686. Exploring Different Formulations as a Strategy To Enhance Adenoviral Gene Delivery to the Lung
Authors: Rahul Kushwah, Benjamin H. Lee, Jim Hu
Journal: Molecular Therapy (2006)

Adenoviral vectors are currently being investigated for lung gene therapy, particularly for cystic fibrosis. However, one of the challenges is the low efficiency of viral transduction due to the presence of mucous in the airway, localization of CAR receptor on the basolateral surface, sweeping action of ciliated epithelial cells, apical membrane glycoconjugates and the host immune response. Helper dependent adenoviral vectors (HD-Ad) show reduced adaptive immune response compared to first generation adenoviral vectors. However innate immunity is a consistent challenge with the use of these vectors. Therefore, there is a need to identify formulations that can enhance the transduction efficiency and decrease immune response against the adenoviral vectors. LPC has previously been shown to enhance adenoviral delivery to the lung epithelium, which can be due to its mucolytic properties along with reduction of cilial motility. DEAE-Dextran has also been shown to enhance adenoviral delivery to the lung, presumably by complexing with the virus and facilitating virus binding to cells through charge interaction. NAC and its derivative NAL have been shown to possess mucolytic and anti-oxidant properties. However, they have not been evaluated in enhancing viral gene delivery to the lung. Inflammatory cells produce reactive oxygen species which may affect adenoviral particles and decrease efficacy of viral transduction. Therefore, the mucolytic and antioxidant properties of NAC and NAL may enhance viral transduction. NAC and NAL have also been shown to decrease NFkB which could be of further significance in enhancing viral transduction. In this study we chose to study the efficacy of LPC, DEAE- Dextran, NAC and NAL in enhancing adenoviral transduction to the lung. C57BL/6 mice were intranasally instilled with viral formulations in 0.1% LPC, 10 μg/ml DEAE-Dextran, 20mM NAL combined with 10 μg/ml DEAE-Dextan or instilled first with 20mM NAC or NAL followed by viral formulation in 10 μg/ml DEAE-Dextran. Nasal instillations were carried out in a volume of 20 μl with a titer of 1010 viral particles (HD-Ad encoding LacZ). Mice were sacrificed after 3 days and lungs were isolated to quantify the amount of viral transduction by assaying for beta-galactosidase activity. Results indicate no statistically significant difference between the transduction efficiency of DEAE-Dextran and LPC. However, pre-treatment of mice with NAC or NAL, resulted in enhancement of viral transduction. The highest increase in viral transduction efficiency was seen with NAL pre-treatment. However, simultaneous instillation of NAL with virus did not result in statistically significant increase, indicating that perhaps NAL primes the epithelium for enhanced viral transduction. The results suggest that NAL may be a very useful reagent in enhancing adenoviral gene delivery to the lung. The immune responses associated with the use of various formulations are currently being examined in detail and the findings will be presented at the meeting.