Bovine lactoferrin improves bone mass and microstructure in ovariectomized rats via OPG/RANKL/RANK pathway

Alendronate Functionalized Mesoporous Bioactive Glass Nanospheres

In this work we synthesized mesoporous bioactive glass nanospheres (nMBG) with the aim to utilize them as substrates for loading one of the most potent amino-bisphosphonates, alendronate (AL). The results of the chemical and structural characterization show that the nMBG display a relatively high surface area (528 m²/g) and a mean pore volume of 0.63 cm³/g, both of which decrease on increasing alendronate content. It is possible to modulate the amount of AL loaded into the nanospheres up to a maximum value of about 17 wt %. In vitro tests were performed using a human osteosarcoma cell line (MG63) and a murine monocyte/macrophage cell line as osteoclast model (RAW 264.7). The results indicate that even the lower concentration of alendronate provokes decreased tumor cell viability, and that osteoclast activity exhibits an alendronate dose-dependent inhibition. The data suggest that nMBG can act as a suitable support for the local delivery of alendronate, and that the antiresorptive and antitumor properties of the functionalized mesoporous nanospheres can be modulated by varying the amount of alendronate loading.

Multi-Scale Agent-Based Multiple Myeloma Cancer Modeling and the Related Study of the Balance between Osteoclasts and Osteoblasts

Research Background

Currently, multiple myeloma is the second most common hematological malignancy in the U.S., constituting 1% of all cancers. With conventional treatment, the median survival time is typically 3–4 years, although it can be extended to 5–7 years or longer with advanced treatments. Recent research indicated that an increase in osteoclast (OC) activity is often associated withmultiple myeloma (MM) and that a decrease inosteoblast (OB) activity contributesto the osteolytic lesions in MM. Normally, the populations of OCs and OBs are inequilibrium, and an imbalance in this statecontributes to the development of lesions.

Research procedures

A multi-scale agent-based multiple myeloma model was developed to simulate the proliferation, migration and death of OBs and OCs. Subsequently, this model was employed to investigate the efficacy of thethree most commonly used drugs for MM treatment under the following two premises: the reduction in the progression of MM and the re-establishment of the equilibrium between OCs and OBs.

Research purposes

The simulated results not only demonstrated the capacity of the model to choose optimal combinations of the drugs but also showed that the optimal use of the three drugs can restore the balance between OCs and OBs as well as kill MMs. Furthermore, the drug synergism analysis function of the model revealed that restoring the balance between OBs and OCs can significantly increase the efficacy of drugs against tumor cells.

Coupling Hydroxyapatite Nanocrystals with Lactoferrin as a Promising Strategy to Fine Regulate Bone Homeostasis

Lactoferrin (LF) is an interesting glycoprotein in the field of bone biology for its regulatory effect on cells involved in bone remodeling, that results compromised in several pathological conditions, as osteoporosis. In a previous study we observed that the coupling of LF and biomimetic hydroxyapatite nanocrystals (HA), a material well-known for its bioactivity and osteoconductive properties, leads to a combined effect in the induction of osteogenic differentiation of mesenchymal stem cells. On the basis of this evidence, the present study is an extension of our previous work aiming to investigate the synergistic effect of the coupling of HA and LF on bone homeostasis. Biomimetic HA nanocrystals were synthesized and functionalized with LF (HA-LF) and then pre-osteoblasts (MC3T3-E1) and monocyte/macrophage cells lines (RAW 264.7), using as osteoclastogenesis in vitro model, were cultured separately or in co-culture in presence of HA-LF. The results clearly revealed that HA and LF act in synergism in the regulation of the bone homeostasis, working as anabolic factor for osteoblasts differentiation and bone matrix deposition, and as inhibitor of the osteoclast formation and activity.

Bone Regeneration Is Promoted by Orally Administered Bovine Lactoferrin in a Rabbit Tibial Distraction Osteogenesis Model

BACKGROUND

Lactoferrin, an iron-binding glycoprotein which belongs to the transferrin family, has been shown to promote bone growth. However, reports regarding effects of lactoferrin on bone regeneration during distraction osteogenesis are limited. Our study was designed to investigate the effect of bovine lactoferrin treatment on bone formation of the distracted callus.

QUESTIONS/PURPOSES

We asked whether bovine lactoferrin enhances bone formation of the distraction callus as determined by (1) radiographic and histologic appearances; (2) dual-energy x-ray absorptiometry (DXA) analysis of bone mineral composition and bone mineral density; (3) micro-CT measures of trabecular architecture; and (4) biomechanical strength of the healing bone. Additionally, serology, reverse transcription (RT)-PCR, and immunohistochemistry were used to explore the possible mechanisms of bovine lactoferrin use on bone formation during distraction osteogenesis.

