Comparing the caveolae mediated endocytosis of two DNA-chitosan polyplexes

Abstract

Understanding intracellular processing of gene vectors will help to improve vector design in gene therapy. Chitosan nanoparticles have been previously identied as safe and non toxic gene vector. Linear chitosan oligomer (LCO) and self branched trisaccharide chitosan oligomer (SBTCO) have been shown to be able to pack DNA, balancing betweencomplexation and intracellular unpacking . However, the transfection ecacies of thesetwo chitosans diers considerably with the level of transgene expression higher for SBTCOcompared to LCO. SBTCO have been recently reported to be taken up solely by caveolaemediated endocytosis (CvME) while LCO uses both clathrin mediated endocytosis (CME)and CvME.In the present study, the CvME was studied. An immunostaining protocol for detectionof caveolin (cav) was established. Polyplexes of SBTCO seemed to trigger the formationof more caveosomes than did LCO polyplexes. SBTCO polyplexes were more localisedin the caveosome than LCO polyplexes at 3 hours incubation period. These ndingssuggested that SBTCO polyplexes delivers more DNA into the cell than LCO polyplexesand that SBTCO polyplexes are processed intracellularly solely via the CvME pathway.Likewise, it suggested LCO polyplexes have preferred intracellular processing pathwaywhich is not CvME. Collectively, these results demonstrated that SBTCO is protectedfrom the degradative endosome and might therefore be an ecient and good tool to delivertherapeutic DNA.