Surfactant Effects on Aerosolized and Instilled Adenoviral-Mediated Gene Transfer

Abstract

The effects of surfactant on aerosolization of adenovirus and the distribution of aerosolized and instilled adenovirus in rabbit lungs were measured. Using ⁹⁹Tc sulfur colloid as a marker for the aerosol, ³³P-adenovirus with and without ³H-surfactant, we found that the aerosol had the same particle size distribution independent of surfactant and the ³³P-adenovirus distributed proportionately to the other radiolabels in the aerosol. Rabbits received aerosolized or instilled suspensions of adenovirus and ⁹⁹Tc-sulfur colloid with or without 10 mg/ml surfactant. Rabbit lungs were separated into large airways (trachea, carina, and primary bronchi) and more distal lung parenchyma either immediately after treatment for measurement of ⁹⁹Tc distribution or 3 days after treatment for luciferase transgene expression. More instillate (94 ± 1%) than aerosol (68 ± 2%) was recovered in the parenchyma immediately after treatment (p < 0.01). Transgene expression in the parenchyma as a percent of total lung expression was lower for both instillation (72 ± 8%) and aerosolization (30 ± 8%) than for the initial distributions (p < 0.01). Surfactant did not change the distributions of ⁹⁹Tc sulfur colloid or transgene expression. The adenovirus was aerosolized successfully but the distribution of the aerosol did not favor transgene expression in the lung parenchyma.

Overview summary

The distributions and subsequent transgene expression of vectors delivered to the lungs by instillation or aerosol have not been well described. We evaluated the distribution of an aerosolized ³³P-adenovirus vector in particles generated by a low-flow gas jet aerosolizer and found the vector was aerosolized proportionately to the mass of the particles. Pulmonary surfactant added to the aerosol did not influence vector aerosolization. We then asked if the initial distribution of the adenovirus in aerosol or instillate reflected the distribution of reporter gene expression 3 days after treatment of rabbits. Reporter gene expression was higher in the large airways than in lung parenchyma relative to the initial distribution of the vector given by either aerosol or instillation. These studies evaluate some of the variables that influence vector delivery and transgene expression in the lungs.