Lung stem cells in health, repair and disease

Last updated:

16 Dec 2010

Chronic lung diseases like cancer and Chronic Obstructive Pulmonary Disease (COPD) are among the most common causes of death in Europe. They cost the EU over €100 billion a year. These diseases involve changes in the cells within the lungs. Research on lung stem cells could shed light on the causes of such diseases, and may provide the basis for future treatments.

Lung stem cells in health, repair and disease

Did you know?

Adult lungs have a total cell surface area of 70m² - that’s as big as half a tennis court.

Green fluorescence tagged stem cells in the developing lung

Differentiating lung epithelial (lung lining) cells

Stem cells in the lung

Our lungs work hard. In an average lifetime, human lungs take 20-40 million breaths and experience a daily airflow of between 7000 and 10,000 litres. Mammalian lungs are made up of two distinct regions:

1. The conducting airway tubes, including the trachea, bronchi, and bronchioles.
2. The gas exchange regions, or alveolar spaces.

Scientists have discovered that these regions each contain unique types of stem cells and progenitor cells. In normal lungs, progenitor cells are present in abundance throughout each region. These cells divide to replace old or damaged lung cells, which keeps the lung healthy. The progenitor cells include tracheal basal cells, bronchiolar Clara cells, and alveolar type 2 cells.

Stem cells are much rarer than progenitors, but they are found in both embryonic and adult lungs. They contribute to initial lung development and help repair and regenerate the lung throughout life. Problems with stem cells appear to contribute to lung diseases. The stem cells are found in unique anatomical locations within the lung, including the branch points of airway tubes and the junctions between the conducting airway and gas exchange regions.

Left: Adult lung structure. Right: Lung anatomy and lung stem cells

Why study lung stem cells?

A better understanding of lung stem cell and progenitor cell biology will improve our knowledge of how the healthy lung works. This in turn will shed light on the causes of lung diseases such as chronic obstuctive pulmonary disease (COPD). Such research could lead to the development of new drugs or other treatments. Lung stem cells themselves may also be used in future therapies to repair or regenerate the lungs of patients with severe lung damage or disease.

Current research

Lung stem cells have most frequently been identified and characterised in genetically modified mice. These studies have allowed researchers to identify the differences between embryonic and adult lung stem cells, discover the role of stem cells in lung repair and investigate how changes to lung stem cells may lead to lung disease.

Fluorescence tagging of progenitor and stem cells before and after lung injury

Scientists are now gaining a better understanding of the identity and function of stem cells in human lungs. Researchers are working to determine the role of stem cells in various human lung diseases, including cancer and COPD. They have also begun exploring potential clinical applications with several ‘first-in-human’ studies to investigate whether lung stem cells might improve organ replacement or regeneration in patients. One scientific paper reporting such a study is Clinical transplantation of a tissue-engineered airway by P Macchiarini et al. in The Lancet.

The future

As scientists improve their understanding of the exact identity and function of human lung stem cells, the potential for clinical applications will be revealed. Researchers will identify drugs that control lung stem cells and can be tested as treatments for lung diseases. Further research will also investigate the uses of lung stem cells for personalised medicine.