Cell Penetrating Peptides And Analogues To Enhance The Study Of In Vivo Degradation Of Polyethylene Imine Transfection Efficiency

In order to improve the cell transfection efficiency, several chemical modification methods of polyethyleninime(PEI) and their derivatives for gene delivery were discussed in this paper. Due to its high gene transfection efficiency and easy availability, branched 25kDa PEI has become a benchmark to which other polymers , especially newly designed and synthesized materials, were often compared. However it is cytotoxic in many cell lines. In order to minimize the cytotoxicity , lots of biodegradable polymers were prepared by non-cytotoxic smaller PEI (2000Da) reacting with different potentially biodegradable crosslinkers, then we modified the primary amines in the surface of polymers to enhance the gene delivery efficiency. Firtly, some polymers with good biodegradability were synthesized and modified with cyclodextrin to improve its water-solubility. Secondly , we modified the 25kDa PEI with cell penetrating peptide (CPP), such as R8, which is also a good gene vector and able to ferry much larger molecules into cells independent of classical endocytosis. because the gene delivery ability of R8 depends on it's guanidinium side groups, the guanidination would lead to the delocalization of charge present on primary amines of the polymer thereby leading to enhancement in gene delivery efficiency along with reduction in cytotoxicity. we modified 25kDa PEI and crosslinked PEI with arginine and guanidination reagents respectively. The polymers with good water-solubility were assessed when HEK293 and A549 cells were used as receptor cells respectively and enhanced green fluorescent protein (EGFP) was used as gene reporter. Results showed the highest transfection efficiency of the polymers modified with cyclodextrin and guanidination reagents in the A549 cells is up to 69% and 92%(P8) respectively, while the efficiency of 25kDa PEI is about 10%. the transfection efficiency of P8 in the B16F10 and HBZY-1 rat mesangial cells is about 70%. in addition , the cytotoxicity of the polymers was measured, the results indiciate that these polymers have lower cytotoxicity than 25kDa PEI. The study exhibits that these polymer are safe and efficient gene delivery vectors in vitro and they are promising to be used in vivo.