Concentrations Of Zoledronate Research Articles

Inflammation Can Be a High-Risk Factor for Mucosal Nonunion of MRONJ by Regulating SIRT1 Signaling When Treated with an Oncologic Dose of Zoledronate.

Zoledronate (ZA) stands as a highly effective antiresorptive agent known to trigger medication-related osteonecrosis of the jaw (MRONJ). Its clinical dosages primarily encompass those used for oncologic and osteoporosis treatments. While inflammation is recognized as a potential disruptor of mucosal healing processes associated with ZA, prior research has overlooked the influence of varying ZA dosages on tissue adaptability. Therefore, a deeper understanding of the specific mechanisms by which inflammation exacerbates ZA-induced MRONJ, particularly when inflammation acts as a risk factor, remains crucial. Cell proliferation and migration of human oral keratinocytes (HOK) was analyzed after treatment with different doses of ZA and/or lipopolysaccharide (LPS) to assess their possible effect on mucosal healing of extraction wounds. Mouse periodontitis models were established using LPS, and histological changes in extraction wounds were observed after the administration of oncologic dose ZA. Hematoxylin and eosin (HE) staining and immunofluorescence were used to evaluate mucosal healing. In vitro, LPS did not exacerbate the effects of osteoporosis therapeutic dose of ZA on the proliferation and migration of HOK cells, while aggravated these with the oncologic dose of ZA treatment by inducing mitochondrial dysfunction and oxidative stress via regulating SIRT1 expression. Furthermore, SIRT1 overexpression can alleviate this process. In vivo, local injection of LPS increased the nonunion of mucous membranes in MRONJ and decreased the expression of SIRT1, PGC-1α, and MnSOD. Inflammation aggravates oncologic dose of ZA-induced mitochondrial dysfunction and oxidative stress via a SIRT1-dependent pathway, enhancing the risk of impaired mucosal healing in MRONJ. Our study implies that inflammation becomes a critical risk factor for MRONJ development at higher ZA concentrations. Elucidating the mechanisms of inflammation as a risk factor for mucosal non-healing in MRONJ could inform the development of SIRT1-targeted therapies.

Influence of Bisphosphonates or Recombinant Human Parathyroid Hormone on in Vitro Chemotherapy Sensitivity in Acute Lymphoblastic Leukemia Cells

BACKGROUNDOsteonecrosis and low bone mineral density (BMD) are serious osteogenic side effects of acute lymphoblastic leukemia (ALL) treatment. Bisphosphonates and recombinant human parathyroid hormone (rPTH) tend to be used to ameliorate osteonecrosis-related symptoms as well as to enhance bone mineral density in children with ALL and severe bone fragility. Only one preclinical study on the safety of bisphosphonates during ALL treatment is available, which raises concerns about their impact on leukemic drug sensitivity. Here, we assessed the influence of various bone-modifying agents (zoledronate, pamidronate and rPTH) on in vitro cytotoxicity of chemotherapeutic agents (vincristine (VCR), daunorubicin (DNR), dexamethasone (DEXA), 6-mercaptopurine (6-MP), PEG-asparaginase (PEG-ASP)) and prednisone (PRED) that are commonly used in ALL treatment.METHODSPotential cytotoxic effects of the bone-modifying agents on leukemia cell viability and on in vitro cytotoxic responses of chemotherapeutic agents were tested in various T-cell and B-cell leukemia cell lines using methyl-thiazol-tetrazolium (MTT) assays. Bone-modifying agents were added at concentrations up to a five-fold of their physiological peak plasma concentration. For each assay, 50th percentile of maximal inhibitory concentration was determined. To quantify the combined effects of the bone-modifying agents on chemotherapeutic agent-induced cytotoxicity, median (interquartile range) combination indexes (CI) were calculated. We considered a median CI of < 0.8 as synergism and > 1.2 as antagonism (based on the method of Chou).RESULTSZoledronate, pamidronate or rPTH in combination with DNR, 6-MP and PEG-ASP showed median CI values between 0.8 and 1.2. Variable inconclusive results were obtained in combination with VCR. Only the combination of a five-fold peak plasma concentration of zoledronate or pamidronate with DEXA resulted in median CI values of 1.15 (range, 1.08-1.48), and 1.34 (range, 1.07-1.62), respectively. Additional experiments using DEXA as well as PRED in combination with one-, three- or five-fold physiological peak plasma concentrations of zoledronate or pamidronate revealed that median CI values stay within 0.8 and 1.2, except for DEXA exposed leukemia cells in combination with a five-fold physiological peak plasma concentration of pamidronate which repeatedly showed a median CI value above 1.2 (1.34, range 1.04-1.86).CONCLUSIONSZoledronate, pamidronate or rPTH do not seem to influence drug sensitivity of DNR, 6-MP or PEG-ASP, even at a five-fold physiological peak plasma concentration. Nevertheless, our findings suggest a minimal effect of pamidronate on DEXA-induced leukemia cell death. This suggests that even though zoledronate or pamidronate do not seem to negatively influence DEXA- or PRED- induced toxicity in expected physiological concentrations (one- to three-fold physiological peak plasma concentrations), these bone-modifying agents may only be considered with caution in individual cases, and preferably in clinical trial settings before being applied on a large scale in children with ALL. DisclosuresNo relevant conflicts of interest to declare.

