Integrin α6β4 identifies an adult distal lung epithelial population with regenerative potential in mice
Harold A. Chapman, … , Ying Wei, Thiennu H. Vu
Harold A. Chapman, … , Ying Wei, Thiennu H. Vu
Published June 23, 2011
Citation Information: J Clin Invest. 2011;121(7):2855-2862. https://doi.org/10.1172/JCI57673.
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Integrin α6β4 identifies an adult distal lung epithelial population with regenerative potential in mice

Abstract

Laminins and their integrin receptors are implicated in epithelial cell differentiation and progenitor cell maintenance. We report here that a previously unrecognized subpopulation of mouse alveolar epithelial cells (AECs) expressing the laminin receptor α6β4, but little or no pro–surfactant C (pro-SPC), is endowed with regenerative potential. Ex vivo, this subpopulation expanded clonally as progenitors but also differentiated toward mature cell types. Integrin β4 itself was not required for AEC proliferation or differentiation. An in vivo embryonic lung organoid assay, which we believe to be novel, was used to show that purified β4+ adult AECs admixed with E14.5 lung single-cell suspensions and implanted under kidney capsules self-organized into distinct Clara cell 10-kDa secretory protein (CC10+) airway-like and SPC+ saccular structures within 6 days. Using a bleomycin model of lung injury and an SPC-driven inducible cre to fate-map AECs, we found the majority of type II AECs in fibrotic areas were not derived from preexisting type II AECs, demonstrating that SPC– progenitor cells replenished type II AECs during repair. Our findings support the idea that there is a stable AEC progenitor population in the adult lung, provide in vivo evidence of AEC progenitor cell differentiation after parenchymal injury, and identify a strong candidate progenitor cell for maintenance of type II AECs during lung repair.

Authors

Harold A. Chapman, Xiaopeng Li, Jonathan P. Alexander, Alexis Brumwell, Walter Lorizio, Kevin Tan, Arnoud Sonnenberg, Ying Wei, Thiennu H. Vu

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Figure 6

Role for SPC– progenitor cells in type II cell replenishment after bleomycin-induced injury.

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Role for SPC– progenitor cells in type II cell replenishment after bleom...
(A) Insertion site of CreER2T, rtTA, and Neo cassette cDNAs into the stop codon of the endogenous SPC gene. A new stop codon was created at the 3′ end of rtTA, which was not used in these experiments. The Neo cassette had not been removed. See Supplemental Methods for details. (B) Southern blot of ES cell DNA using 5′ probe positioned as indicated in A revealed 4 correctly targeted clones (21-kb band in the Nde1 digest). (C) Merged image of pro-SPC and endogenous GFP fluorescence of SPCcreT2/loxp-tm-TR/GFP lungs 7 days after i.p. injection of 1 mg 4OH-tamoxifen. (D) Quantification of GFP+SPC+ cells as a fraction of total SPC+ cells in noninjured lungs (7 or 30 days after tamoxifen) or in injured regions of day 30 littermates injected with bleomycin 14 days before sacrifice. Greater than 200 SPC+ cells in more than 10 ×20 fields were counted in 3 sections per lung. Fibrotic areas were identified by crowded nuclei and distorted/collapsed alveolar architecture and confirmed by α-SMA staining of adjacent sections. *P < 0.0001. (E) Merged images of pro-SPC and GFP fluorescence of fibrotic and less-injured or uninjured lung areas of SPCcreT2/loxp-tm-TR/GFP mice 30 days after tamoxifen and 14 days after bleomycin. Arrowheads denote 2 GFP+SPC+ cells in fibrotic region. (F) Endogenous red fluorescence of bleomycin-injured loxp-tm-TR/GFP lung in the absence of cre. Scale bars: 50 μm.