Green tea and bone metabolism

Therapeutic potential of green tea catechins on the development of Parkinson's disease symptoms in a transgenic A53T mouse model

Objectives: This study aimed to evaluate the effects of green tea catechins on the prevention of Parkinson's disease neurobehavioral symptoms and α-synuclein blood plasma concentration in a hemizygous transgenic A53T mouse model.Methods: Thirty 6-month-old male mice were randomly assigned to three groups (n = 10/group): control, low-dose, and high-dose, receiving green tea polyphenol (GTP) treatment in their drinking water at 0%, 0.5%, and 1.5%, respectively, over a 90-day period. The efficacy of ad libitum dosing was assessed by analyzing the bioaccumulation of tea catechins in urine samples collected from metabolic cages on days 0, 30, 60, and 90, using LC/Q-TOF analysis. PD-related behavioral impairments were measured with open field and rotarod performance tests on days 0, 45, and 90. On day 90, plasma α-synuclein levels were analyzed via enzyme-linked immunosorbent assay (ELISA) to assess treatment effects.Results: Circulating tea catechin metabolites were detected in treated groups by day 30, with levels progressively increasing through day 90. By day 90, control mice exhibited significant deficits in rotarod performance, while both low- and high-dose groups maintained or improved their maximum time on the rotarod. Open field testing indicated reduced anxiety-related behavior in control mice compared to treated groups. ELISA analysis revealed significantly lower circulating α-synuclein levels in high-dose mice compared to controls.Conclusion: Our findings indicate that sustained administration of tea catechins significantly reduces circulating α-synuclein levels in blood plasma, improves motor coordination in a dose-dependent manner, and modulates anxiety-related behaviors in a PD mouse model.

The association between dietary flavonoid intake and bone mineral density and osteoporosis in US adults: data from NHANES 2007-2008, 2009-2010 and 2017-2018

BACKGROUND

Epidemiological studies investigating the association between flavonoid intake and bone mineral density (BMD) draw inconsistent conclusions. Our study aims to investigate the association between flavonoid intake and BMD and osteoporosis and the mediating role of composite dietary antioxidant index (CDAI) in their relationship using data from the National Health and Nutrition Examination Survey (NHANES).

METHODS

The study assessed the relationship between flavonoid intake and femur BMD and osteoporosis in 10,225 individuals from NHANES 2007-2010 and 2017-2018. Multivariable linear regression analyses were used to detect the association between flavonoid intake and femur BMD in adult Americans. Restricted cubic splines (RCS) were used to examine the nonlinear relationship between flavonoid intake and their subclasses and osteoporosis risk in individuals 20 years or older. We explored the mediating role of CDAI in the association between flavonoid intake and BMD.

RESULTS

In fully adjusted multivariable regression analyses, compared with people in the first quartile, people in the fourth quartile of total flavonoid intake have a higher BMD at total femur (0.013, 95% CI: 0.004, 0.022, P = 0.001), femur neck (0.010, 95% CI: 0.004, 0.017, P = 0.001), trochanter (0.010, 95% CI: 0.004, 0.017, P = 0.001), and intertrochanter (0.012, 95% CI: 0.003, 0.020, P = 0.006). The positive relationship between flavonoid intake and femur BMD was present in both sexes. Furthermore, we found that people in the fourth quartile of total flavonoid intake have a lower risk of osteoporosis compared with the first quartile (OR = 0.686, 95% CI: 0.528-0.890, P = 0.005). RCS found a linear inverse relationship between total flavonoid intake and osteoporosis in individuals ≥ 20 years (Overall P = 0.015, nonlinear P = 0.086). Moreover, CDAI partially mediates the association of total flavonoid intake with femur BMD.

CONCLUSIONS

Our findings suggest that higher flavonoid intake is associated with higher BMD and lower risk of osteoporosis in Americans. Furthermore, we found distinct associations between different flavonoid subclasses and osteoporosis risk. More studies with stronger evidence are needed to explore the causal association between flavonoid intake and bone health and their underlying mechanisms.

Tea intake and total body bone mineral density of all ages: a Mendelian randomization analysis

Background

There is increasing evidence indicating that tea intake affects bone mineral density levels; however, the causality between tea intake and bone mineral density is inconclusive. This study aimed to assess the causal relationship between tea intake and total body bone mineral density (TB-BMD) through two-sample Mendelian randomization (MR) analysis.

Methods

We conducted a two-sample MR approach to estimate the potential causal effects of tea intake on TB-BMD at all ages in a European population. The analyses were performed using summary statistics obtained for single-nucleotide polymorphisms (SNPs), identified from a genome-wide association meta-analysis of tea intake (N = up to 447,485 individuals) and from the GEnetic Factors for OSteoporosis (GEFOS) Consortium's genome-wide association meta-analysis (N = up to 56,284 individuals), with baseline data collected in 2018 and populations derived from the European ancestry. The association between each SNP and TB-BMD was weighted by its association with tea intake, and estimates were combined mainly using an inverse-variance weighted meta-analysis. In addition, we explored the potential causal effects between green tea intake, herbal tea intake, and TB-BMD.

Results

The MR analysis revealed that genetically determined tea intake exerts a causal impact on TB-BMD, with an odds ratio (OR) of 1.204 (95% CI: 1.062-1.366, p = 0.004), especially in the age group of 45-60 years (OR = 1.360, 95% CI: 1.088-1.700, p = 0.007). No horizontal pleiotropy and heterogeneity were observed. However, there was no causal effect of tea intake on TB-BMD in the age groups of 0-15, 15-30, 30-45, and over 60 years. In the subgroup analysis, when green tea intake was regarded as the exposure factor, no salient associations were found between green tea consumption and TB-BMD (IVW p = 0.368). Similarly, there was also no causal association between herbal tea intake and TB-BMD (IVW p = 0.264).

Conclusion

The findings of this study support the evidence that tea consumption increases bone density and reduces the risk of osteoporosis in the age group of 45-60 years within the European population.

The synergistic effects of polyphenols and intestinal microbiota on osteoporosis

Osteoporosis is a common metabolic disease in middle-aged and elderly people. It is characterized by a reduction in bone mass, compromised bone microstructure, heightened bone fragility, and an increased susceptibility to fractures. The dynamic imbalance between osteoblast and osteoclast populations is a decisive factor in the occurrence of osteoporosis. With the increase in the elderly population in society, the incidence of osteoporosis, disability, and mortality have gradually increased. Polyphenols are a fascinating class of compounds that are found in both food and medicine and exhibit a variety of biological activities with significant health benefits. As a component of food, polyphenols not only provide color, flavor, and aroma but also act as potent antioxidants, protecting our cells from oxidative stress and reducing the risk of chronic disease. Moreover, these natural compounds exhibit anti-inflammatory properties, which aid in immune response regulation and potentially alleviate symptoms of diverse ailments. The gut microbiota can degrade polyphenols into more absorbable metabolites, thereby increasing their bioavailability. Polyphenols can also shape the gut microbiota and increase its abundance. Therefore, studying the synergistic effect between gut microbiota and polyphenols may help in the treatment and prevention of osteoporosis. By delving into how gut microbiota can enhance the bioavailability of polyphenols and how polyphenols can shape the gut microbiota and increase its abundance, this review offers valuable information and references for the treatment and prevention of osteoporosis.

