Naringin promotes differentiation of bone marrow stem cells into osteoblasts by upregulating the expression levels of microRNA-20a and downregulating the expression levels of PPARγ

The Development of Naringin for Use against Bone and Cartilage Disorders

Bone and cartilage disorders are the leading causes of musculoskeletal disability. There is no absolute cure for all bone and cartilage disorders. The exploration of natural compounds for the potential therapeutic use against bone and cartilage disorders is proving promising. Among these natural chemicals, naringin, a flavanone glycoside, is a potential candidate due to its multifaceted pharmacological activities in bone and cartilage tissues. Emerging studies indicate that naringin may promote osteogenic differentiation, inhibit osteoclast formation, and exhibit protective effects against osteoporosis in vivo and in vitro. Many signaling pathways, such as BMP-2, Wnt/β-catenin, and VEGF/VEGFR, participate in the biological actions of naringin in mediating the pathological development of osteoporosis. In addition, the anti-inflammatory, anti-oxidative stress, and anti-apoptosis abilities of naringin also demonstrate its beneficial effects against bone and cartilage disorders, including intervertebral disc degeneration, osteoarthritis, rheumatoid arthritis, bone and cartilage tumors, and tibial dyschondroplasia. Naringin exhibits protective effects against bone and cartilage disorders. However, more efforts are still needed due to, at least in part, the uncertainty of drug targets. Further biological and pharmacological evaluations of naringin and its applications in bone tissue engineering, particularly its therapeutic effects against osteoporosis, might result in developing potential drug candidates.

Naringin Release from a Nano-Hydroxyapatite/Collagen Scaffold Promotes Osteogenesis and Bone Tissue Reconstruction

Bone fractures and defects are a major health issue and have reportedly affected over 455 million individuals globally to date. Bone tissue engineering has gained great success in bone defect repair and bone reconstruction based on the use of nano-hydroxyapatite (nHA) or collagen (COL). Both nHA and COL exhibit osteogenic induction capacity to support bone tissue regeneration; however, the former suffers from poor flexibility and the latter lacks mechanical strength. Biological scaffolds created by combining nHA and COL (nHA/COL) can overcome the drawbacks imposed by individual materials and, therefore, have become widely applied in tissue engineering. The composite scaffolds can further promote tissue reconstruction by allowing the loading of various growth factors. Naringin (NG) is a natural flavonoid. Its molecular weight is 580.53 Da, lower than that of many growth factors, and it causes minimal immune responses when being introduced in vivo. In addition, naringin is safe, non-toxic, inexpensive to produce, and has superior bio-properties. In this study, we introduced NG into a nHA/COL scaffold (NG/nHA/COL) and exploited the potentials of the NG/nHA/COL scaffold in enhancing bone tissue regeneration. NG/nHA/COL scaffolds were fabricated by firstly combining nHA and collagen at different compositional ratios, followed by NG encapsulation. NG release tests showed that the scaffold with a nHA/COL mass ratio of 7:3 exhibited the optimal property. The in vitro cell study showed the desirable biocompatibility of the NG/nHA/COL scaffold, and its effective promotion for the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs), as proved by an increased alkaline phosphatase (ALP) activity, the formation of more calcium nodules, and a higher expression of osteogenic-related genes involving Osteocalcin (OCN), BMP-2, and Osteopontin (OPN), compared with the control and nHA/COL groups. When administered into rats with skull defects, the NG/nHA/COL scaffold significantly promoted the reconstruction of bone tissues and the early repair of skull defects, indicating the great potential of NG/nHA/COL scaffolds in bone tissue engineering.

Angiogenic and Osteogenic Effects of Flavonoids in Bone Regeneration

Bone is a highly vascularised tissue that relies on a close spatial and temporal interaction between blood vessels and bone cells. As a result, angiogenesis is critical for bone formation and healing. The vascular system supports bone regeneration by delivering oxygen, nutrients, and growth factors, as well as facilitating efficient cell-cell contact. Most clinical applications of engineered bone grafts are hampered by insufficient vascularization after implantation. Over the last decade, a number of flavonoids have been reported to have osteogenic-angiogenic potential in bone regeneration because of their excellent bioactivity, low cost, availability, and minimal in vivo toxicity. During new bone formation, the osteoinductive nature of certain flavonoids is involved in regulating multiple signaling pathways contributing toward the osteogenic-angiogenic coupling. This review briefly outlines the osteogenic-angiogenic potential of those flavonoids and the mechanisms of their action in promoting bone regeneration. However, further studies are needed to investigate their delivery strategies and establish their clinical efficacy. This article is protected by copyright. All rights reserved.

The circadian clock has roles in mesenchymal stem cell fate decision

The circadian clock refers to the intrinsic biological rhythms of physiological functions and behaviours. It synergises with the solar cycle and has profound effects on normal metabolism and organismal fitness. Recent studies have suggested that the circadian clock exerts great influence on the differentiation of stem cells. Here, we focus on the close relationship between the circadian clock and mesenchymal stem cell fate decisions in the skeletal system. The underlying mechanisms include hormone signals and the activation and repression of different transcription factors under circadian regulation. Additionally, the clock interacts with epigenetic modifiers and non-coding RNAs and is even involved in chromatin remodelling. Although the specificity and safety of circadian therapy need to be further studied, the circadian regulation of stem cells can be regarded as a promising candidate for health improvement and disease prevention.

Re-appraising the role of flavonols, flavones and flavonones on osteoblasts and osteoclasts- A review on its molecular mode of action

Bone disorders have become a global concern illustrated with decreased bone mineral density and disruption in microarchitecture of natural bone tissue organization. Natural compounds that promote bone health by augmenting osteoblast functions and suppressing osteoclast functions has gained much attention and offer greater therapeutic value compared to conventional therapies. Amongst several plant-based molecules, flavonoids act as a major combatant in promoting bone health through their multi-faceted biological activities such as antioxidant, anti-inflammatory, and osteogenic properties. They protect bone loss by regulating the signalling cascades involved in osteoblast and osteoclast functions. Flavonoids augment osteoblastogenesis and inhibits osteoclastogenesis through their modulation of various signalling pathways. This review discusses the role of various flavonoids and their molecular mechanisms involved in maintaining bone health by regulating osteoblast and osteoclast functions.

