studies related to Wnt signaling and Phytochemicals related to Cancer, Alzheimer's and Osteoporosis. The electronic databases Scopus, Web of Science and Pubmed database were used for the systematic search of literatures from 2005 up to 2019 using keywords Canonical Wnt signaling pathway, Cancer, Alzheimer's disease, Osteoporosis, Phytochemicals. The focus was to identify the target specific modulation of Wnt signaling mediated by phytochemicals.

RESULTS

Approximately 30 phytochemicals of different class have been identified to modulate Wnt signaling pathway acting through Axin, β-catenin translocation, GSK-3β, AKT, Wif-1 in various experimental studies. The down regulation of Wnt signaling is observed in Cancer mostly colorectal cancer, breast cancer mediated through mutations in APC and Axin genes. Different class of Phytochemicals such as flavonoid, glycosides, polyphenol, alkaloids etc. have been found to target Wnt signaling markers and alleviate Cancer. Similarly, Up regulation of Wnt signaling has been reported in Osteoporosis and neurodegenerative disease like Alzheimer's disease.

CONCLUSION

This review highlights the possibility of the Phytochemicals to target Wnt markers and its potential to either activate or deactivate the Wnt signaling pathway. It also describes the challenges in proper targeting of Wnt signaling and the potential risk and consequences of either up regulation or down regulation of the signaling pathway. This article highlights the possibility of Wnt signaling pathway as a therapeutic option in different diseases.

Effects of soybean isoflavone on metabolism of rat osteoblasts and cytokines in vitro

The effects and mechanisms of soybean isoflavone on osteoblast (OB) proliferation in vitro were investigated. Fifty female Wistar rats were randomly divided into five groups with 10 rats in each group. Rat OBs were separated and cultured. The first generation of OBs cultured for 48 hr at various concentrations of isoflavone were set as the experimental groups, the OBs exposed to estradiol (E2 ) culture were considered as positive control group. The biological characterization of OBs was investigated by phase contrast microscopy and alkaline phosphatase (ALP) histochemistry. The concentrations of interleukin (IL-1), osteoprotegerin (OPG), transforming growth factor (TGF), granulocyte-macrophage colony-stimulating factor (GM-CSF), and vascular endothelial growth factor (VEGF) in isoflavone culture solutions were determined. Proliferation rate of OBs was increased in experimental group comparing that in the blank group. ALP activity in experimental group was higher than that in blank group. No significant differences of ALP activity were observed between E2 culture group and isoflavone group at concentrations of 10-5 and 10-7 mM (P > 0.05). Furthermore, in the experimental groups at low isoflavone concentrations, the concentrations of OPG, TGF, and VEGF were increased and positively correlated with OB proliferation. However, the concentrations of IL-1, GM-CSF were decreased at higher concentration of isoflavone and were negatively correlated with OB proliferation. Soybean isoflavone could promote the growth and proliferation of rat OB, it might act as the stimulator of OPG, TGF, and VEGF pathway, and the inhibitor of IL-1, GM-CSF pathway as well.

Effect of Nano-Montmorillonite on Osteoblast Differentiation, Mineral Density, and Osteoclast Differentiation in Bone Formation

Calcium-type montmorillonite, a phyllosilicate mineral, has diverse health benefits when introduced into the gastrointestinal tract or applied to the skin. However, the predominant use of this layered material has thus far been in traditional industries, despite its potential application in the pharmaceutical industry. We investigated the effects and mechanism of nano-montmorillonite (NM) on osteoblast and osteoclast differentiation in vivo and in vitro. We examined the osteogenic effects of NM with high calcium content (3.66 wt%) on alkaline phosphatase (ALP) activity, mineralization, bone microarchitecture, and expression level of osteoblast and osteoclast related genes in Ca-deficient ovariectomized (OVX) rats. Micro-computed tomography of OVX rats revealed that NM attenuated the low-Ca-associated changes in trabecular and cortical bone mineral density. It improved ALP activity and mineralization, as well as the expression of osteoblast and osteoclast differentiation associated genes. NM also activated the expression of runt-related transcription factor 2, osteocalcin, bone morphogenetic protein 2, and type 1 collagen via phosphorylated small mothers against decapentaplegic homolog 1/5/8 signaling. Further, NM repressed the expression of receptor activator for cathepsin K, nuclear factor kappa-B ligand and tartrate-resistant acid phosphatase. Therefore, NM inhibits osteoclastogenesis, stimulates osteoblastogenesis, and alleviates osteoporosis.

Inhibition of miR-22 promotes differentiation of osteoblasts and improves bone formation via the YWHAZ pathway in experimental mice

INTRODUCTION

In senile osteoporosis countering the age-mediated bone loss, promotion of osteoblastogenesis and identification of responsible micro-RNA (miR) would be a successful strategy.

MATERIAL AND METHODS

miR microarray screening was carried out to identify the suppressed miRs after real time polymerase chain reaction (RT-PCR) analysis in mesenchymal stem cells (MSCs) derived from adult bone marrow during the proliferation to the mineralization stage. The primary calvarial pre-osteoblasts (human) were harvested and received transfection of miR-22's antagomir or agomir in vitro. Bioinformatics study suggested YWHAZ as the favorable target gene. Next, YWHAZ knockdown was studied for its effect on differentiation of osteoblasts. For in vivo studies, ovariectomized or sham mice were injected with miR-22's antagomir for a period of 6 weeks. The stromal cells were isolated in the 6^th week for ex vivo experiments.

