Effect of Adenoviral Vector Infection on Cell Proliferation in Cultured Primary Human Airway Epithelial Cells

Abstract

Although recombinant adenoviruses are used as vectors for delivering therapeutic genes to the airways of cystic fibrosis (CF) patients, the effects of these vectors on the kinetics of airway epithelial cell growth have not been investigated. We tested whether E1, E3-deleted Ad vectors (Ad5-CMV-lacZ) affect the kinetics of cell proliferation of human airway epithelial cells in primary culture. There was a dose-dependent relationship between the vector multiplicity of infection (moi) and the efficiency of Ad-mediated lacZ gene transfer. Growth curves of cells exposed to vector were shifted to the right as compared to vehicle in a dose-dependent manner. The vector-induced slowing of cell proliferation resulted from both (i) increased apoptotic cell death and (ii) lower recruitment into S phase. UV inactivation of the vector genes abolished the effects on cell proliferation. These data demonstrate that as the moi of vectors is increased to achieve effective gene transfer, apoptosis and slowing of the cell cycle of infected cells increases concomitantly. The identification and inactivation of these vector effects on human airway cells may be important for reducing the toxicity of adenovirus vectors for gene therapy of CF airways.

Overview summary

We found that E1, E3-deleted adenovirus vector (Ad5-CMV-lacZ) infection inhibits cell proliferation in human primary airway culture cells, reflecting both vector-induced apoptosis and slowing of the cell cycle. The dose effect data relating Ad vector titer and slowing of cell proliferation paralleled relationships between vector titer and gene transfer efficiency. UV-inactivation of the vector eliminated the effects on cell proliferation, indicating an involvement of viral gene expression in the induction of the slowing of cell growth. The identification and inactivation of these adverse effects of adenovirus vectors on airway epithelial cells are probably necessary to improve the duration of expression and the safety of future generations of adenovirus vectors for gene therapy, particularly in patients with lung disease associated with lung damage and repair.