Naringin Improves Osteoblast Mineralization and Bone Healing and Strength through Regulating Estrogen Receptor Alpha-Dependent Alkaline Phosphatase Gene Expression

Phytoestrogens are strongly recommended for treating osteoporosis. Our previous study showed that naringin, a citrus flavonoid, can enhance the bone mass in ovariectomized rats. In this study, we further elucidated the mechanisms of naringin-induced osteoblast maturation and bone healing. Treatment of human osteoblasts with naringin increased cell viability and proliferation. In parallel, exposure to naringin enhanced translocation of estrogen receptor alpha (ERα) to nuclei and its transactivation activity. Sequentially, naringin induced alkaline phosphatase (ALP) mRNA and protein expression and its enzyme activity. Pretreatment with methylpiperidinopyrazole (MPP), a specific inhibitor of ERα, attenuated naringin-induced augmentations in ERα transactivation activity, ALP gene expression, and cell mineralization. The beneficial effects of naringin were also confirmed in mouse MC3T3-E1 cells. Moreover, administration of mice with a bone defect with naringin increased levels of ERα and ALP in damaged sites and simultaneously enhanced the healing rate and bone strength. Nevertheless, treatment with MPP weakened naringin-triggered expression of ERα and ALP and improved bone healing and mass. Therefore, naringin could improve osteoblast mineralization and bone healing via regulating ERα-dependent ALP gene expression. Naringin can be clinically applied for treatment of osteoporosis-related bone diseases.

Polyphenols-loaded electrospun nanofibers in bone tissue engineering and regeneration

Bone is a complex structure with unique cellular and molecular process in its formation. Bone tissue regeneration is a well-organized and routine process at the cellular and molecular level in humans through the activation of biochemical pathways and protein expression. Though many forms of biomaterials have been applied for bone tissue regeneration, electrospun nanofibrous scaffolds have attracted more attention among researchers with their physicochemical properties such as tensile strength, porosity, and biocompatibility. When drugs, antibiotics, or functional nanoparticles are taken as additives to the nanofiber, its efficacy towards the application gets increased. Polyphenol is a versatile green/phytochemical small molecule playing a vital role in several biomedical applications, including bone tissue regeneration. When polyphenols are incorporated as additives to the nanofibrous scaffold, their combined properties enhance cell attachment, proliferation, and differentiation in bone tissue defect. The present review describes bone biology encompassing the composition and function of bone tissue cells and exemplifies the series of biological processes associated with bone tissue regeneration. We have highlighted the molecular mechanism of bioactive polyphenols involved in bone tissue regeneration and specified the advantage of electrospun nanofiber as a wound healing scaffold. As the polyphenols contribute to wound healing with their antioxidant and antimicrobial properties, we have compiled a list of polyphenols studied, thus far, for bone tissue regeneration along with their in vitro and in vivo experimental biological results and salient observations. Finally, we have elaborated on the importance of polyphenol-loaded electrospun nanofiber in bone tissue regeneration and discussed the possible challenges and future directions in this field.

Naringin promotes osteogenesis and ameliorates osteoporosis development by targeting JAK2/STAT3 signalling

Osteoporosis is a systemic bone metabolism disorder, which increases the risk of fractures, and in severe cases it may cause disability or even death. An important factor contributing to osteoporosis is the imbalance between bone formation and resorption. Naringin was reported to promote osteoblast differentiation, thus enhancing bone formation and alleviating osteoporosis development. However, the signalling pathways related to the regulatory mechanism of naringin in osteoporosis development are not clear. Proliferation of bone mesenchymal stem cells (BMSCs) treated with naringin in vitro was detected by CCK-8. An osteogenesis differentiation medium supplemented with naringin was applied to explore the effects of naringin on BMSC osteogenic differentiation, as detected by Alizarin red staining. Ovariectomy (OVX)-induced postmenopausal osteoporosis (PMOP) rats were orally administered with naringin. Dual-energy X-ray absorptiometry (DEXA) and micro-CT were applied to measure bone mineral density (BMD), bone volume/total volume (BV/TV), trabecula thickness (Tb.Th), trabecula number (Tb.N), trabecular separation (Tb.Sp) and bone surface/bone volume (BS/BV). H&E staining was performed to show pathological changes of the femur in PMOP rats after naringin treatment. Bone metabolism indicators were assessed by ELISA. We found that naringin suppressed the activation of the JAK2/STAT3 pathway. Naringin promoted BMSC proliferation and osteogenic differentiation. Furthermore, naringin alleviates bone loss and improves abnormal bone metabolism of PMOP rats. Collectively, naringin promotes BMSC osteogenic differentiation to ameliorate osteoporosis development by targeting JAK2/STAT3 signalling.

miR-129-5p Promotes Osteogenic Differentiation of BMSCs and Bone Regeneration via Repressing Dkk3

Objective

Accumulating evidence indicates that microRNAs (miRNAs) play crucial roles in osteogenic differentiation. However, the associated mechanisms remain elusive. This paper is aimed at exploring the role of miR-129-5p in regulating bone marrow mesenchymal stem cell (BMSC) differentiation and bone regeneration in vivo and in vitro.

Methods

BMSCs were transduced by miR-129-5p mimic, miR-129-5p inhibitor, and negative control lentivirus. The ability of BMSC differentiation to osteoblast was tested by alkaline phosphatase (ALP) and alizarin red staining (ARS). The expression of osteogenic genes (Runx2, Bmp2, and OCN) was examined via quantitative RT-PCR and western blot. A mouse model of calvaria defect was investigated by Micro-CT, immunohistochemistry, and histological examination. The luciferase reporter gene assay was performed to confirm the binding between Dkk3 and miR-129-5p. For the transfection experiments, lipofectamine 3000 was used to transfect pcDNA-Dkk3 into BMSCs to overexpress Dkk3. Coimmunoprecipitation and immunofluorescent localization assay were included for exploring the role of Dkk3 and β-catenin.

Results

miR-129-5p was induced in BMSCs and MSC cell line C3H10T1/2 cells under osteogenic medium. Overexpression of miR-129-5p significantly promoted osteogenic differentiation of BMSCs in vitro. Moreover, BMSCs transduced with miR-129-5p mimic exhibited better bone regeneration compared with BMSCs transduced with control counterpart in vivo. Luciferase and western blot data showed that Dickkopf3 (Dkk3) is a target gene of miR-129-5p and the expression of Dkk3 was inhibited in BMSCs transduced with miR-129-5p mimic but enhanced in BMSCs transduced with miR-129-5p inhibitor. In addition, Dkk3 interacted with β-catenin directly.

Conclusions

miR-129-5p promotes osteogenic differentiation of BMSCs and bone regeneration, and miR-129-5p/Dkk3 axis may be new potential targets for the treatment of bone defect and bone loss.

MSC-derived small extracellular vesicles overexpressing miR-20a promoted the osteointegration of porous titanium alloy by enhancing osteogenesis via targeting BAMBI

BACKGROUND

Patients with osteoporosis have a high risk of implant loosening due to poor osteointegration, possibly leading to implant failure, implant revision, and refracture. RNA interference therapy is an emerging epigenetic treatment, and we found that miR-20a could enhance osteogenesis. Moreover, small extracellular vesicles (sEVs) derived from bone marrow mesenchymal stem cells (hBM-MSCs) were utilized as nanoscale carriers for the protection and transportation of miR-20a (sEV-20a). In this study, we intended to determine whether sEVs overexpressing miR-20a could exert a superior effect on osteoporotic bone defects and the underlying mechanism.

