Cell Stem Cell
Volume 19, Issue 2, 4 August 2016, Pages 217-231
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Article
Dual SMAD Signaling Inhibition Enables Long-Term Expansion of Diverse Epithelial Basal Cells

https://doi.org/10.1016/j.stem.2016.05.012Get rights and content
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Highlights

  • SMAD activity is active in suprabasal cells but is weaker in basal epithelial cells

  • SMAD signaling activity correlates with mucociliary differentiation in the airway

  • Dual TGFβ/BMP inhibition prevents spontaneous differentiation in culture

  • Dual TGFβ/BMP inhibition allows prolonged culture of diverse epithelial basal cells

Summary

Functional modeling of many adult epithelia is limited by the difficulty in maintaining relevant stem cell populations in culture. Here, we show that dual inhibition of SMAD signaling pathways enables robust expansion of primary epithelial basal cell populations. We find that TGFβ/BMP/SMAD pathway signaling is strongly activated in luminal and suprabasal cells of several epithelia, but suppressed in p63+ basal cells. In airway epithelium, SMAD signaling promotes differentiation, and its inhibition leads to stem cell hyperplasia. Using dual SMAD signaling inhibition in a feeder-free culture system, we have been able to expand airway basal stem cells from multiple species. Expanded cells can produce functional airway epithelium physiologically responsive to clinically relevant drugs, such as CFTR modulators. This approach is effective for the clonal expansion of single human cells and for basal cell populations from epithelial tissues from all three germ layers and therefore may be broadly applicable for modeling of epithelia.

Keywords

TGFβ/BMP4/SMAD signaling
dual SMAD signaling inhibition
p63+ basal cells
stemness
differentiation
dedifferentiation
replicative exhaustion
senescence
epithelial basal and stems cells
telomeres

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