Publications (86)312.05 Total impact
- [Show abstract] [Hide abstract] ABSTRACT: Osteonecrosis of the jaw has been reported in patients receiving high doses of intravenous nitrogen-containing bisphosphonates (N-BPs) because of malignant disease. The exact pathomechanisms have been elusive and questions of paramount importance remain unanswered. Recent studies have indicated toxic effects of bisphosphonates on different cell types, apart from osteoclast inhibition. Multipotent stem cells play an important role in the processes of wound healing and bone regeneration, which seem to be especially impaired in the jaws of patients receiving high doses of N-BPs. Therefore, the aim of the present study was to investigate the effects of different bisphosphonate derivatives and dose levels combined with varying pH levels on the mesenchymal stem cells in vitro. The effect of 2 N-BPs (zoledronate and ibandronate) and 1 non-N-BP (clodronate) on immortalized mesenchymal stem cells was tested at different concentrations, reflecting 1, 3, and 6 months and 1, 3, 5, and 10 years of exposure to standard oncology doses of the 2 N-BPs and equimolar concentrations of clodronate at different pH values (7.4, 7.0, 6.7, and 6.3). Cell viability and activity were analyzed using a WST assay. Cell motility was investigated using scratch wound assays and visualized using time-lapse microscopy. Both types of bisphosphonates revealed remarkable differences. Zoledronate and ibandronate showed a dose- and pH-dependent cellular toxicity. Increasing concentrations of both N-BPs and an acidic milieu led to a significant decrease in cell viability and activity (P < .01), with more pronounced effects for zoledronate. Equimolar concentrations of clodronate did not affect the cell survival or activity significantly, apart from the effect of pH reduction itself, which was also detectable in the patients in the control group who did not receive bisphosphonates. Our results have shown that high concentrations of N-BPs and a local acidic milieu, which is commonly present in infections of the jaw, might play a key role in the pathogenesis of osteonecrosis of the jaw in patients receiving high doses of N-BPs for malignant diseases. Also the potency of N-BPs might be different, suggesting a greater risk of osteonecrosis of the jaw with zoledronate.
- [Show abstract] [Hide abstract] ABSTRACT: The aim of this study was to investigate the effects of the bisphosphonate ibandronate (IBN) in a male osteoporosis animal model. Two studies were performed in 9-month-old orchidectomised (ORX) or sham-operated rats. In prevention study, subcutaneous IBN was administered daily (1 μg/kg) or monthly (28 μg/kg every 28 days) starting on day of surgery for 5 months. In treatment study, the same treatment started 6 months after ORX. After sacrifice, bone analyses by dual-energy X-ray absorptiometry, 3-dimensional micro-computed tomography, and 3-point bending were performed in femora or vertebrae. Serum tartrate-resistant acid phosphatase 5b (TRAP-5b) and aminoterminal propeptide of collagen I (PINP) were analysed for resorption and osteocalcin (BGP) for bone formation. In both studies, ORX resulted in significant femoral and vertebral bone loss and microarchitectural deterioration after 5 months of ORX, and became more pronounced after 11 months. Biomechanical strength was also decreased. Serum levels for TRAP-5b and BGP increased while PINP levels were reduced or unchanged. Both daily and monthly IBN prevented or even restored ORX-induced changes in both studies, with the intermittent regimen showing a improvement in efficacy with respect to many of the biomechanical parameters.