METHODS

For evaluating the effect of sEV-20a on osteogenesis, in vitro and in vivo studies were performed. In vitro, we first showed that miR-20a was upregulated in the osteogenic process and overexpressed sEVs with miR-20a by the transfection method. Then, the proliferation, migration, and osteogenic differentiation abilities of hBM-MSCs treated with sEV-20a were detected by CCK-8 assays, alkaline phosphatase staining and alizarin red staining, qRT-PCR, and western blot. In vivo, we established an osteoporotic bone defect model and evaluated the effect of sEV-20a on bone formation by micro-CT, sequential fluorescent labeling, and histological analysis. To further explore the mechanism, we applied a bioinformatics method to identify the potential target of miR-20a.

RESULTS

In vitro, sEV-20a was successfully established and proved to promote the migration and osteogenesis of hBM-MSCs. In vivo, sEV-20a promoted osteointegration in an osteoporotic rat model. To further elucidate the related mechanism, we proved that miR-20a could enhance osteogenesis by targeting BAMBI.

CONCLUSIONS

Collectively, the in vitro and in vivo results confirmed that MSC-derived sEV-20a therapy effectively promoted osteoporotic porous titanium alloy osteointegration via pro-osteogenic effects by targeting BAMBI.

Fabrication of Chinese Traditional Medicines incorporated collagen biomaterials for human bone marrow mesenchymal stem cells

Chinese Traditional Medicines (CTMs) are very popular for therapeutic applications to cure several chronic diseases. Many researchers are trying to discover the potential application and actual mechanism of CTMs in order to scientifically prove their effects for commercial use. One of the main functions of CTMs is to aid stem cell regeneration. Since, this study was focused to fabricate CTMs incorporated fish collagen film, which has good biocompatibility in mammalian cell growth and thus investigated the effect on human Mesenchymal stem cells (hMSCs) proliferation and differentiation. In this study, three types of CTMs such as Genistein, Icariin, and Naringin were used for film fabrication. Mechanical properties of collagen films were improved by the addition of CTMs, especially in Collagen-Naringin films. Solubility and In-vitro biodegradation of collagen films were enhanced by the hydrophobicity and chemical interaction of CTMs with collagen. The proliferation rate was accelerated in hMSCs cultured on CTMs incorporated collagen films in a dose- and time-dependent manner. Proliferation biomarkers such as Ki-67 and BrdU levels were higher in hMSCs cultured on CTMs incorporated collagen films. The proliferative and differentiation effect of CTMs was further confirmed by higher gene expression of Collagen I, Runx2, c-Fos, SMAD3 and TGF-β1 in hMSCs. Overall, this study provides a new insight on novel biomaterial fabrication using CTMs and fish collagen for making a compatible platform for in-vitro stem cell culture.

Effect of Naringin Treatment on Postmenopausal Osteoporosis in Ovariectomized Rats: A Meta-Analysis and Systematic Review

Background

Osteoporosis is a major disease that affects the quality of life of middle-aged and old people, so it is very important to find efficient and safe drugs to treat osteoporosis. The purpose of this study was to investigate the therapeutic effect of naringin on postmenopausal osteoporosis in ovariectomized (OVX) rats.

Methods

Chinese biomedical databases, CNKI, PubMed, EMBASE, and Wan Fang were searched for articles from inception to March 2020. Two independent researchers screened articles according to inclusion criteria. RevMan 5.3 was used for data analysis.

Results

Ten studies were included in the systematic review. The bone mineral density (BMD) significantly increased after naringin treatment (weighted mean difference, 0.06; 95% CI, 0.03–0.09; P < 0.01). There was no significant increase in BMD after estrogen treatment compared with naringin (weighted mean difference, 0.00; 95% CI, −0.00 to 0.01; P = 0.06). The trabecular bone volume (BV/TV) (weighted mean difference, 2.09; 95% CI, 1.85–2.34; P < 0.01) and trabecular thickness (Tb.Th) (weighted mean difference, 6.65; 95% CI, 6.55–6.74; P < 0.01) significantly increased after using naringin.

Conclusions

Naringin had been shown to promote bone formation in OVX rats. However, the mechanism of naringin needs more research to confirm.

Emerging Natural-Product-Based Treatments for the Management of Osteoarthritis

Osteoarthritis (OA) is a complex degenerative disease in which joint homeostasis is disrupted, leading to synovial inflammation, cartilage degradation, subchondral bone remodeling, and resulting in pain and joint disability. Yet, the development of new treatment strategies to restore the equilibrium of the osteoarthritic joint remains a challenge. Numerous studies have revealed that dietary components and/or natural products have anti-inflammatory, antioxidant, anti-bone-resorption, and anabolic potential and have received much attention toward the development of new therapeutic strategies for OA treatment. In the present review, we provide an overview of current and emerging natural-product-based research treatments for OA management by drawing attention to experimental, pre-clinical, and clinical models. Herein, we review current and emerging natural-product-based research treatments for OA management.

Shared Genetic and Epigenetic Mechanisms between the Osteogenic Differentiation of Dental Pulp Stem Cells and Bone Marrow Stem Cells

OBJECTIVE

To identify the shared genetic and epigenetic mechanisms between the osteogenic differentiation of dental pulp stem cells (DPSC) and bone marrow stem cells (BMSC).

MATERIALS AND METHODS

The profiling datasets of miRNA expression in the osteogenic differentiation of mesenchymal stem cells from the dental pulp (DPSC) and bone marrow (BMSC) were searched in the Gene Expression Omnibus (GEO) database. The differential expression analysis was performed to identify differentially expressed miRNAs (DEmiRNAs) dysregulated in DPSC and BMSC osteodifferentiation. The target genes of the DEmiRNAs that were dysregulated in DPSC and BMSC osteodifferentiation were identified, followed by the identification of the signaling pathways and biological processes (BPs) of these target genes. Accordingly, the DEmiRNA-transcription factor (TFs) network and the DEmiRNAs-small molecular drug network involved in the DPSC and BMSC osteodifferentiation were constructed.

RESULTS

16 dysregulated DEmiRNAs were found to be overlapped in the DPSC and BMSC osteodifferentiation, including 8 DEmiRNAs with a common expression pattern (8 upregulated DEmiRNAs (miR-101-3p, miR-143-3p, miR-145-3p/5p, miR-19a-3p, miR-34c-5p, miR-3607-3p, miR-378e, miR-671-3p, and miR-671-5p) and 1 downregulated DEmiRNA (miR-671-3p/5p)), as well as 8 DEmiRNAs with a different expression pattern (i.e., miR-1273g-3p, miR-146a-5p, miR-146b-5p, miR-337-3p, miR-382-3p, miR-4508, miR-4516, and miR-6087). Several signaling pathways (TNF, mTOR, Hippo, neutrophin, and pathways regulating pluripotency of stem cells), transcription factors (RUNX1, FOXA1, HIF1A, and MYC), and small molecule drugs (curcumin, docosahexaenoic acid (DHA), vitamin D3, arsenic trioxide, 5-fluorouracil (5-FU), and naringin) were identified as common regulators of both the DPSC and BMSC osteodifferentiation.