Zoledronate repositioning as a potential trypanocidal drug. Trypanosoma cruzi HPRT an alternative target to be considered

Chagas disease is caused by the protozoan parasite Trypanosoma cruzi and affects 7 million people worldwide. Considering the side effects and drug resistance shown by current treatments, the development of new anti-Chagas therapies is an urgent need. T. cruzi hypoxanthine phosphoribosyltransferase (TcHPRT), the key enzyme of the purine salvage pathway, is essential for the survival of trypanosomatids. Previously, we assessed the inhibitory effect of different bisphosphonates (BPs), HPRT substrate analogues, on the activity of the isolated enzyme. BPs are used as a treatment for bone diseases and growth inhibition studies on T. cruzi have associated BPs action with the farnesyl diphosphate synthase inhibition. Here, we demonstrated significant growth inhibition of epimastigotes in the presence of BPs and a strong correlation with our previous results on the isolated TcHPRT, suggesting this enzyme as a possible and important target for these drugs. We also found that the parasites exhibited a delay at S phase in the presence of zoledronate pointing out enzymes involved in the cell cycle, such as TcHPRT, as intracellular targets. Moreover, we validated that micromolar concentrations of zoledronate are capable to interfere with the progression of cell infection by this parasite. Altogether, our findings allow us to propose the repositioning of zoledronate as a promising candidate against Chagas disease and TcHPRT as a new target for future rational design of antiparasitic drugs.

Inhibition Effect of Zoledronate on the Osteoclast Differentiation of RAW264.7 Induced by Titanium Particles.

Objective This study is aimed at studying the effect of zoledronate (ZOL) on the differentiation of osteoclast precursor RAW264.7 cells induced by titanium (Ti) particles and explores the possibility of preventing and treating periprosthetic osteoporosis using ZOL. Methods RAW264.7 cells were cultured in vitro. Ti particles were prepared. The cell proliferation curve of RAW264.7 cells was plotted using the MTT assay to find the best concentration of ZOL for intervention. The cells were divided into three groups: control, Ti particles, and Ti particles+ZOL. The cell morphology was observed using tartaric acid–resistant acid phosphatase (TRAP) staining, and the activity of TRAP in cell supernatant was determined using the biochemical method. The number of bone resorption lacunae was detected using toluidine blue staining. The mRNA expression of RANK, NFATcl, CAII, and MMP-9 was detected using real-time polymerase chain reaction. The protein expression of RANK, NFATcl, and MMP-9 was detected using Western blot analysis. Results Ti particles stimulated the differentiation of RAW264.7 cells into osteoclasts. They also increased the activity of TRAP, number of bone resorption lacunae, and mRNA and protein expression of RANK, NFATcl, and MMP-9. However, ZOL could suppress the effect of TI particles on the osteoclast differentiation of RAW264.7 cells. Conclusions ZOL could effectively inhibit the differentiation of RAW264.7 cells into osteoclasts induced by Ti particles, decrease the activity of TRAP, reduce the number of bone resorption lacunae, and decrease the mRNA and protein expression of RANK, NFATcl, and MMP-9. Hence, it may be a promising candidate for preventing and treating periprosthetic osteoporosis after the artificial joint operation.

