Specialized stem cells in the lungs of mice can take the first steps towards regenerating damaged air sacs, or alveoli, after influenza infection.

Alveoli, where gas exchange occurs, are particularly vulnerable to damage during infections. Frank McKeon and Wa Xian at the Agency for Science, Technology and Research in Singapore and their colleagues infected mice with the H1N1 flu virus. They found that stem cells expressing a protein called p63 divide rapidly in the bronchioles — airway branches that lead to the alveoli — of the animals' lungs. The cells then move into areas of injured alveolar tissue, where they cluster together and express alveolar markers.

The p63 protein has previously been linked to the regeneration of other lung tissues. The researchers found similar p63-expressing stem cells in human lungs. In culture, these cells form alveoli-like structures, suggesting that they have a similar regenerative potential to those of mice, the authors say.

Cell 147, 525–538 (2011)