The effects of a bisphosphonate on angiogenesis using zebrafish as an in vivo animal model
Date Issued
2015
Date
2015
Author(s)
Hsu, Tan-Ching
Abstract
Objectives： The prescriptions of bisphosphonates are world-wide, often used in osteoporosis, bone metastasis of malignant tumors, multiple myeloma. Bisphosphonate-related osteonecrosis of the jaw (BRONJ) was first reported in 2003 by the American Oral and Maxillofacial Surgeons, Marx. Due to wound healing of the jaw bone was delayed after bisphosphonate use, all dentoalveolar surgeries were involved, such as tooth extraction, root planing, periodontal surgeries, or implantation. Dentists pay special attention to this topic and phenomenon. Thus, we would like to unveil the etiology of BRONJ, and hopping to find the preventive measures and treatment methods. Several causative mechanisms of BRONJ have been proposed. Inhibition of osteoclast function and angiogenesis were considered to be the two main mechanism recently, leading to defect in bone remodeling. The direct mechanism of action was still unknown. To date, there is no effective therapy of the BRONJ. Bisphosphonates inhibit pyrophosphate synthase (FPPS) in the mevalonate pathway, with decreased synthesis of the downstream metabolites, geranylgeraniol (GGOH). Therefore, the research goal of this experiment was to explore the effects of a bisphosphonate on angiogenesis, and demonstrate that the application of GGOH may reverse the adverse effects of bisphosphonates. Materials and Methods： We used transgenic zebrafish (TG (fli1:EGFP)) as an animal model to explore the effects of bisphosphonates on angiogenesis. First of all, we amputated the zebrafish tail fin in half, and all fishes were divided into five groups according to breeding condition by concentration of Alendronate: the control group, 2.5 × 10-5M of Alendronate, 5.0 × 10-5M of Alendronate, 2.5 × 10-5M of Alendronate and GGOH, 5.0 × 10-5M of Alendronate and GGOH. The observation of the angiogenesis took place on day 2, day 3, day 5 and day 7 after fin amputation by the fluorescence microscopy. Furthermore, these findings could help us understand the inhibited angiogenic function affected by bisphosphonates, and expecting to find the potential medication for BRONJ. Results： The results showed that the vascular plexus and inter-vessel density were decreased after bisphosphonate treatments, suggesting that bisphosphonates could supress angiogenesis, and delayed wound healing. The angiogenesis impaired by alendronate was reversed to normal in the presence of GGOH. Hence, systemic application of GGOH may reduce the adverse effects of bisphosphonate therapy. Conclusion： Our study in zebrafish provides a vivid animal model to investigate the role of angiogenesis in the BRONJ in vivo. This experiment showed that angiogenesis may be suppressed under the influence of bisphosphonates, leading to defects in wound healing, bone repair and regeneration eventually resulting in BRONJ. We also demonstrate that the impairing effects of alendronate on angiogenesis may be reversed by application of GGOH. And the results may further extend to the clinical applications in treating BRONJ. In this study, the results suggested that there was close relationship between angiogenesis and osteogenesis, and the complex cross-linked mechanism would require further experiments to confirm.
Subjects
Bisphosphonate
zebrafish
angiogenesis
osteonecrosis
TG(?i1:EGFP) transgenic zebrafish
Type
thesis
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