- [Show abstract] [Hide abstract] ABSTRACT: We previously found that bone loss occurs as soon as 1 month after ovariohysterectomy (OHX) in beagle dogs. Indirect evidence pointed to an early dramatic increase in bone resorption. To verify this hypothesis and evaluate the effects of a newly developed bisphosphonate, BM 21.0955 (Boehringer Mannheim), 36 beagle dogs were subjected to OHX and 12 dogs were sham operated (Sham). OHX dogs were divided into six groups (n = 6 each) and received subcutaneous injections of vehicle or BM 21.0955 at various doses (0.1, 0.3, 1, 10, and 100 micrograms/kg/day) for 1 month. Sham dogs were given vehicle (n = 6) or BM 21.0955 (1 microgram/kg/day, n = 6). Iliac crest biopsies and blood drawings were done at baseline and at month 1. OHX dogs given vehicle exhibited a decrease in cancellous bone volume associated with an increase in erosion depth and a decrease in serum levels of 1,25-dihydroxyvitamin D. BM 21.0955 prevented the bone loss at a dose > or = 1 microgram/kg and the increase in erosion depth and the decrease in serum levels of 1,25-(OH)2D at a dose > or = 0.3 microgram/kg. No osteomalacia was observed at any dose of BM 21.0955. Bone turnover was reduced only when BM 21.0955 was administered at doses of 10 or 100 micrograms/kg. There were no changes in body weight or serum levels of calcium, phosphorus, creatinine, parathyroid hormone, or osteocalcin in all groups. The increase in erosion depth in OHX dogs given vehicle proves that the early rapid bone loss after cessation of ovarian function is related to an increase in osteoclastic activity. The antiosteoclastic activity of BM 21.0955 at a dose > or = 1 microgram/kg prevents this increase and preserves bone volume. The absence of any signs of osteomalacia at any dose confers a relatively wide therapeutic margin to BM 21.0955. BM 21.0955 at a dose > or = 10 micrograms/kg also acts as an inhibitor of bone turnover. This is not observed at a dose of 1 microgram/kg, at least after 1 month of administration.
- [Show abstract] [Hide abstract] ABSTRACT: A total of 300 new bisphosphonates were screened for their effect on bone resorption in the rat. Among these, 1-hydroxy-3-(methylpentylamino)propylidenebisphosphonate (BM 21.0955) was selected for detailed investigation. It inhibited arotinoid-stimulated bone resorption as assessed by calcemia in thyroparathyroidectomized rats at a SC dose as low as 0.001 mg P (0.016 mumol) per kg body weight per day. The compound was thus about 2, 10, 50, and 500 times more potent than risedronate, alendronate, pamidronate, and clodronate, respectively. Intravenous administration was as effective as subcutaneous, and oral administration was 100 times less effective. The effect after one administration decreased with time but was still measurable after 2 weeks. Nonstimulated bone resorption assayed by the urinary excretion of radiolabeled tetracycline from lifelong prelabeled animals was also inhibited. This effect started 3 days after a single dose and was still maximal after 7 days. Histomorphometric analysis of the tibial metaphysis in growing intact rats also showed an inhibition of bone resorption along with an increase in bone mass. The number of osteoclasts increased in animals treated with 0.01 and 0.1 mg P per kg (0.16 and 1.6 mumol/kg) body weight SC but decreased in animals given 1 mg P per kg (16.1 mumol/kg), showing that the inhibition of bone resorption was not due to an inhibition of osteoclast recruitment. No inhibition of mineralization occurred. This new bisphosphonate appears to have great potential for use in human bone disease.
- [Show abstract] [Hide abstract] ABSTRACT: Using a nude rat model of site-specific metastatic bone disease (MBD), we developed a semiquantitative histological score for rapid assessment of lytic lesions in bone. This provides additional information to conventional histological measurement by clarifying the extent and location of metastatic infiltration and the tumor growth pattern. The score can also be used to assess the action of bisphosphonates on bone metastases. Male nude rats (n = 12 per group) were inoculated with the human breast cancer cell line MDA-MB-231 via the femoral artery. Following appearance of radiographically visible osteolytic lesions on day 18, the animals received phosphate-buffered saline (PBS; controls) or ibandronate (IBN, 10 microg P/kg) daily until day 30. Whole body radiographs were obtained on days 18 and 30, and osteolytic areas (OA) were determined by radiographic computer-based analysis (CBA). On day 30, MBD was assessed in both tibias using conventional histological CBA and the new scoring system. Metastatic tumor area correlated with the total sum of the new score in both PBS- (r = 0.762) and IBN-treated animals (r = 0.951; p < 0.001). OA correlated well with the total sum in both groups (r = 0.845 and 0.854, respectively; p < 0.001). Conclusion: Significant reduction of bone marrow and cortical infiltration of tumor cells with IBN suggested local control of metastases.
