Cystic fibrosis (CF) is caused by mutations of the CF transmembrane conductance regulator (CFTR) gene. Airway disease is the leading cause of morbidity and mortality. Gene therapy offers a potential cure for CF. Among gene delivery vehicles, adeno-associated virus (AAV) vectors have demonstrated success in clinical trials. AAV vectors have also been tested in CF patients via airway delivery for gene addition but without measurable success perhaps due to physical airway barriers and inefficient transduction. Studies have shown that higher AAV transduction of airway epithelial cells occur via the basolateral membrane in vitro and our preliminary study demonstrated that systemic administration of AAV vectors induced much more efficient lung transduction than airway delivery in mice. These findings strongly suggest that AAV can transduce airway epithelial cells via systemic administration. The efficiency of AAV transduction in airway epithelial cells after systemic delivery of AAV vectors is usually restricted by the blood vascular barrier and a high prevalence of AAV neutralizing antibodies (Nabs). In this proposal, based on our previous studies, we will explore different strategies to develop novel AAV vectors using directed evolution and AAV virion specific binding peptides via phage display technology to increase AAV vector vascular permeability for enhanced transduction in airway epithelial cells and to evade Nabs after systemic administration. Finally, the novel approaches developed in this proposal will be used to deliver optimized CRISPR/Cas9 specific for CFTR del508 to CF mice and study the long-term phenotypic correction. The results generated from these studies will allow us to develop an effective approach to treat CF patients using AAV vector mediated gene delivery. .
Adeno-associated virus (AAV) vector-mediated gene delivery has been successfully used in patients with blindness and bleeding diseases, however, early clinical trials demonstrated no improvement of lung function in CF patients treated with AAV vector mediated CFTR airway delivery perhaps due to airway physical barriers and low transduction. In this application, we will explore two novel strategies to increase AAV vector ability to cross the blood vascular barrier and enhance AAV transduction in airway epithelial cells after systemic administration for CF gene therapy. The results generated from these studies will allow us to develop an effective approach to treat CF patients using AAV vector mediated gene delivery.