RESULTS

miR-22 was found to be down-regulated in bone marrow derived mesenchymal stem cells. miR-22's antagomir converted the pre-osteoblasts to a more differentiated and mineralized phenotype showing upregulated protein expression of COL1A1, ALP and CBFA1. The miR-22's antagomir suppressed YWHAZ, enhanced stability of CBFA1 and promoted the differentiation of osteoblasts. In vivo, miR-22's antagomir promoted mineralization and osteoblastogenesis, elevated bone strength and reversed the ovariectomy mediated bone loss in sham mice.

CONCLUSIONS

Inhibition of miR-22 may be a potential target for treating osteoporosis clinically. The findings hence suggest that inhibition of miR-22 may be an effective anabolic therapeutic approach in treating osteoporosis clinically.

The shift in the balance between osteoblastogenesis and adipogenesis of mesenchymal stem cells mediated by glucocorticoid receptor

Mesenchymal stem cells (MSCs) are multipotent cells capable of differentiating into several tissues, such as bone, cartilage, and fat. Glucocorticoids affect a variety of biological processes such as proliferation, differentiation, and apoptosis of various cell types, including osteoblasts, adipocytes, or chondrocytes. Glucocorticoids exert their function by binding to the glucocorticoid receptor (GR). Physiological concentrations of glucocorticoids stimulate osteoblast proliferation and promote osteogenic differentiation of MSCs. However, pharmacological concentrations of glucocorticoids can not only induce apoptosis of osteoblasts and osteocytes but can also reduce proliferation and inhibit the differentiation of osteoprogenitor cells. Several signaling pathways, including the Wnt, TGFβ/BMP superfamily and Notch signaling pathways, transcription factors, post-transcriptional regulators, and other regulators, regulate osteoblastogenesis and adipogenesis of MSCs mediated by GR. These signaling pathways target key transcription factors, such as Runx2 and TAZ for osteogenesis and PPARγ and C/EBPs for adipogenesis. Glucocorticoid-induced osteonecrosis and osteoporosis are caused by various factors including dysfunction of bone marrow MSCs. Transplantation of MSCs is valuable in regenerative medicine for the treatment of osteonecrosis of the femoral head, osteoporosis, osteogenesis imperfecta, and other skeletal disorders. However, the mechanism of inducing MSCs to differentiate toward the osteogenic lineage is the key to an efficient treatment. Thus, a better understanding of the molecular mechanisms behind the imbalance between GR-mediated osteoblastogenesis and adipogenesis of MSCs would not only help us to identify the pathogenic causes of glucocorticoid-induced osteonecrosis and osteoporosis but also promote future clinical applications for stem cell-based tissue engineering and regenerative medicine. Here, we primarily review the signaling mechanisms involved in adipogenesis and osteogenesis mediated by GR and discuss the factors that control the adipo-osteogenic balance.

Ginkgolide B promotes osteoblast differentiation via activation of canonical Wnt signalling and alleviates osteoporosis through a bone anabolic way

Osteoporosis has become a worldwide problem as the population ages. Although many advances have been made in the treatment of osteoporosis in the past few years, the outcome are sometimes disturbing because of the adverse effects of these treatments. Further studies are still needed to identify novel alternate agents to improve the therapeutic effect. Ginkgolide B (GB), a derivative of Ginkgo biloba leaves, has numerous pharmacological effects, including anticancer and anti-inflammation activities. However, the effect of GB on the regulation of osteoblast activity and bone formation effect has not yet been investigated. In this study, we showed the in vitro and in vivo effects of GB on osteoblast differentiation and bone formation. We found that GB promotes osteoblast differentiation of Bone Mesenchymal Stem Cells (BMSCs) and MC3T3-E1 cells in vitro in a Wnt/β-catenin-dependent manner. In an in vivo study, we constructed a cranial defect model in rats and treated with GB. Histomorphometric and histological analyses confirmed that the usage of GB significantly promotes bone formation. Further study on ovariectomy (OVX) rats demonstrated that GB is capable of alleviating ovariectomy-induced bone loss by enhancing osteoblast activity. Our findings indicate that GB is a potential therapeutic agent of osteoporosis through an anabolic way in bone.

Effect of the Wnt signal-RANKL/OPG axis on the enhanced osteogenic integration of a lithium incorporated surface

Bone remolding involves the formation of new bone by osteoblasts and the absorption of old bones by osteoclasts. Due to the vital role of osteoblasts and osteoclasts during bone regeneration, it might be feasible to promote osseointegration around the titanium implants by stimulating osteoblasts and inhibiting osteoclasts by modifying the surfaces of the implants. Lithium is used in the treatment of psychiatric patients, and it may be associated with osteogenesis. In this study, lithium was incorporated with sandblasted, large-grit and acid-etched titanium implants via a hydrothermal treatment. In vitro, the nano-scale surface enhanced the adhesion and proliferation of bone marrow mesenchymal stem cells (BMSCs). Moreover, the SLA-Li surface displayed a negative effect on the process of osteoclastogenesis. Further mechanism analysis indicated that the canonical Wnt/β-catenin signaling pathway was activated according to the results of RT-PCR and western blotting. More importantly, the RANKL/OPG signaling axis was also involved in these effects on the SLA-Li surface. The experiments in vivo proved that the SLA-Li surface could induce the bone formation and osseointegration during the early osseointegration after the dental implant surgery. These results suggested that bone homeostasis could be manipulated by an SLA-Li surface, which implied that this new surface might serve as a promising material for clinical application in the future.

