Treatment of osteoporosis: current state of the art

Specific Bioactive Collagen Peptides in Osteopenia and Osteoporosis: Long-Term Observation in Postmenopausal Women

Background

The effects of specific collagen peptides on bone mineral density (BMD) in subjects with osteoporosis or osteopenia have already been investigated in 131 postmenopausal women in a randomized controlled trial. The purpose of this follow-up observation was to determine the longer-term effects of the same specific bioactive collagen peptides after a total intervention time of 4 years.

Methods

In this open-label follow-up observation, 31 postmenopausal women with reduced BMD (initial T-score lower than −1 of either the femoral neck or the lumbar spine) completed the follow-up. BMD was measured via dual energy X-ray absorptiometry. Absolute changes in BMD and T-scores in the spine and femoral neck were assessed. The number of fractures was also recorded. All participants received specific bioactive collagen peptides.

Results

Supplementation with bioactive collagen peptides during follow-up led to a clinically relevant increase in BMD in the spine. These findings were consistent with the results for the femoral neck.

Conclusions

Long-term supplementation with specific bioactive collagen peptides appears to be effective in counteracting losses in BMD. Moreover, significant increases in BMD could contribute to improved bone stability.

Anemarrhena asphodeloides Bunge ameliorates osteoporosis by suppressing osteoclastogenesis

Anemarrhena asphodeloides Bunge has been traditionally used in Korean medicine for its antipyretic, diuretic, sedative, and antitussive effects. In the present study, the effects of an ethanol extract of A. asphodeloides Bunge (AAB) on osteoporosis and its underlying mechanisms on bone remodeling were investigated. Osteoporosis was induced in ICR strain mice by ovariectomy. The mice were divided into four groups: sham, ovariectomized, 17β‑estradiol and 100 mg/kg AAB. The treatment was continued for 4 weeks. Bone mineral density (BMD) and bone mineral content (BMC) were measured using dual‑energy X‑ray absorptiometry. In addition, Raw 264.7 cells were treated in the presence of 0.1, 1 and 10 µg/ml AAB with 100 ng/ml receptor activator of nuclear factor κΒ ligand (RANKL) to induce osteoclast formation and stained with tartrate resistant acid phosphatase. In addition, levels of osteoclast‑related factors were analyzed to investigate the signaling cascades in osteoclasts. The results demonstrated that AAB treatment reversed the decreases of both BMD and BMC in osteoporotic femurs. Additionally, the formation of osteoclasts was significantly suppressed by the AAB treatment in RANKL‑stimulated Raw 264.7 cells. Compared with cells treated with RANKL alone, the AAB‑treated osteoclasts had significantly decreased tumor necrosis factor‑α and interleukin‑6. The protein levels of c‑fos were also decreased in the AAB‑treated osteoclasts. Furthermore, the RANKL‑induced nuclear translocation of nuclear factor‑κB was attenuated in osteoclasts by the AAB treatment compared with cells treated with RANKL alone. Finally, AAB treatment downregulated the phosphorylation of mitogen‑activated protein kinases. The present results demonstrated that AAB exhibited ameliorative effects on osteoporosis by inhibiting osteoclastogenesis, and suggested that AAB may be a potential candidate for the treatment of osteoporosis.

Atorvastatin-loaded micelles with bone-targeted ligand for the treatment of osteoporosis

Osteoporosis is a common bone disorder where the declined bone mass is far more than normal physiological status and usually associated with enhanced fracture risk, reduced bone strength and even deteriorated quality of life. Recent studies showed that statins could exert beneficial effects on bones via promoting osteoblastic activity mediated by increased expression of bone morphogenetic protein 2 and also by suppressing osteoclast proliferation. In this study, we developed atorvastatin-loaded tetracycline-poly (ethylene glycol)-poly(lactic-co-glycolic acid) (TC-PEG-PLGA/ATO) micelles for the targeted treatment of osteoporosis. The TC-PEG-PLGA was synthesized under the action of coupling reagents and then ATO was encapsulated through solvent diffusion method with encapsulation efficiency and drug loading of 89.32 ± 2.48% and 8.20 ± 0.53%, respectively. The release of ATO from micelles could be maintained for more than 48 h in pH 7.4 PBS. Pharmacokinetic results further demonstrated that TC-PEG-PLGA micelles could effectively shield ATO leakage from micelles and prolong their circulation time. Benefiting from TC specifically binding to hydroxyapatite (HAp), TC-PEG-PLGA/ATO micelles exerted good bone-targeted ability, as demonstrated by in vitro HAp affinity assay and biodistribution. Pharmacodynamic studies showed that TC-PEG-PLGA/ATO micelles could effectively improve bone mineral density and bone mechanical strength in osteoporotic rats. These results suggest that TC-PEG-PLGA/ATO micelles hold significant promise for the targeted treatment of osteoporosis.