In vitro biological evaluation of epigallocatechin gallate (EGCG) release from three-dimensional printed (3DP) calcium phosphate bone scaffolds

Three-dimensional printed (3DP) tricalcium phosphate (TCP) scaffolds can guide bone regeneration, especially for patient-specific defect repair applications in low-load bearing sites. Epigallocatechin gallate (EGCG), a green tea compound, has gained attention as a safer alternative treatment for bone disorders. The 3DP TCP scaffold is designed for localized EGCG delivery, which can enhance in vitro osteogenic ability, anti-osteoclastogenic activity, vascularization formation, and chemoprevention. In the cocultures of human bone marrow-derived mesenchymal stem cells (hMSCs) and monocytes (THP-1), EGCG release enhances osteogenic differentiation of hMSCs at day 16 compared to the control; this is indicated by a 2.8- and 4.0-fold upregulation of Runt-related transcription factor 2 (Runx2) and bone gamma-carboxyglutamic acid-containing protein (BGLAP), the early and late osteoblast differentiation marker expressions. However, EGCG significantly downregulates the receptor activator of nuclear factor-κB ligand (RANKL) expression by 7.0-fold, indicating that EGCG suppresses RANKL-induced osteoclast maturation. EGCG also stimulates endothelial tube formation at as early as 3 hours when human umbilical vein endothelial cells (HUVECs) grow on Matrigel. It reduces human osteosarcoma MG-63 cell viability by 66% compared to the control at day 11. An in vitro release kinetics study demonstrates that EGCG shows a ∼64% release within a day followed by a sustained release in the physiological environment (pH 7.4) because its phenolic hydroxyl groups are easily deprotonated at physiological pH. These findings contribute to developing a multifunctional scaffold for the treatment of low load-bearing patient-specific bone defects after trauma and tumor excision.

Association of Coffee and Tea Intake with Bone Mineral Density and Hip Fracture: A Meta-Analysis

Background and Objectives: Osteoporosis is characterized by low bone mass and high bone fragility. Findings regarding the association of coffee and tea intake with osteoporosis have been inconsistent. We conducted this meta-analysis to investigate whether coffee and tea intake is associated with low bone mineral density (BMD) and high hip fracture risk. Materials and Methods: PubMed, MEDLINE, and Embase were searched for relevant studies published before 2022. Studies on the effects of coffee/tea intake on hip fracture/BMD were included in our meta-analysis, whereas those focusing on specific disease groups and those with no relevant coffee/tea intake data were excluded. We assessed mean difference (MD; for BMD) and pooled hazard ratio (HR; for hip fracture) values with 95% confidence interval (CI) values. The cohort was divided into high- and low-intake groups considering the thresholds of 1 and 2 cups/day for tea and coffee, respectively. Results: Our meta-analysis included 20 studies comprising 508,312 individuals. The pooled MD was 0.020 for coffee (95% CI, -0.003 to 0.044) and 0.039 for tea (95% CI, -0.012 to 0.09), whereas the pooled HR was 1.008 for coffee (95% CI, 0.760 to 1.337) and 0.93 for tea (95% CI, 0.84 to 1.03). Conclusions: Our meta-analysis results suggest that daily coffee or tea consumption is not associated with BMD or hip fracture risk.

Green Tea and Benign Gynecologic Disorders: A New Trick for An Old Beverage?

Green tea is harvested from the tea plant Camellia sinensis and is one of the most widely consumed beverages worldwide. It is richer in antioxidants than other forms of tea and has a uniquely high content of polyphenolic compounds known as catechins. Epigallocatechin-3-gallate (EGCG), the major green tea catechin, has been studied for its potential therapeutic role in many disease contexts, including pathologies of the female reproductive system. As both a prooxidant and antioxidant, EGCG can modulate many cellular pathways important to disease pathogenesis and thus has clinical benefits. This review provides a synopsis of the current knowledge on the beneficial effects of green tea in benign gynecological disorders. Green tea alleviates symptom severity in uterine fibroids and improves endometriosis through anti-fibrotic, anti-angiogenic, and pro-apoptotic mechanisms. Additionally, it can reduce uterine contractility and improve the generalized hyperalgesia associated with dysmenorrhea and adenomyosis. Although its role in infertility is controversial, EGCG can be used as a symptomatic treatment for menopause, where it decreases weight gain and osteoporosis, as well as for polycystic ovary syndrome (PCOS).

Effects of green tea extract epigallocatechin-3-gallate (EGCG) on orthodontic tooth movement and root resorption in rats

OBJECTIVE

To study the effect of EGCG on tooth movement and root resorption during orthodontic treatment in rats.

METHODS

A total of thirty six male Wistar rats were randomly and equally divided into three groups: control, 50 mg/kg EGCG, and 100 mg/kg EGCG. During the experiment, the subjects were submitted to an orthodontic tooth movement (OTM) model, rats in the experimental groups were given the corresponding dose of EGCG, while rats in the control group were administrated with an equal volume of normal saline solution by gavage. After 14 days of OTM, the rats were sacrificed by transcardial perfusion. Micro-CT of rat maxillaes was taken to analyze OTM distance and root resorption. The maxillary samples were prepared as histological sections for H&E staining, tartrate-resistant acid phosphatase (TRAP) staining and immunohistochemical (IHC) staining to be observed and analyzed.

RESULTS

The OTM distance and root resorption of rats in the dosed group decreased, and the number of TRAP positive cells in their periodontium decreased significantly. The expression level of RANKL was decreased in the EGCG group compared to the control group, while that of OPG, OCN and Runx2 was increased. Effects were more pronounced in 100 mg/kg group than in 50 mg/kg group.

CONCLUSION

EGCG reduces OTM and orthodontic induced root resorption (OIRR) in rats, and is able to attenuate osteoclastogenesis on the pressure side and promote osteogenesis on the tension side.

Prevalence of osteopenic syndrome and osteoporosis among residents of the older age group of Kyrgyzstan

Osteoporosis is the most common metabolic bone disease. However, because it is asymptomatic, it cannot be diagnosed until a clinical event such as a fracture occurs. It is osteoporotic fractures, not osteoporosis itself, that lead to noticeable clinical and economic consequences.

The aim. To study the frequency of osteopenia and osteoporosis in the older age group of the population of Kyrgyzstan using ultrasound bone densitometry.

Materials and methods. A total of 1988 people were examined – 1105 women, 883 men. By age, the patients were divided into three age groups: 40–59, 60–74 and 75–90 years old. A portable ultrasonic bone densitometer SONOST-3000 (South Korea) was used to measure bone mineral density.

Results. The prevalence of osteoporosis, osteopenia, and normal bone mineral density in the first age group was 20.9 %, 40.0 % and 39.1 %; in the second group – 30.2 %, 38.9 % and 30.9 %, and in the third group – 39.9 %, 34.9 % and 25.2 %, respectively. The incidence of osteoporosis increased with age and was gender-dependent – more common in women (p < 0.05 and p < 0.041, respectively). The probability of developing osteoporosis was lower in patients with a higher body weight (p < 0.002). Smoking had a bad effect on bone density (p < 0.001), physical exercise, on the contrary, inhibited the development of osteoporosis (p < 0.001). The use of alcohol and tea had no effect on the development of osteoporosis in our study (p = 0.421, p = 0.387, respectively).

Conclusions. The study of osteoporosis from an epidemiological point of view in Kyrgyz residents revealed a higher-than-expected incidence of osteoporosis according to densitometry. Further large-scale studies are needed throughout the country, which will help to understand the outcome of low bone mineral density in the population of Kyrgyz residents.

The Effect of Intragastric Gavage of High Dose Green Tea Extract on Serum Status of Magnesium, Calcium, and Zinc

OBJECTIVE

Green tea (GT) contains polyphenolic flavonoids, different minerals like magnesium, calcium, and zinc, vitamins, amino acids, carbohydrates, proteins, and others. It has a different health benefit. The aim of the present study was to investigate the effect of intragastric gavage of a high dose GT extract on serum biochemical analysis of magnesium, calcium, and zincin juvenile Wistar albino rats.

