Scientists in the UK say they have made a significant step towards making human lungs for transplantation.
A team at Imperial College London, encouraged in human embryonic stem cells to grow into cells found in adult lungs, which are the type needed to allow oxygen to cross into the blood.
The lung cells, made in the laboratory by the Imperial team, are known as mature small airway epithelium, which line the part of the lung where oxygen is absorbed and carbon dioxide is excreted.
The team believe it may, eventually, also be possible to grow them from other stem cell sources such as bone marrow.
Stem cells are the body's "master cells" and can develop into a wide variety of different cell types, therefore this development is seen as a major step forward.
But it will be some years however before they will be able to build actual human lungs for transplantation.
According to researcher Dr Anne Bishop this would avoid some of the ethical concerns surrounding the use of embryonic tissue.
At present it is possible to treat people with lung disease by using donor organs, but as there is a shortage of donors, it means many do not get the life-saving treatment they need.
It is hoped that as well as being used to help make whole lungs for transplantation, the cells could also be used to repair parts of damaged lungs.
Stephen Spiro, professor of respiratory medicine at University College London Hospitals NHS Foundation Trust and spokesman for the British Lung Foundation, says the results are very exciting, but there is a lot more work to do.
He says the cells that the Imperial team have made, were crucial for lung function, but there were many other cell types that make up the lung that would be needed to make new organs.
Spiro says it has always been a challenge to replace the damaged air sacks in ARDS, and maybe these cells will be the beginning of something.
Dr Anne Bishop and colleagues plan to use their findings to treat conditions such as acute respiratory distress syndrome (ARDS) - a condition which damages these lining cells and which currently kills many critically ill hospital patients.
The work was supported by the Medical Research Council.
The Imperial researchers plan to commercialise their findings through NovaThera.