(484g) Development of An Improved Adenovirus Gene Therapy Vector That Employs Cell Penetrating Peptides for Transformation of Difficult to Infect Cell Lines

Adenovirus is a promising gene therapy vector and is currently used in more than 25 % of the clinical gene therapy trials. The viral vector, however, has serious drawbacks such as immunogenicity, promiscuous tropism, and the inability to efficiently infect certain types of cells. We have developed an improved vector that is composed of adenovirus and a synthetic conjugate comprised of polyethylene glycol (PEG) and cell penetrating peptides (CPP). PEG has been shown to reduce the susceptibility of the virus to immune inactivation and eliminate the promiscuous tropism. The CPP, in this case, enables the virus to transform cells that lack the native coxsackie-adenovirus receptor (CAR) thereby delivering genes to cells that are difficult to infect.

The nanoparticle complexes, comprised of adenovirus, PEG, and CPPs, were synthesized using heterobifunctional PEG with a thiol-reactive maleimide (MAL) group and an amine-reactive N-hydroxyl succinimidyl ester (NHS) group (MAL-PEG-NHS). The MAL-PEG-NHS was used to PEGylate adenovirus and link PEGylated adenovirus to CPPs (e.g. TAT, Penetratin, polyarginine). The transduction efficiency of the resulting nanoparticles was studied on cells with and without the native adenovirus receptor (CAR+ and CAR-). The transduction efficiencies of the particles were optimized by varying the type of CPP, degree of PEGylation, PEG molecular weight, and ratio of CPPs to adenovirus. Nanoparticle size, zeta-potential and polydispersity were characterized using dynamic light scattering, and particle morphology was studied using electron microscopy. Compared to the native virus, the complexes show similar transduction efficiency on CAR+ cells and higher transduction efficiency on CAR- cells.