Metal-drug nanoparticles-mediated osteolytic microenvironment regulation for enhanced radiotherapy of orthotopic osteosarcoma

• we firstly developed a new “carrier free” core-shell metal-drug nanoparticles (HA@FeZOL). • HA@FeZOL was synthesized by coordination‐driven self‐assembly using drugs as bridging ligands. • HA@FeZOL combined radiotherapy sensitization and osteolysis inhibition to enhance the treatment of osteosarcoma. • The nanoparticles with inbuilt ZOL could escape skeleton absorption and minimize side effects. Osteosarcoma is the most common primary malignant bone tumor with the pathological essence of osteolysis, which seriously reduces the quality of life. To improve the treatment of osteosarcoma, current strategies focus on inhibiting osteolysis and cancer cell growth through combination therapy. Here, we firstly developed a new “carrier free” core-shell metal-drug nanoparticles to enhance the treatment of orthotopic osteosarcoma through inhibiting osteoclast activity and sensitizing radiotherapy. The core was formed by self-assembly of ferric ions with zoledronate (ZOL). The resultant nanoparticles with active pharmaceutical ingredient (API) content over 60 wt% and changeless ingredients of Fe and ZOL can induce efficient cell death and easy for large-scale synthesis. In addition, the inbuilt ZOL and surface modified hyaluronic acid could make the nanoparticles escape skeleton absorption and increase the concentration of zoledronate at the tumor site. Once accumulated in tumor, the released ZOL attenuated osteoclast activity around the tumors to prevent osteolysis. Meanwhile, the free radicals generated efficiently from HA@FeZOL through Fenton-like reaction sensitized radiotherapy to kill the tumor cells. The results corroborated the feasibility of HA@FeZOL mediated synergistic therapy against orthotopic osteosarcoma through sensitized radiotherapy and osteolysis inhibition. Therefore, this facile nanoplatform provides a new combinatorial strategy for treating osteosarcoma and opens a window for the application of metal-drug nanoparticles.

Abstract P2-06-23: New biomarkers for adjuvant bisphosphonate use in triple-negative breast cancer

Abstract We first showed that triple-negative breast cancer (TNBC) patients with low Toll-like receptor 9 (TLR9) expression have significantly worse prognosis than patients with high TLR9 expression. TLR9 is an innate immunity DNA receptor which is also expressed in several cancers, including TNBC. Later, we showed that low-TLR9 cells and tumors are more sensitive to amino-bisphosphonates, especially to zoledronate. Bisphosphonates (BP) inhibit osteoclasts and thereby effectively prevent bone fractures in osteoporosis and in cancer-induced bone disease. BPs also have direct anticancer effects. Interestingly, adjuvant BP use is associated with significantly improved progression-free and overall survival, but only among post-menopausal breast cancer patients. The molecular mechanisms behind this observation is unclear. CD73 is a 70 kDa glycophosphatidylinositol-anchored cell protein, which converts adenosine monophosphate to adenosine and organic phosphate. High CD73 expression has been shown to have cancer cell invasion-promoting properties. On the other hand, CD73 is associated with poor prognosis in TNBC. Interestingly, TLR9 and CD73 have been shown to have inverse relationship in T cells and during colonic inflammation. Currently, we study the relationship of CD73 and TLR9 in vitroand in vivo upon BP treatment. Our preliminary results show that TLR9 and CD73 have an inverse relationship also in TNBC cells. We use both nitrogen-containing (zoledronate and alendronate) and pyrophosphate-like (clodronate) BPs together with doxorubicin to study TNBC cell responses. We have seen that zoledronate and alendronate, but not clodronate, inhibited 4T1 murine triple-negative mammary tumor cell proliferation in a dose-dependent manner. Also, high concentrations of zoledronate and alendronate significantly inhibited 4T1 cell migration. Additionally, CD73 shRNA cells are more sensitive to zoledronate and alendronate, showing morphological changes and disruption in actin organization. Our results suggest that CD73 expression may affect treatment responses to BPs in TNBC. Further, low-CD73 tumors could benefit more of BP therapy, compared with high-CD73 tumors. Citation Format: Sandholm JA, Petruk N, Selander KS, Tuomela JM. New biomarkers for adjuvant bisphosphonate use in triple-negative breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-06-23.

Geranylgeraniol (GGOH) as a Mevalonate Pathway Activator in the Rescue of Bone Cells Treated with Zoledronic Acid: An In Vitro Study.

Bisphosphonates (BPs) are the keystone to treat bone disorders. Despite the great benefits of BPs, medication-related osteonecrosis of the jaw (MRONJ) arouse as a potential side effect. Nitrogen-containing BPs (N-BPs) as zoledronate (ZA) act by the inhibition of specific enzymes of the mevalonate pathway resulting in altering protein prenylation which is required for the posttranslational maturation of the small GTP-binding proteins. Geranylgeraniol (GGOH) is an intermediate product in the mevalonate pathway having positive effects on different cell types treated with BPs by salvaging protein prenylation improving cell viability and proliferation in tissue regeneration, thus overcoming N-BP-induced apoptosis. Here, the effect of different concentrations of zoledronate (ZA) on the bone cells has been investigated by cell viability assay, live/dead staining, and western blot to understand if GGOH was able to rescue bone cells and levels of statistical significance were indicated at ∗P < 0.05, ∗∗P < 0.01, ∗∗∗P < 0.001, and ∗∗∗∗P < 0.0001. Although the high concentration of ZA had significantly decreased the cell viability in the bone cells, GGOH reversed the action of ZA on the cells while at very high concentration; it caused severe reduction in the cell viability. Rap1A, a member of the GTPases family, was expressed in the negative controls but was absent in cells treated with high concentrations of ZA. The addition of GGOH had increased the expression of Rap1A up to a certain limit. The experiments proved that ZA acts directly on the mevalonate pathway and protein prenylation and that GGOH could be applied as a future local therapy to MRONJ.

