Exogenous chondroitin sulfate glycosaminoglycan associate with arginine-rich peptide-DNA complexes to alter their intracellular processing and gene delivery efficiency.

Abstract Arginine-rich peptides have been used extensively as efficient cellular transporters. However, gene deliverywith such peptides requires development of strategies to improve their efficiency. We had earlier demonstrated that addition of small amounts of exogenous glycosaminoglycans (GAGs) like heparan sulfateor chondroitin sulfateto different arginine-rich peptide–DNA complexes (polyplexes) led to an increase in their gene deliveryefficiency. This was possibly due to the formation of a ‘GAG coat’ on the polyplex surface through electrostatic interactions which improved their extracellular stability and subsequent cellular entry. In this report, we have attempted to elucidate the differences in intracellular processing of the chondroitin sulfate(CS)-coated polyplexes in comparison to the native polyplexes by using a combination of endocytic inhibitors and co-localization with endosomalmarkers in various cell lines. We observed that both the native and CS-coated polyplexes are internalized by multiple endocytic pathways although in some cell lines, the coated polyplexes are taken up primarily by caveolaemediated endocytosis. In addition, the CS-coat improves the endosomalescape of the polyplexes as compared to the native polyplexes. Interestingly, during these intracellular events, exogenous CS is retained with the polyplexes until their accumulation near the nucleus. Thus we show for the first time that exogenous GAGs in small amounts improve intracellular routing and nuclear accumulation of arginine-based polyplexes. Therefore, addition of exogenous GAGs is a promising strategy to enhance the transfection efficiency of cationic arginine-rich peptides in multiple cell types.