CONCLUSION

Common genetic and epigenetic mechanisms are involved in the osteodifferentiation of DPSCs and BMSCs.

Naringin increases osteoprotegerin expression in fibroblasts from periprosthetic membrane by the Wnt/β-catenin signaling pathway

Background

The osteoclast bone resorption is critical in aseptic loosening after joint replacement. The balance between activator of nuclear factor kappa B ligand (RANKL) and osteoprotegerin (OPG) is considered to play a central role in osteoclast maturation. Fibroblasts from the periprosthetic membrane express RANKL and promote osteoclast formation. Studies have demonstrated that naringin inhibited osteoclastogenesis and wear particle-induced osteolysis. In this study, the naringin-induced OPG/RANKL effects and its underlying mechanism were studied in fibroblasts from periprosthetic membrane.

Methods

Fibroblasts were isolated from the periprosthetic membrane during hip arthroplasty for revision due to aseptic loosening. Fibroblasts were cultured and treated with or without naringin and DKK-1 (the classical inhibitor of Wnt/β-catenin signaling pathway). OPG and RANKL mRNA and protein levels, gene expression of β-catenin, and cyclin D1, which participate in the Wnt signaling pathway, were examined by real-time polymerase chain reaction and enzyme-linked immunosorbent assay.

Results

The mRNA and protein levels of OPG were enhanced by naringin in a dose-dependent manner compared to that of the non-treated control. In contrast, naringin did not affect the expression of RANKL. Importantly, DKK-1 attenuated OPG expression in fibroblasts under naringin treatment. Moreover, naringin stimulated the gene expression of β-catenin and cyclin D1 in fibroblasts, and the effect could be inhibited by DKK-1.

Conclusion

The results indicated that naringin enhanced OPG expression through Wnt/β-catenin signaling pathway in fibroblasts from periprosthetic membrane, which may be useful to inhibit periprosthetic osteolysis during aseptic loosening after total joint arthroplasty.

Gelatin Methacryloyl (GelMA) Nanocomposite Hydrogels Embedding Bioactive Naringin Liposomes

The development of nanocomposite hydrogels that take advantage of hierarchic building blocks is gaining increased attention due to their added functionality and numerous biomedical applications. Gathering on the unique properties of these platforms, herein we report the synthesis of bioactive nanocomposite hydrogels comprising naringin-loaded salmon-derived lecithin nanosized liposomal building blocks and gelatin methacryloyl (GelMA) macro-sized hydrogels for their embedding. This platform takes advantage of liposomes’ significant drug loading capacity and their role in hydrogel network reinforcement, as well as of the injectability and light-mediated crosslinking of bioderived gelatin-based biomaterials. First, the physicochemical properties, as well as the encapsulation efficiency, release profile, and cytotoxicity of naringin-loaded nanoliposomes (LipoN) were characterized. Then, the effect of embedding LipoN in the GelMA matrix were characterized by studying the release behavior, swelling ratio, and hydrophilic character, as well as the rheological and mechanical properties of GelMA and GelMA-LipoN functionalized hydrogels. Finally, the dispersion of nanoliposomes encapsulating a model fluorescent probe in the GelMA matrix was visualized. The formulation of naringin-loaded liposomes via an optimized procedure yielded nanosized (114 nm) negatively charged particles with a high encapsulation efficiency (~99%). Naringin-loaded nanoliposomes administration to human adipose-derived stem cells confirmed their suitable cytocompatibility. Moreover, in addition to significantly extending the release of naringin from the hydrogel, the nanoliposomes inclusion in the GelMA matrix significantly increased its elastic and compressive moduli and decreased its swelling ratio, while showing an excellent dispersion in the hydrogel network. Overall, salmon-derived nanoliposomes enabled the inclusion and controlled release of pro-osteogenic bioactive molecules, as well as improved the hydrogel matrix properties, which suggests that these soft nanoparticles can play an important role in bioengineering bioactive nanocomposites for bone tissue engineering in the foreseeable future.

Re-appraising the potential of naringin for natural, novel orthopedic biotherapies

Naringin is a naturally occurring flavonoid found in plants of the Citrus genus that has historically been used in traditional Chinese medical regimens for the treatment of osteoporosis. Naringin modulates signaling through numerous molecular pathways critical to musculoskeletal development, cellular differentiation, and inflammation. Administration of naringin increases in vitro expression of bone morphogenetic proteins (BMPs) and activation of the Wnt/β-catenin and extracellular signal-related kinase (Erk) pathways, thereby promoting osteoblastic proliferation and differentiation from stem cell precursors for bone formation. Naringin also inhibits osteoclastogenesis by both modifying RANK/RANKL interactions and inducing apoptosis in osteoclasts in vitro. In addition, naringin acts on the estrogen receptor in bone to mimic the native bone-preserving effects of estrogen, with few systemic side effects on other estrogen-sensitive tissues. The efficacy of naringin therapy in reducing the osteolysis characteristic of common musculoskeletal pathologies such as osteoporosis, degenerative joint disease, and osteomyelitis, as well as inflammatory conditions affecting bone such as diabetes mellitus, has been extensively demonstrated in vitro and in animal models. Naringin thus represents a naturally abundant, cost-efficient agent whose potential for use in novel musculoskeletal biotherapies warrants re-visiting and further exploration through human studies. Here, we review the cellular mechanisms of action that have been elucidated regarding the action of naringin on bone resident cells and the bone microenvironment, in vivo evidence of naringin’s osteostimulative and chondroprotective properties in the setting of osteolytic bone disease, and current limitations in the development of naringin-containing translational therapies for common musculoskeletal conditions.

