| Summary: | 碩士 === 高雄醫學大學 === 生理及分子醫學研究所 === 98 === Abstract
Introduction:
Simvastatin, a hydroxy-3-methylglutaryl coenzyme A (HMG -CoA) reductase inhibitor, is a common clinical use cholesterol lowering drug. Recent reports indicated that simvastatin had a potent stimulating effect on osteogensis in vitro and in vivo. Our previous study also demonstrated that simvastatin stim- ulates osteoblast proliferation and enhances osteogenesis of hBMSCs. However, the systemic administration of simvastatin showed diverse and controversial effect on osteogensis because it’s difficult to maintain the therapeutic concentration of simva- statin for a long time around the defect site. Therefore, this study is to develop the drug loaded carriers with the properties of controlled releasing simvastatin and with osteogensis effect
Materials and Methods:
Simvastatin encapsulated PLGA were prepared by electrospining (fibrous carrier) and spray drying (microsphere). Fibrous carrier included two groups: [F-0(simvasatatin /PLGA /0 mg HAp),F-200 (simvasatatin/PLGA /200 mg HAp)]. Micro-sphere included two groups: [S-0(simvasatatin/PLGA/0mgHAp), S-100 (simvasatatin/PLGA/ 100mg HAp)].Microspheres was additionally characterized the surface morphology by a scanning electron microscope(SEM) and the size distribution by a particle size analyzer. The releasing profile and encapsulate efficiency of carriers were analyzed by HPLC (High performance liquid chromat- ography). To elevate the effect of carriers in vitro, we tested cell viability by MTT assay and mineralization by Alizarin red staining on D1 cells (mouse bone marrow mesenchymal stem cell). In vivo study, we tested the effect of carriers on bone repair with a mouse model of bone defect grafted with a necrotic bone. We evaluated the bone repair by using radiography and histology (H&E staining for callus formation, osteocyte/ necrotic-bone area and vWF staining for neo-vasculization ).
Results and conclusion:
Results from particle size analysis showed that the size distribution of microspheres are following: S-0:111±20 um、S-100:26±14 um. The SEM images showed that the surface morphology of microsphere is smooth. The results from in vitro releasing test showed daily release concentrations of simva- statin from each mg of the carrier were following : S-0:0.88~2.3uM, S-100:0.77~0.32uM, F-0:0.2~4.1uM, F-20- 0:0.8~2.9uM and sustained release of simvastatin is for 2 weeks. The results of cell vialibity test showed F-0, F-200, S-0(2mg) and S-100(10mg) significantly decrease the cell viability. The bioactivity test showed that simvastatin/PLGA fibrous carrier and microsphere significantly enhanced mineralization of D1 cell. The results of in vivo test further showed that simvastatin /PLGA fibrous carriers (F-0 and, F-200) increased callus formation, the rate of cell grown in the grafted and neo-vasculization. Our results illustrated the feasibility of using simvastatin/PLGA fibrous carriers with controlled-release property not only sustainedly release the constant concentration of simvastatin ,but also enhanced osteogensis in vitro and in vivo. Simvastatin/ PLGA microspheres with contro- lled-release property that can sustained release the constant concentration of simvastatin and enhanced osteogensis in vitro.
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