An in-vivo biocompatibility study of biodegradable and thermosensitive PEG-PLGA-PEG / HA composites

• Main Authors: Mei-Chun Lai, 賴玫君
• Other Authors: Ming-Fa Hsieh
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/47004838985330259500

博士 === 中原大學 === 化學研究所 === 97 === The present study is aimed to observe osteogenesis in-vivo when a composite hydrogel of biodegradable thermosensitive poly(ethylene glycol) - block poly(lactide-co-glycolide) - block poly(ethylene glycol) triblock copolymer (PEG-PLGA-PEG) and hydroxyapatite (HA) is injected subcutaneously. The composite hydrogel was also mixed with recombinant bone morphologenesis protein 2 (BMP-2) for the osteoinduction. PEG-PLGA-PEG was synthesized using ring opening polymerization technique whereas HA was synthesized in a chemical co-precipitation method. The hydrogel was formed by vortexing predetermined amount of PEG-PLGA-PEG and HA and injected into skin throught a syringe in rat. Tissue sections at various time point post injection were prepared and In-vivo biocompatibility of injected materials was evaluated accordingly. In the part of chemical synthesis of PEG-PLGA-PEG, the structure was determined by 1H nuclear magnetic resonance spectrophotometer and Fourier-transform infrared spectrum. The thermosensitivity and in-vitro degradation of PEG-PLGA-PEG and its composites with HA were studied by following the viscometer of hydrogels and in-vitro degradation test, respectively. On the other hand, the crystal structure of HA was measured by powder X-ray diffraction, scanning electron microscope - energy dispersive spectrometer and inductively coupled plasma atomic emission spectrometry, respectively. Results show that 2-theta degree appeared a peak at 25.8° which is the obviously characteristic peak of HA and the Ca/P ratio is close to composition of nature bone. Secondly, the quantitative assessment of the injectability of composite hydrogel was conducted using in syringe. Finally, In-vivo injection of the composite hydrogels (PEG-PLGA-PEG hydrogel, HA disc, composite hydrogel of PEG-PLGA-PEG and HA, PEG-PLGA-PEG, HA and BMP-2 composite hydrogel) under skin of the rat was conducted for a research period of 8 weeks. Results demonstrated that osteoinductive BMP-2 can be injected through biocompatible hydrogel of PEG-PLGA-PEG and HA. The biocompatibility of materials can be observed by the optical microscope. After eight weeks, fibroblasts not only grow but also osteocytes. The adding bone morphogenetic proteins-2 can be clearly observed more of osteocytes. Then conclusion is the as-prepared composite hydrogel of PEG-PLGA-PEG and HA, with small additive amount (e.g. 0.01 wt%) of BMP-2 as bone promoter, is a suitable material for osteoinduction.