Effect of MicroRNA-20a on Osteogenic Differentiation of Human Adipose Tissue-Derived Stem Cells

Osteogenic differentiation of human adipose tissue-derived stem cells (hASCs) is a complex process that is regulated by multiple factors, including microRNAs (miRNAs). The miRNA miR-20a was shown to promote bone formation from bone marrow-derived mesenchymal stem cells. However, the role of miR-20a in osteogenic differentiation of hASCs remains unclear. In this study, we systematically evaluated the function of miR-20a in regulating hASC osteogenesis in vitro. hASCs were transduced with miR-20a-overexpressing and miR-20a-sponge lentiviral vectors, with green fluorescent protein (GFP) as a control. The results showed that miR-20a transcription was upregulated after hASC mineralization. Compared with the miR-20a-sponge, GFP, and hASC groups, the miR-20a-overexpressing group showed higher alkaline phosphatase (ALP) activity on days 7 and 14. Moreover, the mRNA level of ALP increased significantly in the miR-20a-overexpressing group on day 14. Furthermore, the protein of the target gene PPARγ was decreased, and the osteogenic differentiation-associated proteins ALP, osteocalcin, and RUNX2 were upregulated. hASCs anchored to HA/β-TCP revealed a healthy polygonal morphology and developed cytoplasmic extensions. miR-20a promoted osteogenic differentiation of the cell scaffold. Taken together, these data -confirm that miRNA-20a promotes the osteogenesis of hASCs in vitro, and its essential role in vivo needs further -investigation.

MicroRNA‑20a negatively regulates the growth and osteoclastogenesis of THP‑1 cells by downregulating PPARγ

The present study aimed to explore the mechanisms through which microRNA (miR)‑20a may be involved in the differentiation of THP‑1 human acute monocytic leukemia cells into osteoclasts. THP‑1 cells were differentiated into macrophages (osteoclast precursors) and subsequently into osteoclast cells. The expression levels of miR‑20a in THP‑1 cells were significantly reduced in a time‑dependent manner during phorbol‑12‑myristate‑13‑acetate (PMA), macrophage colony‑stimulating factor (M‑CSF) and receptor activator of nuclear factor‑κB ligand RANKL‑induced osteoclastogenesis. Following transfection with a miR‑20a mimics, the levels of miR‑20a in PMA‑treated THP‑1 cells increased more than 40‑fold as compared with expression in the control cells. In addition, the overexpression of miR‑20a inhibited proliferation, initiated S phase cell cycle arrest and induced apoptosis of PMA‑treated THP‑1 cells. Additionally, miR‑20a mimics treatment notably decreased the levels of tartrate‑resistant acid phosphatase, nuclear factor of activated T‑cells, cytoplasmic 1 and peroxisome proliferator‑activated receptor γ (PPARγ) during THP‑1 cell further differentiation progress. In summary, miR‑20a may negatively regulate the proliferation and osteoclastogenesis of THP‑1 cells during its osteoclast differentiation progress by downregulating PPARγ.

Anti-Osteoporotic and Anti-Adipogenic Effects of the Water Extract of Drynaria roosii Nakaike in Ovariectomized Mice Fed a High-Fat Diet

In traditional oriental medicine, Drynaria roosii Nakaike is widely used in treating bone diseases. Postmenopausal women are strongly associated with osteoporosis and obesity. This study aimed to investigate the effects of the water extract of D. roosii (WDR) on bone loss and obesity in ovariectomized (OVX) mice fed a high-fat diet (HFD). Body weight, gonadal fat weight, histological findings, and morphometric parameters in trabecular bone were evaluated after OVX mice were treated with WDR and HFD for four weeks. The receptor activator of nuclear κ-B ligand (RANKL)-induced osteoclast differentiation in bone marrow-derived macrophages (BMMs) was examined. Phytochemical identification of WDR using ultrahigh-performance liquid chromatography-tandem mass spectrometry was performed. WDR reversed the changes in body weight gain, gonadal fat mass, and trabecular bone parameters by ovariectomy. However, ovariectomy-induced uterine atrophy was not affected by WDR. WDR decreased adipocyte size and pro-inflammatory cytokines (interleukin (IL)-1β and IL-6) in gonadal fats and lipid accumulation in the bone marrow, which were induced by ovariectomy. WDR significantly decreased RANKL-induced osteoclast differentiation in BMMs. Fifteen phytochemicals were identified in WDR: Seven and nine with anti-osteoporotic and anti-adipogenic activities, respectively. Our findings suggest that WDR may have beneficial effects on postmenopausal osteoporosis and obesity.

Deregulated miRNAs in bone health: Epigenetic roles in osteoporosis

MicroRNA (miRNA) has shown to enhance or inhibit cell proliferation, differentiation and activity of different cell types in bone tissue. The discovery of miRNA actions and their targets has helped to identify them as novel regulations actors in bone. Various studies have shown that miRNA deregulation mediates the progression of bone-related pathologies, such as osteoporosis. The present review intends to give an exhaustive overview of miRNAs with experimentally validated targets involved in bone homeostasis and highlight their possible role in osteoporosis development. Moreover, the review analyzes miRNAs identified in clinical trials and involved in osteoporosis.

MicroRNA-related transcription factor regulatory networks in human colorectal cancer

OBJECTIVE

Colorectal cancer (CRC) is an extremely common gastrointestinal malignancy. The present study aimed to identify microRNAs (miRNAs) and transcription factors (TFs) associated with tumor development.

METHODS

Three miRNA profile datasets were integrated and analyzed to elucidate the potential key candidate miRNAs in CRC. The starBase database was used to identify the potential targets of common differentially expressed miRNAs (DEMs). Transcriptional Regulatory Element Database and Transcriptional Regulatory Relationships Unraveled by Sentence-based Text databases were used to identify cancer-related TFs and the TF-regulated target genes. Functional and pathway enrichment analyses were performed using the Database for Annotation, Visualization and Integration Discovery (DAVID) database, and the miRNA-TF-gene networks were constructed by Cytoscape. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) was used to detect the expression of genes and miRNAs.

RESULTS

In total, 14 DEMs were found in CRC. By bioinformatics analysis, 5 DEMs (miR-145, miR-497, miR-30a, miR-31, and miR-20a) and 8 TFs (ELK4 (ETS-family transcription factor), myeloblastosis proto-oncogene like (MYBL)1, MYBL2, CEBPA, PPARA, PPARD, PPARG, and endothelial PAS domain protein (EPAS1)) appeared to be associated with CRC and were therefore used to construct miRNA-TF-gene networks. From the networks, we found that miR-20a might play the most important role as an miRNA in the networks. By qRT-PCR, we demonstrated that miR-20a was significantly upregulated in CRC tissues. We also performed qRT-PCR to identify the expression of miR-20a-related TFs (PPARA, PPARD, PPARG, EPAS1). Three of them, PPARA, PPARG, and EPAS1, were downregulated in CRC tissues, with statistically significant differences, while the downregulation of PPARD in CRC tissues was not significantly different. Pathway enrichment analyses indicated that the phosphoinositide 3-kinase (PI3K)-Akt signaling pathway was the most significantly enriched pathway. Two main elements of the PI3K-Akt signaling pathway, phosphatase and tensin homolog deleted on chromosome 10 and B-cell lymphoma 2-associated agonist of cell death, were demonstrated to be downregulated in CRC.

