Influence of pH on osteoclasts treated with zoledronate and alendronate

Increased apoptosis of gingival epithelium is associated with impaired autophagic flux in medication-related osteonecrosis of the jaw

Macroautophagy/autophagy has both negative and positive aspects in the development of many diseases. Yet, its exact role and specific mechanism in the onset of medication-related osteonecrosis of the jaw (MRONJ) is still not fully understood. Retarded gingiva healing is the primary clinical manifestation in patients with MRONJ. In this study, we aimed to explore the relationship between autophagy and apoptosis in MRONJ gingival epithelium and search for a method to prevent this disease. First, we examined clinical samples from patients diagnosed with MRONJ and healthy controls, finding that autophagy-related markers MAP1LC3/LC3 and SQSTM1/p62 synchronously increased, thus suggesting that autophagic flux was suppressed in MRONJ. Moreover, mRNA sequencing analysis and TUNEL assay showed that the process of apoptosis was upregulated in patients and animals with MRONJ, indicating autophagy and apoptosis participate in the development of MRONJ. Furthermore, the level of autophagy and apoptosis in zoledronic acid (ZA)-treated human keratinocytes cell lines (HaCaT cells) was concentration dependent in vitro. In addition, we also found that RAB7 (RAB7, member RAS oncogene family) activator ML098 could rescue MRONJ gingival lesions in mice by activating the autophagic flux and downregulating apoptosis. To sum up, this study demonstrated that autophagic flux is impaired in the gingival epithelium during MRONJ, and the rescued autophagic flux could prevent the occurrence of MRONJ.Abbreviations: ACTB: actin beta; Baf-A1: bafilomycin A1; CASP3: caspase 3; CASP8: caspase 8; CT: computed tomography; DMSO: dimethyl sulfoxide; GFP: green fluorescent protein; HaCaT cells: human keratinocytes cell lines; H&E: hematoxylin and eosin; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; MRONJ: medication-related osteonecrosis of the jaw; PARP: poly(ADP-ribose) polymerase; RAB7: RAB7, member RAS oncogene family; RFP: red fluorescent protein; SQSTM1/p62: sequestosome 1; TEM: transmission electron microscopy; ZA: zoledronic acid.

Aloe polysaccharide promotes osteogenesis potential of adipose-derived stromal cells via BMP-2/Smads and prevents ovariectomized-induced osteoporosis

BACKGROUND

Aloe polysaccharide (AP) is a type of an active macromolecule of Aloe vera, which contributes to its function. However, whether AP possesses anti-osteoporosis properties is unknown.

METHODS

Adipose-derived stromal cells were treated with different concentrations of AP. Early and late osteogenesis were, respectively, evaluated by ALP and Alizarin Red S staining. The effect of AP on the processes of adipogenesis inhibition in ADSCs was analyzed by oil red O staining. Western blot was used to assess the expression of osteogenic and adipogenic related factors. Then, Noggin was administered to further confirm the mechanism by which AP promotes the osteogenesis of ADSCs. Finally, 40 female SD rats were classified into a bilateral laparotomy group (Sham group) and three bilateral ovariectomy groups: OVX group, OVX + AP group, and OVX + AP + Noggin group. The bilateral rat femurs were collected to perform micro-CT scanning, HE, Masson trichrome, and Oil red O staining.

RESULTS

The results indicated that AP could increase ALP expression and calcium deposition. Through molecular mechanisms, AP promotes the protein expression of COL1A1, OPN, and ALP in ADSCs, but downregulates the expression of PPARγ. Also, AP directs ADSCs' fate by stimulating the BMP2/Smads signaling pathway. In vivo, the rat AP-treated had more trabecular bone than the OVX rat, indicating partial protection from cancellous bone loss after treatment with AP.

CONCLUSION

Our results show that AP may promote osteogenesis of ADSCs through BMP-2/Smads signaling pathway and inhibits lipogenic differentiation. Thus, AP might be a promising alternative medicine to treat postmenopausal osteoporosis.

