Cycloastragenol prevents age-related bone loss: Evidence in d-galactose-treated and aged rats.

BACKGROUND AND AIMS: Aging-induced bone loss is a multifactorial, age-related, and progressive phenomenon among the general population and may further progress to osteoporosis and increase the risk of fractures. Cycloastragenol (CAG), currently the only compound reported that activates human telomerase, is thought to be able to alleviate or delay the symptoms of aging and chronic diseases. Previous research has suggested that CAG may have the potential to alleviate age-related bone loss. However, to date, no research has specifically focused on this aspect. In this study, we aimed to investigate whether CAG could prevent senile osteoporosis, and further reveal its underlying mechanism. METHODS: CAG treatment was administrated into two bone loss rat models (D-galactose administration and aging) for 20 weeks and 33 weeks, respectively. Serum biomarkers analyses, bone biomechanical tests, micro-computed tomography assessment, and bone histomorphometry analyses were performed on the bone samples collected at the endpoint, to determine whether CAG could prevent or alleviate age-related bone loss. Proteomic analysis was performed to reveal the changes in protein profiles of the bones, and western blot was used to further verify the identity of the key proteins. The viability, osteoblastic differentiation, and mineralization of MC3T3-E1 cells were also evaluated after CAG treatment in vitro. RESULTS: The results suggest that CAG treatment improves bone formation, reduces osteoclast number, alleviates the degradation of bone microstructure, and enhances bone biomechanical properties in both d-galactose- and aging-induced bone loss models. CAG treatment promotes viability, osteoblastic differentiation, and mineralization in MC3T3-E1 cells. Proteomic and western blot analyses revealed that CAG treatment increases osteoactivin (OA) expression to alleviate bone loss. CONCLUSION: The results revealed that CAG alleviates age-related bone loss and improves bone microstructure and biomechanical properties. This may due to CAG-induced increase in OA expression. In addition, the results support preclinical investigations of CAG as a potential therapeutic medicine for the treatment of senile osteoporosis.

Ginsenoside Rb1 does not halt osteoporotic bone loss in ovariectomized rats.

Osteoporosis (OP) is a systemic skeletal disorder, manifesting with a reduction in bone mass and deterioration of the microarchitecture. Mesenchymal stem cells (MSCs) have an innate ability to differentiate into several cell types, including osteoblasts (OB). Ginsenoside Rb1 (GRb1) is an ethanol extract from ginseng and contains a highly concentrated form of ginsenoside. GRb1 shows extensive beneficial health effects such as anti-oxidative and anti-inflammatory functions, modulating the immune system and inhibiting osteoclastogenesis. We hypothesized that GRb1 can promote MSC differentiation into OBs and inhibit bone loss. In the present study, we aimed to address two questions: (1) Will GRb1 have a positive effect on osteogenic differentiation of MSCs? and (2) Will GRb1 halt bone loss in ovariectomized (OVX) rats? We investigated the effects of GRb1 on viability and osteogenic differentiation of rat mesenchymal stem cells (rMSCs). Our results showed that GRb1 at concentrations of 10-8 M and 10-6 M can increase alkaline phosphatase activity, mineralization and the expression of osteogenic related proteins, such as osteopontin and osteoprotegerin, while incubating rMSCs with osteogenic induction medium and GRb1. Adding GRb1 into the medium can prevent rMSCs from Oxidative damage at the concentration of 25µM H2O2. Furthermore, 40 4-month-old rats were assigned to 5 groups(8 rats per group): the basal group, the sham group, the OVX group, the high dose of GRb1 group (6 mg/kg/day) and the low dose of GRb1 group (3 mg/kg/day). Rats recrived treatment 3days after surgery and last for 14 weeks. Examinations included serum analysis, mechanical testing, Masson-Goldner trichrome staining and bone histomorphometry analysis. The results showed that OVX can lead to dyslipidemia and excessive oxidative stress, whereas GRb1 cannot significantly halt dyslipidemia and excessive oxidative stress in OVX rats. In addition, the bone density of the lumbar vertebra and femur were decreased significantly in the OVX rats, and GRb1 could not inhibit bone loss. Bone histomorphometry analysis showed that the number and width of bone trabecula of the tibia were reduced in OVX rats, and GRb1 could not prevent their occurrence. A bone biomechanics assay showed that GRb1 cannot improve the ability of bone structure to resist fracture of the femur in OVX rats. The current study demonstrated that GRb1 has an obvious effect on osteogenic differentiation in rMSCs but no obvious effect on bone loss in OVX rats. These findings indicate GRb1 has a positive effect on rMSCs but does not have an effect on bone loss in OVX rats at the concentration we used.