METHODS

Twelve rats were used in the study and divided in to two equal groups. All the animals in the control group were intragastically gavaged by distilled water and continues for ten days, from day 24 to day 34 of age, while the animals in the study group were intragastically gavaged by GT extract (300mg/kg/day) which continues also for ten days from day 24 to day 34 of age. On day 34 of age, and two hours after the last dose, the rats were anaesthetized and blood collection by cardiac puncture was taken.

RESULTS

The results showed that the intragastric gavage of a high dose of GT extract caused a non-significant increase in serum magnesium, and calcium levels (p>0.05), but a significant increase in zinc serum level was seen(p< 0.05).

CONCLUSION

GT can cause a significant increase in zinc serum level, and this may explain the significant role of GT in the response to different oxidative stress. It is recommended to measure the Zn serum level in rats after a period longer than two hrs from the time of the last dose of intragastric gavage of GT extract.

Non-fermented tea consumption protects against osteoporosis among Chinese male elders using the Taiwan biobank database

Few studies compared the effects of non-fermented and fermented tea among the general population. We aimed to compare the risk of incident osteoporosis (OP) between non-fermented tea and fermented tea drinkers by this retrospective nationwide population-based analysis from the Taiwan Biobank. Participants ≥ 40 years who drink fermented tea (n = 2205) were compared with those who drink non-fermented tea (n = 1034) from 2008 to 2015 with a mean follow-up period of 3.64 years. OP was defined by T-score ≤ − 2.5. Multivariate Cox proportional hazards regression models were performed to estimate the risk of developing OP between the two groups. Separate models were used to determine the relationship between tea consumption and OP stratified by sex and age. There was a significant interaction between sex, age, and type of tea consumed. In men aged ≥ 60 years, the risk of developing OP decreased by 79% for those who drank non-fermented tea (hazard ratio, 0.21; 95% confidence level, 0.05–0.94) than those who drank fermented tea. Additionally, those with a family history of OP had a higher risk of developing osteoporosis. This study suggests that male elderly who consume non-fermented tea have a lower risk of OP. Drinking non-fermented tea, such as green tea, could be suggested, especially for those with a family history of osteoporosis.

Relationship between Regular Green Tea Intake and Osteoporosis in Korean Postmenopausal Women: A Nationwide Study

Mixed results have been reported regarding whether habitual tea intake affects bone health. This study investigated the relationship between green tea intake and bone mineral density (BMD) in postmenopausal Korean women. We used data from the Korean National Health and Nutrition Examination Surveys from 2008 to 2011 and divided the participants into three groups according to their frequency of green tea intake over the past 12 months. BMD of the lumbar spine, total femur, and femur neck was measured using dual-energy X-ray absorptiometry. The odds ratios (ORs) and 95% confidence intervals (CIs) of osteoporosis and osteopenia according to green tea consumption were analyzed. Participants who did not consume green tea or consumed less than one cup per day were more likely to have osteopenia of the lumbar spine or femur than those who consumed it once to three times a day (OR 1.81 and 1.85, 95% CI, 1.20–2.71; and 1.23–2.77). Moreover, ORs for osteoporosis were 1.91 (95% CI 1.13–3.23) and 1.82 (95% CI 1.09–3.05) in non-consumers and consumers who drank less than one cup per day, respectively, compared with the reference group. These results support that green tea consumption may have benefits on bone health.

Drinking tea before menopause is associated with higher bone mineral density in postmenopausal women

BACKGROUND

Though tea drinking years and menopause stages have been indicated to be related with bone mineral density (BMD), most human studies have not considered the impact of tea drinking beginning time. Whether drinking tea before or after menopause plays a role in BMD is still unclear. This study aims to analyze whether drinking tea before or after menopause influences BMD in Chinese postmenopausal women.

METHODS

A total of 1377 postmenopausal women under 80 years were enrolled from the baseline survey of the Lanxi Cohort Study. Participants were initially categorized into non-tea drinking, tea drinking beginning after menopause and tea drinking beginning before menopause groups. Tea drinking groups were subdivided according to tea drinking frequency, concentration and type. Multiple linear regression models were applied to evaluate associations between tea drinking before or after menopause and BMD and the impacts of tea drinking frequency, concentration and type on their associations in analyses including all participants. Interactions of tea drinking frequency, concentration and type with drinking tea before or after menopause were further analyzed.

RESULTS

After adjusting for confounding factors, women who began drinking tea before menopause had significantly higher total and regional BMD than non-tea drinking participants and participants who began drinking tea after menopause. Differences in spine BMD were more significant among those who drank tea ≥four times per week. In addition, significant associations between tea drinking and BMD were found among participants who began drinking tea before menopause in both models, irrespective of the concentration and type of tea. No significant associations were found in subgroups of participants who began drinking tea after menopause in either model.

CONCLUSIONS

The results indicate that drinking tea before menopause is related to higher BMD in Chinese postmenopausal women. The relationship is independent of tea drinking concentration and type.

Control Release of Adenosine Potentiate Osteogenic Differentiation within a Bone Integrative EGCG-g-NOCC/Collagen Composite Scaffold toward Guided Bone Regeneration in a Critical-Sized Calvarial Defect

The regeneration of critical-sized bone defects with biomimetic scaffolds remains clinically challenging due to avascular necrosis, chronic inflammation, and altered osteogenic activity. Two confounding mechanisms, efficacy manipulation, and temporal regulation dictate the scaffold's bone regenerative ability. Equally critical is the priming of the mesenchymal stromal cells (MSCs) toward lineage-specific differentiation into bone-forming osteoblast, which particularly depends on varied mechanochemical and biological cues during bone tissue regeneration. This study sought to design and develop an optimized osteogenic scaffold, adenosine/epigallocatechin gallate-N,O-carboxymethyl chitosan/collagen type I (AD/EGCG-g-NOCC@clgn I), having osteoinductive components toward swift bone regeneration in a calvarial defect BALB/c mice model. The ex vivo findings distinctly establish the pro-osteogenic potential of adenosine and EGCG, stimulating MSCs toward osteoblast differentiation with significantly increased expression of alkaline phosphatase, calcium deposits, and enhanced osteocalcin expression. Moreover, the 3D matrix recapitulates extracellular matrix (ECM) properties, provides a favorable microenvironment, structural support against mechanical stress, and acts as a reservoir for sustained release of osteoinductive molecules for cell differentiation, proliferation, and migration during matrix osteointegration observed. Evidence from in vivo experiments, micro-CT analyses, histology, and histomorphometry signify accelerated osteogenesis both qualitatively and quantitatively: effectual bone union with enhanced bone formation and new ossified tissue in 4 mm sized defects. Our results suggest that the optimized scaffold serves as an adjuvant to guide bone tissue regeneration in critical-sized calvarial defects with promising therapeutic efficacy.

Epigallocatechin gallate regulates inflammatory responses and new bone formation through Wnt/β-Catenin/COX-2 pathway in spondyloarthritis

OBJECTIVE

Spondyloarthritis (SpA) is mainly characterized by bone erosion, new bone formation, inflammation and potential disability. Epigallocatechin gallate (EGCG) has been proved to be closely related with the regulation of inflammation and bone metabolism. However, whether EGCG could improve SpA remains unclear.

METHODS

SpA animal model was established using proteoglycan. Cell proliferation were measured by CCK-8 assay. The mRNA expression levels of genes were detected using qRT-PCR, protein levels were assessed via western blotting and immunohistochemistry. ELISA assay was performed to examined the inflammatory cytokine release. Lesions in spine cartilage tissues were observed using hematoxylin-eosin (HE) and Safranin O staining. Alkaline phosphatase (ALP) assay and Alizarin Red S staining was used to investigate osteoblast mineralization.