METHODS

Unilateral tibial osteodistraction was performed on 80 New Zealand White rabbits with a distraction rate of 1 mm per day for 10 days. Animals then were divided randomly into two groups: (1) vehicle and (2) bovine lactoferrin. At 4 and 8 weeks after completion of distraction, the animals were sacrificed. Lengthened tibias and serum samples were obtained and subjected to radiologic, DXA, micro-CT, histologic, and biomechanical examinations, and serum, RT-PCR and immunohistochemical analyses.

RESULTS

Radiologic, DXA, micro-CT, histologic, and biomechanical examinations indicated that bovine lactoferrin treatment not only accelerated bone formation at early stages of distraction osteogenesis but also promoted bone consolidation at late stages. The ultimate force of the distracted calluses was increased by 37% (118.8 ± 6.65 N in the lactoferrin group and 86.5 ± 5.47 N in the vehicle group; p < 0.001) and 84% (384.8 ± 18.4 N in the lactoferrin group and 209.0 ± 15.2 N in the vehicle group; p < 0.001) at 4 and 8 weeks, respectively. Moreover, serum analysis showed that bovine lactoferrin treatment significantly increased serum levels of bone alkaline phosphatase and decreased serum levels of tartrate resistant acid phosphatase 5b. In addition, RT-PCR and immunohistochemical analyses suggested that bovine lactoferrin treatment induced a lower receptor activator of nuclear factor-kappaB (RANK) ligand/osteoprotegerin (RANKL/OPG) ratio in the distracted callus.

CONCLUSIONS

The results of our study suggest that bovine lactoferrin treatment could promote bone regeneration during distraction osteogenesis in the rabbit. The results indicate that the OPG/RANKL/RANK system might be a major mechanism for increased bone formation and decreased bone resorption in distraction osteogenesis with bovine lactoferrin treatment.

CLINICAL RELEVANCE

Oral administration of bovine lactoferrin may provide a feasible approach for promoting osteogenesis during distraction osteogenesis.

Antiosteoporosis Activity of New Oriental Medicine Preparation (Kyungokgo Mixed with Water Extract of Hovenia dulcis) on the Ovariectomized Mice

Protective effect of new oriental medicine (Kyungokgo mixed with water extract of Hovenia dulcis, KOGHD) was assessed on the bone loss induced mice by ovariectomy. In the in vivo experiments, antiosteoporosis effect of KOGHD was investigated using ovariectomized osteoporosis mice model. After 6 weeks of treatment, the mice were euthanized, and the effect of Kyungokgo (KOG) and KOGHD on body weight, spleen weigh, thymus weight, uterine weight, serum biochemical indicators, bone weight and length, immune cell population, bone morphometric parameters, and histological stains was observed. Our results showed that KOGHD prevented the deterioration of trabecular microarchitecture caused by ovariectomy, which were accompanied by the lower levels of bone turnover markers and immune cell population as evidenced by the inhibition of RANKL-mediated osteoclast differentiation without cytotoxic effect on bone marrow derived macrophages (BMMs). Therefore, these results suggest that the Hovenia dulcis (HD) supplementation in the KOG may also prevent and treat bone loss.

Lactoferrin Induces Osteoblast Growth through IGF-1R

Objectives. To investigate the role of the IGF-1R by which lactoferrin induces osteoblast growth. Methods. Osteoblast received 5 d lactoferrin intervention at a concentration of 0.1, 1, 10, 100, and 1000 μg/mL, and the IGF-1 and IGF-1R were detected using RT-PCR and western blot. The osteoblast into the control, 100 μg/mL lactoferrin, Neo-scramble (NS, empty vector), NS + 100 μg/mL lactoferrin, shIGF-1R and shIGF-1R + 100 μg/mL lactoferrin group. We test the apoptosis and proliferation and the level of PI3K and RAS in osteoblasts after 5 d intervention. Results. (1) 1, 10, 100, and 1000 μg/mL lactoferrin induced the expression of IGF-1 mRNA and protein. 10 μg/mL and 100 μg/mL lactoferrin induced the expression of IGF-1R mRNA and protein. (2) Lactoferrin (100 μg/mL) induced osteoblast proliferation while inhibiting apoptosis. Osteoblasts with silenced IGF-1R exhibited decreased proliferation but increased apoptosis. MMT staining and flow cytometry both indicated that there was no significant difference between the shIGF-1R group and the shIGF-1R + 100 μg/mL lactoferrin group. (3) Lactoferrin (100 μg/mL) induced PI3K and RAS phosphorylation and silence of IGF-1R resulted in decreased p-PI3K and p-RAS expression. Lactoferrin-treated shIGF-1R cells showed significantly higher level of p-PI3K and p-RAS when compared with shIGF-1R. Conclusion. Lactoferrin induced IGF-1/IGF-1R in a concentration-dependent manner. Lactoferrin promoted osteoblast proliferation while inhibiting apoptosis through IGF-1R. Lactoferrin activated PI3K and RAS phosphorylation via an IGF-1R independent pathway.