MicroRNA-672-5p Identified during Weaning Reverses Osteopenia and Sarcopenia in Ovariectomized Mice

Post-menopausal condition augments the biological aging process, characterized by multiple metabolic disorders in which bone loss is the most prevalent outcome and usually coupled with sarcopenia. Coexistence of such associated pathogenesis have much worse health outcomes, compared to individuals with osteoporosis only. Pre- and post-natal bone development demands calcium from mother to fetus during pregnancy and lactation leading to a significant maternal skeletal loss. It follows an anabolic phase around weaning during which there is a notable recovery of the maternal skeleton. Here, we have studied the therapeutic effect of microRNA-672-5p identified during weaning when it is predominantly expressed, in ovariectomized mice for both osteopenia and sarcopenia. miR-672-5p induced osteoblast differentiation and mineralization. These actions were mediated through inhibition of Smurf1 with enhanced Runx2 transcriptional activation. In vivo, miR-672-5p significantly increased osteoblastogenesis and mineralization, thus reversing bone loss caused by ovariectomy. It also improved bone-mineral density, load-bearing capacity, and bone quality. Sarcopenia was also alleviated by miR-672-5p, as we observed increased cross-sectional area and Feret's diameter of muscle fibers. We hypothesize that elevated miR-672-5p expression has therapeutic efficacy in estrogen-deficiency-induced osteopenia along with sarcopenia.

MicroRNA-451 blockade promotes osteoblastic differentiation and skeletal anabolic effects by promoting YWHAZ-mediated RUNX2 protein stabilization

Background: senile osteoporosis researchers are now seeking to promote osteoblastogenesis and resultant bone formation to directly counteract age-related bone loss. Targeting microRNA (miRNA) activity in adult osteoblasts may be a successful therapeutic strategy for age-related bone loss. We investigated the mechanism(s) by which miRNAs negatively regulate osteoblastogenesis and bone formation in vitro and in vivo. Methods: we performed a miRNA microarray screen followed by PCR validation in adult bone marrow-derived mesenchymal stem cells during the proliferation-to-mineralization transition to identify downregulated miRNAs, most notably miR-451. Primary human calvarial pre-osteoblasts were isolated and transfected with miR-451's agomir or antagomir for in vitro assays. Bioinformatics analysis and in vitro experiments verified YWHAZ as a miR-451 target gene. We next investigated the effects of YWHAZ knockdown on osteoblastic differentiation. To examine the effects of miR-451's antagomir in vivo, we injected ovariectomized (OVX) or sham-operated mice with miR-451's antagomir over a period of six weeks. We isolated stromal cells from murine bone marrow on week six for further ex vivo experimentation. Results: miR-451's antagomir stimulated pre-osteoblast differentiation into a more differentiated, mineralized phenotype. This phenotype was associated with upregulated RUNX2, ALP, and COL1A1 protein expression. miR-451's antagomir derepresses YWHAZ expression, thereby enhancing RUNX2 protein stability and promoting osteoblastic differentiation. When injected in vivo, miR-451's antagomir promotes osteoblastogenesis and mineralization, reversed OVX-induced bone loss, and increased bone strength in OVX and sham-operated mice. Conclusions: miR-451 suppresses osteoblastogenesis in vitro and in vivo. miR-451 inhibition may serve as an effective anabolic therapeutic strategy in senile osteoporosis patients.

Dried and free flowing granules of Spinacia oleracea accelerate bone regeneration and alleviate postmenopausal osteoporosis

OBJECTIVE

The aim of this study was to demonstrate the efficacy of extract derived from Spinacia oleracea extract (SOE) in reversing bone loss induced by ovariectomy and bone healing properties in a drill-hole fracture model in rats.

METHODS

SOE was administered orally for 12 weeks in adult ovariectomized Sprague Dawley rats after inducing osteopenic condition. Bone micro-architecture, expressions of osteogenic and resorptive gene markers, biomechanical strength, new bone formation, and bone turnover markers were studied. Uterine histomorphometry was used to assess estrogenicity. Bone regeneration potential of SOE was assessed in a drill-hole fracture model. Fracture healing was assessed by calcein intensity and micro-CT analysis of callus at fracture region.

RESULTS

SOE prevented ovariectomy-induced bone loss as evident from 122% increase in bone volume/tissue volume (BV/TV) and 29% decline in Tb.Sp in femoral trabecular micro-architecture. This was corroborated by the more than twofold stimulation in the expression of osteogenic genes runt-related transcription factor 2, osterix, osteocalcin, bone morphogenetic protein 2, collagen-1. Furthermore in the fracture healing model, we observed a 25% increase in BV/TV and enhancement in calcein intensity at the fractured site. The extract when converted into dried deliverable Spinaceae oleracea granule (SOG) form accelerated bone regeneration at fracture site, which was more efficient as evident by a 39% increase in BV/TV. Transforming SOE into dried granules facilitated prolonged systemic availability, thus providing enhanced activity for a period of 14 days.

CONCLUSIONS

SOE treatment effectively prevents ovariectomy-induced bone loss and stimulated fracture healing in adult rats. The dried granular form of the extract of Spinaceae oleracea was effective in fracture healing at the same dose.