Apoptosis repressor with caspase recruitment domainenhances survival and promotes osteogenic differentiation of human osteoblast cells under Zoledronate treatment.

Zoledronate is one of the most potent nitrogen-containing bisphosphonates which has been demonstrated to result in osteoblast apoptosis and impact osteogenic differentiation in vitro. This effect of Zoledronate on osteoblasts may partially explain bisphosphonate-associated osteonecrosis of the jaw, a serious complication associated with treatment with bisphosphonates. Apoptosis repressor with caspase recruitment domain (ARC) is a multifunctional inhibitor of apoptosis that is physiologically expressed predominantly in post-mitotic cells such as cardiomyocytes, neurons and skeletal muscle cells. However, its effect on human osteoblasts remains unclear. The current study aimed to investigate the effects of ARC on human osteoblasts under the treatment of high concentrations of Zoledronate. ARC-overexpressed human osteoblasts were established and were exposed to Zoledronate with different concentrations (0, 1 and 5 µM) in vitro. Cell numbers were detected using the MTT assay, and flow cytometry was used to identity cell apoptosis. Alkaline phosphatase staining, quantitative analysis and ectopic osteogenesis in nude mice were used to evaluate the osteogenic differentiation of ARC-overexpressed osteoblasts. It was observed that ARC is able to reverse the inhibitory effect of Zoldronate on osteoblasts. ARC is additionally able to promote osteogenic differentiation of osteoblasts and inhibit their apoptosis. These observations suggest a critical role for ARC in the regulation of human osteoblasts under Zoledronate treatment.

Measurement of Ototoxicity Following Intracochlear Bisphosphonate Delivery.

Assessing the maximum safe dose for local bisphosphonate delivery to the cochlea enables efficient delivery without ototoxicity. Otosclerosis is a disease of abnormal bone metabolism affecting the otic capsule, which can cause conductive hearing loss. Larger otosclerotic lesions involving the cochlear endosteum and spiral ligament can result in sensorineural hearing loss. Bisphosphonates are used to treat patients with metabolic bone diseases, including otosclerosis. Local delivery is the most efficient way of delivery to the cochlea while avoiding systemic side effects. To attain intracochlear bisphosphonate delivery without ototoxicity, the maximum safe dose of bisphosphonates requires definition. In the present study, we tested increasing concentrations of zoledronate, a third-generation bisphosphonate in an intracochlear delivery system. We measured ototoxicity by monitoring distortion product otoacoustic emissions and compound action potentials. Artificial perilymph and increasing molar concentrations of zoledronate were administered to the cochlea in guinea pigs via a cochleostomy. Hearing was measured at multiple time points. A fluorescently labeled zoledronate derivative (6-FAM-ZOL) was coadministered as an internal control for drug delivery. Specimens embedded in the resin blocks were ground to a mid-modiolar section and fluorescent photomicrographs were taken. No significant shift in hearing was observed in animals treated either with artificial perilymph or with 4% of the human systemic zoledronate dose. However, compound action potentials thresholds increased during infusion of 8% of the human systemic zoledronate dose, improved 4 hours later, and then increased again 4 weeks later. Using fluorescent photomicrography, intracochlear bisphosphonate delivery up to the apical cochlear turn was confirmed by visualizing 6-FAM-ZOL. These findings provide reference values for intracochlear bisphosphonate delivery in the treatment of cochlear otosclerosis and describe a useful method for tracking cochlear drug delivery.