Dioscin promotes osteoblastic proliferation and differentiation via Lrp5 and ER pathway in mouse and human osteoblast-like cell lines

Background

Dioscin, a typical steroid saponin, is isolated from Dioscorea nipponica Makino and Dioscorea zingiberensis Wright. It has estrogenic activity and many studies have also reported that dioscorea plants have an effect in preventing and treating osteoporosis. However, the molecular mechanisms underlying their effect on osteoporosis treatment are poorly understood. Therefore, the present study aims to investigate the mechanism (s) by which dioscin promotes osteoblastic proliferation and differentiation in mouse pre-osteoblast like MC3T3-E1 cells and human osteoblast-like MG-63 cells.

Results

We found that dioscin (0.25 μg/ml, 0.5 μg/ml, and 1.0 μg/ml) promoted MC3T3-E1 cells and MG-63 cells proliferation and differentiation dose dependently. Western blot analysis results showed that estrogen receptor α (ER-α), estrogen receptor β (ER-β), β-catenin and Bcl-2 protein expression increased after MC3T3-E1 cells were treated with dioscin. Quantitative reverse transcription-polymerase chain reaction (RT-PCR) analysis indicated that dioscin could increase the ratio of osteoprotegerin (OPG)/receptor activator of NF-κB ligand (RANKL) and up-regulate the level of Lrp5 and β-catenin. And by RNA interference analysis, we proved that the effect of dioscin increasing the ratio of OPG/RANKL was dependent on Lrp5 pathway. In addition, we also found that these effects of dioscin were abolished by ICI 182, 780 (100 nM), an antagonist of ER, indicating that an ER signaling pathway was also involved. We also found that dioscin (0.25 μg/ml, 0.5 μg/ml, and 1.0 μg/ml) induced MG-63 cells proliferation and differentiation in a dose-dependent manner. Western blot analysis results indicated that ER-α, ER-β and β-catenin protein expression increased after MG-63 cells were treated with dioscin.

Conclusions

The current study is the first to reveal that dioscin can promote osteoblasts proliferation and differentiation via Lrp5 and ER pathway.

Lactoferrin inhibits apoptosis through insulin-like growth factor I in primary rat osteoblasts

AIM

Excessive apoptosis of osteoblasts is the major cause of low bone mass, and bovine lactoferrin (bLF), an iron-binding glycoprotein, might protect osteoblastic cells from apoptosis induced by serum withdrawal. The aim of this study was to elucidate the mechanisms underlying the anti-apoptotic action of bLF in rat osteoblasts in vitro.

METHODS

Primary rat osteoblasts were incubated in the presence of varying concentrations of bLF for 24 h. The expression of insulin-like growth factor I (IGF-I) and IGF-I receptor (IGF-IR) was measured uisng RT-PCR and Western blotting. Cell apoptosis was examined with flow cytometry. siRNAs targeting IGF-I was used in this study.

RESULTS

Treatment of bLF (0.1-1000 μg/mL) dose-dependently increased the expression of IGF-I and IGF-IR in the osteoblasts. Treatment with bLF (10, 100 μg/mL) markedly inhibited the osteoblast apoptosis (with the rate of total apoptosis of 70% at 10 μg/mL), but the high concentration of bLF (1000 μg/mL) significantly promoted the osteoblast apoptosis. Knockdown of the IGF-I gene in osteoblasts with siRNA markedly increased the osteoblast apoptosis.

CONCLUSION

Lactoferrin (10 and 100 μg/mL) effectively inhibits apoptosis of primary rat osteoblasts by upregulating IGF-I expression.

Influence of hormone replacement therapy on osteoprotegerin and receptor activator of nuclear factor kappa-B ligand concentrations in menopausal women

The study was designed to compare the levels of the receptor activator of nuclear factor kappa-B ligand (RANKL) and osteoprotegerin (OPG) in the serum and saliva of menopausal women and verify whether there is a correlation between concentrations of these cytokines and bone mineral density (BMD) of the femur and mandible. Blood and saliva samples were collected from a group of 60 women during menopause--30 untreated (control group) and 30 treated with hormone replacement therapy (HRT) (research group). Densitometry was conducted on the femoral bone and mandible. BMD in the research group was significantly higher than in the control group. The OPG concentration was slightly higher in the research group. The concentration of RANKL was slightly higher in the control group. Differences in RANKL/OPG between groups were not high enough to be statistically significant. Analysis of the RANKL in saliva revealed a significantly higher concentration of this factor in the control group. Observed beneficial effects of HRT on bone tissue may be exerted through the RANKL/OPG ratio, but further research is required to clearly confirm this thesis.