Well-differentiated primary human bronchial epithelial (HBE) cell cultures are vital for cystic fibrosis (CF) research, particularly for the development of cystic fibrosis transmembrane conductance regulator (CFTR) modulator drugs. Culturing of epithelial cells with irradiated 3T3 fibroblast feeder cells plus the RhoA kinase inhibitor Y-27632 (Y), termed conditionally reprogrammed cell (CRC) technology, enhances cell growth and lifespan while preserving cell-of-origin functionality. We initially determined the electrophysiological and morphological characteristics of conventional versus CRC-expanded non-CF HBE cells. On the basis of these findings, we then created six CF cell CRC populations, three from sequentially obtained CF lungs and three from F508 del homozygous donors previously obtained and cryopreserved using conventional culture methods. Growth curves were plotted, and cells were subcultured, without irradiated feeders plus Y, into air-liquid interface conditions in nonproprietary and proprietary Ultroser G-containing media and were allowed to differentiate. Ussing chamber studies were performed after treatment of F508 del homozygous CF cells with the CFTR modulator VX-809. Bronchial epithelial cells grew exponentially in feeders plus Y, dramatically surpassing the numbers of conventionally grown cells. Passage 5 and 10 CRC HBE cells formed confluent mucociliary air-liquid interface cultures. There were differences in cell morphology and current magnitude as a function of extended passage, but the effect of VX-809 in increasing CFTR function was significant in CRC-expanded F508 del HBE cells. Thus, CRC technology expands the supply of functional primary CF HBE cells for testing CFTR modulators in Ussing chambers.
Keywords: cystic fibrosis; electrophysiology; human bronchial epithelial cells; in vitro models.