Effect of quercetin on preosteoblasts and bone defects

Extrusion 3D-printed tricalcium phosphate-polycaprolactone biocomposites for quercetin-KCl delivery in bone tissue engineering

Critical-sized bone defects pose a significant challenge in advanced healthcare due to limited bone tissue regenerative capacity. The complex interplay of numerous overlapping variables hinders the development of multifunctional biocomposites. Phytochemicals show promise in promoting bone growth, but their dose-dependent nature and physicochemical properties halt clinical use. To develop a comprehensive solution, a 3D-printed (3DP) extrusion-based tricalcium phosphate-polycaprolactone (TCP-PCL) scaffold is augmented with quercetin and potassium chloride (KCl). This composite material demonstrates a compressive strength of 30 MPa showing promising stability for low load-bearing applications. Quercetin release from the scaffold follows a biphasic pattern that persists for up to 28 days, driven via diffusion-mediated kinetics. The incorporation of KCl allows for tunable degradation rates of scaffolds and prevents the initial rapid release. Functionalization of scaffolds facilitates the attachment and proliferation of human fetal osteoblasts (hfOB), resulting in a 2.1-fold increase in cell viability. Treated scaffolds exhibit a 3-fold reduction in osteosarcoma (MG-63) cell viability as compared to untreated substrates. Ruptured cell morphology and decreased mitochondrial membrane potential indicate the antitumorigenic potential. Scaffolds loaded with quercetin and quercetin-KCl (Q-KCl) demonstrate 76% and 89% reduction in bacterial colonies of Staphylococcus aureus, respectively. This study provides valuable insights as a promising strategy for bone tissue engineering (BTE) in orthopedic repair.

Flavonoid-Loaded Biomaterials in Bone Defect Repair

Skeletons play an important role in the human body, and can form gaps of varying sizes once damaged. Bone defect healing involves a series of complex physiological processes and requires ideal bone defect implants to accelerate bone defect healing. Traditional grafts are often accompanied by issues such as insufficient donors and disease transmission, while some bone defect implants are made of natural and synthetic polymers, which have characteristics such as good porosity, mechanical properties, high drug loading efficiency, biocompatibility and biodegradability. However, their antibacterial, antioxidant, anti-inflammatory and bone repair promoting abilities are limited. Flavonoids are natural compounds with various biological activities, such as antitumor, anti-inflammatory and analgesic. Their good anti-inflammatory, antibacterial and antioxidant activities make them beneficial for the treatment of bone defects. Several researchers have designed different types of flavonoid-loaded polymer implants for bone defects. These implants have good biocompatibility, and they can effectively promote the expression of angiogenesis factors such as VEGF and CD31, promote angiogenesis, regulate signaling pathways such as Wnt, p38, AKT, Erk and increase the levels of osteogenesis-related factors such as Runx-2, OCN, OPN significantly to accelerate the process of bone defect healing. This article reviews the effectiveness and mechanism of biomaterials loaded with flavonoids in the treatment of bone defects. Flavonoid-loaded biomaterials can effectively promote bone defect repair, but we still need to improve the overall performance of flavonoid-loaded bone repair biomaterials to improve the bioavailability of flavonoids and provide more possibilities for bone defect repair.

Exploring Quercetin Anti-Osteoporosis Pharmacological Mechanisms with In Silico and In Vivo Models

Since osteoporosis critically influences the lives of patients with a high incidence, effective therapeutic treatments are important. Quercetin has been well recognized as a bone-sparing agent and thus the underlying mechanisms warrant further investigation. In the current study, the network pharmacology strategy and zebrafish model were utilized to explain the potential pharmacological effects of quercetin on osteoporosis. The potential targets and related signaling pathways were explored through overlapping target prediction, protein–protein interaction network construction, and functional enrichment analysis. Furthermore, we performed docking studies to verify the specific interactions between quercetin and crucial targets. Consequently, 55 targets were related to osteoporosis disease among the 159 targets of quercetin obtained by three database sources. Thirty hub targets were filtered through the cytoNCA plugin. Additionally, the Gene Ontology functions in the top 10 respective biological processes, molecular functions, and cell components as well as the top 20 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were depicted. The most significance difference in the KEGG pathways was the TNF signaling pathway, consisting of the Nuclear Factor Kappa B Subunit (NF-κB), Extracellular Regulated Protein Kinases (ERK) 1/2, Activator Protein 1 (AP-1), Interleukin 6 (IL6), Transcription factor AP-1 (Jun), and Phosphatidylinositol 3 Kinase (PI3K), which were probably involved in the pharmacological effects. Moreover, molecular docking studies revealed that the top three entries were Interleukin 1 Beta (IL1B), the Nuclear Factor NF-Kappa-B p65 Subunit (RelA), and the Nuclear Factor Kappa B Subunit 1 (NFKB1), respectively. Finally, these results were verified by alizarin red-stained mineralized bone in zebrafish and related qPCR experiments. The findings probably facilitate the mechanism elucidation related to quercetin anti-osteoporosis action.

