| Poly(ethylenimine) (PEI) is a polycation with proven success as a gene delivery vehicle both in vitro and in vivo. The work described herein addresses several aspects of PEI-mediated gene delivery. First, a model system was developed, and an assessment of what PEI molecular weights should be considered for optimal transfection was made. Next, PEI/DNA complexes were examined and their physical characteristics (such as surface charge concentration and buffering capacity) defined in an attempt to further improve PEI/DNA transfection efficiencies. After characterizations were completed, cellular trafficking studies were performed to yield a pictorial overview of the route taken by PEI/DNA complexes during transfection. With the general trafficking route in place, the stage was set for a more in-depth examination of the mechanism behind PEI-mediated transfection. The intracellular route of PEI/DNA complexes during transfection was then re-evaluated with respect to lysosomes, and a novel finding was made that disproves a popular hypothesis that has attempted to explain the success of PEI-mediated transfection. Additionally, the stability of PEI/DNA complexes was established, and applied toward the fact that the complexes are shuttled into cell nuclei during transfection. Finally, the effects of PEI's nuclear entry were addressed in terms of secreted cellular products and cell viability. |
