(352a) Invited Speaker: Influence of Uptake Pathway On Polymer-Mediated DNA and siRNA Delivery

Continued progress in human gene therapy requires the development of safe and effective delivery strategies.  Polymeric gene delivery agents hold important advantages including safety, targetability and versatility, but are hindered by generally poor efficiency.  Design of polymers capable of efficient delivery will be facilitated by understanding of the structure-function relationships by which polymers mediate cellular internalization, escape from endocytic vesicles, cytosolic transport, nuclear translocation, and release of nucleic acids.  We have recently begun to investigate how the first step in this process, cellular uptake, affects the subsequent steps.  In particular, we show that internalization may occur through pathways including clathrin-dependent endocytosis, caveolin-dependent endocytosis, macropinocytosis, etc.  The subsequent processing of polyplexes can differ significantly for each pathway.  Most importantly, we demonstrate that, depending on the polymer chemistry, the nucleic acid (DNA or siRNA), and the cell type, some uptake pathways lead to more effective transgene expression than other pathways.  Thus we conclude that uptake pathway is a key parameter for gene delivery polymer design, especially for vectors that are targeted to cell-specific ligands.