Traditional Chinese Medicine Compound-Loaded Materials in Bone Regeneration

Bone is a dynamic organ that has the ability to repair minor injuries via regeneration. However, large bone defects with limited regeneration are debilitating conditions in patients and cause a substantial clinical burden. Bone tissue engineering (BTE) is an alternative method that mainly involves three factors: scaffolds, biologically active factors, and cells with osteogenic potential. However, active factors such as bone morphogenetic protein-2 (BMP-2) are costly and show an unstable release. Previous studies have shown that compounds of traditional Chinese medicines (TCMs) can effectively promote regeneration of bone defects when administered locally and systemically. However, due to the low bioavailability of these compounds, many recent studies have combined TCM compounds with materials to enhance drug bioavailability and bone regeneration. Hence, the article comprehensively reviewed the local application of TCM compounds to the materials in the bone regeneration in vitro and in vivo. The compounds included icariin, naringin, quercetin, curcumin, berberine, resveratrol, ginsenosides, and salvianolic acids. These findings will contribute to the potential use of TCM compound-loaded materials in BTE.

Effect of red wine or its polyphenols on induced apical periodontitis in rats

AIM

To evaluate the effect of red wine consumption or its polyphenols on the inflammation/resorption processes associated with apical periodontitis in rats.

METHODOLOGY

Thirty-two three-month-old Wistar rats had apical periodontitis induced in four first molars and were then arranged into four groups: control (C)-rats with apical periodontitis; wine (W)-rats with apical periodontitis receiving 4.28 ml/kg of red wine; resveratrol+quercetin (R+Q)-rats with apical periodontitis receiving 4.28 ml/kg of a solution containing 1.00 mg/L of quercetin and 0.86 mg/L of resveratrol and alcohol (ALC)-rats with apical periodontitis receiving the alcoholic dose contained in the wine. The oral gavage treatments were administered daily, from day 0 to day 45. On the 15th day, apical periodontitis was induced, and on the 45th day, the animals were euthanized. Histological, immunohistochemical (RANKL, OPG, TRAP, IL-10, TNF-⍺ and IL-1β) and micro-computed tomography for bone resorption analysis were performed in the jaws. The Kruskal-Wallis with Dunn's test was performed for nonparametric data, and the anova with Tukey's test for parametric data, p < .05.

RESULTS

The median score of the inflammatory process was significantly lower in the R+Q group (1) compared to the C (2) (p = .0305) and ALC (3) (p = .0003) groups, and not different from the W (1.5) group. The immunolabeling for OPG was significantly higher in the R+Q group (p = .0054) compared to all groups; the same was observed for IL-10 (p = .0185), different from groups C and ALC. The R+Q group had the lowest TRAP cell count (p < .0001), followed by the W group, both inferior to C and ALC groups. The lowest bone resorption value was in the R+Q group (0.50mm³  ± 0.21mm³ ), significantly lower (p = .0292) than the C group (0.88mm³  ± 0.10mm³ ). The W group (0.60 mm³  ± 0.25 mm³ ) and R+Q group had less bone resorption compared to the ALC group (0.97 mm³  ± 0.22 mm³ ), p = .0297 and p = .0042, respectively.

CONCLUSION

Red wine administration to rats for 15 days before induction of apical periodontitis decreased inflammation, TRAP marking and periapical bone resorption compared to alcohol. Resveratrol-quercetin administration reduced the inflammatory process in apical periodontitis, periapical bone resorption, and altered the OPG, IL-10 and TRAP expression compared to C and ALC groups.