- [Show abstract] [Hide abstract] ABSTRACT: Intravenous bisphosphonates may be involved in the development of osteonecrosis of the jaw (ONJ). However, a mechanistic causality has not been demonstrated. To evaluate whether there is higher drug uptake by the jaw versus other bones that might be involved in ONJ pathogenesis, we performed a pilot experiment comparing ibandronate uptake in rat mandible, femur, and lumbar vertebrae after repeated administration. Rats (n = 1/group) received daily subcutaneous injections of ibandronate in doses ranging from 0.003 to 0.3 mg/kg/day for 9 days. Five days after the last injection, the animals were killed and the right femur, lumbar vertebrae L3-L5, and the right mandible were removed. After cleaning and drying, bone dry weight was recorded, and ibandronate concentration was determined in whole-bone hydrolyzates by gas chromatography mass spectrometry. Concentrations of ibandronate increased dose-dependently in all bones with similar concentrations per bone at each dose level ranging from values below quantification limit (low dose) up to approximately 10 ng ibandronate/mg bone dry weight (high dose). In this rat study, there was a relatively similar bisphosphonate uptake between the femur and lumbar vertebrae bones whereas the uptake in the jaw was statistically smaller with regard to the absolute values (P < 0.05). Thus, there is no suggestion of preferential bisphosphonate uptake in the jaw.
- [Show abstract] [Hide abstract] ABSTRACT: Bisphosphonates are potent inhibitors of osteoclast-mediated bone resorption and play an important role in the treatment of osteoporosis, metastatic bone disease, and Paget disease. However, nephrotoxicity has been reported with some bisphosphonates. Nitrogen-containing bisphosphonates directly inhibit farnesyl diphosphate (FPP) synthase activity (mevalonate pathway) and reduce protein prenylation leading to osteoclast cell death. The aim here was to elucidate if this inhibition also occurs in kidney cells and may directly account for nephrotoxicity. In an exploratory study in rats receiving zoledronate or ibandronate an approximate 2-fold increase in FPP synthase mRNA levels was observed in the kidney. The involvement of the mevalonate pathway was confirmed in subsequent in vitro studies with zoledronate, ibandronate, and pamidronate, using the non-nitrogen containing bisphosphonate clodronate as a comparator. In vitro changes in FPP synthase mRNA expression, enzyme activity, and levels of prenylated proteins were assessed. Using two cell lines (a rat normal kidney cell line, NRK-52E, and a human kidney proximal tubule cell line, HK-2), ibandronate and zoledronate were identified as most cytotoxic (EC50: 23/>1000 microM and 16/82 microM, respectively) and as the most potent inhibitors of FPP synthase (IC50; 1.6/7.4 microM and 0.5/0.7 microM, respectively). In both cell lines, inhibition of FPP synthase activity occurred prior to a decrease in levels of prenylated proteins followed by cytotoxicity. This further supports that the mechanism responsible for osteoclast inhibition (therapeutic effect) might also underlie the mechanism of nephrotoxicity.
- [Show abstract] [Hide abstract] ABSTRACT: Over half of all chronic cancer pain arises from metastases to bone and bone cancer pain is one of the most difficult of all persistent pain states to fully control. Currently, bone pain is treated primarily by opioid-based therapies, which are frequently accompanied by significant unwanted side effects. In an effort to develop nonopioid-based therapies that could rapidly attenuate tumor-induced bone pain, we examined the effect of intravenous administration of the bisphosphonate, ibandronate, in a mouse model of bone cancer pain. Following injection and confinement of green fluorescent protein-transfected murine osteolytic 2472 sarcoma cells into the marrow space of the femur of male C3H/HeJ mice, ibandronate was administered either as a single dose (300 microg/kg), at Day 7 post-tumor injection, when tumor-induced bone destruction and pain were first evident, or in three consecutive doses (100 microg/kg/day) at Days 7, 8, and 9 post-tumor injection. Intravenous ibandronate administered once or in three consecutive doses reduced ongoing and movement-evoked bone cancer pain-related behaviors, neurochemical markers of central sensitization, tumor burden, and tumor-induced bone destruction. These results support limited clinical trials that suggest the potential of ibandronate to rapidly attenuate bone pain and illuminate the mechanisms that may be responsible for limiting pain and disease progression.
