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.