Long term correction of 621+1G>T in Cystic Fibrosis airways

Québec has a high rate of cystic fibrosis (CF) often caused by genetic mutations that are rare in other populations. The most frequent of these rare mutations, which occurs on ~24% of all CF chromosomes in the population of the Saguenay-Lac St. Jean region, leads to the loss of CFTR protein and an inability to respond to CF drugs. There has been progress in developing gene-based therapies that aim to fix CF mutations or deliver a healthy copy of the CFTR gene to cells lining the airways. However, delivery of the normal CFTR gene to airway surface cells remains a challenge and needs to be repeated regularly because the cells are replaced every 1 – 2 months. This obstacle could be overcome by repairing basal stem cells, which self-renew and replenish the different cell types on the airway surface. However, basal stem cells lie underneath the surface cell layer, which acts as a barrier to gene therapies delivered from the airway lumen. This project will develop methods to temporarily disrupt the barrier so that gene-based therapeutics can reach the basal stem cells. Recently it has become possible to alter the genetic code and potentially repair mutations that cause CF, although some mutations occur at sites that are more difficult to correct. A second goal of this project is to develop a genome editing method for the most frequent rare mutation in Québec and to test it in the laboratory using lung cells.