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A Model for Osteonecrosis of the Jaw with Zoledronate Treatment following Repeated Major Trauma.

ABSTRACT: This study aims to develop a reproducible rat model for post-traumatic bisphosphonate-related osteonecrosis of the jaw (BRONJ). In our previous studies using dental extraction as an inducing factor, only 30%-60% of zoledronate-treated animals fulfilled the definition of clinical BRONJ. We modified the zoledronate regimen and introduced repeated surgical extraction to illicit quantifiable BRONJ in all animals. Eighty retired-breeder female Sprague-Dawley rats were divided between the treatment (i.v. zoledronate; 80 ?g/kg/week for 13 weeks) and control (saline) groups. On week 13, the left mandibular first molar was surgically extracted, followed by the second molar a week later. Animals were euthanized at 1-week, 2-weeks, and 8-weeks following extraction. The occurrence and severity of BRONJ were scored in each animal based on gross and MicroCT analysis. Parameters of bone formation and osteoclast functions at the extraction site were compared between groups. All zoledronate-treated animals developed a severe case of BRONJ that fulfilled the clinical definition of the condition in humans. Osteoclast attachment continued to be defective eight weeks after stopping the treatment. There were no signs of kidney or liver toxicity. Our data confirmed that repeated surgical extraction (major trauma) by itself consistently precipitated massive bone necrosis in ZA-treated animals, eliminating the need to induce pre-existing infection or comorbidity. These results will be the basis for further studies examining the in-vivo pathogenesis and prevention of BRONJ.

SUBMITTER: Howie RN

PROVIDER: S-EPMC4505856 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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A Model for Osteonecrosis of the Jaw with Zoledronate Treatment following Repeated Major Trauma.

Howie R Nicole RN Borke James L JL Kurago Zoya Z Daoudi Asma A Cray James J Zakhary Ibrahim E IE Brown Tara L TL Raley J Nathan JN Tran Loan T LT Messer Regina R Medani Fardous F Elsalanty Mohammed E ME

PloS one 20150717 7

This study aims to develop a reproducible rat model for post-traumatic bisphosphonate-related osteonecrosis of the jaw (BRONJ). In our previous studies using dental extraction as an inducing factor, only 30%-60% of zoledronate-treated animals fulfilled the definition of clinical BRONJ. We modified the zoledronate regimen and introduced repeated surgical extraction to illicit quantifiable BRONJ in all animals. Eighty retired-breeder female Sprague-Dawley rats were divided between the treatment (i ...[more]

PMID: 26186665

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Project description:Bisphosphonate (BP)-related osteonecrosis of the jaw, previously known as BRONJ, now referred to more broadly as medication-related osteonecrosis of the jaw (MRONJ), is a morbid condition that represents a significant risk for oncology patients who have received high dose intravenous (IV) infusion of a potent nitrogen containing BP (N-BP) drug. At present, no clinical procedure is available to prevent or effectively treat MRONJ. Although the pathophysiological basis is not yet fully understood, legacy adsorbed N-BP in jawbone has been proposed to be associated with BRONJ by one or more mechanisms. We hypothesized that removal of the pre-adsorbed N-BP drug common to these pathological mechanisms from alveolar bone could be an effective preventative/therapeutic strategy. This study demonstrates that fluorescently labeled BP pre-adsorbed on the surface of murine maxillo-cranial bone in vivo can be displaced by subsequent application of other BPs. We previously described rodent BRONJ models involving the combination of N-BP treatment such as zoledronate (ZOL) and dental initiating factors such as tooth extraction. We further refined our mouse model by using gel food during the first 7 days of the tooth extraction wound healing period, which decreased confounding food pellet impaction problems in the open boney socket. This refined mouse model does not manifest BRONJ-like severe jawbone exposure, but development of osteonecrosis around the extraction socket and chronic gingival inflammation are clearly exhibited. In this study, we examined the effect of benign BP displacement of legacy N-BP on tooth extraction wound healing in the in vivo model. Systemic IV administration of a low potency BP (lpBP: defined as inactive at 100 μM in a standard protein anti-prenylation assay) did not significantly attenuate jawbone osteonecrosis. We then developed an intra-oral formulation of lpBP, which when injected into the gingiva adjacent to the tooth prior to extraction, dramatically reduced the osteocyte necrosis area. Furthermore, the tooth extraction wound healing pattern was normalized, as evidenced by timely closure of oral soft tissue without epithelial hyperplasia, significantly reduced gingival inflammation and increased new bone filling in the extraction socket. Our results are consistent with the hypothesis that local application of a rescue BP prior to dental surgery can decrease the amount of a legacy N-BP drug in proximate jawbone surfaces below the threshold that promotes osteocyte necrosis. This observation should provide a conceptual basis for a novel strategy to improve socket healing in patients treated with BPs while preserving therapeutic benefit from anti-resorptive N-BP drug in vertebral and appendicular bones.

Project description:ObjectiveThe purpose of this study was to provide a cross-sectional view of all registered clinical trials enrolling patients with osteonecrosis of the jaw (ONJ). The primary aim was to report predictors of trial completion and publication of results.Materials and methodsThis is a cross-sectional study of ONJ trials registered with ClinicalTrials.gov. For each included entry, trial characteristics and endpoints were recorded. Predictors were enrollment size, etiology, study type, intervention type, sponsor, funding, study locations, number of centers, and specialty of the principal investigator. Outcomes were trial status, publication on PubMed, journal of publication, and length of time between endpoints. Associations between predictors and outcomes were evaluated using chi-square tests and t-tests.ResultsThe final sample included 26 trials. Overall, 50% of trials were completed and 69% of completed trials were published. Three out of four terminated trials were suspended due to lack of funding. The median enrollment for completed trials was 149 participants with a mean length of five years. All trials included medication-related osteonecrosis of the jaw (MRONJ) patients and 26% also included osteoradionecrosis of the jaw (ORNJ) patients. The majority of trials were observational (65%), conducted internationally (62%), and involved multiple centers (54%). Published trials had a mean time of 5.9 years between trial start and publication, which was comparable to trial length (p=0.90) and appeared in either dental (44%) or cancer (56%) journals. Completion and publication rates were not significantly increased by industry sponsorship/funding, larger enrollment sizes, or multi-center involvement. Oral and maxillofacial surgery was the most represented dental specialty of principal investigators (56%).ConclusionsThe majority of completed ONJ trials had their results published in a timely manner. Evidence-based investigation of ONJ is a multi-disciplinary and international effort. Among all specialists, oral and maxillofacial surgeons led the most ONJ trials.

Dataset Information

A Model for Osteonecrosis of the Jaw with Zoledronate Treatment following Repeated Major Trauma.

Publications

A Model for Osteonecrosis of the Jaw with Zoledronate Treatment following Repeated Major Trauma.

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