Title: Novel Polymer Based Gene Carrier and Control Released Gene Transfection

Abstract:
 The study of gene therapy has developed rapidly with the improvement of disease consciousness to people. During the development of gene therapy, the key of gene therapy in clinical application is whether the gene carriers can safely carry the genes to the appointed positions and express effectively for a long time. So the aim of our research is the biologic value about the novel polymer gene carriers and the study of gene controlled release complex materials.
 The gene carriers include viral carrier and nonviral carrier. Because of the problem of safety on nonviral carrier, the study of viral carrier has been payed more attention recently. Now, the most important nonviral gene carrier is cation polymer. Large numbers of study in the world has converted to the application of water-soluble and biodegradable cation polymers as gene carriers. The cation gene carrier in our study is amphiphilic hyperbranched multi-arm polyethylene- imine-poly(-benzyl L-glutamate) (PEI-PELG). The test of gel electrophoresis, MTT and transfection in vitro proved that this gene carrier can transfer into the cell after complexed with DNA, the cell toxicity is less than PEI obviously and the transfection efficiency is higher than PEI. So the PEI-PBLG with good biocompatibility and strong transfection efficiency is a perfect and novel gene carrier. 
 One novel method in tissue engneering is using gene theropy to improve the regeneration of tissue and apparatus. However, only cells and scaffold materials can not improve the regeneration of tissue effectively, the appropriate growth factor is necessary. The growth factor is one of the important factor to tissue engneering. Due to the growth factor is not very steady in vivo, it need some protect avoiding the enzyme decomposition. Nowadays, the popular method is that using the controlled release technology to regeneration positions to controll the release of the growth factor and keeping for a long time. Compared with traditional methods, controlled realeased system can improve growth factor transfer and be master of scope and time of transfer express. This system will reduce cytotoxicity of non-target cell and immunoreaction. According to drug controlled release theory, PEI-PBLG and pcDNA3.0-VEGF165 are incubated and mixed with sodium alginate to prepare gene slow released composites(gene/sodium alginate hydrogel composites). The study of gene released and gene express in vivo and in vitro experiments indicated that gene/sodium alginate hydrogel composites have good biocompatibility. The composites can release gene locally. Cells around the composites are tranfered and maintain protein expression level for comparatively long time. The gene/sodium alginate hydrogel composites have potential application value on skin tissue damage repair and provide a new therapy scheme.
 The results of this study indicates that the method of gene controlled release can not noly protect the activity of gene, but also control the speed of gene release. Consequently the method can maintain biological effect of gene in vivo for a long period. So the study has important meaning in the field of gene therapy and tissue engineering.