RESULTS

We found that EGCG could inhibit inflammation and new bone formation in SpA mice. Besides, inflammatory factor expression and osteogenic differentiation in osteoblasts isolated from SpA mice were also decreased by EGCG. Further, EGCG treatment suppressed the activation of Wnt/β-Catenin/COX-2 pathway and the activator of this pathway partially reversed the effects of EGCG on inflammation and osteoblast differentiation.

CONCLUSIONS

EGCG repressed inflammatory responses and new bone formation, and further improved SpA through Wnt/β-Catenin/COX-2 pathway. Our findings may provide a new thought for the prevention and treatment of SpA.

Natural medicine delivery from biomedical devices to treat bone disorders: A review

With an increasing life expectancy and aging population, orthopedic defects and bone graft surgeries are increasing in global prevalence. Research to date has advanced the understanding of bone biology and defect repair mechanism, leading to a marked success in the development of synthetic bone substitutes. Yet, the quest for functionalized bone grafts prompted the researchers to find a viable alternative that regulates cellular activity and supports bone regeneration and healing process without causing serious side-effects. Recently, researchers have introduced natural medicinal compounds (NMCs) in bone scaffold that enables them to release at a desirable rate, maintains a sustained release allowing sufficient time for tissue in-growth, and guides bone regeneration process with minimized risk of tissue toxicity. According to World Health Organization (WHO), NMCs are gaining popularity in western countries for the last two decades and are being used by 80% of the population worldwide. Compared to synthetic drugs, NMCs have a broader range of safety window and thus suitable for prolonged localized delivery for bone regeneration. There is limited literature focusing on the integration of bone grafts and natural medicines that provides detailed scientific evidences on NMCs, their toxic limits and particular application in bone tissue engineering, which could guide the researchers to develop functionalized implants for various bone disorders. This review will discuss the emerging trend of NMC delivery from bone grafts, including 3D-printed structures and surface-modified implants, highlighting the significance and potential of NMCs for bone health, guiding future paths toward the development of an ideal bone tissue engineering scaffold. STATEMENT OF SIGNIFICANCE: To date, additive manufacturing technology provids us with many advanced patient specific or defect specific bone constructs exhibiting three-dimensional, well-defined microstructure with interconnected porous networks for defect-repair applications. However, an ideal scaffold should also be able to supply biological signals that actively guide tissue regeneration while simultaneously preventing post-implantation complications. Natural biomolecules are gaining popularity in tissue engineering since they possess a safer, effective approach compared to synthetic drugs. The integration of bone scaffolds and natural biomolecules exploits the advantages of customized, multi-functional bone implants to provide localized delivery of biochemical signals in a controlled manner. This review presents an overview of bone scaffolds as delivery systems for natural biomolecules, which may provide prominent advancement in bone development and improve defect-healing caused by various musculoskeletal disorders.

10-Gingerol Suppresses Osteoclastogenesis in RAW264.7 Cells and Zebrafish Osteoporotic Scales

Osteoporosis is the most common aging-associated bone disease and is caused by hyperactivation of osteoclastic activity. We previously reported that the hexane extract of ginger rhizome [ginger hexane extract (GHE)] could suppress receptor activator of nuclear factor kappa-B ligand (RANKL)-induced osteoclastogenesis in RAW264.7 cells. However, the anti-osteoclastic components in GHE have not yet been identified. In this study, we separated GHE into several fractions using silica gel column chromatography and evaluated their effects on osteoclastogenesis using a RAW264.7 cell osteoclast differentiation assay (in vitro) and the zebrafish scale model of osteoporosis (in vivo). We identified that the fractions containing 10-gingerol suppressed osteoclastogenesis in RAW264.7 cells detected by tartrate-resistant acid phosphatase (TRAP) staining. In zebrafish, GHE and 10-gingerol suppressed osteoclastogenesis in prednisolone-induced osteoporosis regenerated scales to promote normal regeneration. Gene expression analysis revealed that 10-gingerol suppressed osteoclast markers in RAW264.7 cells [osteoclast-associated immunoglobulin-like receptor, dendrocyte-expressed seven transmembrane protein, and matrix metallopeptidase-9 (Mmp9)] and zebrafish scales [osteoclast-specific cathepsin K (CTSK), mmp2, and mmp9]. Interestingly, nuclear factor of activated T-cells cytoplasmic 1, a master transcription regulator of osteoclast differentiation upstream of the osteoclastic activators, was downregulated in zebrafish scales but showed no alteration in RAW264.7 cells. In addition, 10-gingerol inhibited CTSK activity under cell-free conditions. This is the first study, to our knowledge, that has found that 10-gingerol in GHE could suppress osteoclastic activity in both in vitro and in vivo conditions.

Green tea extracts containing epigallocatechin-3-gallate modulate facial development in Down syndrome

Trisomy of human chromosome 21 (Down syndrome, DS) alters development of multiple organ systems, including the face and underlying skeleton. Besides causing stigmata, these facial dysmorphologies can impair vital functions such as hearing, breathing, mastication, and health. To investigate the therapeutic potential of green tea extracts containing epigallocatechin-3-gallate (GTE-EGCG) for alleviating facial dysmorphologies associated with DS, we performed an experimental study with continued pre- and postnatal treatment with two doses of GTE-EGCG supplementation in a mouse model of DS, and an observational study of children with DS whose parents administered EGCG as a green tea supplement. We evaluated the effect of high (100 mg/kg/day) or low doses (30 mg/kg/day) of GTE-EGCG, administered from embryonic day 9 to post-natal day 29, on the facial skeletal development in the Ts65Dn mouse model. In a cross-sectional observational study, we assessed the facial shape in DS and evaluated the effects of self-medication with green tea extracts in children from 0 to 18 years old. The main outcomes are 3D quantitative morphometric measures of the face, acquired either with micro-computed tomography (animal study) or photogrammetry (human study). The lowest experimentally tested GTE-EGCG dose improved the facial skeleton morphology in a mouse model of DS. In humans, GTE-EGCG supplementation was associated with reduced facial dysmorphology in children with DS when treatment was administered during the first 3 years of life. However, higher GTE-EGCG dosing disrupted normal development and increased facial dysmorphology in both trisomic and euploid mice. We conclude that GTE-EGCG modulates facial development with dose-dependent effects. Considering the potentially detrimental effects observed in mice, the therapeutic relevance of controlled GTE-EGCG administration towards reducing facial dysmorphology in young children with Down syndrome has yet to be confirmed by clinical studies.

Assessing the analgesic efficacy of oral epigallocatechin-3-gallate on epidural catheter analgesia in patients after surgical stabilisation of multiple rib fractures: a prospective double-blind, placebo-controlled clinical trial

CONTEXT

Thoracic trauma results in multiple rib fractures (MRF), and surgical stabilisation of rib fractures (SSRF) can relieve fracture pain. Epigallocatechin-3-gallate (EGCG) is reported to exhibit beneficial effects in bone-related metabolic and differentiation processes.

OBJECTIVE

To study the clinical effect of EGCG on regional analgesia for pain relief in MRF patients after SSRF.

MATERIALS AND METHODS

Ninety-seven MRF patients (61 males, 36 females) who were on epidural catheter analgesia after SSRF were recruited. They were randomly divided into: oral EGCG 100 mg (oral grade) twice daily for 10 days and placebo groups. Pain scores, incentive spirometry (IS) volumes, respiratory rate and oxygen saturation (SpO₂) were assessed day 10 after SSRF.