Baculovirus-Mediated miR-214 Knockdown Shifts Osteoporotic ASCs Differentiation and Improves Osteoporotic Bone Defects Repair

Osteoporotic patients often suffer from bone fracture but its healing is compromised due to impaired osteogenesis potential of bone marrow-derived mesenchymal stem cells (BMSCs). Here we aimed to exploit adipose-derived stem cells from ovariectomized rats (OVX-ASCs) for bone healing. We unraveled that OVX-ASCs highly expressed miR-214 and identified 2 miR-214 targets: CTNNB1 (β-catenin) and TAB2. We demonstrated that miR-214 targeting of these two genes blocked the Wnt pathway, led to preferable adipogenesis and hindered osteogenesis. As a result, OVX-ASCs implantation into OVX rats failed to heal critical-size metaphyseal bone defects. We further engineered the OVX-ASCs with a novel Cre/loxP-based hybrid baculovirus vector that conferred prolonged expression of miR-214 sponge. Gene delivery for miR-214 sponge expression successfully downregulated miR-214 levels, activated the Wnt pathway, upregulated osteogenic factors β-catenin/Runx2, downregulated adipogenic factors PPAR-γ and C/EBP-α, shifted the differentiation propensity towards osteogenic lineage, enhanced the osteogenesis of co-cultured OVX-BMSCs, elevated BMP7/osteoprotegerin secretion and hindered exosomal miR-214/osteopontin release. Consequently, implanting the miR-214 sponge-expressing OVX-ASCs tremendously improved bone healing in OVX rats. Co-expression of miR-214 sponge and BMP2 further synergized the OVX-ASCs-mediated bone regeneration in OVX rats. This study implicates the potential of suppressing miR-214 by baculovirus-mediated gene delivery in osteoporotic ASCs for regenerative medicine.

Suppression of osteogenic activity by regulation of WNT and BMP signaling during titanium particle induced osteolysis

Periprosthetic osteolysis remains the leading obstacle for total joint replacements. Primarily, it was thought that aseptic loosening is mainly caused by macrophage mediated inflammatory process arising from production of wear debris. The role of osteoclasts and its sequential bone resorption ability has been extensively studied, but little is known about impaired osteogenesis during osteolysis. In the current study, we have tried to delineate the regulatory mechanism of osteogenic signals by Ti particles in osteoprogenitor cells as well its participatory role in wear debris induced osteolysis. Implantation of Ti particles on mice calvaria induced pro-inflammatory response, elevated expression of COX2 and reduced the expression of Osterix. Treatment of Ti particles to MC3T3 E-1 cells displayed decreased osteogenic activity including ALP activity, mineralization and mRNA levels several osteogenic genes. Moreover, the basal activity of WNT and BMP signaling pathways was suppressed in MC3T3 E-1 cells treated with Ti particles. As an early response to Ti particles, MC3T3 E-1 cells showed activation of ERK and JNK. Co-inhibition of ERK and JNK with their specific inhibitors resulted in partial recovery of WNT and BMP signaling activity as well as ALP activity and collagen synthesis. Finally, LiCl mediated activation of WNT signaling pathway demonstrated rescue of Ti particle facilitated suppression of Osterix expression in mice calvaria. Our results provide evidences that WNT signaling pathway is regulated by ERK, JNK, and BMP signaling pathway during wear debris induced inflammatory osteolysis and may be considered as suitable therapeutic targets for the treatment. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 912-926, 2017.

Benzofuran-dihydropyridine hybrids: A new class of potential bone anabolic agents

A series of novel benzofuran-dihydropyridine hybrids were designed by molecular hybridization approach and evaluated for bone anabolic activities. Among the screened library, ethyl 4-(7-(sec-butyl)-2-(4-methylbenzoyl)benzofuran-5-yl)-2-methyl-5-oxo-1,4,5,6,7,8-hexahydroquinoline-3-carboxylate (compound 21) significantly enhanced the ALP production and mineralized nodule formation, which are primary requisites in the process of in vitro osteogenesis. Oral administration of compound 21 at 10 mg.kg^-1 day^-1 for two weeks led to restoration of trabecular bone microarchitecture in drill hole fracture model by significantly increasing BV/TV and Tb.N. Furthermore, histological and molecular studies showed compound 21 triggering the new bone regeneration in a drill hole defect site by increasing BMP expression. Furthermore, molecular modeling studies were performed to gain insight into the binding approach, which revealed that both benzofuran and dihydropyridine moieties are essential to show similar binding interactions to fit into the active site of BMP2 receptor, an important target of the osteogenic agents. Our results suggest that compound 21 stimulates BMP2 synthesis in osteoblast cells that promotes new bone formation (∼40%) at the fracture site which helps in shorten the healing period.

New Molecules Modulating Bone Metabolism – New Perspectives in the Treatment of Osteoporosis

In this review the authors outline traditional antiresorptive pharmaceuticals, such as bisphosphonates, monoclonal antibodies against RANKL, SERMs, as well as a drug with an anabolic effect on the skeleton, parathormone. However, there is also a focus on non-traditional strategies used in therapy for osteolytic diseases. The newest antiosteoporotic pharmaceuticals increase osteoblast differentiation via BMP signaling (harmine), or stimulate osteogenic differentiation of mesenchymal stem cells through Wnt/β-catenin (icarrin, isoflavonoid caviunin, or sulfasalazine). A certain promise in the treatment of osteoporosis is shown by molecules targeting non-coding microRNAs (which are critical for osteoclastogenesis) or those stimulating osteoblast activity via epigenetic mechanisms. Vitamin D metabolites have specific antiosteoporotic potencies, modulating the skeleton not only via mineralization, but markedly also through the direct effects on the bone microstructure.

Molecular signaling mechanisms behind polyphenol-induced bone anabolism

For millennia, in the different cultures all over the world, plants have been extensively used as a source of therapeutic agents with wide-ranging medicinal applications, thus becoming part of a rational clinical and pharmacological investigation over the years. As bioactive molecules, plant-derived polyphenols have been demonstrated to exert many effects on human health by acting on different biological systems, thus their therapeutic potential would represent a novel approach on which natural product-based drug discovery and development could be based in the future. Many reports have provided evidence for the benefits derived from the dietary supplementation of polyphenols in the prevention and treatment of osteoporosis. Polyphenols are able to protect the bone, thanks to their antioxidant properties, as well as their anti-inflammatory actions by involving diverse signaling pathways, thus leading to bone anabolic effects and decreased bone resorption. This review is meant to summarize the research works performed so far, by elucidating the molecular mechanisms of action of polyphenols in a bone regeneration context, aiming at a better understanding of a possible application in the development of medical devices for bone tissue regeneration.