CONCLUSION

The present study identified hub miRNAs and miRNA-related TF regulatory networks in CRC, which might be potential targets for the diagnosis and treatment of CRC.

Interplay between microRNAs and Wnt, transforming growth factor-β, and bone morphogenic protein signaling pathways promote osteoblastic differentiation of mesenchymal stem cells

Osteoblasts are terminally differentiated cells with mesenchymal origins, known to possess pivotal roles in sustaining bone microstructure and homeostasis. These cells are implicated in the pathophysiology of various bone disorders, especially osteoporosis. Over the last few decades, strategies to impede bone resorption, principally by bisphosphonates, have been mainstay of treatment of osteoporosis; however, in recent years more attention has been drawn on bone-forming approaches for managing osteoporosis. MicroRNAs (miRNAs) are a broad category of noncoding short sequence RNA fragments that posttranscriptionally regulate the expression of diverse functional and structural genes in a negative manner. An accumulating body of evidence signifies that miRNAs direct mesenchymal stem cells toward osteoblast differentiation and bone formation through bone morphogenic protein, transforming growth factor-β, and Wnt signaling pathways. MiRNAs are regarded as excellent future therapeutic candidates because of their small size and ease of delivery into the cells. Considering their novel therapeutic significance, this review discusses the main miRNAs contributing to the anabolic aspects of bone formation and illustrates their interactions with corresponding signaling pathways involved in osteoblastic differentiation.

The controlled naringin release from TiO2 nanotubes to regulate osteoblast differentiation

To design titanium (Ti)-based biomaterials with controlled drug-releasing bioactive property, TiO2 nanotubes with a diameter of approximately 110 nm was fabricated by electrochemical anodization. TiO2 nanotubes were then loaded with naringin by direct dropping and coated with chitosan layers. The surface morphologies, chemical compositions and wettability of different substrates were characterized by field emission scanning electron microscopy, atomic force microscope, X-ray photoelectron spectroscopy and contact angle measurement, respectively. The in vitro release behavior of naringin was evaluated by UV-visible-spectrophotometer. The biological properties of osteoblasts on different substrates were investigated in vitro. Our results indicate that the chitosan-coated naringin-loaded TiO2 nanotubes enhanced osteoblast spreading, proliferation, alkaline phosphatase activity and late-stage osteoblast mineralization. This study provides a platform to help enhance osteointegration between the bone and implant surface in clinical applications.

Bioinstructive Naringin-Loaded Micelles for Guiding Stem Cell Osteodifferentiation

Naringin is a naturally occurring flavanone with recognized neuroprotective, cardioprotective, anti-inflammatory, and antiosteoporotic properties. Herein, the delivery of Naringin-loaded methoxy-poly(ethylene glycol)-maleimide-thiol-poly(l-lactide) (mPEGMSPLA) diblock polymeric micelles to human adipose-derived stem cells (hASCs) with the aim to augment its pro-osteogenic effect in these cells is reported for the first time. The synthesis of the diblock copolymer is performed via Michael-type addition reaction between hydrophilic methoxy-poly(ethylene glycol)-maleimide (mPEGMAL) and hydrophobic thiol-poly(l-lactide) (PLASH) and confirmed by ¹ H NMR and attenuated total reflectance Fourier transformed infrared (ATR-FTIR) spectroscopy. The resulting mPEGMSPLA copolymer self-assembles into monodispersed polymeric micelles (≈84.4 ± 2 nm) and presents a high Naringin encapsulation efficiency (87.8 ± 4%), with a sustained release profile at physiological pH. Alongside, in vitro data reveal that upon internalization into hASC 2D cultures, Naringin nanomicellar formulations attain a higher pro-osteogenic effect than that of free drug. Notably, these bioactive carriers also induce superior osteopontin expression and increase matrix mineralization in these cells over free drug administration. Overall, such findings support for the first time the use of polymeric nanomicelles for Naringin delivery into hASCs as a valid approach for modulating stem cell osteogenic differentiation.

Naringin promotes cellular chemokine synthesis and potentiates mesenchymal stromal cell migration via the Ras signaling pathway

Directional migration of mesenchymal stem cells (MSCs) is known to serve roles in bone fracture healing. Naringin is a traditional medicine used in China to treat bone injury and has been confirmed to act as a chemoattractant to MSCs. In the present study, the secretion of chemokines and stimulation of relevant signaling pathways by naringin were detected to determine the molecular mechanism of naringin-induced MSC migration. In these experiments, Quantibody^® arrays were used to detect chemokines secreted by MSCs with or without the addition of naringin. The results revealed differential naringin-induced chemokine secretion of C-X-C motif chemokine (CXCL)5, CXCL6 and C-C motif chemokine 20. Furthermore, the Ras signaling pathway was markedly activated in the naringin-treated groups, suggesting that naringin may enhance the migrational ability of MSCs via Ras activation. Furthermore, naringin was able to promote the secretion of various chemokines derived from MSCs, which would, in turn, increase the mobility of MSCs. The aim of the present study was to provide novel candidate agents for clinical orthopedics and theoretical basis for the future improvement of adjunctive medication for bone fracture healing.

Bioinspired bone therapies using naringin: applications and advances

The use of natural compounds for treating chronic bone diseases holds remarkable potential. Among these therapeutics, naringin, a flavanone glycoside, represents one of the most promising candidates owing to its multifaceted effect on bone tissues. This review provides an up-to-date overview on naringin applications in the treatment of bone disorders, such as osteoporosis and osteoarthritis, and further highlights its potential for stem cell pro-osteogenic differentiation therapies. A critical perspective on naringin clinical translation is also provided. The topic is discussed in light of recently developed biomaterial-based approaches that potentiate its bioavailability and bioactivity. Overall, the reported pro-osteogenic, antiresorptive and antiadipogenic properties establish this flavanone as an exciting candidate for application in bone tissue engineering and regenerative medicine.

Preliminary Analysis of MicroRNAs Expression Profiling in MC3T3-E1 Cells Exposed to Fluoride

Overexposure to fluoride from environmental sources can cause serious public health problems. Disrupted osteoblast function and impaired bone formation were found to be associated with excessive fluoride exposure. A massive analysis of microRNAs (miRNAs) was used to figure out the possible pathways in which fluoride affects osteoblast function. MC3T3-E1 cells were treated with 8 mg/L of fluorine for 7 days. Total RNA of cells was extracted, and their integrity and purity were tested. RNA samples were analyzed by using miRNA array, including miRNA labeling, hybridization, scanning, and expression data analysis to compare the profiling of miRNA expression between control and fluoride-treated group. Transcriptome analysis console and enrichment analysis calculated by miRSystem were used to predict target genes and collect miRNAs pathway maps. Forty-five upregulated and 31 downregulated miRNAs expression were found in the fluoride-treated group, and most of the verified miRNAs were mature. The KEGG pathway enrichment analysis searched out 36 pathways that scored more than 0.1. These pathways mainly included intracellular signaling, cytokines, metabolism, and cytoskeleton-related pathways. Among them, the Wnt, insulin, TGF-beta, hedgehog, VEGF, and notch pathways in osteoblasts were those mainly affected by fluoride treatment. These results have shown a number of higher level systemic pathways activated by overexposure of fluoride in osteoblastic cells and verified that fluoride affected the molecular crosstalk in the osteoblasts.