RESULTS

Comparing results from the placebo and EGCG group, in the 10-day intervention course, oral EGCG reduced pain score (8 at base line vs. 4 at end of intervention in EGCG group, p < 0.05; 4 in EGCG group vs. 6 in placebo group at end of intervention, p < 0.05), improved IS volume (713 at base line vs. 1072 at end of intervention in EGCG group, p < 0.05; 1072 in EGCG group vs. 953 in placebo group at end of intervention, p < 0.05) and respiratory rate (24 at base line vs. 15 at end of intervention in EGCG group, p < 0.05; 15 in EGCG group vs. 19 in placebo group at end of intervention, p < 0.05). However, no further enhancing effect on SpO₂ was observed in the EGCG group (0.98 in EGCG group vs. 0.98 in placebo group at end of intervention, p > 0.05).

DISCUSSION AND CONCLUSIONS

Although the study is limited by a relatively small sample size and lack of serum factor analysis, the key results and the study design, for the first time, nevertheless pave the way for trials with larger number of patients to understand the effect of EGCG in MRF patients that are undergoing SSRF.

Osteoprotective effect of green tea polyphenols and annatto-extracted tocotrienol in obese mice is associated with enhanced microbiome vitamin K2 biosynthetic pathways

The role of the gut microbiome in bone health has received significant attention in the past decade. We investigated the effects of green tea polyphenols (GTP) and annatto-extracted tocotrienols (AT) on bone properties and gut microbiome in obese mice. Male mice were assigned to a two (no AT vs. 400 mg/kg diet AT) × two (no GTP vs. 0.5% w/v GTP) factorial design, namely control, G, T, and G+T group respectively, for 14 weeks. The 4th lumbar vertebra (LV-4) and femur were harvested for bone microstructural analysis using μ-CT. Microbiome analysis using 16S rRNA gene sequencing of cecal feces was performed. AT increased bone volume at distal femur. GTP increased serum procollagen type 1 N-terminal propeptide concentration, bone volume at the distal femur and the LV-4, and trabecular number at distal femur; whereas GTP decreased trabecular separation at distal femur. Interactions between GTP and AT were observed in serum C-terminal telopeptide of type I collagen level (control>G=T=G+T) as well as the cortical bone area (control<G=T=G+T) and thickness (T≥G+T≥G≥control) at femur mid-diaphysis. Redundancy analysis showed a significant difference in the gut microbiome profile among different groups and the relative abundance of Akkermansia muciniphila, Clostridum saccharogumia, and Subdoligranulum variabile was increased in the GTP- and AT-supplemented groups. Functional profiling of the gut microbiome showed the combination of GTP and AT induced biosynthetic pathways for vitamin K₂. Our results suggest that GTP and AT supplementation benefits bone properties in obese mice through modifying gut microbiome composition and function.

The Effect of Abnormal Iron Metabolism on Osteoporosis

Iron is one of the important trace elements in life activities. Abnormal iron metabolism increases the incidence of many skeletal diseases, especially for osteoporosis. Iron metabolism plays a key role in the bone homeostasis. Disturbance of iron metabolism not only promotes osteoclast differentiation and apoptosis of osteoblasts but also inhibits proliferation and differentiation of osteoblasts, which eventually destroys the balance of bone remodeling. The strength and density of bone can be weakened by the disordered iron metabolism, which increases the incidence of osteoporosis. Clinically, compounds or drugs that regulate iron metabolism are used for the treatment of osteoporosis. The goal of this review summarizes the new progress on the effect of iron overload or deficiency on osteoporosis and the mechanism of disordered iron metabolism on osteoporosis. Explaining the relationship of iron metabolism with osteoporosis may provide ideas for clinical treatment and development of new drugs.

Green Tea Catechin (-)-Epigallocatechin-3-Gallate (EGCG) Facilitates Fracture Healing

Green tea drinking can ameliorate postmenopausal osteoporosis by increasing the bone mineral density. (-)-Epigallocatechin-3-gallate (EGCG), the abundant and active compound of tea catechin, was proven to be able to reduce bone loss and ameliorate microarchitecture in female ovariectomized rats. EGCG can also enhance the osteogenic differentiation of murine bone marrow mesenchymal stem cells and inhibit the osteoclastogenesis in RAW264.7 cells by modulation of the receptor activator of nuclear factor-kB (RANK)/RANK ligand (RANKL)/osteoprotegrin (OPG) (RANK/RANKL/OPG) pathway. Our previous study also found that EGCG can promote bone defect healing in the distal femur partially via bone morphogenetic protein-2 (BMP-2). Considering the osteoinduction property of BMP-2, we hypothesized that EGCG could accelerate the bone healing process with an increased expression of BMP-2. In this manuscript, we studied whether the local use of EGCG can facilitate tibial fracture healing. Fifty-six 4-month-old rats were randomly assigned to two groups after being weight-matched: a control group with vehicle treatment (Ctrl) and a study group with 10 µmol/L, 40 µL, EGCG treatment (EGCG). Two days after the operation, the rats were treated daily with EGCG or vehicle by percutaneous local injection for 2 weeks. The application of EGCG enhanced callus formation by increasing the bone volume and subsequently improved the mechanical properties of the tibial bone, including the maximal load, break load, stiffness, and Young’s modulus. The results of the histology and BMP-2 immunohistochemistry staining showed that EGCG treatment accelerated the bone matrix formation and produced a stronger expression of BMP-2. Taken together, this study for the first time demonstrated that local treatment of EGCG can accelerate the fracture healing process at least partly via BMP-2.

Natural Medicinal Compounds in Bone Tissue Engineering

Recent advances in 3D printing have provided unprecedented opportunities in bone tissue engineering applications for producing a variety of complex patient-specific implants for the treatment of critical-sized bone defects. Natural medicinal compounds (NMCs) with osteogenic potential can be incorporated into these 3D-printed parts to improve bone formation and therefore enhance implant performance. Using NMCs to treat bone-related disorders may prove to be a healthy preventive choice as they are considered safe, have lesser or no side effects, and are more suitable for prolonged use than synthetic drugs. In this review paper, the current challenges of bone tissue engineering are addressed briefly, highlighting the immense potential of NMCs integrated within tissue engineering scaffolds for orthopedic and dental applications.

Epigallocatechin-3-Gallate Protects Neuro-2a Cells From Sodium Fluoride-Induced Oxidative Damage In Vitro

Fluoride is an essential trace element, but its beneficial range is narrow, and excess fluoride may have negative health effects. The objective of this study was to investigate the potential cytoprotective effects of epigallocatechin-3-gallate (EGCG) in cultured neuro-2a neuroblastoma cells exposed to sodium fluoride (NaF)-induced oxidative stress. Isolated Neuro-2a cells were exposed to increasing concentrations of NaF (0, 1, 2, 4, 6, and 8 mM) for 24 hours to induce oxidative stress. Moreover, to determine the concentration of EGCG necessary for protective effects, we exposed isolated Neuro-2a cells to increasing concentrations of EGCG (0, 0.5, 1, 5, 10, 20, 40, 60, 80, and 100 μg/mL) for 24 and 48 hours. Pretreatment with EGCG at various doses (0, 0.5, 1, 5, 10, 20, and 40 μg/mL) was evaluated in Neuro-2a cells for 24 hours, followed by an NaF (4 mM per culture well) challenge for 24 hours. As shown in this study, EGCG can protect Neuro-2a cells from NaF-induced apoptosis. This effect may be due to the reactive oxygen species scavenging activity of EGCC.

Associated Factors for Osteoporosis and Fracture in Chinese Elderly

Background

The factors associated with osteoporosis are poorly understood in the Chinese population. This study aimed to examine the factors associated with osteoporosis and with fractures in a Chinese elderly population.

