Gene therapy is a promising alternative to pharmaceutical drugs for treating or preventing diseases either through gene silencing or transfection pathway. Some of the most effective delivery agents are polycationic dendrimers, which are highly branched constructs consisting mainly of positively charged groups. Two of the most effective dendrimers are polyethyleneimine (PEI) and poly (amidoamine) (PAMAM), which show high proficiency at overcoming barriers for oligonucleotide delivery. However due to the abundance in cationic charges, this causes severe toxicity towards mammalian cells. To overcome this problem, we are currently developing a multicomponent delivery system that is designed to be proficient at delivering thearapeutic oligonucleotide into cells.
However, individual components need to be optimised to ensure only the best parts are chosen for the system. This project focuses on optimising an easy to synthesize dendron structure, which is smaller and contains less positive charge than PEI and PAMAM dendrimers, as a handle for oligonucleotide binding, and to enhance cellular uptake. A cell penetrating peptide (CPP) TAT (48 – 60) was chemically attached to each dendron structure to ensure efficient uptake into cells.
A library of different dendron structures was synthesized using solid phase peptide synthesis (SPPS) and characterised. We investigated the capacity of these peptides to bind and condense DNA, and improve cellular uptake, as well as their toxicity towards mammalian cells, and the size and zeta – potential particles formed with DNA. The best dendron structure from this study would be incorporated to the multicomponent delivery system.