Researchers found lung tissue can repair itself in the event of injury more easily than previously believed.
These finding could have implications for disorders such as chronic obstructive pulmonary disease, the University of Pennsylvania School of Medicine reported.
"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 Jon Epstein, MD, chair of the department of Cell and Developmental Biology. "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]."
There are two types of airway cells in the alveoli, but they can transform into one another under the right circumstances. Long, thin Type 1 cells work to exchange gases (oxygen and carbon dioxide), while type 2 cells secrete surfactant (a soap substance that keeps the airways open). The recent findings showed these two types of cells originate from a common precursor stem cell in the embryo, and a mouse model demonstrated these types of cells can morph into each other.
In the past, the researchers had already shown Type 2 cells produce surfactant and function as progenitors in adult mice in a similar fashion to gas-exchanging Type 1 cells.
"We decided to test that hypothesis about Type 1 cells. 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. 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," said co-first authors Rajan Jain, MD, a cardiologist and instructor in the Department of Medicine.
This study is one of the first to show a specialized cell type on its final limb morphing into an earlier state. The researchers hope to apply these findings to other lung conditions such as acute respiratory distress syndrome and idiopathic pulmonary fibrosis, in which the alveoli cannot get enough oxygen into the blood.
"We want to know if we can, and how, to make new lung cells as work-arounds for diseased alveoli cells," Jain concluded.
The findings were published in a recent edition of the journal Nature Communications.