Material/Methods

This was a cross-sectional study of elderly people living in Tianjin between 2012 and 2014. Bone mineral density was measured by dual X-ray absorptiometry. The subjects completed a questionnaire about lifestyle habits, personal and family medical history, calcium intake, and exercising. Data were gathered on occurrence of fracture at 5 years or August 2018, whichever occurred first.

Results

There were 298 individuals with osteoporosis (18.5% male, median age 67 years) and 397 without (46.3% male, median age 62 years). Male sex (OR=0.051, 95% CI: 0.021–0.126), age (OR=1.049, 95% CI: 1.099–1.202), being divorced/widowed (OR=2.445, 95% CI: 1.219-4.904), digestive ulcer history (OR=3.805, 95% CI: 1.539–9.405), family history of hunchback (OR=2.659, 95% CI: 1.145–6.175), family history of osteoarthropathy (OR=4.222, 95% CI: 2.128–8.375), fracture history (OR=2.138, 95% CI: 1.307–3.496), drinking green tea (OR=0.352, 95% CI: 0.217–0.574), and exercising (OR=0.303, 95% CI: 0.193–0.475) were independently associated with osteoporosis. Digestive ulcer history (OR=3.183, 95% CI: 1.178–8.5992), exercising (OR=0.354, 95% CI: 0.139–0.903), and taking calcium supplements during follow-up (OR=0.262, 95% CI: 0.112–0.611) were independently associated with fractures in patients with osteoporosis.

Conclusions

Female sex, age, marital status, history of digestive ulcer and fracture, and family history of hunchback and osteoarthropathy are associated with osteoporosis among elderly subjects, while drinking green tea and exercising are inversely associated. Among the patients with osteoporosis, a history of digestive ulcer is associated with fractures, while exercising and taking calcium supplements are inversely associated.

Association of Lifestyle and Food Consumption with Bone Mineral Density among People Aged 50 Years and Above Attending the Hospitals of Kathmandu, Nepal

BACKGROUND

Bone mineral density (BMD) is the measure of the minerals, mostly calcium and phosphorous, contained in certain volume of bone to diagnose osteoporosis. The aim of the study was to find out the association of lifestyle and food consumption with BMD.

METHODS

An analytical cross-sectional study was conducted among 169 people of age 50 years and above who underwent Dual Energy X-Ray Absorptiometry (DEXA or DXA) scan in the hospitals of Kathmandu valley of Nepal. Food frequency questionnaire and 24-hour recall methods were followed. The DXA reports of the participants were observed to identify osteoporosis. Chi-square test, independent sample t-test, and binary logistic regression were applied to explore the association of BMD with different variables.

RESULT

The prevalence of osteoporosis, osteopenia, and normal BMD was 37.3%, 38.5%, and 24.2%, respectively. The prevalence of osteoporosis increased with sex and age (AOR 3.339, CI: 1.240-8.995, p-value 0.017; AOR 3.756, CI: 1.745-8.085, p-value 0.001), respectively. Higher BMI was associated with lower odds of osteoporosis (AOR 0.428, CI: 0.209-0.877, p-value 0.020). Smoking had bad effect on the health of bone (AOR 3.848, CI: 1.179-12.558, p-value 0.026). Daily dietary calcium intake had negative association with osteoporosis with the p-value of 0.003; however, the daily consumption of vitamin D rich food had no association with osteoporosis.

CONCLUSION

High prevalence of osteoporosis and osteopenia was found in older people. Osteoporosis was found to be significantly associated with sex, age, lower BMI, smoking habit, and daily calcium consumption. Further research can be conducted by making the relationship of calcium consumption with the numerical T-value of scanned body parts.

Influence of epigallocatechin-3-gallate in promoting proliferation and osteogenic differentiation of human periodontal ligament cells

BACKGROUND

Epigallocatechin-3-gallate (EGCG) was recently proposed to have the potential to regulate bone metabolism, however, its influence on osteogenesis remains controversial. The present study aimed to investigate the effects of EGCG on the proliferation and osteogenesis of human periodontal ligament cells (hPDLCs).

METHODS

Cells were cultured in osteogenic medium and treated with EGCG at various concentrations. Cell proliferation was analyzed using a CCK-8 assay and acridine orange (AO)/ethidium bromide (EB) staining. Flow cytometry was used to measure the intracellular reactive oxygen species (ROS) potential of hPDLCs. The expression levels of osteogenic marker genes and proteins in hPDLCs, including type I collagen (COL1), runt-related transcription factor 2 (RUNX2), osteopontin (OPN), and osterix (OSX), were determined by quantitative real-time polymerase chain reaction (qRT-PCR) and western blot analysis. In addition, alkaline phosphatase (ALP) activity was monitored both quantitatively and qualitatively. Extracellular matrix mineralization was further analyzed by alizarin red S staining.

RESULTS

The results showed that EGCG concentrations from 6 to 10 μM increased the ROS level and inhibited the cell proliferation of hPDLCs. EGCG concentrations from 2 to 8 μM effectively increased extracellular matrix mineralization, in which 4 and 6 μM EGCG generated the most mineralizing nodules. The ALP activity and the mRNA and protein expression levels of the tested osteogenic markers were most strongly up-regulated by treatment with 4 and 6 μM EGCG.

CONCLUSIONS

The present study demonstrated that EGCG might promote the osteogenesis of hPDLCs in a dose-dependent manner, with concentrations of 4 and 6 μM EGCG showing the strongest osteogenic enhancement without cytotoxicity, indicating a promising role for EGCG in periodontal regeneration in patients with deficient alveolar bone in the future.

(-)-Epigallocatechin-3-gallate (EGCG) enhances healing of femoral bone defect

BACKGROUND

Previously, we found that (-)-epigallocatechin-3-gallate (EGCG) enhanced osteogenic differentiation of murine bone marrow mesenchymal stem cells by increasing the mRNA expression of osteogenesis-related genes, alkaline phosphatase activity and eventually mineralization. We further found EGCG supplementation preserved bone mass and microarchitecture in female rats during estrogen deficiency in the proximal tibia and lumbar spine at least in part by increasing bone morphogenetic protein-2 (BMP2). BMP2 can enhance de novo bone formation.

PURPOSE

In this study, we evaluate the effect of local EGCG application in de novo bone formation in bone defect healing.

METHODS

Twenty-four rats aged 4 months were weight-matched and randomly allocated to 2 groups: defect control with vehicle treatment (control) and defect with 10 µM EGCG treatment (EGCG). Daily vehicle and EGCG were applied locally by percutaneous local injection 2 days after defect creation for 2 weeks. Four weeks after treatment, animals were sacrificed for micro-computed tomography (μ-CT) and biomechanical analysis.

RESULTS

Local EGCG at femoral defect can enhance de novo bone formation by increasing bone volume and subsequently improve mechanical properties including max load, break point, stiffness, area under the max load curve, area under the break point curve and ultimate stress.

CONCLUSIONS

Local EGCG may enhance bone defect healing via at least partly by the de novo bone formation of BMP-2.

