Figure 1.

Tracheal aspirate (TA) basal stem cells (BSCs) are bona fide lower respiratory epithelial progenitor cells. (A) Schematic of the workflow. The images show TP63 staining of fresh neonatal TA sample (arrow) and the TA sample culture after 1–2 weeks. Cultures were expanded for 6–8 weeks and assayed at P2–P4. (B) Costaining for TP63 and Ki67 of BSC clones after 1–2 weeks in a culture of TA samples. (C) Representative images of KRT5, TP63, and NKX2.1 staining of confluent cultures of BSCs derived from TA and NP samples of term and preterm newborns. Scale bar, 25 μm. NP = nasopharyngeal; P2–P4 = passage 2–passage 4.