Aminobisphosphonates Synergize with Human Cytomegalovirus To Activate the Antiviral Activity of Vγ9Vδ2 Cells

Human Vγ9Vδ2 T cells are activated through their TCR by neighboring cells producing phosphoantigens. Zoledronate (ZOL) treatment induces intracellular accumulation of the phosphoantigens isopentenyl pyrophosphate and ApppI. Few attempts have been made to use immunomanipulation of Vγ9Vδ2 lymphocytes in chronic viral infections. Although Vγ9Vδ2 T cells seem to ignore human CMV (HCMV)-infected cells, we examined whether they can sense HCMV when a TCR stimulus is provided with ZOL. Fibroblasts treated with ZOL activate Vγ9Vδ2 T cells to produce IFN-γ but not TNF. Following the same treatment, HCMV-infected fibroblasts stimulate TNF secretion and an increased production of IFN-γ, indicating that Vγ9Vδ2 cells can sense HCMV infection. Increased lymphokine production was observed with most clinical isolates and laboratory HCMV strains, HCMV-permissive astrocytoma, or dendritic cells, as well as "naive" and activated Vγ9Vδ2 cells. Quantification of intracellular isopentenyl pyrophosphate/ApppI following ZOL treatment showed that HCMV infection boosts their accumulation. This was explained by an increased capture of ZOL and by upregulation of HMG-CoA synthase and reductase transcription. Using an experimental setting where infected fibroblasts were cocultured with γδ cells in submicromolar concentrations of ZOL, we show that Vγ9Vδ2 cells suppressed substantially the release of infectious particles while preserving uninfected cells. Vγ9Vδ2 cytotoxicity was decreased by HCMV infection of targets whereas anti-IFN-γ and anti-TNF Abs significantly blocked the antiviral effect. Our experiments indicate that cytokines produced by Vγ9Vδ2 T cells have an antiviral potential in HCMV infection. This should lead to in vivo studies to explore the possible antiviral effect of immunostimulation with ZOL in this context.

Strontium and zoledronate hydroxyapatites graded composite coatings for bone prostheses

Both strontium and zoledronate (ZOL) are known to be useful for the treatment of bone diseases associated to the loss of bone substance. In this work, we applied an innovative technique, Combinatorial Matrix-Assisted Pulsed Laser Evaporation (C-MAPLE), to deposit gradient thin films with variable compositions of Sr-substituted hydroxyapatite (SrHA) and ZOL modified hydroxyapatite (ZOLHA) on Titanium substrates. Compositional gradients were obtained by simultaneous laser vaporization of the two distinct material targets. The coatings display good crystallinity and granular morphology, which do not vary with composition. Osteoblast-like MG63 cells and human osteoclasts were co-cultured on the thin films up to 21days. The results show that Sr counteracts the negative effect of relatively high concentration of ZOL on osteoblast viability, whereas both Sr and ZOL enhance extracellular matrix deposition. In particular, ZOL promotes type I collagen production, whereas Sr increases the production of alkaline phosphatase. Moreover, ZOL exerts a greater effect than Sr on osteoprotegerin/RANKL ratio and, as a consequence, on the reduction of osteoclast proliferation and activity. The deposition method allows to modulate the composition of the thin films and hence the promotion of bone growth and the inhibition of bone resorption.

Zoledronate but not denosumab suppresses macrophagic differentiation of THP-1 cells. An aetiologic model of bisphosphonate-related osteonecrosis of the jaw (BRONJ).

Bisphosphonates and denosumab are antiresorptive drugs used for the treatment of osteoporosis and oncological tumors. A severe side effect is osteonecrosis of the jaw. Monocyte/macrophage dysfunction is considered to play a distinct role in osteonecrosis. THP-1 monocytic cells were used in this study to elucidate the influence of zoledronate and denosumab on phorbol-12-myrisate-13-acetate (PMA)-induced macrophage differentiation and function in real-time. Macrophagic differentiation of the THP-1 suspension cells was measured by cell adherence in the presence or absence of different concentrations of zoledronate (0.5, 5, 50μM) and denosumab (1, 10, 20, 40μg/mL) using the real-time xCELLigence system. Additionally, a live/dead staining was performed by fluorescence microscopy. THP-1 cells demonstrated a regular initial PMA-induced differentiation to macrophages by live measurements of cell adherence and by an increase in CD68 surface expression as detected by flow cytometry. The addition of zoledronate led to cell detachment of the THP-1-derived macrophages in a dose-dependent manner in contrast to denosumab. Cell detachment was based on cell death as confirmed by live/dead staining, revealing elevated numbers of dead cells following addition of high zoledronate concentrations. However, denosumab did not deteriorate THP-1 cell viability. Our results demonstrate that zoledronate but not denosumab suppresses monocytic THP-1 cell viability after macrophagic differentiation dose-dependently. This is the first real-time study providing evidence for a dose-dependent immunosuppressive effect of zoledronate in contrast to denosumab on local macrophages.