- [Show abstract] [Hide abstract] ABSTRACT: Bisphosphonates (BPs) are powerful inhibitors of bone resorption. They exert a strong affinity to bone mineral which allows the rapid and selective targeting to bone in vivo. We synthesized and evaluated two new classes of compounds: phosphono succinic acid (PSA) and phosphono glutaric acid (PGA) derivatives. In order to transfer the antiresorptive properties of bisphosphonates attempts have been made to elucidate the key elements of the putative BP pharmacophore. Whereas the new compounds revealed similar or better bone mineral affinity properties than BPs in vitro, the inhibition of endogenous bone resorption in vivo was less effective, but in contrast to BPs the effects were reversible after discontinuation of treatment, which suggests that these compounds are metabolically degradable.
- [Show abstract] [Hide abstract] ABSTRACT: Bisphosphonates, like ibandronate (Bondronat), represent the mainstay of treatment for metastatic bone disease. Ibandronate selectively binds to bone mineral and prevents osteoclast-mediated skeletal destruction. This review describes the preclinical and clinical profiles of ibandronate for treatment of cancer metastatic to bone. In preclinical studies ibandronate reduced metastatic processes and tumor growth, induced tumor cell apoptosis, decreased bone pain, and enhanced biomechanical indices. Skeletal destruction was completely prevented with ibandronate, and this directly correlated with histomorphometry and markers of bone turnover. Ibandronate efficacy in combination with anti-cancer therapies is discussed. Preclinical studies demonstrated that ibandronate does not compromise safety, including renal health. Intravenous and oral ibandronate had comparable efficacy in three Phase III clinical trials. Ibandronate achieved significant risk reductions in the incidence of skeletal-related events and bone pain. In additional clinical studies, ibandronate reduced markers of bone turnover. Furthermore, loading-dose ibandronate rapidly reduced bone pain in Phase II trials. Adjuvant trials are ongoing. The clinical safety profile (including a 4-year follow-up study) has demonstrated renal health is maintained with ibandronate. Overall, ibandronate preserves skeletal integrity, has a favorable safety profile, maintains renal function, and can rapidly reduce and maintain bone pain below baseline levels in patients with cancer metastatic to bone.
- [Show abstract] [Hide abstract] ABSTRACT: The Göttingen minipig is one of the few large animal models that show glucocorticoid (GC)-induced bone loss. We investigated whether GC-induced loss of bone mineral density (BMD) and bone strength in minipigs can be recovered by treatment with the bisphosphonate ibandronate (IBN). 40 primiparous sows were allocated to 4 groups when they were 30 months old: GC treatment for 8 months (GC8), for 15 months (GC15), GC treatment for 15 months plus IBN treatment for months 8-15 (GC&IBN), and a control group without GC treatment. Prednisolone was given at a daily oral dose of 1 mg/kg body weight for 8 weeks and thereafter 0.5 mg/kg body weight. IBN was administered intramuscularly and intermittently with an integral dose of 2.0 mg/kg body weight. BMD of the lumbar spine (L1-3) was assessed in vivo by Quantitative Computed Tomography (QCT) at months 0, 8, and 15. Blood and urine samples were obtained every 2-3 months. After sacrificing the animals lumbar vertebrae L4 were tested mechanically (Young's modulus and ultimate stress). Histomorphometry was performed on L2 and mineral content determined in ashed specimens of T12 and L4. In the GC&IBN group, the GC associated losses in BMD of -10.5%+/-1.9% (mean+/-standard error of the mean, p<0.001) during the first 8 months were more than recovered during the following 7 months of IBN treatment (+14.8%+/-1.2%, p<0.0001). This increase was significantly larger (p<0.0001) than the insignificant +2.1%+/-1.2% change in group GC15. At month 15, the difference between groups GC&IBN and GC15 was 22% (p<0.01) for BMD, 48% (p<0.05) for Young's modulus, and 31% (p<0.14) for ultimate stress; bone-specific alkaline phosphatase showed trends to lower values (p<0.2) while deoxypyridinoline was comparable. This minipig study demonstrates that GC-induced impairment of bone strength can be effectively and consistently treated by IBN. GC&IBN associated alterations in BMD and bone turnover markers can be monitored in vivo using QCT of the spine and by biochemical analyses, reflecting the changes in bone strength.
