A Technique to Harvest Viable Tracheobronchial Epithelial Cells from Living Human Donors

The ability to obtain airway epithelial cells from the lower respiratory tract in living human donors will facilitate study of the biologic properties of these cells. We report our experience harvesting tracheobronchial epithelial cells from living human donors by brushing the mucosal surface of the trachea and mainstem bronchi. Cells were obtained on 21 occasions from 18 healthy adult subjects under direct vision with a brush-tipped catheter during fiberoptic bronchoscopy. The average number of cells harvested per subject was 14 ± 2 × 106, and cell viability determined by trypan blue exclusion averaged 36 ± 4%. Of note, cell viability was significantly enhanced when lidocaine was confined to the nares. Lidocaine was also observed to diminish cell viability in vitro in a dose-dependent fashion. Morphologic and staining properties were used to classify harvested cells into the three major cell types present in the mucosa (i.e., ciliated, secretory, and basal cells). All three subtypes were obtained. The percentage of ciliated, secretory, and basal-like cells was 24 ± 2%, 11 ± 1%, 29 ± 1%, respectively, while the remaining 36% were difficult to type. In one subject in whom brushing was performed on three occasions over a 7-wk period, the percentage of each of the three subtypes was similar across procedures. Harvested cells could be successfully placed in primary culture with a plating efficiency of 50 to 60% and could be subcultured for up to seven passages. Acutely dissociated cells could be used to study the β-adrenergic receptor adenylyl cyclase system since they produced cAMP in response to isoproterenol. Finally, the procedure was well tolerated in all subjects; no adverse reactions were observed. We conclude that tracheobronchial epithelial cells of all major subtypes (i.e., secretory, ciliated, basal) can be harvested safely and in relatively large numbers from living human subjects by tracheobronchial brushing and that harvested cells can be studied acutely or placed in culture.