Stephen Loughran
Queens University Belfast, Northern Ireland
Title: Development of a peptide-based, multifunctional gene delivey vector for metastatic prostate cancer
Biography
Biography: Stephen Loughran
Abstract
RALA is a 30mer, arginine-rich, amphipathic peptides with both cell-penetrating and endosomolytic properties. When mixed with plasmid DNA it condenses to form small, serum-stable nanoparticles which, when administered in vivo, are capable of transfecting cells. However, bioavailability in vivo was limited to the lungs and liver of treated mice. In order to improve nanoparticle pharmacokinetics, polyethylene glycol (PEG) 5K was conjugated to the C-terminus of the RALA peptide and the resulting conjugate (RALA-P) was characterized in vitro. Disappointingly, activity in vitro was nullified following addition of PEG which lead us to adopt an alternative strategy that involved mixing of RALA-P with native RALA at various w/w ratios in an attempt to restore cellular level activity without compromising pharmacokinetic benefits instilled through the addition of PEG. The resulting nanoparticle exhibited improved salt stability at physiological concentrations of NaCL and was also capable of transfecting cells in vitro. To test biodistribution of the modified nanoparticle, various w/w ratios of RALA/RALA-P containing plasmid fire-fly luciferase were administered to tumour-bearing mice in order to determine whether introduction of PEG in this way could enable transfection in vivo, augment accumulation in the tumour by EPR and reduce accumulation in off-target organs. The results demonstrate a significant reduction in accumulation in the liver and lungs of treated mice and an increase in tumour expression for RALA/RALA-P nanoparticles as compared to RALA only.