A path breaking study has revealed that lung tissue has more dexterity in repairing tissue than once thought and that lung tissue can regenerate after injury.
Researchers from the Perelman School of Medicine at the University of Pennsylvania and Duke University, including co-senior authors Jon Epstein, MD, chair of the department of Cell and Developmental Biology, and Brigid L.M Hogan, Duke Medicine, along with co-first authors Rajan Jain, MD, a cardiologist and instructor in the Department of Medicine and Christina E. Barkauskas, also from Duke, have published their findings in Nature Communications.
Epstein said, “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. 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 .”
There are two types of airway cells in the alveoli which is the part of the lungs where the actual exchange of gasses takes place. Both the airway cells are markedly different from one another but they can change into one another under right circumstances. The Long thin Type 1 cells are where the exchange of the gases takes place while the Type 2 cells secrete surfactant, a soapy substance that helps keep airways open.
The team discovered in the mouse models that the two types of cells originate from a common source stem cell in the embryo. The team then used mouse models in which part of the lung was removed and single cell culture to study the plasticity of cell types during lung re-growth. The team found that Type 1 cells can give rise to Type 2 cells, and vice-versa.
Jain said, “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.”
It is in fact the first study of its kind to show a specific cell type which seemed to have lost its ability to differentiate could revert to its earlier state under the right conditions. In this case no special process of transcription factors were used but damage was done to the cells to provoke the body to repair itself by producing new cells of certain type.
Dr. Jain said, “We want to know if we can, and how, to make new lung cells as work-arounds for diseased alveoli cells.”