The effect of Cornus mas extract consumption on bone biomarkers and inflammation in postmenopausal women: A randomized clinical trial

The drastic decrease in estrogen levels in menopausal women can elevate bone resorption and osteoporosis. Cornus mas extract (C. mas extract) is a potential candidate for treating menopausal-related bone complications because of its phytoestrogen and anti-inflammatory contents. It was an interventional double-blind placebo-controlled randomized study. Eighty-four women aged 45-60 years old were randomly allocated to either the extract group receiving 3 capsules of 300 mg C. mas extract or the placebo group receiving 3 capsules of 300 mg of starch powder per day for 8 weeks. Then, venous blood was used to measure bone-specific alkaline phosphatase (BAP), osteocalcin (OC), C-terminal telopeptide (TC) as well as serum levels of PTH and hsCRP. Our results indicated the decrease in alkaline phosphatase, PTH, and as an inflammation biomarker, hsCRP, between two groups at the end of the study. No statistically significant difference was observed in telopeptide C, osteocalcin, and calcium between the placebo and extract groups after 8 weeks of intervention. In conclusion, the results indicate that the C. mas extract supplement of 900 mg/day may decrease levels of BAP, PTH, and hsCRP. However, this intervention had no beneficial effect on OC and TC in healthy postmenopausal women.

Oral Administration of Quercetin or Its Derivatives Inhibit Bone Loss in Animal Model of Osteoporosis

Objectives. Quercetin (Q) and its derivatives are the major members of the naturally occurring flavonoid family, which possess beneficial effects on disease prevention including osteoporosis. The present study is aimed at further investigating the efficacy of the Q and its derivatives on bone pathology, bone-related parameters under imageology, bone maximum load, and serum bone metabolism indexes in animal model of osteoporosis. Potential mechanisms of Q and its derivatives in the treatment of osteoporosis as well as the existing problems regarding the modeling method and limitations of researches in this area were also summarized. Eight databases were searched from their inception dates to February 2020. Nineteen eligible studies containing 21 comparisons were identified ultimately. The risk of bias and data on outcome measures were analyzed by the CAMARADES 10-item checklist and Rev-Man 5.3 software separately. The results displayed the number of criteria met varied from 3/10 to 7/10 with an average of 5.05. The present study provided the preliminary preclinical evidence that oral administration of Q or its derivatives was capable of improving bone pathology, bone-related parameters under imageology and bone maximum load, increasing serum osteocalcin, alkaline phosphatase, and estradiol, and reducing serum c-terminal cross-linked telopeptide of type I collagen (P < 0.05). No statistical difference was seen in survival rate, index of liver, or kidney function (P > 0.05). Q and its derivatives partially reverse osteopenia probably via antioxidant, anti-inflammatory, promoting osteogenesis, inhibiting osteoclasts, and its estrogen-like effect. The findings reveal the possibility of developing Q or its derivatives as a drug or an ingredient in diet for clinical treatment of osteoporosis.

Quercetin as an Agent for Protecting the Bone: A Review of the Current Evidence

Quercetin is a flavonoid abundantly found in fruits and vegetables. It possesses a wide spectrum of biological activities, thus suggesting a role in disease prevention and health promotion. The present review aimed to uncover the bone-sparing effects of quercetin and its mechanism of action. Animal studies have found that the action of quercetin on bone is largely protective, with a small number of studies reporting negative outcomes. Quercetin was shown to inhibit RANKL-mediated osteoclastogenesis, osteoblast apoptosis, oxidative stress and inflammatory response while promoting osteogenesis, angiogenesis, antioxidant expression, adipocyte apoptosis and osteoclast apoptosis. The possible underlying mechanisms involved are regulation of Wnt, NF-κB, Nrf2, SMAD-dependent, and intrinsic and extrinsic apoptotic pathways. On the other hand, quercetin was shown to exert complex and competing actions on the MAPK signalling pathway to orchestrate bone metabolism, resulting in both stimulatory and inhibitory effects on bone in parallel. The overall interaction is believed to result in a positive effect on bone. Considering the important contributions of quercetin in regulating bone homeostasis, it may be considered an economical and promising agent for improving bone health. The documented preclinical findings await further validation from human clinical trials.

