Study On The Preparation Of Peptide-grafted Chitosan-polyethyleneimine-polyethylene Glycol As A Gene Carrier And The Application In Neural Regeneration

The application of gene transfer techniques can regulate the expression of protein of cells,in which case an efficient gene carrier plays an important role.Neurotrophin-3(NT-3)can promote the differentiation of NSC into neurons,and maintain neuron survival.But the effectiveness of NT-3 decreases greatly due to its instability in vivo.The recipient cells could express NT-3 for a long time after transfection with NT-3 gene.In this study,a gene delivery system was established by using a cationic polymer modified by functional peptides.The effect of NT-3 expressed by the transfected cells on the differentiation of NSC was investigated.The specific work is presented as follows:(1)Chitosan was grafted onto PEI after oxidation and opening ring.The bifunctional PEG was grafted onto peptides through addition reaction.Finally CS-g-PEI-PEG-PEP was formed by amidation reaction between CS-g-PEI and PEG-PEP.The results suggested that the quaternary polymer could be successfully synthesized,the distribution of Zeta potential and particle size was suitable.This quaternary polymer was a compact spherical shape which could effectively encapsulate DNA and was less toxic to the cells as compared to PEI.The reporter gene from the complex could be released and transcribed when it was transduced into NIH-3T3,Hela and 293 T cells.(2)When the NT-3 gene was transduced into the recipient cells by CS-g-PEI-PEG-PEP,it can be effectively expressed from the recipient cells evidenced by the detection of enzyme-linked immunesorbent assay(ELISA).The proportion of NSC differentiate into neurons in the differential medium including the cell culture medium of transfected recipient cell increased,and the neuronal axon length increased and the survival rate was higher.