Adeno-associated virus-based gene therapy for treating lung surfactant deficiencies
Monogenic lung surfactant deficiencies are fatal and lead to death in neonates within a year of life unless they receive a lung transplant. Deficiencies such as Surfactant protein-B (SP-B) deficiency or ATP-binding cassette subfamily A member 3 (ABCA3) deficiency lead to decreased functionality of lung surfactant, atelectasis, and severe respiratory distress. We investigated three different strategies to deliver therapeutic transgenes for transient expression to prolong life, or integrate corrective genes to cure the disorder. The first method utilized a single AAV6.2FF vector to deliver SP-B cDNA to a deficient mouse model and we observed an extension of survival. The second method employed a split-vector system to deliver both halves of ABCA3 cDNA separately to recombine in vivo, and was found to result in efficient expression of full length ABCA3 in the distal airways of mice. Thirdly, we developed an AAV6.2FF- mediated CRISPR/Cas9 gene-editing platform that caused efficient insertion and expression of promoterless transgenes in dividing alveolar type II cells. Together, these findings show efficacy of AAV-based gene therapy options to either extend life, or replace a gene in dividing cells to correct lung surfactant deficiency.