Puerarin improves graft bone defect through microRNA‑155‑3p‑mediated p53/TNF‑α/STAT1 signaling pathway

Bone graft defects may lead to dysfunction of bone regeneration and metabolic disorders of bone mesenchymal stem cells (BMSCs). Puerarin has demonstrated pharmacological activities in the treatment of human metabolic diseases. The purpose of the present study was to investigate the role of puerarin and to explore its possible protective mechanism of action in rats with bone grafts. A bone graft rat model was established using bone grafting surgery and the rats received puerarin or PBS. Reverse transcription‑quantitative PCR, western blot, TUNEL, immunofluorescence and immunohistochemistry assays were used to analyze the beneficial effects of puerarin on bone repair. The results demonstrated that puerarin effectively ameliorated pathological graft bone defects, decreased bone loss and apoptosis of BMSCs, promoted BMSC proliferation and differentiation, and increased bone mass and the parameters of bone formation in rats with bone grafts. Puerarin decreased the levels of pro‑inflammatory cytokines [tumor necrosis factor (TNF)‑α, interleukin (IL)‑1β, IL‑17A, IL‑6 and transforming growth factor (TGF)‑β1] and increased the levels of anti‑inflammatory cytokines (IL‑2 and IL‑10) in the serum compared with the PBS group. Puerarin treatment was associated with lower serum alanine transaminase, glutamic oxaloacetic transaminase, γ‑glutamyl transferase, alkaline phosphatase, direct bilirubin and total bilirubin levels compared with those in the PBS group in experimental rats. The expression of microRNA‑155‑3p (miR‑155‑3p) was upregulated, whereas that of p53, TNF‑α and signal transducer and activator of transcription (STAT)1 was downregulated in BMSC cultures of puerarin‑treated rats. In vitro assay demonstrated that knockdown of miR‑155‑3p increased p53, TNF‑α and STAT1 expression in BMSCs, and blocked puerarin‑regulated p53/TNF‑α/STAT1 signaling. Most importantly, miR‑155‑3p knockdown inhibited puerarin‑regulated apoptosis, proliferation and differentiation of BMSCs. Moreover, the results demonstrated that puerarin regulated vascular endothelial growth factor expression via the miR‑155‑3p signaling pathway. In conclusion, the results of the present study demonstrated that the upregulation of miR‑155‑3p induced by puerarin promoted BMSC differentiation and bone formation and increased bone mass in rats with bone grafts, thereby supporting the potential application of puerarin in the prevention of bone graft defects.

A BMSCs-laden quercetin/duck's feet collagen/hydroxyapatite sponge for enhanced bone regeneration

Treating critical-sized bone defects is an important issue in the field of tissue engineering and bone regeneration. From the various biomaterials for bone regeneration, collagen is an important and widely used biomaterial in biomedical applications, hence, it has numerous attractive properties including biocompatibility, hyper elastic behavior, prominent mechanical properties, support cell adhesion, proliferation, and biodegradability. In the present study, collagen was extracted from duck's feet (DC) as a new collagen source and combined with quercetin (Qtn), a type of flavonoids found in apple and onions and has been reported to affect the bone metabolism, for increasing osteogenic differentiation. Further, improving osteoconductive properties of the scaffold hydroxyapatite (HAp) a biodegradable material was used. We prepared 0, 25, 50, and 100 μM Qtn/DC/HAp sponges using Qtn, DC, and HAp. Their physiochemical characteristics were evaluated using scanning electron microscopy, compressive strength, porosity, and Fourier transform infrared spectroscopy. To assess the effect of Qtn on osteogenic differentiation, we cultured bone marrow mesenchymal stem cells on the sponges and evaluated by alkaline phosphatase, 3-4-2, 5-diphenyl tetrazolium bromide assay, and real-time polymerase chain reaction. Additionally, they were studied implanting in rat, analyzed through Micro-CT and histological staining. From our in vitro and in vivo results, we found that Qtn has an effect on bone regeneration. Among the different experimental groups, 25 μM Qtn/DC/HAp sponge was found to be highly increased in cell proliferation and osteogenic differentiation compared with other groups. Therefore, 25 μM Qtn/DC/HAp sponge can be used as an alternative biomaterial for bone regeneration in critical situations.