Osteoporosis and autophagy: What is the relationship?

Autophagy is a survival pathway wherein non-functional proteins and organelles are degraded in lysosomes for recycling and energy production. Therefore, autophagy is fundamental for the maintenance of cell viability, acting as a quality control process that prevents the accumulation of unnecessary structures and oxidative stress. Increasing evidence has shown that autophagy dysfunction is related to several pathologies including neurodegenerative diseases and cancer. Moreover, recent studies have shown that autophagy plays an important role for the maintenance of bone homeostasis. For instance, in vitro and animal and human studies indicate that autophagy dysfunction in bone cells is associated with the onset of bone diseases such as osteoporosis. This review had the purpose of discussing the issue to confirm whether a relationship between autophagy dysfunction and osteoporosis exits.

The effect of atorvastatin, 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor (HMG-CoA), on the prevention of osteoporosis in ovariectomized rabbits

Osteoporosis is a most frequent systemic skeletal disease characterized as low bone mineral density and microarchitectural deterioration of bone tissue, resulting in increased bone fragility and fracture risk. Although several drugs such as bisphosphonates, estrogen replacement treatment, and selective estrogen receptor modulators have been used to treat osteoporosis, all these are not the ideal drugs because of insufficient curative ability and adverse side effects. Recently, atorvastatin has ordinarily been prescribed as an anti-hyperlipidemia drug, not as an anti-osteoporosis drug. However, its clinical outcome and potential treatment mechanism are still unclear. In this study, the bilateral ovariectomy of rabbits was duplicated to develop osteoporosis animal model. The effect of atorvastatin on in vivo was determined, and the functional mechanism was studied in vitro after the curative effect was explored. Atorvastatin was observed to significantly increase the mechanical parameters such as maximum load, stiffness, and energy-absorbing capacity, and it improved the microarchitecture. The anti-osteoporosis activity of atorvastatin may be the result of the promotion of differentiation of osteoblasts by inducing synthesis of vascular endothelial growth factor, bone morphogenetic protein 2 (BMP2), core-binding factor alpha 1 (CBFα1), and inhibition of osteoclast formation through the osteoprotegerin (OPG)-receptor activator for the nuclear factor κB ligand (RANKL) system. Our study observations give reliable experimental evidence for clinical application of atorvastatin to treat the disorder of osteoporosis.

Pamidronate Disodium Leads to Bone Necrosis via Suppression of Wnt/β-Catenin Signaling in Human Bone Marrow Mesenchymal Stem Cells In Vitro

PURPOSE

Pamidronate disodium-associated bone necrosis is poorly understood at the cellular and molecular levels. This study proposes a pathway leading to the pamidronate disodium-mediated inhibition of osteogenic differentiation of human bone marrow mesenchymal stem cells (BMMSCs) derived from the mandible in vitro.

MATERIALS AND METHODS

Primary human BMMSCs were isolated from the mandible and marrow tissue. A proliferation assay was performed to determine the experimental concentration of pamidronate disodium. Alkaline phosphatase (ALP) activity, ALP staining, and Alizarin red S (ARS) staining were assessed after treatment with pamidronate disodium (0, 0.1, 0.5, 1, 5, 10 μg/mL). Quantitative real-time polymerase chain reaction and western blotting specific for Wnt and β-catenin signaling genes or proteins were performed after treatment with pamidronate disodium 0.5 μg/mL. Wnt3a was used to observe the osteogenic differentiation of BMMSCs during treatment with pamidronate disodium 0.5 μg/mL.

RESULTS

As expected, pamidronate disodium 1, 5, and 10 μg/ml were unfavorable for BMMSC growth (P < .05), whereas 0.1 and 0.5 μg/mL did not affect BMMSC growth (P ≥ .05). BMMSCs treated with pamidronate disodium 0.5 μg/mL had lower ALP activity, ALP staining, and ARS staining (P < .05), and BMMSCs treated with low concentrations (<0.5 μg/mL) of pamidronate disodium had the same levels of ALP activity, ALP staining, and ARS staining as the control (0 μg/mL). Pamidronate disodium 0.5 μg/mL decreased the expression of genes and proteins involved in Wnt and β-catenin signaling. BMMSCs with Wnt3a and pamidronate disodium 0.5 μg/mL had higher ALP activity, ALP staining, and ARS staining (P < .05).

CONCLUSIONS

Pamidronate disodium inhibited Wnt and β-catenin signaling, which controls osteogenic differentiation in BMMSCs. Wnt3a, a Wnt and β-catenin signaling activator, reversed the negative effects caused by pamidronate disodium to salvage the osteogenic defect in BMMSCs.