Dickkopf1 destabilizes atherosclerotic plaques and promotes plaque formation by inducing apoptosis of endothelial cells through activation of ER stress

Several clinical studies reported that Dickkopf1 (DKK1) plasma levels are correlated with atherosclerosis. However, the impact of DKK1 on the formation and vulnerability of atherosclerotic plaques remains elusive. This study investigated DKK1’s effects on enlargement and destabilization of plaques by targeting endothelial cells and assessing the possible cellular mechanisms involved. The effects of DKK1 on atherogenesis and plaque stability were evaluated in ApoE−/− mice using lentivirus injections to knockdown and knock-in the DKK1 gene. The presence of DKK1 resulted in enlarged and destabilized atherosclerotic lesions and increased apoptosis, while silencing of DKK1 alleviated plaque formation and vulnerability in the whole progression of atherosclerosis. DKK1 expression was upregulated in response to ox-LDL treatment in a time- and concentration-dependent manner on human umbilical vein endothelial cell (HUVEC). The interference of DKK1 reversed ox-LDL-induced apoptosis in HUVECs. The mechanism underlying this effect was DKK1’s activation of the JNK signal transduction pathway and inhibition of canonical Wnt signaling, following by activation of the IRE1α and eif2α/CHOP pathways. In conclusion, DKK1 promotes plaque formation and vulnerability partly by inducing apoptosis in endothelial cells, which partly through inducing the JNK-endoplasmic reticulum stress pathway and inhibiting canonical Wnt signaling.

Osthole improves function of periodontitis periodontal ligament stem cells via epigenetic modification in cell sheets engineering

Inflammatory microenvironment causes the change of epigenetic modification in periodontal ligament stem cells derived from periodontitis tissues (P-PDLSCs), which results in defective osteogenic differentiation compared to cells from healthy tissues. It’s urgent to explore therapeutic strategies aimed at epigenetic targets associated with the regenerative ability of PDLSCs. Osthole, a small-molecule compound extracted from Chinese herbs, has been documented to promote osteogenesis and cell sheets formation of healthy PDLSCs. However, whether osthole shows same effect on P-PDLSCs and the mechanism of promotive effect is still unknown. The purpose of this study was to determine whether Osthole could restore defective osteogenic differentiation of P-PDLSCs via epigenetic modification. We demonstrated that 10⁻⁷ Mol/L of Osthole was the best concentration for osteogenic differentiation and proliferation of P-PDLSCs. Mechanistically, we also found that Osthole upregulated MOZ and MORF, histone acetylases that specifically catalyze acetylation of Histone3 lisine9 (H3K9) and Histone3 lisine14 (H3K14), which are key regulators in osteogenic differentiation of P-PDLSCs. Furthermore, Osthole treatment improved cell sheet formation and enhanced the bone formation of PDLSC sheets in animal models of periodontitis. Our study suggests that Osthole is a promising drug to cure periodontitis via regulating epigenetic modification in cell sheets engineering.

Heartwood extract from Dalbergia sissoo promotes fracture healing and its application in ovariectomy-induced osteoporotic rats

OBJECTIVES

This study was undertaken to investigate the effects of a heartwood ethanolic extract (HEE) made from the Dalbergia sissoo on facture healing and in the prevention of pathological bone loss resulting from estrogen deficiency in ovariectomized (Ovx) rats.

METHODS

Heartwood ethanolic extract (250, 500 and 1000 mg/kg per day) was administered orally immediately next day after drill-hole injury and continued for 2 weeks. Ovx rats received HEE at same doses for 12 weeks and compared with 17-β estradiol (E2; 100 μg/kg for 5 days/week subcutaneously) group. Confocal imaging for fracture healing, micro-architecture of long bones, biomechanical strength, formation of mineralized nodule by bone marrow osteoprogenitor cells, bone turnover markers and gene expression were studied. One-way ANOVA was used to test significance.

KEY FINDINGS

Heartwood ethanolic extract treatment promoted fracture healing, formation of new bone at the drill-hole site and stimulated osteogenic genes at callus region. HEE administration to the Ovx rats exhibited better micro-architectural parameters at various anatomical positions, better bone biomechanical strength and more osteoprogenitor cells in the bone marrow compared with Ovx + vehicle group. HEE exhibited no uterine estrogenicity.

CONCLUSIONS

Oral administration of HEE was found to promote fracture healing and exhibited osteoprotective effect by possibly stimulation of osteoblast function.

Guava fruit extract and its triterpene constituents have osteoanabolic effect: Stimulation of osteoblast differentiation by activation of mitochondrial respiration via the Wnt/β-catenin signaling

The aim of this study was to evaluate the skeletal effect of guava triterpene-enriched extract (GE) in rats and identify osteogenic compounds thereof, and determine their modes of action. In growing female rats, GE at 250 mg/kg dose increased parameters of peak bone mass including femur length, bone mineral density (BMD) and biomechanical strength, suggesting that GE promoted modeling-directed bone growth. GE also stimulated bone regeneration at the site of bone injury. In adult osteopenic rats (osteopenia induced by ovariectomy, OVX) GE completely restored the lost bones at both axial and appendicular sites, suggesting a strong osteoanabolic effect. Serum metabolomics studies showed changes in several metabolites (some of which are related to bone metabolism) in OVX compared with ovary-intact control and GE treatment to OVX rats reversed those. Out of six abundantly present triterpenes in GE, ursolic acid (UA) and 2α-hydroxy ursolic acid (2α-UA) induced osteogenic differentiation in vitro as did GE by activating Wnt/β-catenin pathway assessed by phosphorylation of GSK-3β. Over-expressing of constitutively active GSK-3β (caGSK-3β) in osteoblasts abolished the differentiation-promoting effect of GE, UA and 2α-UA. All three increased both glycolysis and mitochondrial respiration but only rotenone (inhibitor of mitochondrial electron transfer) and not 2-deoxyglucose (to block glycolysis) inhibited osteoblast differentiation. In addition, caGSK-3β over-expression attenuated the enhanced mitochondrial respiration caused by GE, UA and 2α-UA. We conclude that GE has osteoanabolic effect which is contributed by UA and 2α-UA, and involve activation of canonical Wnt signaling which in turn modulates cellular energy metabolism leading to osteoblast differentiation.