Bone Formation on Biomimetic Calcium Phosphate–Coated and Zoledronate-Immobilized Titanium Implants in Osteoporotic Rat Tibiae

Coating prostheses with calcium phosphate (CaP) can boost ossification and provide an appropriate vehicle for drug delivery. In this study, CaP coating was performed using a biomimetic method, and zoledronate (ZOL) was incorporated to promote peri-implant bone formation in an osteoporotic environment. Twenty female 8-week-old rats were ovariectomized to induce osteoporosis. Twelve weeks later, the animals were randomly separated into four groups representing different ZOL concentrations in the immersion solution: 0 (control), 8, 80, and 800 μg/mL. Surface-treated implants were inserted in both tibiae, and the rats were sacrificed 8 weeks after implantation. Specimens were retrieved for histomorphometric and microcomputed tomographic analyses. A thin CaP coating was formed on the surface of the titanium implants, and ZOL was successfully incorporated into the structure of the biomimetic CaP coating. There were significant differences between the groups with regard to bone volume, whereas bone-implant contact comparisons did not yield any significant differences. The microstructural results clearly illustrated the positive effect of ZOL loading on the implants, as compared to the controls. The data suggest that biomimetic CaP coating followed by bisphosphonate immobilization is effective in improving bone quality and preserving bone volume around dental implants; therefore, this technique may be beneficial for osteoporosis patients.

Low Zoledronate Concentrations Stimulate Human Keratinocyte Proliferation

Aim: To evaluate, in an in vitro wound healing model, the effect of zoledronate on keratinocyte cellular behavior. -Materials and Methods: Human spontaneously immortalized keratinocytes (HaCaT) were treated with low zoledronate concentrations (10 nmol/l to 10 µmol/l) and its effect on cell proliferation was evaluated by means of a fluorescent assay (Tox-8), along with the analysis of cytokeratin 5 and filaggrin gene expression. Moreover, zoledronate effects on cell migration were evaluated by in vitro wound healing, and matrix metalloproteinase (MMP) activity was investigated by gelatin zymography. Results: At the tested concentrations, zoledronate stimulated keratinocyte proliferation, upregulating cytokeratin 5 while downregulating filaggrin expression and wound healing ability, without any significant effect on MMP-9 activity. The lack of zoledronate effects on MMP-9 activity indicates that, in our experimental model, wound closure is mainly due to an increase in cell proliferation rather than an increase in cell migration. Moreover, the observed increase in cell proliferation could be ascribed to a zoledronate-mediated reduction of farnesyl pyrophosphate endogenous levels. Conclusions: These results could foster new clinical applications for this ‘old' drug in the field of epithelial regeneration.

Effect of low level laser therapy and zoledronate on the viability and ALP activity of Saos-2 cells

A limited number of clinical studies indicate the supportive role of low level laser therapy (LLLT) on medical and/or surgical approaches carried out in treatment modalities for bisphosphonate related necrosis of jaws (BRONJ), the most common side effect of bisphosphonates used to inhibit bone resorption. The purpose of this study was to investigate the effects of LLLT on cell proliferation and alkaline phosphatase (ALP) activity of human osteoblast-like cells (Saos-2) treated with different doses of zoledronate, the most potent bisphosphonate. Saos-2 cells were treated with different concentrations of zoledronate and were irradiated with diode laser (wavelength 808nm, 10s, 0.25 or 0.50W). Cell numbers and ALP activity of the cells were determined. LLLT mildly increased the proliferation rate or ALP activity, while zoledronate reduced both. When applied together, LLLT lessened the detrimental effects of zoledronate and improved cell function and/or proliferation. Based on the results of this study, it was concluded that LLLT has biostimulative effects on Saos-2 cells, even after treatment with zoledronate. LLLT may serve as a useful supportive method for BRONJ treatment through enhancement of healing by osteoblasts.

Zoledronate, ibandronate and clodronate enhance osteoblast differentiation in a dose dependent manner – A quantitative in vitro gene expression analysis of Dlx5, Runx2, OCN, MSX1 and MSX2

