(233c) Combinatorial Modification Of Polymers Enhances DNA Binding Constants And Greatly Increases In Vitro And In Vivo Gene Delivery Efficacy

Gene therapy holds the promise of treating a myriad of diseases from genetic disorders to the leading causes of death in the United States, heart disease and cancer. The traditional approach to gene therapy, viral vectors, has high efficacy, but is plagued by multiple problems. These include serious safety risks, production and manufacturing challenges, and other limitations including limited nucleic acid cargo capacity.¹ In contrast, non-viral gene delivery systems have the design flexibility to potentially address these challenges, but currently remain much less effective.²

Here, we show the development of a biodegradable polymer library for non-viral gene delivery. First, we use combinatorial chemistry to generate a diverse polymer library. Next, we utilize a high-throughput method for quantifying polymer/DNA binding, a key gene delivery bottleneck, to evaluate the polymers. We then use insights from this screen to rationally design the next-generation of polymers for improved transfection efficacy. We show that these end-modified poly(-amino ester)s, easy-to-synthesize degradable polymers, are able to deliver DNA at levels comparable to adenovirus and two orders of magnitude better than the commonly used non-viral polymeric vector, polyethylenimine (PEI). This effective transfection takes place under conditions generally seen as difficult: fully confluent human primary cells in the presence of a high concentration of serum proteins.

Interestingly, small structural changes to these polymers were found to have dramatic effects on DNA binding affinity and final protein expression. In vivo, these polymer modifications dramatically enhance DNA delivery to ovarian tumors. We believe the development of polymeric vectors with gene delivery efficacy comparable to adenovirus could set a new benchmark in non-viral transfection capability.

1. Thomas, C.E., Ehrhardt, A. & Kay, M.A. Progress and problems with the use of viral vectors for gene therapy. Nature Reviews Genetics 4, 346-358 (2003).

2. Pack, D.W., Hoffman, A.S., Pun, S. & Stayton, P.S. Design and development of polymers for gene delivery. Nature Reviews Drug Discovery 4, 581-593 (2005).