Highly Efficient Repair of the ΔF508 Mutation in Airway Stem Cells of Cystic Fibrosis Patients with Functional Rescue of the Differentiated Epithelia

Abstract

AbstractCystic fibrosis (CF) is a monogenic autosomal recessive disorder caused by mutations in the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Cl- channel. CF results in multiorgan dysfunction and ultimately mortality from respiratory sequelae. Although pharmacologic approaches have demonstrated efficacy in reducing symptoms and respiratory decline, a curative treatment modality remains elusive. Gene therapy, a promising curative strategy, has been limited due to poor correction efficiencies both in vitro and in vivo. Here, we use Cas9 and adeno-associated virus 6 (AAV6) to correct the ΔF508 mutation (found in ∼70% of CF alleles and ∼90% of CF patients in North America) in upper airway basal stem cells (UABCs) obtained from CF and non-CF patients undergoing functional endoscopic sinus surgery (FESS). In UABCs from homozygous (ΔF508/ΔF508) and compound heterozygous (ΔF508/Other) CF patients, we achieved 28 ± 5 % and 42 ± 15% correction, respectively. In homozygous human bronchial epithelial cells (HBECs), we achieved 41± 4 % correction. Upon differentiation in air-liquid interface (ALI), cultures of corrected CF cells displayed partial restoration of CFTRinh-172 sensitive Cl- currents relative to non-CF controls: 31± 5 % in UABCs and 51 ± 3 % in HBECs (both from subjects homozygous for ΔF508 CFTR). Finally, gene edited cells embedded successfully and retained expression of cytokeratin 5 (KRT5), a basal cell marker, on a FDA-approved porcine small intestinal submucosal (pSIS) membrane previously shown to improve re-mucosalization after FESS. In summary, we present an efficient, feeder-free, selection-free and clinically compatible approach to generate cell-based therapies for CF from autologous airway stem cells. This approach represents a first step towards developing patient-specific autologous airway stem cell transplant as a curative treatment for CF.