- [Show abstract] [Hide abstract] ABSTRACT: Osteoporosis is a skeletal disorder characterized by low bone mass and deterioration of bone microarchitecture resulting in bone fragility, which increases the risk of fracture. The clinical efficacy of bisphosphonates is evaluated through improvements in bone mineral density (BMD) and reductions in the risk for fracture. However, as bisphosphonates are administered long term, there is increasing interest in their effects on bone quality, which includes bone mass, strength and architecture. Ibandronate is a potent, nitrogen-containing bisphosphonate with significant antifracture efficacy when administered daily and in regimens with extended between-dose intervals. Clinical studies with ibandronate are supported by an extensive preclinical program that investigated the efficacy and bone safety of ibandronate in various animal models of osteoporosis. In preclinical studies, treatment with ibandronate maintained, or improved the quality, strength and architecture of bone. Intermittent and daily ibandronate regimens provided similar benefits. During ibandronate treatment, the bone retains its capacity for repair and bone mineralization is not adversely affected. Notably, positive relationships among BMD, bone strength and bone architecture have been demonstrated. This review describes the preclinical evidence for the preservation of bone quality with ibandronate, irrespective of the dosing regimen and even when administered at doses higher than those used therapeutically.
- [Show abstract] [Hide abstract] ABSTRACT: We investigated the effect of ibandronate on three-dimensional (3-D) microstructure and bone mass in experimentally induced tumor osteolysis. Walker carcinosarcoma cells were implanted into the left femur of female rats that received 26-day ibandronate pretreatment followed by continued therapy or ibandronate posttreatment only. A tumor-only group received isotonic saline. At endpoint, excised femurs were scanned using microcomputed tomography (microCT) to assess bone volume density, bone mineral content, trabecular number/thickness, and separation for cortical plus trabecular bone or trabecular bone alone. Compared with the nonimplanted right femur, bone volume and surface density and trabecular number and thickness were reduced in the distal left femur following tumor cell implantation. microCT analysis revealed greater cortical and trabecular bone mineral content in the preventative and interventional (pre-post tumor) ibandronate group, and the interventional (post-tumor) ibandronate group, versus the tumor-only group. Bone volume density was significantly higher in pre-post and post-tumor groups compared to the tumor-only group. After preventative and interventional ibandronate, bone volume density and trabecular thickness were 13% and 60% greater, respectively, than in the post-tumor treatment group. 3-D microCT images confirmed microstructural changes. We conclude that combined interventional and preventative ibandronate preserves bone strength and integrity more than intervention alone.
- [Show abstract] [Hide abstract] ABSTRACT: The local distribution, retention, and effects of intraosseous administration of ibandronate in the infarcted femoral heads were studied. Intraosseous administration effectively delivered and distributed ibandronate in the infarcted femoral heads and decreased the femoral head deformity in a large animal model of Legg-Calve-Perthes disease. Bisphosphonate therapy has gained significant attention for the treatment of ischemic osteonecrosis of the femoral head (IOFH) because of its ability to inhibit osteoclastic bone resorption, which has been shown to contribute to the pathogenesis of femoral head deformity. Because IOFH is a localized condition, there is a need to explore the therapeutic potential of local, intraosseous administration of bisphosphonate to prevent the femoral head deformity. The purpose of this study was to investigate the distribution, retention, and effects of intraosseous administration of ibandronate in the infarcted head. IOFH was surgically induced in the right femoral head of 27 piglets. One week later, a second operation was performed to inject (14)C-labeled or unlabeled ibandronate directly into the infarcted head. (14)C-ibandronate injected heads were assessed after 48 h, 3 weeks, or 7 weeks later to determine the distribution and retention of the drug using autoradiography and liquid scintillation analysis. Femoral heads injected with unlabeled ibandronate were assessed at 7 weeks to determine the degree of deformity using radiography and histomorphometry. Autoradiography showed that (14)C-Ibandronate was widely distributed in three of the four heads examined at 48 h after the injection. Liquid scintillation analysis showed that most of the drug was retained in the injected head, and almost negligible amount of radioactivity was present in the bone and organs elsewhere at 48 h. At 3 and 7 weeks, 50% and 30% of the (14)C-drug were found to be retained in the infarcted heads, respectively. Radiographic and histomorphometric assessments showed significantly better preservation of the infarcted heads treated with intraosseous administration of ibandronate compared with saline (p < 0.001). This study provides for the first time the evidence that local intraosseous administration is an effective route to deliver and distribute ibandronate in the infarcted femoral head to preserve the femoral head structure after ischemic osteonecrosis. In a localized ischemic condition such as IOFH, local administration of bisphosphonate may be preferable to oral or systemic administration because it minimizes the distribution of the drug to the rest of the skeleton and bypasses the need for having a restored blood flow to the infarcted head for the delivery of the drug.