The Effect of Alendronate on Osteoclastogenesis in Different Combinations of M-CSF and RANKL Growth Factors

Bisphosphonates (BPs) are compounds resembling the pyrophosphate structure. BPs bind the mineral component of bones. During the bone resorption by osteoclasts, nitrogen-containing BPs are released and internalized, causing an inhibition of the mevalonate pathway. As a consequence, osteoclasts are unable to execute their function. Alendronate (ALN) is a bisphosphonate used to treat osteoporosis. Its administration could be associated with adverse effects. The purpose of this study is to evaluate four different ALN concentrations, ranging from 10⁻⁶ to 10⁻¹⁰ M, in the presence of different combinations of M-CSF and RANKL, to find out the effect of low ALN concentrations on osteoclastogenesis using rat and human peripheral blood mononuclear cells. The cytotoxic effect of ALN was evaluated based on metabolic activity and DNA concentration measurement. The alteration in osteoclastogenesis was assessed by the activity of carbonic anhydrase II (CA II), tartrate-resistant acid phosphatase staining, and actin ring formation. The ALN concentration of 10⁻⁶ M was cytotoxic. Low ALN concentrations of 10⁻⁸ and 10⁻¹⁰ M promoted proliferation, osteoclast-like cell formation, and CA II activity. The results indicated the induction of osteoclastogenesis with low ALN concentrations. However, when high doses of ALN were administered, their cytotoxic effect was demonstrated.

Study on Zoledronic Acid Reducing Acute Bone Loss and Fracture Rates in Elderly Postoperative Patients with Intertrochanteric Fractures

OBJECTIVE

To observe the effect of zoledronic acid on the reduction of acute bone loss and fracture rate in elderly postoperative patients with intertrochanteric fracture.

METHODS

From August 2012 to January 2015, a total of 482 patients with senile osteoporotic femoral intertrochanteric fracture, who accepted proximal femoral intramedullary fixation under anesthesia were analysed. The patients were divided into two groups. Treatment group (353 cases) were treated with 100 mL/5 mg of zoledronic acid injection in 1 week after operation, as well as orally taken 600 mg/d of calcium carbonate and active vitamin D3 400 IU/d. Control group (129 cases) were given the same dose of calcium carbonate and active vitamin D3 orally. Efficacy evaluation were conducted during different periods of medication RESULTS: Compared with pre-medication, indexes of bone metabolism (TARP-5b, CTX) in the treatment group were brought down, especially significantly statistically different after 12 months of medication. The treatment group performed superior to control group in alleviating the pain of back and posture changing (P < 0.05), improving bone density (P < 0.05), depressing re-fracture rate (P < 0.01) after 24 months of medication. In addition, BP, PF and MH dimension scores were demonstrated with statistical significance (P < 0.05).

CONCLUSIONS

The application of zoledronic acidin elderly postoperative patients with intertrochanteric fracture can not only relieve acute bone loss, reduce the incidence rate of re-fracture, alleviate osteoporosis pain and the pain from osteoporotic fracture, but also improve bone metabolism and quality of life, which may offer an acceptable clinical opinion.

Impact of bisphosphonates on the proliferation and gene expression of human fibroblasts

The aim of this study was to elucidate the role of fibroblasts in bisphosphonate-related osteonecrosis of the jaw (BRONJ), evaluating the effect of zoledronate, alendronate, and ibandronate on the proliferation of fibroblasts and on their expression of genes essential for fibroblast physiology. Human CCD-1064Sk epithelial fibroblast cells were incubated in culture medium with 10^-5, 10^-7, or 10^-9 M zoledronate, alendronate, or ibandronate. The proliferative capacity of fibroblasts was determined by spectrophotometry (MTT) at 24 of culture. Real-time polymerase chain reaction (RT-PCR) was used to study the effects of BPs at a dose of 10^-9 M on the expression of FGF, CTGF, TGF-β1, TGFβR1, TGFβR2, TGFβR3, DDR2, α-actin, fibronectin, decorin, and elastin. Fibroblasts proliferation was significantly increased at the lowest dose (10^-9M) of each BP but was not affected at the higher doses (10^-5 and 10^-7M). The proliferation increase may be related to the rise in TGF-β1 and TGFβR1 expression detected after the treatment of cells with 10^-9M of zoledronate, alendronate, or ibandronate. However, the expression of CTGF, DDR2, α-actin, fibronectin, and decorin decreased versus controls. The results of this in vitro study indicate that a very low BP dose (10^-9 M) can significantly affect the physiology of fibroblasts, increasing their proliferative capacity and modulating the expression of multiple genes involved in their growth and differentiation.