Polygonum multiflorm alleviates glucocorticoid­induced osteoporosis and Wnt signaling pathway.

It is known that long­term excessive administration of glucocorticoid (GC) results in osteoporosis. The present study aimed to evaluate the protective effects of Polygonum multiflorm (PM) on the bone tissue of rats with GC­induced osteoporosis (GIO). A total of 90 6­month­old female Sprague Dawley rats (weight range, 190­210 g) were randomly divided into nine groups: Control (normal saline); prednisone (GC; 6 mg·kg­1·d­1; Model); GC plus PMR30 (the 30% ethanol eluent fraction of PM) (H) (400 mg·kg­1·d­1); GC plus PMR30 (M) (200 mg·kg­1·d­1); GC plus PMR30 (L) (100 mg·kg­1·d­1); GC plus PMRF (fat­soluble fraction of PM) (H) (400 mg·kg­1·d­1); GC plus PMRF (M) (200 mg·kg­1·d­1); GC plus PMRF (L) (100 mg·kg­1·d­1); GC plus calcitriol (CAL; 0.045 µg·kg­1·d­1; positive). Rats were administered intragastrically with prednisone and/or the aforementioned extracts for 120 days, and weighed once/week. The serum was collected for detection of biochemical markers. The left tibia was used for bone histomorphometry analysis. The right tibia was prepared for hematoxylin and eosin staining. The left femur was used to analyze the protein expression of dickkopf­1 (DKK1), WNT inhibitory factor 1 (WIF1) and secreted frizzled related protein 4 using western blotting. Long­term excessive treatment of prednisone inhibited the bone formation rate accompanied with a decrease in bone mass, growth plate, body weight, and the level of bone­specific alkaline phosphatase and hydroxyl­terminal propeptide of type I procollagen in the serum. Furthermore, a simultaneously increase in the level of tartrate resistant acid phosphatase­5b and cross­linked carboxy­terminal telopeptide of type I collagen in the serum, in addition to DKK1, and WIF1 protein expression, was observed. PMR30 (M and L) and PMRF (H) groups were able to reduce the negative effects of GC on the bones. PMR30 (M and L) and PMRF (H) dose demonstrated a protective effect of PM on bone tissue in GIO rats. The mechanism underlying the preventive effect of PM for the treatment of GIO may be associated with direct upregulation of the canonical Wnt/ß­catenin signaling pathway.

Tetrahydroxystilbene glucoside isolated from Polygonum multiflorum Thunb. demonstrates osteoblast differentiation promoting activity.

Polygonum multiflorum Thunb. is a traditional Chinese medicinal herb that has been widely used to treat age-associated diseases. Tetrahydroxystilbene glucoside (TSG), also known as 2,3,5,4-tetrahydroxystilbene-2-O-ß-D-glucoside, is a major component of this herb. The present study was designed to investigate the osteogenic differentiation promoting activity of TSG in rat mesenchymal stem cells (MSCs) and in zebrafish. Preliminary experiments using MTT assay and ALP methods indicate that the high potential activity for promoting osteogenic differentiation was observed when 50% ethanol eluate was used. Further isolation and purification of TSG from the 50% ethanol eluate was performed by bioassay-guided fractionation, and its structure was confirmed using nuclear magnetic resonance and mass spectrometry analyses. In addition, the relative content of TSG with the highest potential activity in the promotion of osteogenic differentiation was identified as 14.34% by reversed-phase high performance liquid chromatography. Subsequently, the osteogenic differentiation promoting abilities of TSG in MSCs were examined. The results demonstrated that TSG promoted the alkaline phosphatase activity at concentrations of 1.56-25 µg/ml, while it increased the content of osteocalcin 7 days after treatment with 6.25-25 µg/ml in MSCs. Furthermore, experiments in zebrafish indicated that different concentrations of TSG (3.12-12.5 µg/ml) protected against further bone loss induced by 10 µmol/l dexamethasone (Dex), simulating an osteoporosis (OP) model. TSG treatment (12.5 µg/ml) in Dex-induced zebrafish significantly increased the area of nodules by 50.14% compared with the untreated model group. In conclusion, TSG, as a major component of P. multiflorum Thunb. exhibited an osteogenic promoting activity in MSCs and in zebrafish. The results provided scientific evidence to support the potential use of TSG for protecting the bone in degenerative diseases, such as OP.