Vitamin K2 promotes mesenchymal stem cell differentiation by inhibiting miR‑133a expression

Vitamin K₂ has been demonstrated to promote the osteogenic differentiation of mesenchymal stem cells; however, the mechanisms underlying this effect remain unclear. As microRNA (miR)-133a has been identified as a negative regulator of osteogenic differentiation, the present study hypothesized that vitamin K₂ promoted osteogenesis by inhibiting miR-133a. Using human bone marrow stromal cells (hBMSCs) overexpressing miR-133a, or a control, the expression levels of osteogenesis-associated proteins, including runt-related transcription factor 2, alkaline phosphatase and osteocalcin, were analyzed. miR-133a significantly suppressed the osteogenic differentiation of hBMSCs. To determine the effect of vitamin K₂ on miR-133a expression and osteogenesis, hBMSCs were treated with vitamin K₂. Vitamin K₂ inhibited miR-133a expression, which was accompanied by enhanced osteogenic differentiation. Furthermore, the expression levels of vitamin K epoxide reductase complex subunit 1, the key protein in γ-carboxylation, were downregulated by miR-133a overexpression and upregulated by vitamin K₂ treatment, indicating a positive feedback on γ-carboxylation. The results of the present study suggested that vitamin K₂ targets miR-133a to regulate osteogenesis.

Effects of yuja peel extract and its flavanones on osteopenia in ovariectomized rats and osteoblast differentiation

SCOPE

Yuja (Citrus junos Tanaka) possesses various health benefits, but its effects on bone health are unknown. In this study, the preventative effects of yuja peel ethanol extract (YPEE) on osteopenia were determined in ovariectomized (OVX) rats, and the mechanisms by which YPEE and its flavanones regulate osteoblastogenesis were examined in vitro.

METHODS AND RESULTS

The effects of YPEE on osteoblastogenesis were investigated in MC3T3-E1 cells. YPEE promoted alkaline phosphatase (ALP) activity, mineralization, and the expression of osteoblast differentiation marker genes, such as ALP, runt-related transcription factor 2 (Runx2), and osteocalcin. YPEE and its flavanones promoted osteoblast differentiation via BMP-2-mediated p38 and the Smad1/5/8 signaling pathway. YPEE supplementation significantly decreased body weight and increased uterine weight and bone mineral density in OVX rats. Based on a micro-CT analysis of femurs, YPEE significantly attenuated osteopenia and increased trabecular volume fraction, trabecular separation, and trabecular number (p < 0.05).

CONCLUSION

Dietary YPEE has a protective effect on OVX-induced osteopenia. YPEE and its flavanones promote osteoblastogenesis via the activation of the BMP/p38/Smad/Runx2 pathways. These results extend our knowledge of the beneficial effects of YPEE and provide a basis for the development of novel therapies for osteoporosis.

Traditional Chinese medicine formulas for the treatment of osteoporosis: Implication for antiosteoporotic drug discovery

ETHNOPHARMACOLOGICAL RELEVANCE

Osteoporosis is a chronic epidemic which can leads to enhanced bone fragility and consequent an increase in fracture risk. Traditional Chinese medicine (TCM) formulas have a long history of use in the prevention and treatment of osteoporosis. Antiosteoporotic TCM formulas have conspicuous advantage over single drugs. Systematic data mining of the existing antiosteoporotic TCM formulas database can certainly help the drug discovery processes and help the identification of safe candidates with synergistic formulations. In this review, the authors summarize the clinical use and animal experiments of TCM formulas and their mechanism of action, and discuss the potential antiosteoporotic activity and the active constituents of commonly used herbs in TCM formulas for the therapy of osteoporosis.

MATERIALS AND METHODS

The literature was searched from Medline, Pubmed, ScienceDirect, Spring Link, Web of Science, CNKI and VIP database from 1989 to 2015, and also collected from Chinese traditional books and Chinese Pharmacopoeia with key words such as osteoporosis, osteoblast, osteoclast, traditional Chinese medicine formulas to identify studies on the antiosteoporotic effects of TCM formulas, herbs and chemical constituents, and also their possible mechanisms.

RESULTS

Thirty-three TCM formulas were commonly used to treat osteoporosis, and showed significant antiosteoporotic effects in human and animal. The herb medicines and their chemical constituents in TCM formulas were summarized, the pharmacological effects and chemical constituents of commonly used herbs in TCM formulas were described in detail. The action mechanisms of TCM formulas and their chemical constituents were described. Finally, the implication for the discovery of antiosteoporotic leads and combinatory ingredients from TCM formulas were prospectively discussed.

CONCLUSIONS

Clinical practice and animal experiments indicate that TCM formulas provide a definite therapeutic effect on osteoporosis. The active constituents in TCM formulas are diverse in chemical structure, and include flavonoids, lignans, saponins and iridoid glycosides. Antiosteoporotic mechanism of TCM formulas and herbs involves multi regulatory pathways, such as Wnt/β-catenin, BMP/Smad, MAPK pathway and RANKL/OPG system. Phytochemicals from TCM formulas and their compositional herb medicines offer great potential for the development of novel antiosteoporotic drugs. The active ingredients in TCM formulas can be developed in combination as potent drugs, which may exhibit better antiosteoporotic effects compared to the individual compound.

Evaluation of the osteogenic potential of Hancornia speciosa latex in rat calvaria and its phytochemical profile

ETHNOPHARMACOLOGICAL RELEVANCE

Hancornia speciosa Gomes, commonly known as Mangabeira, is a Brazilian native fruit tree belonging to the Apocynaceae family. In folk medicine, the latex obtained from Mangabeira's trunk has been used as an adjunct therapy for bone fractures. Few pharmacological studies on the Hancornia speciosa latex have been developed and despite its popular use for bone healing there is no data about its biological effect on bone.

AIM OF THE STUDY

The present study aimed to investigate the osteogenic potential of Hancornia speciosa latex in rat calvaria, as well as its phytochemical profile.

MATERIALS AND METHODS

A neutral gel composition containing 5% latex was topical applied to a critical size bone defect and over intact calvaria of rats. Areas of newly formed bone on the borders of the defect and of calvaria periosteum were quantified, as well as the percentage of BrdU-positive cells and total cells in the periosteum at different periods of time after latex application. The cytotoxicity of the latex aqueous phase was evaluated in rat calvarial cells in vitro by MTT assay and its phytochemical profile was investigated by ESI-MS/MS.