Ethyl acetate and n-butanol fraction of Cissus quadrangularis promotes the mineralization potential of murine pre-osteoblast cell line MC3T3-E1 (sub-clone 4)

In a sequel to investigate osteogenic potential of ethanolic extract of Cissus quadrangularis (CQ), the present study reports the osteoblast differentiation and mineralization potential of ethyl acetate (CQ-EA) and butanol (CQ-B) extracts of CQ on mouse pre-osteoblast cell line MC3T3-E1 (sub-clone 4) with an objective to isolate an antiosteoporotic compound. Growth curve, proliferation, and viability assays showed that both the extracts were nontoxic to the cells even at high concentration (100 µg/ml). The cell proliferation was enhanced at low concentrations (0.1 µg/ml and 1 µg/ml) of both the extracts. They also upregulated the osteoblast differentiation and mineralization processes in MC3T3-E1 cells as reflected by expression profile of osteoblast marker genes such as RUNX2, Osterix, Collagen (COL1A1), Alkaline Phosphatase (ALP), Integrin-related Bone Sialoprotein (IBSP), Osteopontin (OPN), and Osteocalcin (OCN). CQ-EA treatment resulted in early differentiation and mineralization as compared with the CQ-B treatment. These findings suggest that low concentrations of CQ-EA and CQ-B have proliferative and osteogenic properties. CQ-EA, however, is more potent osteogenic than CQ-B.

Alleviation of bone markers in rats induced nano-zinc oxide by qurecetin and α-lipolic acid

The purpose of this study was to evaluate the potential protective effect of qurecetin (Qur) and α-lipolic acid (ALA) to modulate the perturbation of bone turnover which is induced by nano-zinc oxide (n-ZnO). Rats were fasted overnight and randomly divided into two groups: G1, normal healthy animals and the other rats were administered zinc oxide nanoparticles orally by guava in a dose of 600 mg/kg body weight/d for 5 sequential days in Wistar albino male rats. N-ZnO-exposed animals were randomly sub-divided into three groups: G2, n-ZnO-exposed animals; G3, n-ZnO-exposed animals co-treated with Qur (200 mg/kg daily); and G4, n-ZnO-exposed animals co-treated with ALA (200 mg/kg). Qur and ALA were administered orally by guava daily for three sequential weeks from the beginning of the experiment. The results revealed a significant reduction of nitiric oxide (NO) and serum level and comet assay in n-ZnO exposure rats after treatment of Qur and ALA. It was found the alteration of pro-inflammatory markers (tumor necrosis factor alpha; TNF-α, interleukin-6; IL-6 and C-reactive protein; CRP), bone alkaline phosphatase (B-ALP, bone formation marker), and C-terminal peptide type I collagen (CTx, bone resorption marker) levels compared with the normal group. Co-administration of Qur and ALA in n-ZnO-exposed rats significantly alleviated the mentioned alterations of biochemical parameters. These results suggest that Qur and ALA as antioxidant agents may be a candidate for preventive and treatment applications of impaired bone markers induced bone loss caused by nano-particles of metal oxide.

Ethanol Extract of Cissus quadrangularis Enhances Osteoblast Differentiation and Mineralization of Murine Pre-Osteoblastic MC3T3-E1 Cells

Traditional medicinal literature and previous studies have reported the possible role of Cissus quadrangularis (CQ) as an anti-osteoporotic agent. This study examines the effectiveness of CQ in promoting osteoblast differentiation of the murine pre-osteoblast cell line, MC3T3-E1. Ethanolic extract of CQ (CQ-E) was found to affect growth kinetics of MC3T3-E1 cells in a dosage-dependent manner. High concentrations of CQ-E (more than 10 μg/ml) have particularly adverse effects, while lower concentrations of 0.1 and 1 µg/ml were non-toxic and did not affect cell viability. Notably, cell proliferation was significantly increased at the lower concentrations of CQ-E. CQ-E treatment also augmented osteoblast differentiation, as reflected by a substantial increase in expression of the early osteoblast marker ALP activity, and at later stage, by mineralization of extracellular matrix compared to the control group. These findings suggest dose-dependent effect of CQ-E with lower concentrations exhibiting anabolic and osteogenic properties. J. Cell. Physiol. 232: 540-547, 2017. © 2016 Wiley Periodicals, Inc.

