Exploring the efficacy of ethylene glycol dimethacrylate crosslinked cationised pullulan for gene delivery in cancer cells

The balance between cytotoxicity and transfection efficiency is essential for any cationic polymers intended for gene delivery. However, increase in transfection efficiency of these cationic polymers is usually associated with an increase in the toxicity owing to the high positive surface charge. In this study pullulan was cationised with polyethyleneimine (pullulan-PEI) and was cross-linked with ethylene glycol dimethacrylate (EGDMA). Cross linked pullulan -PEI (PPE) was found to be cytocompatible and formed nanoplexes of size of about 150 nm and 9.96 mV. The presence of EGDMA groups reduced the plasma protein interactions as well. The nanoplex uptake and transfection efficacy studies of PPE were done in C6 and HeLa cells. The interesting observation was that these nanoplexes exhibited differential uptake in these cell lines. The cellular uptake was very high in C6 glioma cells where as it was very low in HeLa and consequently gene expression was observed in the former cells only. Transfection efficacy of PPE derivatives was evaluated using p53 plasmid whose expression induces apoptosis in the cancerous cells. Immunostaining experiments and flow cytometry analysis following Annexin V staining confirmed the expression of p53 protein and apoptosis respectively in the PPEI/p53 poyplex transfected C6 cells.