RESULTS

The area of newly formed bone on the borders of the calvaria defect was larger in rats that received latex at 15 and 30 days of healing. After 3 days of latex application over the intact calvaria, the periosteum area was increased and newly formed bone was observed after 5 and 11 days. There was also an increase in periosteum cell proliferation and population followed latex application on calvaria (p<0.05). The latex aqueous phase limited rat calvarial cell viability in vitro in concentrations larger than 0.6mg/mL. Chlorogenic acid and naringenin-7-O-glucoside were identified in the latex aqueous phase, along with catechin and procyanidin compounds.

CONCLUSION

There was a stimulus for periosteum cell proliferation and bone formation when Hancornia speciosa latex was topically applied on rat calvaria. In addition, chlorogenic acid and naringenin-7-O-glucoside present in Hancornia speciosa latex may contribute to its effects on bone formation.

Genistein induces adipogenic differentiation in human bone marrow mesenchymal stem cells and suppresses their osteogenic potential by upregulating PPARγ

Genistein is a soy isoflavone that exists in the form of an aglycone. It is the primary active component in soy isoflavone and has a number of biological activities (anti-inflammatory and anti-oxidative). However, the specific effect of genistein on human bone marrow mesenchymal stem cells (BMSCs) remains unclear. In the present study, the mechanism underlying the effect of genistein on the suppression of BMSC adipogenic differentiation and the enhancement of osteogenic potential was investigated using an MTT assay. It was observed that genistein significantly increased BMSC cell proliferation in a time- and dose-dependent manner (P<0.01). In addition, reverse transcription-quantitative polymerase chain reaction revealed that genistein significantly inhibited the expression of runt-related transcription factor 2 (Runx2), type I collagen (Col I) and osteocalcin (OC; P<0.01). Furthermore, 20 µm genistein significantly inhibited the activity of alkaline phosphatase (ALP) and increased the activity of triglycerides (TGs) increased (P<0.01) as determined by an enzyme-linked immunosorbent assay. Finally, western blotting revealed that BMSC pretreatment with 20 µm genistein significantly increased peroxisome proliferator-activated receptor γ (PPARγ) protein expression (P<0.01). This suggests that the downregulation of PPARγ may significantly reduce the effect of genistein on cell proliferation, suppress the expression of Runx2, Col I and OC mRNA, and reduce ALP and promote TG activity in BMSCs. Thus, the results of the present study conclude that genistein induces adipogenic differentiation in human BMSCs and suppresses their osteogenic potential by upregulating the expression of PPARγ. In conclusion, genistein may be a promising candidate drug for treatment against osteogenesis.

Naringin Stimulates Osteogenic Differentiation of Rat Bone Marrow Stromal Cells via Activation of the Notch Signaling Pathway

Naringin is a major flavonoid found in grapefruit and is an active compound extracted from the Chinese herbal medicine Rhizoma Drynariae. Naringin is a potent stimulator of osteogenic differentiation and has potential application in preventing bone loss. However, the signaling pathway underlying its osteogenic effect remains unclear. We hypothesized that the osteogenic activity of naringin involves the Notch signaling pathway. Rat bone marrow stromal cells (BMSCs) were cultured in osteogenic medium containing-naringin, with or without DAPT (an inhibitor of Notch signaling), the effects on ALP activity, calcium deposits, osteogenic genes (ALP, BSP, and cbfa1), adipogenic maker gene PPARγ2 levels, and Notch expression were examined. We found that naringin dose-dependently increased ALP activity and Alizarin red S staining, and treatment at the optimal concentration (50 μg/mL) increased mRNA levels of osteogenic genes and Notch1 expression, while decreasing PPARγ2 mRNA levels. Furthermore, treatment with DAPT partly reversed effects of naringin on BMSCs, as judged by decreases in naringin-induced ALP activity, calcium deposits, and osteogenic genes expression, as well as upregulation of PPARγ2 mRNA levels. These results suggest that the osteogenic effect of naringin partly involves the Notch signaling pathway.

Natural Products from Chinese Medicines with Potential Benefits to Bone Health

Osteoporosis is a progressive, systemic bone disorder characterized by loss of bone mass and microstructure, leading to reduced bone strength and increased risk of fracture. It is often associated with reduced quality of life and other medical complications. The disease is common in the aging population, particularly among postmenopausal women and patients who receive long-term steroidal therapy. Given the rapid growth of the aging population, increasing life expectancy, the prevalence of bone loss, and financial burden to the healthcare system and individuals, demand for new therapeutic agents and nutritional supplements for the management and promotion of bone health is pressing. With the advent of global interest in complementary and alternative medicine and natural products, Chinese medicine serves as a viable source to offer benefits for the improvement and maintenance of bone health. This review summarizes the scientific information obtained from recent literatures on the chemical ingredients of Chinese medicinal plants that have been reported to possess osteoprotective and related properties in cell-based and/or animal models. Some of these natural products (or their derivatives) may become promising leads for development into dietary supplements or therapeutic drugs.

Naringin promotes osteogenic differentiation of bone marrow stromal cells by up-regulating Foxc2 expression via the IHH signaling pathway

Naringin is an active compound extracted from Rhizoma Drynariae, and studies have revealed that naringin can promote proliferation and osteogenic differentiation of bone marrow stromal cells (BMSCs). In this study, we explored whether naringin could promote osteogenic differentiation of BMSCs by upregulating Foxc2 expression via the Indian hedgehog (IHH) signaling pathway. BMSCs were cultured in basal medium, basal medium with naringin, osteogenic induction medium, osteogenic induction medium with naringin and osteogenic induction medium with naringin in the presence of the IHH inhibitor cyclopamine (CPE). We examined cell proliferation by using a WST-8 assay, and differentiation by Alizarin Red S staining (for mineralization) and alkaline phosphatase (ALP) activity. In addition, we detected core-binding factor α1 (Cbfα1), osteocalcin (OCN), bone sialoprotein (BSP), peroxisome proliferation-activated receptor gamma 2 (PPARγ2) and Foxc2 expression by using RT-PCR. We also determined Foxc2 and IHH protein levels by western blotting. Naringin increased the mineralization of BMSCs, as shown by Alizarin red S assays, and induced ALP activity. In addition, naringin significantly increased the mRNA levels of Foxc2, Cbfα1, OCN, and BSP, while decreasing PPARγ2 mRNA levels. Furthermore, the IHH inhibitor CPE inhibited the osteogenesis-potentiating effects of naringin. Naringin increased Foxc2 and stimulated the activation of IHH, as evidenced by increased expression of proteins that were inhibited by CPE. Our findings indicate that naringin promotes osteogenic differentiation of BMSCs by up-regulating Foxc2 expression via the IHH signaling pathway.