Preventive effects of Polygonum multiflorum on glucocorticoid-induced osteoporosis in rats.

In Traditional Chinese Medicine, Polygonum multiflorum (PM) is known for its anti-aging properties. A previous study by our group showed that extracts of PM were able to prevent and treat bone loss in vivo, and the active components emodin and 2,3,5,4,-tetrahydroxystilbene-2-O-ß-glucoside (TSG) promoted the osteogenic differentiation of mesenchymal stem cells in vitro. The aim of the present study was to investigate the preventive effects of PM on glucocorticoid-induced osteoporosis (GIO) in rats. A crude extract of PM was prepared with 75% ethanol, purified and enriched using a D-101 macroresin column and elution with 30% ethanol, and the material obtained was assessed by high-performance liquid chromatography. Male or female Sprague Dawley rats (n=180) were randomly divided into nine groups: Control, prednisone, prednisone plus calcitriol (CAL), prednisone plus 30% ethanolic eluate of PM [high (H), medium (M) and low (L) dose] and prednisone plus crude extract of PM (H, M and L dose). Prednisone was orally administered to the osteoporosis model rats for 21 weeks, alongside which they received PM extracts. The weight of the viscera, anterior tibial muscle and other tissues was recorded at the end of the experiment. The femur and lumbar vertebra were collected for the measurement of three-dimensional microarchitecture by micro-computed tomography scanning, assessment of biomechanical properties and determination of bone mineral density (BMD). In the 30% ethanolic eluate of the PM extract, the content of TSG and combined anthraquinone was 9.20 and 0.15%, respectively, and that in the crude extract of PM was 2.23 and 0.03%, respectively. Over 6 weeks, the weight of the rats the in prednisone group decreased (P<0.05), while the weight of rats treated with M and H doses of 30% ethanolic eluate was increased compared with that in the prednisone group (P<0.05). Rats exposed to prednisone exhibited a deteriorated bone microarchitecture, low BMD, decreased bone volume/total volume and poor biomechanical properties. Furthermore, the weight of the adrenal gland and the anterior tibial muscle was decreased. 30% ethanolic eluate of PM at M and L doses and crude extract of PM at the H dose counteracted the alterations of skeletal and other characteristics induced by prednisone in rats, as did CAL. In conclusion, extracts of PM exerted a protective effect on bone tissue in GIO rats.

Upper gastrointestinal safety and tolerability of oral alendronate: A meta-analysis.

Osteoporosis (OP), which is a common bone disease associated with reduced bone mineral density and disordered bone microstructure, may result in an increased risk of bone fracture. The present study aimed to investigate the frequency of alendronate (Aln)-associated upper gastrointestinal tract adverse events (GIAEs) in postmenopausal women with OP. The following databases were searched in order to identify relevant studies: Medline (using PubMed as the search engine), Embase, the Web of Science and the Cochrane Central Register of Controlled Trials (up to December 2014). Studies were selected for inclusion if they were randomized, double-blind, placebo-controlled trials, which had investigated the safety of Aln versus a placebo for the treatment of postmenopausal women with OP. The primary outcomes of the included studies were total adverse events (AEs) and upper GIAEs, whereas individual upper GIAEs were considered as secondary outcomes. The general characteristics and outcomes of each study were abstracted by two independent researchers, and Review Manager 5.3 software was used for data syntheses and the meta-analysis. A total of nine studies, including 15,192 randomized patients, met the inclusion criteria and contributed to some or all of the meta-analysis outcomes. The Mantel-Haenszel method was used to calculate risk ratios, and their 95% confidence intervals (CI) were determined using either the fixed or random effects model, depending on the level of heterogeneity. The relative risk (95% CI) of AEs associated with Aln treatment, as compared with the placebo group, was 1.01 (0.97-1.06), and the relative risk (95% CI) of discontinued Aln treatment due to AEs was 1.04 (0.91-1.19). In addition, the relative risk (95% CI) of upper GIAEs was 1.02 (0.99-1.06), and the relative risk (95% CI) of discontinued Aln treatment due to upper GIAEs was 1.23 (0.97-56). In addition, these results remained robust to sensitivity analyses. The results of the present study suggested that Aln has a good GI tract tolerability, and that daily treatment with 10 mg Aln sodium does not increase the risk of GIAEs in postmenopausal women with OP.