Global Breakthrough In Animal Experiment: Stem Cells To Repair The Lungs, Highly Promising Results From British Team

Researchers from London's Imperial College have successfully implanted lung cells grown from embryonic stem cells into the lungs of mice.
This worldwide breakthrough, presented to the annual Congress of the European Respiratory Society (ERS) in Stockholm, opens up exciting new horizons for the treatment of lung disease.


Tissue engineering and stem cell therapy are giving rise to great hopes for the treatment of many conditions. These new treatment methods should, with time, make it possible to replace or repair failing organs with laboratory-grown tissue or cells.
Stem cells' ability to divide and differentiate means they can produce many types of body cells, of various degrees of specialisation.


From Parkinson's disease to diabetes, these therapies have already provided very encouraging results in many fields, although essentially on animal models. Yet lung diseases had not really benefited so far from this promising area of research. So the experiment presented in Stockholm could open up new, exciting horizons.


Bringing hope to millions


"The lung is a very difficult target for tissue engineering researchers", explained S?­le Lane, of Imperial College, London, who presented this novel study to the Congress. "Especially since it is an extremely complex organ and contains a large variety of cells, some of which have a very slow renewal rate."


But the capacity to regenerate lungs damaged by disease or accident would help tens of millions of patients. Chronic obstructive pulmonary disease (COPD) alone currently affects 80 million people, and several million die every year. By 2020, the World Health Organisation believes, the various forms of this disease, caused largely by smoking, could even become the third leading cause of death globally.


And COPD is not the only condition that could benefit from stem cell therapy: there are many other chronic lung diseases that still have no cure, and whose sufferers can be saved only by a difficult, costly transplant at a time when the number of donors is tending to decline.


Right on target


So immense hopes have been raised by the study presented to the ERS Congress.
For their research, the Imperial College team decided to work with mouse ESCs (embryonic stem cells) that are capable of differentiating into any other type of cell.
They had already succeeded in cultivating cells of this type in order for them to develop into specialised lung cells that expressed certain markers (epithelial, endothelial or adult stem cell markers).
It remained for them to prove that the cells, which had taken on lung cell features, were capable of embedding themselves in the lungs. This was the goal of the second phase of their research, the results of which they presented to the ERS Congress.















S?­le Lane and her team marked the stem cells using iron oxide nanoparticles containing a fluorescent green marker visible with the aid of a microscope. Then the researchers injected them into the tail veins of two groups of mice. One group was made up of normal mice, while the other group had been treated with a toxin that damaged the pulmonary epithelium.


Two days later, the mice were euthanised and the researchers used the fluorescence microscope to examine their lungs for the presence of stem cells. They were not disappointed: the mice had marked cells in their lungs, in the exact location where the researchers had expected to find them!


In the main, the stem cells had colonised the areas of the pulmonary epithelium where gas exchange takes place. Better still, no fluorescent cells were found in any other organs. This demonstrates the high degree of specialisation of these cells, which attach only to their target organ, i.e. the lungs.


Humans next in line


"This is the first time that researchers have injected lung cells produced from stem cells into laboratory animals and found them attached to the lungs", Lane emphasised proudly. "So our study shows that embryonic stem cells really do have the capacity to recolonise damaged lungs."


While stem cell therapy is now on the horizon for pulmonology, the British researchers recognise that human medical applications for their work are still a long way off. They now need to determine the precise nature, functions and longevity of the grafted cells.
It is also important to rule out any possible toxicity from this therapy, in particular "the potential for accidental implantation of undifferentiated cells", according to Anne Bishop, another member of the team, who led a symposium on the subject during the Congress.
In the meantime, she is confident that stem cells will, at the very least, find indirect medical applications, for example in the creation of model animals that can be used in drug design research or in toxicological screening.


Bishop is also considering the use of epithelial cells produced from stem cells in extra-corporal gas exchangers. These would provide a sort of semi-artificial support to the lungs until science managed to produce an implantable artificial lung!

European Respiratory Society