Bisphosphonates are widely used in the clinical treatment of bone diseases with increased bone resorption. In terms of side effects, they are known to be associated with osteonecrosis of the jaw (BONJ). There are two groups of bisphosphonates: the nitrogen-containing bisphosphonates, e.g. zoledronate and ibandronate, and the non-nitrogen-containing bisphosphonates, e.g. clodronate. Their impact on bone metabolism seems to differ. The objective of this study was to compare the osteogenic differentiation potency of these two pharmacologic groups. Human osteoblasts were stimulated with zoledronate and ibandronate at concentrations of 5 × 10 −5 M, 5 × 10 −6 M and 5 × 10 −7 M over the experimental periods of 1, 2, 5, 10 and 14 days. Clodronate was applied with concentrations of 5 × 10 −3, 5 × 10 −5 M and 5 × 10 −6 M. At each time point, the cells were dissolved, the mRNA extracted, and the gene expression level of the osteoblast specific differentiation markers of the homeobox transcription factors MSX1 and MSX2, the distal-less homeobox 5 (Dlx5), the Runt-related transcription factor 2 (Runx2/CBF1a) and osteocalcin (OCN) were quantified by Real-Time PCR. The gene expression was compared to an unstimulated osteoblast cell culture as control. The results showed a significant difference between the nitrogen-containing and the non-nitrogen-containing bisphosphonates. Zoledronate and ibandronate at concentrations of 5 × 10 −5 M enhanced the gene expression of all differentiation markers by several hundred folds compared to unstimulated control after 10 days, whereas clodronate had less influence on gene expression, even at higher concentrations of 5 × 10 −3 M. Lower concentrations of zoledronate and ibandronate, however, led to a decreased gene expression. These data confirm the results of other studies which have shown the osteogenic stimulus on osteoblasts in a dose dependent manner. The nitrogen-containing bisphosphonates appear to enhance bone density by stimulation of osteoblast differentiation. Non-nitrogen-containing bisphosphonates seem to have less influence on osteoblast differentiation.

The response of dental pulp-derived cells to zoledronate depends on the experimental model

To investigate whether zoledronate (ZOL) can cause a cytotoxic response in dental pulp-derived cells (DPCs) in vitro. Cell activity was assessed utilizing MTT tests, (3) [H]thymidine, and (3) [H]leucine incorporation assays in human DPCs in response to ZOL. Cell activity assays were also preformed on calcium phosphate-coated plates. Cell death was analysed with annexin V/propidium iodide, trypan blue staining and Western blot analysis. Micromolar concentrations of ZOL were required to decrease the activity of DPCs. The decreased activity of DPCs was associated with the occurrence of apoptosis and necrosis. No adverse effects were observed when DPCs were cultured on calcium phosphate-coated plates with ZOL. High concentrations of soluble ZOL were required to cause adverse effects in vitro. These adverse effects are abolished when the bisphosphonate was bound to a mineralized surface. However, the clinical relevance of these results remains to be determined.

Abstract 1461: Zoledronate inhibits proliferation and invasion of inflammatory breast cancer cells

Abstract Introduction: Inflammatory breast cancer (IBC) is aggressive, as approximately one third of patients present with distant metastases. Bisphosphonates are often administered to breast cancer patients for cancer-induced osteolysis. Recent evidence suggests bisphophanates may also have anti-tumor properties. This study examined the effects of the bisphosphonate, zoledronate (ZA), on the proliferation and invasive capabilities of highly aggressive IBC cell lines. Methods: The IBC cell line SUM149 was cultured utilizing both adherent and serum-free, non-adherent cancer stem cell enriching conditions. An MTT assay was used to quantify proliferation and mammosphere formation of cells. Adherent cell growth was measured at days 1-4 following 0, 0.1, 1, 5, 10, 50 and 100uM zelodronate treatment. Mammosphere formation was measured at 10 days following 0, 0.01, 0.1, 1, 10, and 100uM ZA treatment. Modified Boyden chambers were employed to assess the ability of both adherent and non-adherent cells to invade to SDF-1 (100ng/mL) following 24 hour 1uM ZA treatment. Protein expression was assessed using immunofluorescent staining, protein arrays and Western blotting. Results: ZA treatment with &amp;lt;5uM did not inhibit SUM149 adherent cell growth at any of the measured time points. ZA concentrations ≥10uM significantly inhibited SUM149 adherent cell growth at day 4 (p≤0.05). SUM 149 mammosphere formation was significantly inhibited following 10uM ZA treatment (p≤0.001). However, significantly more SUM149 non-adherent cells invaded to SDF-1 compared to adherent cells (p≤0.001). SUM 149 non-adherent cell invasion was inhibited by 24 hour 1uM ZA treatment (p≤0.001). SUM 149 non-adherent cells expressed significantly increased levels of the epithelial-mesenchymal transition (EMT) associated proteins smooth muscle actin (SMA), fibronectin, and N-Cadherin. The increased expression of SMA, fibronectin, and N-Cadherin observed in non-adherent cells returned to levels comparable to adherent cells following 24 hour 1uM ZA treatment. Conclusions: ZA inhibited the growth of IBC cells grown under adherent and non-adherent conditions. SUM 149 non-adherent cells had much greater invasive potential than adherent cells did, and their invasive capability was inhibited following low dose ZA treatment. Interestingly, ZA inhibited up-regulation of EMT associated proteins SMA, fibronectin, and N-Cadherin in SUM 149 non-adherent cells. These results indicate that some IBC cells grown under cancer stem cell enriching conditions have the potential to undergo EMT and invade. ZA may also inhibit metastases through novel mechanisms. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1461.

