One type of lung cell can regenerate as another type of lung cell, study finds

Brett Smith for – @ParkstBrett
When we think of tissue regeneration, we typically think of stem cells and their capacity to develop into a wide range of different cell types.
However, a team of scientists from Duke University and the University of Pennsylvania have shown that certain cells in the lungs are able to give rise to other lung cell types, according to a new study in the journal Nature Communications.
“It’s 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 study author Dr. Jon Epstein, chair of the department of Cell and Developmental Biology at Penn. “These aren’t 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),” he added.
A mind of its own
There are two types of cells in the air sacs of the lung known as alveoli. Long, slender Type 1 cells are where inhaled gases are exchanged. Type 2 cells release surfactant, a soapy compound that assists in keeping airways open. Sometimes, premature babies need to be given surfactant to assist them with breathing.
In the study, the team used mouse models to find that both of these kinds of cells are derived from a standard precursor stem cell in the embryo. Next, the researchers used other mouse models involving part of the lung that was removed for cell cultures to examine the plasticity of cell types throughout lung regeneration. The team saw that Type 1 cells can give rise to Type 2 cells, and vice-versa.
Researchers from Duke had previously found that Type 2 cells can differentiate into gas-exchanging Type 1 cells. However, the capacity of Type I cells to also differentiate had not been previously reported.
“We found that Type 1 cells give rise to the Type 2 cells over about three weeks in various models of regeneration,” said study author Dr. Rajan Jain, a cardiologist at Duke. “We saw new cells growing back into these new areas of the lung. It’s as if the lung knows it has to grow back and can call into action some Type 1 cells to help in that process.”
The study team noted that they are applying their findings to studies of cells from the intestine and skin. They said they will be investigating other lung conditions where alveoli cannot absorb enough oxygen.
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