Bone regeneration: Biomaterials as local delivery systems with improved osteoinductive properties

Bone is a mineralized conjunctive tissue, with a unique trauma healing capability. However, the replacement or regeneration of lost bone is not always successful and becomes more difficult the wider the bone defect. A significant growth in the demand for orthopedic and maxillofacial surgical procedures as a result of population aging and increase in chronic diseases as diabetes is a fact and successful approaches for bone regeneration are still needed. Until today, autogenous bone graft continues to be the best solution even with important limitations, as quantity and the requirement of a donator area. Alternatively, local delivery systems combining an osteoconductive biomaterial with osteoinductive compounds as hormones, growth factors or drugs is a popular approach aiming to replace the need for autogenous bone grafts. Nevertheless, in spite of the intense research in the area, presently there is no system that can mimic all the biological functions of the autogenous bone grafts. In this context, the present work provides an overview of the most recent advances in the field of synthetic bone grafts. The opportunities and limitations are detailed along with the remaining gaps in the research that are still preventing the successful translation of more products into the market able to be a valuable option in comparison to the autogenous bone grafts.

Formononetin, an isoflavone, activates AMP-activated protein kinase/β-catenin signalling to inhibit adipogenesis and rescues C57BL/6 mice from high-fat diet-induced obesity and bone loss

Balance between adipocyte and osteoblast differentiation is the key link of disease progression in obesity and osteoporosis. We have previously reported that formononetin (FNT), an isoflavone extracted from Butea monosperma, stimulates osteoblast formation and protects against postmenopausal bone loss. The inverse relationship between osteoblasts and adipocytes prompted us to analyse the effect of FNT on adipogenesis and in vivo bone loss, triggered by high-fat diet (HFD)-induced obesity. The anti-obesity effect and mechanism of action of FNT was determined in 3T3-L1 cells and HFD-induced obese male mice. Our findings show that FNT suppresses the adipogenic differentiation of 3T3-L1 fibroblasts, through down-regulation of key adipogenic markers such as PPARγ, CCAAT/enhancer-binding protein alpha (C/EBPα) and sterol regulatory element-binding protein (SREBP) and inhibits intracellular TAG accumulation. Increased intracellular reactive oxygen species levels and AMP-activated protein kinase (AMPK) activation accompanied by stabilisation of β-catenin were attributed to the anti-adipogenic action of FNT. In vivo, 12 weeks of FNT treatment inhibited the development of obesity in mice by attenuating HFD-induced body weight gain and visceral fat accumulation. The anti-obesity effect of FNT results from increased energy expenditure. FNT also protects against HFD-induced dyslipidaemia and rescues deterioration of trabecular bone volume by increasing bone formation and decreasing bone resorbtion caused by HFD. FNT's rescuing action against obesity-induced osteoporosis commenced at the level of progenitors, as bone marrow progenitor cells, obtained from the HFD mice group supplemented with FNT, showed increased osteogenic and decreased adipogenic potentials. Our findings suggest that FNT inhibits adipogenesis through AMPK/β-catenin signal transduction pathways and protects against HFD-induced obesity and bone loss.

Evaluation of anti-osteoporotic activity of butanolic fraction from Passiflora foetida in ovariectomy-induced bone loss in mice

OBJECTIVE

In this study, we have evaluated the skeletal effects of butanolic fraction (BF) from Passiflora foetida in an estrogen deficient mice bone loss model.

STUDY DESIGN

Skeletal effect of BF was studied in ovariectomized (OVx) female Balb/c mice. BF (50 and 100mg/kg/day dose orally) was given for 8 weeks. Micro-architecture of long bones, biomechanical strength, formations of mineralized nodule by bone marrow osteoprogenitor cells, osteoid formation and bone turnover markers were studied. One way ANOVA was used to test the significance of effects of Passiflora foetida.

RESULTS

OVx mice treated with BF represented with better micro-architectural parameters at various anatomical positions, better bone biomechanical strength and more osteoprogenitor cells in the bone marrow compared with OVx group. BF did not exhibit uterine estrogenicity.

CONCLUSION

Oral administration of BF at both the doses (50 and 100mg/kg/day) derived from Passiflora Foetida, was found to afford anti-osteoporotic effect under estrogen deficiency by likely stimulation of osteoblast function and inhibition of osteoclast function.