Effect of Long-Term Green Tea Polyphenol Supplementation on Bone Architecture, Turnover, and Mechanical Properties in Middle-Aged Ovariectomized Rats

We investigated the effects of 6-month green tea polyphenols (GTP) supplementation on bone architecture, turnover, and mechanical properties in middle-aged ovariectomized (OVX) rats. Female rats were sham-operated (n = 39, 13/group) or OVX (n = 143, 13/group). Sham-control and OVX-control rats (n = 39) receiving no GTP were assigned for sample collection at baseline, 3, or 6 months. The remaining OVX rats (n = 104) were randomized to 0.15%, 0.5%, 1%, and 1.5% (g/dL) GTP for 3 or 6 months. Blood and bone samples were collected. Relative to the OVX-control group, GTP (1% and 1.5%) lowered serum procollagen type 1 N-terminal propeptide at 3 and 6 months, C-terminal telopeptides of type I collagen at 3 months, and insulin-like growth factor-I at 6 months. GTP did not affect bone mineral content and density. At 6 months, no dose of GTP positively affected trabecular bone volume based on microCT, but a higher cortical thickness and improved biomechanical properties of the femur mid-diaphysis was observed in the 1.5% GTP-treated group. At 3 and 6 months, GTP (0.5%, 1%, and 1.5%) had lower rates of trabecular bone formation and resorption than the OVX-control group, but the inhibitory effects of GTP on periosteal and endocortical bone mineralization and formation at the tibial midshaft were only evident at 3 months. GTP at higher doses suppressed bone turnover in the trabecular and cortical bone of OVX rats and resulted in improved cortical bone structural and biomechanical properties, although it was not effective in preventing the ovariectomy-induced dramatic cancellous bone loss.

Poly(vinylidene fluoride) Composite Nanofibers Containing Polyhedral Oligomeric Silsesquioxane⁻Epigallocatechin Gallate Conjugate for Bone Tissue Regeneration

To provide adequate conditions for the regeneration of damaged bone, it is necessary to develop piezoelectric porous membranes with antioxidant and anti-inflammatory activities. In this study, composite nanofibers comprising poly(vinylidene fluoride) (PVDF) and a polyhedral oligomeric silsesquioxane–epigallocatechin gallate (POSS–EGCG) conjugate were fabricated by electrospinning methods. The resulting composite nanofibers showed three-dimensionally interconnected porous structures. Their average diameters, ranging from 936 ± 223 nm to 1094 ± 394 nm, were hardly affected by the addition of the POSS–EGCG conjugate. On the other hand, the piezoelectric β-phase increased significantly from 77.4% to 88.1% after adding the POSS–EGCG conjugate. The mechanical strength of the composite nanofibers was ameliorated by the addition of the POSS–EGCG conjugate. The results of in vitro bioactivity tests exhibited that the proliferation and differentiation of osteoblasts (MC3T3-E1) on the nanofibers increased with the content of POSS–EGCG conjugate because of the improved piezoelectricity and antioxidant and anti-inflammatory properties of the nanofibers. All results could suggest that the PVDF composite nanofibers were effective for guided bone regeneration.

(-)-Epigallocatechin-3-Gallate Decreases Osteoclastogenesis via Modulation of RANKL and Osteoprotegrin

Osteoporosis is the second most common epidemiologic disease in the aging population worldwide. Previous studies have found that frequent tea drinkers have higher bone mineral density and less hip fracture. We previously found that (-)-epigallocatechin gallate (EGCG) (20⁻100 µmol/L) significantly suppressed receptor activator of nuclear factor-kB ligand (RANKL)-induced osteoclastogenesis and pit formation via inhibiting NF-κB transcriptional activity and nuclear transport of NF-κB in RAW 264.7 cells and murine primary bone marrow macrophage cells. The most important regulation in osteoclastogenesis is the receptor activator of nuclear factor-kB/RANKL/osteoprotegrin (RANK/RANKL/OPG) pathway. In this study, we used the coculture of RAW 264.7 cells and the feeder cells, ST2, to evaluate how EGCG regulated the RANK/RANKL/OPG pathway in RAW 264.7 cells and ST2 cells. We found EGCG decreased the RANKL/OPG ratio in both mRNA expression and secretory protein levels and eventually decreased osteoclastogenesis by TRAP (+) stain osteoclasts and TRAP activity at low concentrations-1 and 10 µmol/L-via the RANK/RANKL/OPG pathway. The effective concentration can be easily achieved in daily tea consumption. Taken together, our results implicate that EGCG could be an important nutrient in modulating bone resorption.

Preparation of tea polyphenol-modified copper nanoclusters to promote the proliferation of MC3T3-E1 in high glucose microenvironment

Monodisperse, ultra-small copper nanoclusters (ca. 1.8 nm) were prepared by using tea polyphenols (TP) as both the reducing and capping reagent.

Modulatory Effects of Plant Polyphenols on Bone Remodeling: A Prospective View From the Bench to Bedside

During the past, a more comprehensive knowledge of mechanisms implicated in bone resorption processes has driven researchers to develop a compound library of many small molecules that specifically interfere with the genesis of osteoclast precursors cells. Natural compounds that suppress osteoclast commitment may have therapeutic value in treating pathologies associated with bone resorption like osteoporosis, rheumatoid arthritis, bone metastasis, and periodontal disease. The present review is focused on the current knowledge on the polyphenols derived from plants that could be efficacious in suppressing osteoclast differentiation and bone resorption.

(-)-Epigallocatechin-3-Gallate (EGCG) Enhances Osteogenic Differentiation of Human Bone Marrow Mesenchymal Stem Cells

Osteoporosis is the second most-prevalent epidemiologic disease in the aging population worldwide. Cross-sectional and retrospective evidence indicates that tea consumption can mitigate bone loss and reduce risk of osteoporotic fractures. Tea polyphenols enhance osteoblastogenesis and suppress osteoclastogenesis in vitro. Previously, we showed that (-)-epigallocatechin-3-gallate (EGCG), one of the green tea polyphenols, increased osteogenic differentiation of murine bone marrow mesenchymal stem cells (BMSCs) by increasing the mRNA expression of osteogenesis-related genes, alkaline phosphatase activity and, eventually, mineralization. We also found that EGCG could mitigate bone loss and improve bone microarchitecture in ovariectomy-induced osteopenic rats, as well as enhancing bone defect healing partially via bone morphogenetic protein 2 (BMP2). The present study investigated the effects of EGCG in human BMSCs. We found that EGCG, at concentrations of both 1 and 10 µmol/L, can increase mRNA expression of BMP2, Runx2, alkaline phosphatase (ALP), osteonectin and osteocalcin 48 h after treatment. EGCG increased ALP activity both 7 and 14 days after treatment. Furthermore, EGCG can also enhance mineralization two weeks after treatment. EGCG without antioxidants also can enhance mineralization. In conclusion, EGCG can increase mRNA expression of BMP2 and subsequent osteogenic-related genes including Runx2, ALP, osteonectin and osteocalcin. EGCG further increased ALP activity and mineralization. Loss of antioxidant activity can still enhance mineralization of human BMSCs (hBMSCs).

Green tea (Camellia sinensis) aqueous extract alleviates postmenopausal osteoporosis in ovariectomized rats and prevents RANKL-induced osteoclastogenesis in vitro

Background

Green tea (Camelliasinensis [L.] Kuntze) belongs to the plant family Theaceae and is mainly distributed in East Asia, the Indian subcontinent and Southeast Asia. This plant has been proven to be beneficial to human health, and green tea is the second most consumed beverage in the world after water. However, until now, the effect of green tea aqueous extract (GTE) upon postmenopausal osteoporosis has remained unclear. In this study, we investigated the therapeutic effects of GTE on estrogen deficiency-induced osteoporosis and explored the possible mechanisms in vivo and in vitro.

Materials and methods

Ovariectomized (OVX) female rats were orally administered with GTE at doses of 60, 120, and 370 mg kg⁻¹ for 13 consecutive weeks. The biochemical parameters, bone gla protein, alkaline phosphatase, acid phosphatase, estrogen, interleukin-1β, and interleukin-6 in blood samples were detected, and histological change in bones was analyzed by hematoxylin and eosin staining. Meanwhile, the mechanisms of GTE on osteoclast formation were explored in RAW 264.7 cells induced by receptor activation of the nuclear factor kappa B ligand (RANKL).