Enhancement of Periprosthetic Bone Quality with Topical Hydroxyapatite-Bisphosphonate Composite

Implant loosening is associated with inflammatory bone loss induced by ultra-high molecular weight polyethylene wear debris. We hypothesized that a hydroxyapatite-bisphosphonate composite improves periprosthetic bone quality and osseous integration of an intramedullary implant even in the presence of ultra-high molecular weight polyethylene particles in an experimental rat femur model. A preliminary in vitro study determined the optimal concentration of zoledronate (50 microM) that would maximally decrease osteoclasts without harming osteoblasts. Hydroxyapatite-coated intramedullary nails were implanted bilaterally in the femora of sixteen rats (the control group), and hydroxyapatite-zoledronate-coated nails were implanted bilaterally in the femora of sixteen rats (the experimental group). Ultra-high molecular weight polyethylene particles were introduced into the femoral canal before implantation. Eight rats from each group were killed at six weeks, and the remaining rats were killed at six months. Periprosthetic bone mass was analyzed by dual x-ray absorptiometry and microcomputed tomography. Osseous integration was examined by biomechanical testing of pullout strength. The mean bone area (and standard deviation) in the periprosthetic bone region was significantly greater (p < 0.0001) in the hydroxyapatite-zoledronate group (2.388 +/- 0.960 mm2) than in the control group (0.933 +/- 0.571 mm2). This difference was larger in the six-week group than in the six-month group (p = 0.03). The average peak pullout force for the treated femora (241.0 +/- 95.1 N) was significantly greater (p < 0.0001) than that for the controls (55.6 +/- 49.0 N). This difference was similar in the six-week and six-month groups. The energy required for nail pullout was significantly greater (p < 0.0001) for the treated femora (521.6 +/- 293.8 N-mm) than for the controls (142.2 +/- 152.1 N-mm). This difference in energy to pullout was similar in the six-week and six-month groups. Regression analysis demonstrated a high correlation between periprosthetic bone mass and peak pullout force for both the six-week (r = 0.766, p = 0.0005) and six-month (r = 0.838, p < 0.0001) groups. Surface modification of implants with hydroxyapatite-zoledronate improves periprosthetic bone quality and osseous integration. Hydroxyapatite-based site-specific delivery of bisphosphonates may be one way of reducing ultra-high molecular weight polyethylene wear particle-induced periprosthetic osteolysis and implant loosening.

In Vivo and In Vitro Efficacy of Zoledronate for Treating Oral Squamous Cell Carcinoma in Cats

Feline oral squamous cell carcinoma (OSCC) may cause painful bone destruction. Given the local invasiveness and rapid clinical progression of OSCC, conventional therapies are often palliative. In human cancer patients, zoledronate exerts anticancer effects by inhibiting tumor-induced angiogenesis and malignant osteolysis. Zoledronate will exert in vitro and in vivo anti-angiogenic and antiresorptive effects in feline OSCC. Eight cats with OSCC were prospectively treated with zoledronate and conventional treatment modalities. In vitro, zoledronate's effects in modulating soluble vascular endothelial growth factor (VEGF) secretion and receptor activator of nuclear factor kappaB (NF-kappaB) ligand (RANKL) expression were investigated in a feline OSCC cell line (SCCF1). In vivo, basal serum C-telopeptide (CTx) concentrations were compared among normal and OSCC-bearing cats, and the biologic effects of zoledronate administration in cats with naturally occurring OSCC were quantified by serially assessing circulating serum VEGF and CTx concentrations. In vitro, zoledronate concentrations greater than 3 microM reduce soluble VEGF secretion in the SCCF1 cell line. The expression of RANKL in the SCCF1 cell line was also modulated by zoledronate, with low concentrations (3 microM) decreasing but higher concentrations (30 microM) increasing RANKL expression in comparison with untreated cells. In vivo, cats with bone-invasive OSCC had greater serum CTx concentrations in comparison with geriatric, healthy controls. Treatment with zoledronate rapidly decreased circulating serum VEGF and CTx concentrations in cats with spontaneously occurring OSCC. Zoledronate exerts in vitro and in vivo effects that may favor the slowing of tumor growth and pathologic bone turnover associated with OSCC.