PEI基因载体靶向遮蔽体系的制备和表征

Synthesis and characterization of targeting shielding system for PEI gene carrier

将RGD短肽接枝到聚谷氨酸(PGA)上,制备了一种靶向性的基因载体遮蔽材料PGA-RGD.通过凝胶电泳实验及体外转染实验证明得出RGD的引入增加了载体材料与细胞表面受体的特异性作用,在载体表面正电荷得到遮蔽的同时,转染效率还得到了一定程度的增加.同时,对转染了48h的三元复合物进行MTT细胞毒性测试表明,PGA遮蔽的基因载体体系(PGA/PEI/DNA)和PGA-RGD遮蔽的基因载体体系(PGA-RGD/PEI/DNA)的细胞毒性均低于PEI/DNA复合物体系.本文开发的基因载体改性方法不仅可以对复合物颗粒表面的正电荷进行遮蔽,从而降低复合物体系对非目标组织的非特性异作用;同时引入的RGD靶向短肽还可以提高载体的靶向性,这一改性策略对推动阳离子聚合物基因载体在体内的应用具有重要意义.

RGD peptides were grafted to the carboxyl groups of poly（glutamic acid） to get a targeting shielding carrier（PGA-RGD） for polyethyleneimine（PEI） gene carrier.The experiment results showed that PGA-RGD can effectively shield PEI/DNA complex particles.Gel retardation assay showed that DNA can not be released by PGA-RGD from complexes under experimental conditions for gene transfection.For PGA/PEI/DNA system,its gene transfection efficiency obviously decreased because PGA shielding carrier coating on PEI/DNA complex decreased the surface charges of the complex particles.On the other hand,for PGA-RGD/PEI/DNA shielding system,although its surface charges were decreased by PGA-RGD shielding,its gene transfection efficiency were effectively improved because of the specific binding affinity between RGD and receptors on tumor endothelial cell membranes.MTT assay further presented that PGA-RGD/PEI/DNA has better biocompatibility than PEI/DNA.The improvement method developed in this paper for gene carriers can not only shield the positive charges on complex particles and decrease the non-specific uptake by non-targeting cells,but also introduce targeting functions to gene carrier system.The shielding system for gene complex particles is an effective strategy for promoting in vivo application of polycation gene carriers.