Supraphysiological Levels of Quercetin Glycosides are Required to Alter Mineralization in Saos2 Cells

Flavonoid intake is positively correlated to bone mineral density (BMD) in women. Flavonoids such as quercetin exhibit strong anti-oxidant and anti-inflammatory activity that may be beneficial for bone health. Quercetin, previously shown to positively influence osteoblasts, is metabolized into glycosides including rutin and hyperoside. We compared the effects of these glycosides on mineralization in human osteoblast (Saos2) cells. Administration of rutin (≥25 µM) and hyperoside (≥5 µM) resulted in higher mineral content, determined using the alizarin red assay. This was accompanied by higher alkaline phosphatase activity with no cell toxicity. The expression of osteopontin, sclerostin, TNFα and IL6, known stimuli for decreasing osteoblast activity, were reduced with the addition of rutin or hyperoside. In summary, rutin and hyperoside require supraphysiological levels, when administered individually, to positively influence osteoblast activity. This information may be useful in developing nutraceuticals to support bone health.

Danio rerio: the Janus of the bone from embryo to scale

Danio rerio (zebrafish), like the Roman god Janus, is an old animal model which is recently emerged and looks to the future with an increasing scientific success. Unlike other traditional animal models, zebrafish represents a versatile way to approach the study of the skeleton. Transparency of the larval stage, genetic manipulability and unique anatomical structures (scales) makes zebrafish a powerful and versatile instrument to investigate the bone tissue in terms of structure and function. Like Janus, zebrafish offers two different faces, or better, two models in one animal: larval and adult stage. The embryo can be used to isolate new genes involved in osteogenesis by large-scale mutagenesis screenings. The behavior of bone cells and genes in osteogenesis can be investigate by using transgenic lines, vital dyes, mutants and traditional molecular biology techniques. The adult zebrafish represents an important resource to study the pathways related to the bone metabolism and turnover. In particular, the properties of the caudal fin allow to study mechanisms of bone regeneration and reparation whereas the elasmoid scale represents an unique tool to investigate the bone metabolism under physiological or pathological conditions.

Effect of direct loading of phytoestrogens into the calcium phosphate scaffold on osteoporotic bone tissue regeneration

3D porous calcium deficient hydroxyapatite scaffolds with phytoestrogens were fabricated for osteoporotic bone tissue regeneration through a combination of 3D printing techniques and cement chemistry as a room temperature process.

Delivery of small molecules for bone regenerative engineering: preclinical studies and potential clinical applications

Stimulation of bone regeneration using growth factors is a promising approach for musculoskeletal regenerative engineering. However, common limitations with protein growth factors, such as high manufacturing costs, protein instability, contamination issues, and unwanted immunogenic responses of the host reduce potential clinical applications. New strategies for bone regeneration that involve inexpensive and stable small molecules can obviate these problems and have a significant impact on the treatment of skeletal injury and diseases. Over the past decade, a large number of small molecules with the potential of regenerating skeletal tissue have been reported in the literature. Here, we review this literature, paying specific attention to the prospects for small molecule-based bone-regenerative engineering. We also review the preclinical study of small molecules associated with bone regeneration.

Quercetin prevents experimental glucocorticoid-induced osteoporosis: a comparative study with alendronate

Glucocorticoid-induced osteoporosis (GIO) is the most common type of secondary osteoporosis. The aim of this study was to compare the efficacy of quercetin, a plant-derived flavonoid, with alendronate in the prevention of GIO. Fifty-six Sprague–Dawley rats were randomly distributed among 7 groups (8 rats per group) and treated for 6 weeks with one of the following: (i) normal saline; (ii) 40 mg methylprednisolone sodium succinate (MP)/kg body mass; (iii) MP + 40 μg alendronate/kg; (iv) MP + 50 mg quercetin/kg; (v) MP + 40 μg alendronate/kg + 50 mg quercetin/kg; (vi) MP + 150 mg quercetin/kg; and (vii) MP + 40 μg alendronate/kg + 150 mg quercetin/kg. MP and alendronate were injected subcutaneously and quercetin was administered by oral gavage 3 days a week. At the end of the study, femur breaking strength was significantly decreased as a consequence of MP injection. This decrease was completely compensated for in groups receiving 50 mg quercetin/kg plus alendronate, and 150 mg quercetin/kg with or without alendronate. Quercetin noticeably elevated osteocalcin as a bone formation marker, while alendronate did not show such an effect. In addition, administration of 150 mg quercetin/kg increased femoral trabecular and cortical thickness by 36% and 22%, respectively, compared with the MP-treated group. These data suggest that 150 mg quercetin/kg, alone or in combination with alendronate, can completely prevent GIO through its bone formation stimulatory effect.

