Human induced pluripotent stem cells for in vitro modeling of impaired mucociliary clearance in cystic fibrosis lung disease

Severely impaired mucociliary airway function is the primary pathomechanism in Cystic Fibrosis (CF) lung disease. Despite significant advances in CF therapy, there is still a critical need for alternative, individualized treatment options, especially for patients with untreatable CFTR mutations. Although intestinal organoids and primary airway cells are widely used as preclinical models of CF, both systems exhibit limitations with regard to the proper modelling of mucociliary clearance or the availability of sufficient cell quantities. Patient-specific human induced pluripotent stem cells (hiPSCs) are a promising alternative due to their unlimited expansion potential and capacity to differentiate into airway epithelia. However, cellular inhomogeneities in iPSC-derived airway cultures complicated conventional assays that determine CFTR function such as Ussing chamber measurements, and a comprehensive demonstration of CF pathophysiology in hiPSC-derived airway models has been largely lacking. This study provides comprehensive data demonstrating very similar gene expression, (ultra)structure and CFTR function in CF iPSC-derived airway (iALI) and primary airway (pALI) cultures. Addressing current limitations, we have implemented a sensitive, straightforward, and automatable ciliary beat frequency (CBF) assay, which is largely unaffected by inhomogeneities and directly reflects disturbed mucus viscosity and mucociliary transport in CF lung disease. Electron microscopy images confirmed the disease phenotype showing a highly dense and dehydrated mucus layer on top of CF iALI cultures. Furthermore, established CFTR modulator drugs partially rescued the disease phenotype in CF iALI cultures, which validated the utility of iALI cultures as a scalable, patient-specific platform for CF research and personalized drug development.