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A2463 - Induced Pluripotent Stem Cell-Derived Bronchospheres as a Novel Platform for Personalized Cystic Fibrosis Drug Prediction
Author Block: A. Berical1, K. B. McCauley1, D. C. Thomas1, S. H. Randell2, D. N. Kotton1, F. Hawkins1; 1Boston University/Boston Medical Center, Boston, MA, United States, 2Cell Biology and Physiology/Marsico Lung Institute, University of North Carolina, Chapel Hill, Chapel Hill, NC, United States.
Rationale: Cystic fibrosis (CF) is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. CFTR mutations lead to decreased function of the CFTR channel at the apical membrane of several epithelia, in particular the lung. Two CFTR modulators, Ivacaftor and Lumacaftor, were recently approved for a subset of patients (G551D and F508del mutations). Cell-based assays played a pivotal role in the development of these CFTR modulators, extending the approval of Ivacaftor based on in-vitro demonstration of efficacy. However, there are more than 2000 known mutations and many patients are still waiting for effective, targeted therapies. Induced pluripotent stem cells (iPSCs) offer the potential to accelerate drug development for CF. iPSCs can be generated from any patient, do not require an invasive procedure, can differentiate into almost any cell type and are suitable for gene-editing. We recently developed a protocol to generate lung airway spheroids (bronchospheres) from iPSCs by recapitulating key developmental pathways in vitro. These bronchospheres are composed of differentiated airway cells and express functional CFTR protein. We recently reported proof-of-concept use of this platform to model CF and here provide further data characterizing different classes of CFTR mutations.
Methods: We reprogrammed peripheral blood mononucleated cells from patients with different classes of CFTR mutation, including F508del/F508del, W1282X/W1282X and G551D/G551D, into iPSCs. These iPSCs were differentiated into bronchospheres according to our published protocols. Forskolin-induced swelling (FIS) of bronchospheres and Ussing chamber assessment of air-liquid interface cultures were performed at baseline and in response to a panel of CFTR modulators to measure CFTR function.
Results: Bronchosphere swelling, after CFTR activation with forskolin, correlates with and provides a simple read out of CFTR function at baseline and in response to CFTR modulators. Wild-type CFTR bronchospheres swell in response to forskolin (total surface area fold change 2.07 ± 0.6), while CFTR mutants do not (F508del fold change 1.02 ± 0.03). Gene correction of a single F508 allele restores FIS (1.73 ± 0.15 fold change). Ussing chamber assessment of ion transport demonstrates similar patterns of CFTR function in iPSC-derived cells compared to primary human bronchial epithelial cells.
Conclusions: We have demonstrated the efficient differentiation of iPSCs into airway epithelium from patients who harbor both common and rare CFTR mutations. iPSC-derived airway epithelium recapitulates key aspects of CFTR biology. The scalable and patient-specific aspects of this technology offer opportunities to advance drug discovery, accelerate drug approval and predict an individual’s drug responsiveness.