A Novel AAV-mediated Gene Delivery System Corrects CFTR Function in Pigs

Area of Science:

• Gene Therapy
• Molecular Biology
• Respiratory Medicine

Background:

• Cystic fibrosis (CF) is an autosomal-recessive genetic disorder caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene.
• Current gene therapy approaches using adeno-associated virus (AAV) vectors face challenges with transient expression and potential need for readministration due to episomal vector persistence.
• Developing integrating vectors is crucial for achieving sustained therapeutic gene expression in CF.

Purpose of the Study:

• To design and evaluate an integrating AAV-based vector (PB/AAV-CFTR) for delivering functional CFTR to correct the anion transport defect in cystic fibrosis.
• To assess the efficacy of PB/AAV-CFTR in restoring CFTR function and improving airway characteristics in a large-animal model of CF.

Main Methods:

• Development of a novel integrating vector, PB/AAV-CFTR, incorporating the CFTR gene flanked by piggyBac transposon elements.
• Aerosol delivery of PB/AAV-CFTR to the airways of cystic fibrosis pigs.
• Assessment of transepithelial anion current, airway surface liquid pH, bacterial killing, and viscosity in treated CF pigs compared to controls.

Main Results:

• Restoration of transepithelial chloride (Cl-) current in tracheal and bronchial tissues of PB/AAV-CFTR treated CF pigs.
• Significant increase in tracheal airway surface liquid pH and enhanced bacterial killing capacity in treated animals.
• Cultured primary airway cells from treated CF pigs showed increased airway surface liquid pH correlating with decreased viscosity.

Conclusions:

• The PB/AAV-CFTR integrating vector effectively complements CFTR function in a large-animal CF model, rescuing the anion transport defect.
• This study demonstrates the potential of integrating viral vector systems for persistent, potentially life-long, in vivo expression of CFTR.
• Targeting airway progenitor cells with this vector system holds promise for durable CF gene therapy.