Molecular and functional properties of lung SP cells

Susan D. Reynolds, Hongmei Shen, Paul R. Reynolds, Tomoko Betsuyaku, Joseph M. Pilewski, Federica Gambelli, Michelangelo DeGuiseppe, Luis A. Ortiz, Barry R. Stripp

Research output: Contribution to journalArticlepeer-review

53 Citations (Scopus)


Previous analysis of lung injury and repair has provided evidence for region-specific stem cells that maintain proximal and distal epithelial compartments. However, redundant expression of lineage markers by cells at several levels of the stem cell hierarchy has complicated phenotypic and functional characterization of clonogenic airway cells. Based on the demonstration that rapid efflux of the DNA dye Hoechst 33342 can be used to prospectively purify long-term repopulating hematopoietic stem cells, we hypothesized that lung cells with similar biochemical properties would be enriched for clonogenic progenitors. We demonstrate that Hoechst-dim side population (SP) cells isolated from proximal and distal compartments of the mouse lung were relatively small and agranular, exhibited low red and green autofluorescence, and that the SP fraction was highly enriched in clonogenic cells. Quantitative RT-PCR indicated that vimentin mRNA was enriched and that epithelial markers were depleted in these preparations of SP cells. Bleomycin exposure was associated with decreased clonogenicity among alveolar SP and suggested that SP cell function was compromised under profibrotic conditions. We conclude that the SP phenotype is common to clonogenic cells at multiple airway locations and suggest that Hoechst efflux is a property of cells expressing a wound-repair phenotype.

Original languageEnglish
Pages (from-to)L972-L983
JournalAmerican Journal of Physiology - Lung Cellular and Molecular Physiology
Issue number4
Publication statusPublished - 2007 Apr
Externally publishedYes


  • Clonogenic airway cells

ASJC Scopus subject areas

  • Physiology
  • Pulmonary and Respiratory Medicine
  • Physiology (medical)
  • Cell Biology


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