Results

The results showed that GTE could increase bone mass and inhibit trabecular bone loss in OVX rats. Furthermore, real-time quantitative reverse transcription polymerase chain reaction analysis from in vitro experiments also showed that GTE reduced the mRNA expression of osteoclast-associated genes such as cathepsin K (cath-K), c-Fos, matrix metalloproteinase 9, nuclear factor of activated T cells cytoplasmic 1 (NFATc1) and tartrate-resistant acid phosphatase. In addition, GTE caused a reduction in the protein levels of NFATc1, c-Fos, c-src and cath-K.

Conclusion

Evidence from both animal models and in vitro experiments suggested that GTE might effectively ameliorate the symptoms of osteoporosis in OVX rats and inhibit RANKL-induced osteoclast-specific gene and protein expression.

Repression of IGF-I-induced osteoblast migration by (-)-epigallocatechin gallate through p44/p42 MAP kinase signaling

Polyphenolic compounds in beverages may have benefits in the prevention of osteoporosis. It has been demonstrated previously that insulin-like growth factor-I (IGF-I) could stimulate the migration of osteoblasts. In the present study, it was investigated whether chlorogenic acid, a major polyphenol in coffee, and (-)-epigallocatechin gallate (EGCG), a major polyphenol in green tea, could affect this IGF-I-stimulated migration of osteoblast-like MC3T3-E1 cells. The IGF-I-stimulated osteoblast migration, evaluated by Transwell cell migration and wound-healing assays, was inhibited by EGCG but not chlorogenic acid. IGF-I induced the phosphorylation of p44/p42 mitogen-activated protein (MAP) kinase, p70 S6 kinase and Akt. The IGF-I-induced migration was suppressed by PD98059, a MAP kinase kinase 1/2 inhibitor, and deguelin, an Akt inhibitor, but not rapamycin, an inhibitor of the upstream kinase of p70 S6 kinase (mammalian target of rapamycin). EGCG attenuated the IGF-I-induced phosphorylation of p44/p42 MAP kinase but not Akt. Taken together, the present results suggest that EGCG inhibits IGF-I-induced osteoblast migration via p44/p42 MAP kinase.

(-)-Epigallocatechin gallate but not chlorogenic acid suppresses EGF-stimulated migration of osteoblasts via attenuation of p38 MAPK activity

Phenolic compounds provide health benefits in humans. A previous study by our group has indicated that the epidermal growth factor (EGF)‑induced migration of osteoblast‑like MC3T3‑E1 cells is mediated by the phosphorylation of p44/p42 mitogen‑activated protein (MAPK), p38 MAPK, stress‑activated protein kinase (SAPK)/c‑Jun N‑terminal kinase (JNK) and Akt, and that resveratrol, a major polyphenol in grape skin, suppresses the EGF‑induced migration by attenuating Akt and SAPK/JNK activation. In the present study, the effects of chlorogenic acid, a major phenolic acid in coffee, and (‑)‑epigallocatechin gallate (EGCG), a major flavonoid in green tea, on the EGF‑induced migration of MC3T3‑E1 cells were investigated. EGCG significantly reduced the EGF‑induced migration as evaluated by a Transwell migration assay and by a wound healing assay. However, chlorogenic acid failed to affect the EGF‑induced migration. The phosphorylation of p38 MAPK induced by EGF was significantly suppressed by EGCG; however, the EGF‑induced phosphorylation of p44/p42 MAP kinase, SAPK/JNK or Akt was not affected by EGCG. These results suggest that EGCG, but not chlorogenic acid, suppresses EGF‑induced osteoblast migration through inhibiting p38 MAPK activation.

Effect of Black Tea Extract and Thearubigins on Osteoporosis in Rats and Osteoclast Formation in vitro

Background: Osteoporosis is a major health problem that is closely related to substantial morbidity, mortality and decline in life quality for the aging population. Although previous studies and epidemiological evidence have demonstrated an association between black tea consumption and the prevention of bone loss, the underlying mechanism remains unclear. So, the effect of black tea extract (BTE) and thearubigins (TRs) on osteoporosis in rats and osteoclast formation in vitro were investigated.

Methods:In vivo, ovariectomized (OVX) rats were used to establish osteoporosis models. To validate the model and study the effects of BTE and TRs on osteoporosis, the female Wistar rats were divided into a sham-operated group and five OVX groups including model, Xian-Ling-Gu-Bao (XLGB) (as a positive control), BTE, TRs low-dose, and TRs high-dose group. The rats in the four treatment groups were given the corresponding test sample for 12 weeks. Then, the body weight, femur indices, and serum biomarkers were examined and analyzed. In vitro, RAW264.7 murine macrophages were used as model of osteoclast formation. The effects of BTE and TRs on osteoclasts formation and the specific genes and protein levels of osteoclasts were determined.

Results: Although there was no significant effect on the OVX-induced body weight gain by BTE or TRs, the levels of maximum bending force, cortical bone thickness and biomarker of bone resorption (acid phosphatase) can be significantly ameliorated by BTE or TRs in OVX rats. Furthermore, both of BTE and TRs can inhibit the osteoclastogenesis and diminish the expression levels of the related genes and proteins.

Preparation and in vitro evaluation of novel cross-linked chondroitin sulphate nanoparticles by aluminium ions for encapsulation of green tea flavonoids

Chondroitin sulphate is a sulphated glycosaminoglycan biopolymer composed over 100 individual sugars. Chondroitin sulphate nanoparticles (NPs) loaded with catechin were prepared by an ionic gelation method using AlCl₃ and optimised for polymer and cross-linking agent concentration, curing time and stirring speed. Zeta potential, particle size, loading efficiency, and release efficiency over 24 h (RE₂₄%) were evaluated. The surface morphology of NPs was investigated by scanning electron microscopy and their thermal behaviour by differential scanning calorimetric. Antioxidant effect of NPs was determined by chelating activity of iron ions. The cell viability of mesenchymal stem cells was determined by 3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyl tetrazolium bromide assay and the calcification of osteoblasts was studied by Alizarin red staining. The optimised NPs showed particle size of 176 nm, zeta potential of -20.8 mV, loading efficiency of 93.3% and RE₂₄% of 80.6%. The chatechin loaded chondroitin sulphate NPs showed 70-fold more antioxidant activity, 3-fold proliferation effect and higher calcium precipitation in osteoblasts than free catechin.

Epigallocatechin Gallate-Modified Gelatin Sponges Treated by Vacuum Heating as a Novel Scaffold for Bone Tissue Engineering

Chemical modification of gelatin using epigallocatechin gallate (EGCG) promotes bone formation in vivo. However, further improvements are required to increase the mechanical strength and bone-forming ability of fabricated EGCG-modified gelatin sponges (EGCG-GS) for practical applications in regenerative therapy. In the present study, we investigated whether vacuum heating-induced dehydrothermal cross-linking of EGCG-GS enhances bone formation in critical-sized rat calvarial defects. The bone-forming ability of vacuum-heated EGCG-GS (vhEGCG-GS) and other sponges was evaluated by micro-computed tomography and histological staining. The degradation of sponges was assessed using protein assays, and cell morphology and proliferation were verified by scanning electron microscopy and immunostaining using osteoblastic UMR106 cells in vitro. Four weeks after the implantation of sponges, greater bone formation was detected for vhEGCG-GS than for EGCG-GS or vacuum-heated gelatin sponges (dehydrothermal cross-linked sponges without EGCG). In vitro experiments revealed that the relatively low degradability of vhEGCG-GS supports cell attachment, proliferation, and cell-cell communication on the matrix. These findings suggest that vacuum heating enhanced the bone forming ability of EGCG-GS, possibly via the dehydrothermal cross-linking of EGCG-GS, which provides a scaffold for cells, and by maintaining the pharmacological effect of EGCG.