- [Show abstract] [Hide abstract] ABSTRACT: There is evidence that bisphosphonates can improve fixation of cementless metal implants by enhancing the extent of osseointegration. The current preclinical study examined whether the nitrogen-containing bisphosphonate ibandronate can accelerate this process, resulting in early achievement of secondary stability and sealing of the bone-implant interface to prevent wear debris migration. The study was conducted on 88 female Sprague-Dawley rats in which uncoated titanium and hydroxyapatite-coated titanium implants were surgically inserted into the medullary canal of each femur. The animals were randomly assigned to receive subcutaneous treatment with 1.0, 2.5, or 5.0 microg/kg per day ibandronate or saline solution as a control. The extent of osseointegration expressed by the osseointegrated implant surface was quantified by histomorphometry at eleven time points during the study period. To determine the time course of osseointegration, the data were expressed using third-order polynomial regression analysis. For hydroxyapatite-coated implants, the highest dose of ibandronate (5 microg) reduced the time for a sufficient implant fixation of 60% osseointegrated implant surface to 18 days compared to 38 days in the control group. This reduction of 20 days (52.6%) represents a halving in the time required for sufficient osseointegration of the implant. For hydroxyapatite-coated implants and low-dose ibandronate application (1 microg, 2.5 microg) and for uncoated titanium implants, acceleration of osseointegration was not observed in any of the study arms. Continuous treatment with 5 microg/kg per day ibandronate is potent in accelerating osseointegration of hydroxyapatite-coated implants. As a result, improved early secondary stability and prevention of wear debris migration by the sealing of the implant-bone interface can be expected, therefore prolonging the long-term survival of the implant.
- [Show abstract] [Hide abstract] ABSTRACT: Recent studies show that bisphosphonates can decrease the development of femoral head deformity following ischemic osteonecrosis by inhibiting osteoclast-mediated bone resorption. Given the potential new indication, improved understanding of pharmacokinetics of bisphosphonates as it applies to the infarcted head would be beneficial. The purpose of this study was to investigate the local bioavailability and the distribution of ibandronate in the infarcted head at the avascular and vascular phases of the disease process. Ischemic osteonecrosis of the femoral head was surgically induced in 15 piglets. One, 3, and 6 weeks following the induction of ischemia, which represent various stages of revascularization and repair, 14C-labeled ibandronate was administered intravenously. Twenty-four hours following 14C-drug administration, the level of radioactivity and its distribution in the infarcted heads were determined using liquid scintillation analysis and autoradiography. A significant correlation was found between the extent of revascularization and the level of radioactivity measured in the infarcted heads (r=0.80, P<0.05). The radioactivity level in the infarcted heads measured by liquid scintillation was similar to the negative controls at 1 week when revascularization was absent, but it increased significantly at 6 weeks when extensive revascularization was present (P<or=0.00004). Autoradiographic assessment showed similar silver grain counts in the infarcted heads compared to the background at 1 week. At 3 weeks, a significant increase in the silver grain count was observed in the necrotic regions of the infarcted heads compared to the background (P=0.001) even though only a small area of the heads (2%) was found to be revascularized, suggesting diffusion of 14C-drug from the revascularized to the non-revascularized areas of the head. At 6 weeks, extensive 14C-drug binding was observed in the areas of revascularization with preferential binding of 14C-drug to the newly formed bone compared to the remaining necrotic bone (P=0.000001). These results indicate that revascularization and repair produce significant alteration of local bioavailability and distribution of ibandronate in the infarcted head. To our knowledge, this is the first study to examine the local bioavailability and distribution of bisphosphonate in the infarcted head. Current findings have important implications with regard to the timing and dosing of bisphosphonate after the onset of ischemic osteonecrosis.
Ludwig-Maximilians-University of Munich
München, Bavaria, Germany
- Department of Surgery
Alfred HospitalMelbourne, Victoria, Australia
University Hospital FrankfurtFrankfurt, Hesse, Germany
Universität MannheimMannheim, Baden-Württemberg, Germany