(414a) Assessment of In Vivo Murine Transduction Efficiency and Biodistribution Profiles with AAV/cationic Lipid Co-Formulations

Successful viral vector-mediated delivery of therapeutic transgenes to the airway epithelium has been limited by both low efficiency and induced immune response to the vector and encoded transgene.  Adeno-associated viral (AAV) vectors are attractive due to their non-pathogenic nature and sustained transgene expression; however, neutralizing antibodies are generated against the viral capsids preventing effective readministration.  A synthetic cationic glucocorticoid, dexamethasone-spermine (DS), can associate with the AAV capsid altering the biodistribution and immune response following in vivo administration of co-formulated vector/lipid complexes.  Intranasal administration of 1E+11 genome copies of AAV co-formulated with 6.4 µg (total lipid) of liposomes with the neutral lipid dioleoylphosphatidylethanolamine (DOPE)/mouse, resulted in average 1.1 to 2.2 fold increase in transgene expression for AAV2/6.2 in the lung at Day 7 through Day 31 for two different lipid formulations compared to AAV2/6.2 formulated with vehicle control.  Similarly, AAV2/9 co-formulated with lipid resulted in a 1.3 to 3.7 fold increase in transgene expression in the lung at Day 7 through Day 31 for the two lipid formulations compared to AAV2/9 formulated with vehicle control.  Histological examination of lung cross-sections indicated that cohorts receiving AAV/lipid co-formulations had moderately elevated transduction of both the alveolar epithelium and conducting airways following homologous vector re-administration. Our results suggest that formulating AAV with DS/DOPE may improve total transduction efficiency and possibly reduce the host immune response to the vector in mouse airway epithelium in vivo.