Biodegradable porous microspheres with BMP-2 releasing nano-hydroxyapatite for bone tissue engineering

다국어 초록 (Multilingual Abstract)

The fabrication of highly porous microspheres with bone morphogenetic protein (BMP)-2-loaded surface-immobilized nano-hydroxyapatite (N-HAp) is formed for effective bone regeneration. The separate nano-phase of N-HAp on the pore surface of microspheres is accomplished using a surface-repellent stable colloidal N-HAp with surface phosphate anionic groups. The contents of immobilized N-HAp on the pore surface of microspheres are measured by thermal gravimetric analysis (TGA) and the pronounced exposure of nano-level N-HAp is observed by field-emission scanning electron microscopy (FE-SEM). FE-SEM and X-Ray photoelectron spectroscopy (XPS) support that immobilized N-HAp on surface of microspheres. BMP-2 is incorporated onto phosphate functionality of N-HAp surface and is controllably released from N-HAp immobilized microspheres for 1 month. The newly fabricated biodegradable porous microspheres with BMP-2 loaded N-HAp have osteoconductive function of N-HAp and osteoinductive role of BMP-2, which provide favorable environments for enhanced in vitro formation of bone tissue. Specific biomarkers of bone formation are confirmed by histochemistry and quantitative real time polymerase chain reaction (PCR). Moreover cell culture is performed by 3-dimensional rotary tissue culture system to effective cell growth and differentiation.

목차 (Table of Contents)

• Abstract..........................................................................................................................Ⅰ
• Contents..........................................................................................................................Ⅱ
• List of Tables and Figures.............................................................................................Ⅴ
• 1. Introduction.................................................................................................................1
• 2. Materials and Methods...............................................................................................3
• 2.1. Preparation of PolyEGMP-grafted N-HAp............................................................3
• 2.2. Estimation of colloidal stability and characterization of
• N-HAp and PolyEGMP-grafted N-HAp.................................................................3
• 2.3. Fabrication of highly porous PLGA microspheres and
• amine-functionalized PLGA microspheres..............................................................4
• 2.4. Immobilization of PolyEGMP-grafted N-HAp on
• pore surfaces of PLGA microspheres......................................................................5
• 2.5. Thermal gravimetric analysis (TGA).....................................................................6
• 2.6. Field emission scanning electron microscopy (FE-SEM)......................................6
• 2.7. X-Ray photoelectron spectroscopy (XPS)..............................................................6
• 2.8. Incorporation of BMP-2 onto surfaces of
• N-HAp-immobilized PLGA microspheres..............................................................7
• 2.9. Confocal laser scanning microscopy (CLSM)........................................................7
• 2.10. BMP-2 release profile...........................................................................................8
• 2.11. Cell culture............................................................................................................8
• 2.12. Cell seeding and growth on N-HAp-immobilized PLGA microspheres
• incorporated with BMP-2 in vitro..........................................................................9
• 2.13. Histology & immunohistochemistry...................................................................10
• 2.14. Quantitative real time PCR.................................................................................11
• 2.15. Statistical analysis...............................................................................................11
• 3. Results and Discussion..............................................................................................13
• 3.1. Preparation of surface-repellent stable N-HAp colloids......................................13
• 3.2. Fabrication of open porous PLGA microspheres.................................................19
• 3.3. Surface immobilization of N-HAp on pore surfaces of PLGA microspheres......21
• 3.4. Incorporation of BMP-2 with on surfaces of N-HAp-immobilized
• PLGA microspheres and BMP-2 release...............................................................25
• 3.5. In vitro evaluation of biocompatibility and osteogenic potential.........................29
• 4. Conclusions.................................................................................................................36
• 5. References...................................................................................................................37