America
Lung tissue can regenerate after injury: Study
New York, April 13
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.