Lung tissue can regenerate after injury: Study

A team of US scientists, including an Indian-American researcher from the Duke University has discovered that lung tissue can regenerate after injury.The team, including Indian-American researcher Rajan Jain, found that lung tissue has more dexterity in repairing tissue than once thought.

"It is as if the lung cells can regenerate from one another as needed to repair missing tissue, suggesting that there is much more flexibility in the system than we have previously appreciated," said Jon Epstein, chair of the department of cell and developmental biology at the University of Pennsylvania"These are not classic stem cells that we see regenerating the lung.

"They are mature lung cells that awaken in response to injury. We want to learn how the lung regenerates so that we can stimulate the process in situations where it is insufficient, such as in patients with COPD (chronic obstructive pulmonary disease)," Epstein explained.The two types of airway cells in the alveoli, the gas-exchanging part of the lung, have very different functions, but can morph into each other under the right circumstances, the investigators found.Long, thin Type-1 cells are where gases (oxygen and carbon dioxide) are exchanged -- the actual breath.Type-2 cells secrete surfactant, a soapy substance that helps keep airways open.

In fact, premature babies need to be treated with surfactant to help them breathe.In mouse models, the team showed that Type-1 cells can give rise to Type-2 cells and vice-versa."We found that Type-1 cells give rise to the Type-2 cells over about three weeks in various models of regeneration. We saw new cells growing back into these new areas of the lung," Jain informed.It is as if the lung knows it has to grow back and can call into action some Type-1 cells to help in that process, he added.

This is one of the first studies to show that a specialised cell type that was thought to be at the end of its ability to differentiate can revert to an earlier state under the right conditions.The team is also applying the approaches outlined in this paper to cells in the intestine and skin to study basic ideas of stem cell maintenance and differentiation to relate back to similar mechanisms in the heart.They hope to apply this knowledge to such other lung conditions as acute respiratory distress syndrome and idiopathic pulmonary fibrosis, where the alveoli cannot get enough oxygen into the blood.

(The paper appeared in the journal Nature Communications)