Blockade of Osteoclast-Mediated Bone Resorption With a RANKL-Inhibitor Enhances Bone Formation in a Rat Spinal Fusion Model.

STUDY DESIGN: Rat spine fusion model. OBJECTIVE: The present study aimed to determine whether administration of osteoprotegerin (OPG) in a rat model of spinal fusion increases bone volume, bone density, and decreases osteoclasts in the fusion mass. SUMMARY OF BACKGROUND DATA: OPG is a soluble RANK-ligand inhibitor that blocks osteoclast differentiation and activation. This makes it a potential agent to control the remodeling process and enhance bone mass during spinal fusion. MATERIALS AND METHODS: Forty-eight male Sprague-Dawley rats received a one-level spinal fusion of L4-L5 with bone allograft. Rats were then divided into four groups according to initiation of treatment: (1) saline on day 0 (saline), (2) OPG on day 0 (OPG D0), (3) OPG on day 10 (OPG D10), and (4) OPG on day 21 (OPG D21) postsurgery. After their initial injection, rats received weekly subcutaneous injections of OPG (10 mg/kg) and were euthanized six weeks postsurgery. MicroCT analysis of the fusion site and histological analysis of bone surface for quantification of osteoclast lining was performed. RESULTS: Increased bone volume in the fusion site and around the spinous process was seen in OPG D0 and OPG D10 when compared with saline. Mean trabecular thickness was greater in all groups receiving OPG compared with saline, with OPG D0 and OPG D10 having significantly greater mean trabecular thickness than OPG D21. All OPG groups had less bone surface lined with osteoclasts when compared with Saline, with OPG D0 and OPG D10 having fewer than OPG D21. CONCLUSIONS: This study indicates that OPG inhibited osteoclast bone resorption, which led to greater bone at the fusion site. Future studies investigating OPG on its own or in combination with an osteogenic factor to improve spinal fusion outcomes are warranted to further elucidate its potential therapeutic effect.

[Experience with Denosumab in central giant-cell granuloma]. / Experiencia con Denosumab en granuloma central de células gigantes.

INTRODUCTION: Central Giant Cell Granuloma is an infrequent bone lesion located mainly in the maxillary bone. The main treatment is surgery with wide margins, so it sometimes causes great morbidity and esthetic al terations. Denosumab, a RANK-ligand inhibitor monoclonal antibody, has been presented as a valid therapeutic alternative in the treatment of these lesions. OBJECTIVE: to describe the clinical and radio logical response after treatment with Denosumab in a patient with unresected giant cell granuloma. CLINICAL CASE: 12-year-old boy who consulted due to a 24-hour maxillary swelling, without other associated symptoms. Examination revealed a tumor in the upper left maxilla with bulging of the ip- silateral gingiva. A CT scan was performed which showed a large expansive intraosseous lesion in the maxillary alveolar ridge. The biopsy of the lesion was compatible with Central Giant Cell Granuloma. Due to the size and location of the lesion, initial treatment with Denosumab, a human monoclonal antibody with action on RANK-ligand, was indicated. After 10 months of treatment, the patient showed a favorable clinical and radiological response, with a size decrease of the lesion and metabolic activity. As an adverse effect, the boy presented mild hypocalcemia, resolved after supplementation with calcium. CONCLUSION: the use of Denosumab as the first line of treatment in Giant Cell Granu loma may be an adequate therapeutic option in adolescents with lesions that are difficult to resect.

Denosumab: an update.

Denosumab is a fully human monoclonal antibody that inhibits the formation, function and survival of osteoclasts, preventing the interaction of tumor necrosis factor ligand superfamily member 11 (receptor activator of nuclear factor kappa-B ligand, RANKL) with the tumor necrosis factor receptor superfamily member 11A (osteoclast differentiation factor receptor, ODFR, receptor activator of NF-KB, RANK). This results in a reduction in bone resorption and an increase in bone mineral density. In clinical studies, denosumab has been shown to decrease the risk for vertebral, hip and nonvertebral fractures in women with postmenopausal osteoporosis and the risk for new vertebral fractures in men with nonmetastatic prostate cancer receiving androgen deprivation therapy, with a rate of side effects similar to placebo. A number of clinical trials with denosumab are ongoing to demonstrate its value for other indications and to further characterize its effects on immunomodulation. Denosumab is a new alternative for the prevention and treatment of postmenopausal osteoporosis and a promising agent for the treatment of other bone diseases associated with bone loss.