Ethanolic extract of Dalbergia sissoo promotes rapid regeneration of cortical bone in drill-hole defect model of rat

Leaves of Dalbergia sissoo is known to have protective actions against postmenopausal bone loss in rat. In this study, we have evaluated the fracture healing properties of ethanolic extract (EE) of Dalbergia sissoo leaves. To observe the fracture healing property in the drill-hole injury model, we randomly divided total 32 adult female Sprague Dawley rats (180±200g) into 4 groups: (i) Control operated group; (ii) EE (250mg/kg/day); (iii) EE (500mg/kg/day) and (iv) EE (1000mg/kg/day). The right femora were fractured at the mid-diaphysis region and each group of rats received their respective treatment for 15days. Ethanol extract dose dependently induced bone regeneration at the fracture site assessed by fluorochrome labeling. All of three doses, 250mg/kg/day dose significantly increased bone volume fraction, trabecular thickness, trabecular number, and connectivity density and decreased trabecular separation in bone. Furthermore, the extract induced the expression of osteogenic genes including BMP-2, BMP-4, RunX-2 and COL-1 compared to the control group. The EE improved fracture healing much earlier (day 15) than the normal healing process, as assessed by the increased callus volumes and mineralized nodule formation. This extract is found beneficial in fracture healing of rat.

Characterization of BMP signaling dependent osteogenesis using a BMP depletable avianized bone marrow stromal cell line (TVA-BMSC)

Adipogenesis, chondrogenesis and osteogenesis are BMP signaling dependent differentiation processes. However, the molecular networks operating downstream of BMP signaling to bring about these distinct fates are yet to be fully elucidated. We have developed a novel Bone Marrow Stromal Cell (BMSC) derived mouse cell line as a powerful in vitro platform to conduct such experiments. This cell line is a derivative of BMSCs isolated from a tamoxifen inducible Bmp2 and Bmp4 double conditional knock-out mouse strain. These BMSCs are immortalized and stably transfected with avian retroviral receptor TVA (TVA-BMSCs), enabling an easy method for stable transduction of multiple genes in these cells. In TVA-BMSCs multiple components of BMP signaling pathway can be manipulated simultaneously. Using this cell line we have demonstrated that for osteogenesis, BMP signaling is required only for the first three days. We have further demonstrated that Klf10, an osteogenic transcription factor which is transcribed in developing bones in a BMP signaling dependent manner, can largely compensate for the loss of BMP signaling during osteogenesis of BMSCs. TVA-BMSCs can undergo chondrogenesis and adipogenesis, and hence may be used for dissection of the molecular networks downstream of BMP signaling in these differentiation processes as well.

A neoflavonoid dalsissooal isolated from heartwood of Dalbergia sissoo Roxb. has bone forming effects in mice model for osteoporosis

Dalbergia sissoo Roxb. is a well known medicinal plant of India, enriched with various flavonoids used for treating multiple diseases. Earlier, we have shown that extract of Dalbergia sissoo Roxb. leaves mitigate ovariectomy induced bone loss and pure compounds (neoflavonoids) isolated from it, promote osteoblastogenesis in primary calvarial osteoblasts cells in vitro. Here, we hypothesize that dalsissooal (DSL), a novel neoflavonoid isolated from the heartwood of Dalbergia sissoo Roxb. is an important constituent of the extract that imparts bone forming effects. Treatment with DSL enhanced trabecular bone micro-architecture parameters, biomechanical strength, increased bone formation rate and mineral apposition rate in OVx mice comparable to 17β-estradiol. It increased bone formation by enhancing osteoblast gene expression and reduced bone turnover by decreasing osteoclastic gene expressions. Interestingly, we observed that DSL has no uterine estrogenic effects. At cellular levels, DSL promoted differentiation of bone marrow cells as well as calvaria osteoblast cells towards osteoblast lineage by enhancing differentiation and mineralizing ability to form mineralizing nodules via stimulating BMP-2 and RunX-2 expressions. Overall, our data suggest that oral supplementation of a novel neoflavonoid dalsissooal isolated from heartwood of Dalbergia sissoo Roxb. exhibited bone anabolic action by improving structural property of bone, promoting new bone formation and reducing bone turnover rate in post-menopausal model for osteoporosis with no uterine hyperplasia.

An isoflavone cladrin prevents high-fat diet-induced bone loss and inhibits the expression of adipogenic gene regulators in 3T3-L1 adipocyte

Objective

This study evaluates the effect of isoflavone cladrin on high-fat diet (HFD)-induced bone loss and adipogenesis.

Methods

Thirty-two 4-week-old male C57BL/6J mice were divided into four groups: a standard diet group, a HFD group and HFD group with cladrin (5 and 10 mg/kg per day orally) for 12 weeks. The effect of cladrin on bone micro-architecture, bone marrow cell lineages and hyperlipidaemia were assessed. For assessing anti-adipogenic activity of cladrin, 3T3-L1 cells were used.

Key findings

Cladrin attenuated HFD-induced hyperlipidaemia and bone loss by preserving bone micro-architecture and strength. Effect of cladrin was found at the level of bone marrow progenitor cells. Gene expression profile of cladrin-treated mice bone showed upregulation of osteoblast and downregulation of adipogenic transcription factors and increased OPG/RANKL ratio. Cladrin inhibited cellular lipid accumulation through downregulation of transcription factors such as PPAR-γ and C/EBP-α and modulated the expression of major adipokines involved behind obesity stimulation without eliciting cell cytotoxicity in 3T3-L1 adipocytes.

Conclusion

We conclude that cladrin may improve obesity-induced bone loss and hyperlipidaemia in mice fed HFD and adipogenesis in 3T3-L1 cells by modifying adipokines and could offer clinical benefits as a supplement to treat obesity-induced disorders.