Quercetin improves bone strength in experimental biliary cirrhosis

AIM

  Metabolic bone disorders and reduced bone mass are common complications in patients with biliary cirrhosis. As a result of there being no clear etiology, no specific therapy has been established yet. Previous studies have reported that quercetin, a plant-derived flavonoid, might improve bone quality. The present study was designed to investigate the effect of quercetin on bone strength of biliary cirrhotic rats.

METHODS

  Twenty-four male Sprague-Dawley rats aged 6-7 months were randomized into three groups of eight. One group served as control (sham operated), while the other two groups underwent a complete bile duct ligation (BDL). Four weeks after the operation, serum bilirubin, alkaline phosphatase, alanine aminotransferase and aspartate aminotransferase were measured in animal blood samples to confirm the occurrence of cirrhosis in the BDL rats. Then, one of the BDL groups received placebo and the other one was injected once a day with 150 µmol/kg of quercetin for 4 weeks. At the end of the study, femora were removed and tested for bone strength and histomorphometric parameters. The serum levels of osteocalcin, C-terminal cross-linked telopeptide of type I collagen, calcium and phosphorus were determined as bone turnover markers.

RESULTS

  Femur breaking strength was dramatically lower in the BDL group compared with control. However, receiving quercetin could reverse the deteriorating effect of cirrhosis on bone strength of BDL rats. Quercetin could noticeably elevate osteocalcin as a bone formation marker.

CONCLUSION

  These data suggest that quercetin can significantly improve bone strength particularly due to increasing bone formation in biliary cirrhosis.

The role of small molecules in musculoskeletal regeneration

The uses of bone morphogenetic proteins and parathyroid hormone therapeutics are fraught with several fundamental problems, such as cost, protein stability, immunogenicity, contamination and supraphysiological dosage. These downsides may effectively limit their more universal use. Therefore, there is a clear need for alternative forms of biofactors to obviate the drawbacks of protein-based inductive factors for bone repair and regeneration. Our group has studied small molecules with the capacity to regulate osteoblast differentiation and mineralization because their inherent physical properties minimize limitations observed in protein growth factors. For instance, in general, small molecule inducers are usually more stable, highly soluble, nonimmunogenic, more affordable and require lower dosages. Small molecules with the ability to induce osteoblastic differentiation may represent the next generation of bone regenerative medicine. This review describes efforts to develop small molecule-based biofactors for induction, paying specific attention to their novel roles in bone regeneration.

The effect of quercetin on expression of SOX9 and subsequent release of type II collagen in spheno-occipital synchondroses of organ-cultured mice

OBJECTIVE

To identify the expressions of SOX9 and type II collagen in spheno-occipital synchondrosis in response to quercetin, using a mouse in vitro model.

MATERIALS AND METHODS

A total of 50 one-day-old male BALB/c mice were randomly assigned to the control and experimental groups. Each group was subdivided into five different time points, which were 6, 24, 48, 72, and 168 hours, and each subgroup contained 5 mice (n  =  5). In the experimental group, the spheno-occipital synchondrosis was immersed in the BGJb medium + quercetin dihydrate 1 µM. In the control group, the spheno-occipital synchondrosis was immersed in the BGJb medium. Tissue sections were subjected to immunohistochemical staining for SOX9 and type II collagen expressions.

RESULTS

Quantitative analysis revealed there was a statistically significant increase of 32.31% (P < .001) in the expression of SOX9 between experimental groups and control groups at 24 hours. Furthermore, there was a statistically significant increase of 22.99% (P < .001) in the expression of type II collagen between experimental groups and control groups at 72 hours.

CONCLUSION

The expressions of SOX9 and type II collagen in the spheno-occipital synchondrosis can be increased by quercetin.