Azadirachta indica triterpenoids promote osteoblast differentiation and mineralization in vitro and in vivo

Terpenoids were isolated using chromatographic purification through solvent purification technique and identified as Azadirone (1), Epoxyazadiradione (2) Azadiradione (3) Gedunin (4) Nimbin (5) Salannin (6) Azadirachtin A (7) and Azadirachtin B (8) from Azadirachta indica. Out of eight compounds, only three compounds had osteogenic activity and enhanced osteoblast proliferation, differentiation and mineralization in osteoblast cells. Active compounds stimulated osteogenic genes ALP, RunX-2 and OCN expressions in vitro, but Azadirachtin A had a maximum ability to stimulate osteoblast differentiation and mineralization compared to other two active compounds. For in vivo study, Azadirachtin A injected subcutaneously in pups, which enhanced osteogenic gene expressions and promoted bone formation rate significantly. Here, we conclude that active compounds of Azadirachta indica have osteogenic activity and Azadirachtin A has a beneficial effects on bone.

Sialoglycoprotein Isolated from Eggs of Carassius auratus Ameliorates Osteoporosis: An Effect Associated with Regulation of the Wnt/β-Catenin Pathway in Rodents

In the current study, ovariectomized (OVX) rats and the senescence-accelerated mouse strain P6 (SAMP6) were employed to establish models of postmenopausal osteoporosis and senile osteoporosis, respectively. The effects of treatment with sialoglycoprotein isolated from the eggs of Carassius auratus (Ca-SGP) on these two types of osteoporosis were investigated in vivo. Results showed that Ca-SGP significantly increased bone mineral density, ameliorated trabecular bone microstructure, and improved bone biomechanical properties in both OVX rats and SAMP6. The osteogenesis related Wnt/β-catenin pathway was targeted to study the underlying mechanism of Ca-SGP activity. In postmenopausal osteoporosis, Ca-SGP suppressed the activation of Wnt/β-catenin signal via down-regulating the expression of key genes including LRP5, β-catenin, and Runx2, suggesting that overactive osteogenesis was controlled by Ca-SGP. The bone formation was sharply weakened in senile osteoporosis, whereas Ca-SGP treatment promoted osteoblast activity by stimulating the Wnt/β-catenin signal. In conclusion, Ca-SGP ameliorated these two types of osteoporosis by normalizing bone anabolism.

Genetically engineered flavonol enriched tomato fruit modulates chondrogenesis to increase bone length in growing animals

Externally visible body and longitudinal bone growth is a result of proliferation of chondrocytes. In growth disorder, there is delay in the age associated increase in height. The present study evaluates the effect of extract from transgenic tomato fruit expressing AtMYB12 transcription factor on bone health including longitudinal growth. Constitutive expression of AtMYB12 in tomato led to a significantly enhanced biosynthesis of flavonoids in general and the flavonol biosynthesis in particular. Pre-pubertal ovary intact BALB/c mice received daily oral administration of vehicle and ethanolic extract of wild type (WT-TOM) and transgenic AtMYB12-tomato (MYB12-TOM) fruits for six weeks. Animal fed with MYB12-TOM showed no inflammation in hepatic tissues and normal sinusoidal Kupffer cell morphology. MYB12-TOM extract significantly increased tibial and femoral growth and subsequently improved the bone length as compared to vehicle and WT-TOM. Histomorphometry exhibited significantly wider distal femoral and proximal tibial growth plate, increased number and size of hypertrophic chondrocytes in MYB12-TOM which corroborated with micro-CT and expression of BMP-2 and COL-10, marker genes for hypertrophic cells. We conclude that metabolic reprogramming of tomato by AtMYB12 has the potential to improve longitudinal bone growth thus helping in achievement of greater peak bone mass during adolescence.

Fate decision of mesenchymal stem cells: adipocytes or osteoblasts?

Mesenchymal stem cells (MSCs), a non-hematopoietic stem cell population first discovered in bone marrow, are multipotent cells capable of differentiating into mature cells of several mesenchymal tissues, such as fat and bone. As common progenitor cells of adipocytes and osteoblasts, MSCs are delicately balanced for their differentiation commitment. Numerous in vitro investigations have demonstrated that fat-induction factors inhibit osteogenesis, and, conversely, bone-induction factors hinder adipogenesis. In fact, a variety of external cues contribute to the delicate balance of adipo-osteogenic differentiation of MSCs, including chemical, physical, and biological factors. These factors trigger different signaling pathways and activate various transcription factors that guide MSCs to commit to either lineage. The dysregulation of the adipo-osteogenic balance has been linked to several pathophysiologic processes, such as aging, obesity, osteopenia, osteopetrosis, and osteoporosis. Thus, the regulation of MSC differentiation has increasingly attracted great attention in recent years. Here, we review external factors and their signaling processes dictating the reciprocal regulation between adipocytes and osteoblasts during MSC differentiation and the ultimate control of the adipo-osteogenic balance.

MicroRNA 874-3p Exerts Skeletal Anabolic Effects Epigenetically during Weaning by Suppressing Hdac1 Expression

Embryonic skeletogenesis and postnatal bone development require the transfer of calcium from the mother to the offspring during pregnancy and lactation. Therefore, bone resorption in the mother becomes elevated during these periods, resulting in significant maternal skeletal loss. There follows an anabolic phase around weaning during which there is a remarkable recovery of the maternal skeleton. However, the mechanism(s) of this anabolic response remain(s) largely unknown. We identified eight differentially expressed miRNAs by array profiling, of which miR-874-3p was highly expressed at weaning, a time when bone loss was noted to recover. We report that this weaning-associated miRNA is an anabolic target. Therefore, an agomir of miR-874-3p induced osteoblast differentiation and mineralization. These actions were mediated through the inhibition of Hdac1 expression and enhanced Runx2 transcriptional activation. When injected in vivo, the agomir significantly increased osteoblastogenesis and mineralization, reversed bone loss caused by ovariectomy, and increased bone strength. We speculate that elevated miR-874-3p expression during weaning enhances bone formation and that this miRNA may become a therapeutic target for conditions of bone loss.