Scientists announced yesterday that they have been able to stimulate stem cells from a human embryo to develop in a test tube into some of the highly specialised cells of the lungs.
Being able successfully to direct the development of embryonic stem cells into the mature cells of the body is considered essential if these cells are to fulfil the ambition of repairing damaged tissues and organs.
Scientists from Imperial College London said they converted the human embryonic stem cells into specialised cells of the lungs that are involved in the exchange of oxygen and waste carbon dioxide.
Professor Julia Polak, the scientist who led the research team, said the study represented an important development towards the eventual goal of building human organs from stem cells cultured in the laboratory. "This is a very exciting development, and could be a huge step towards being able to build human lungs for transplantation or to repair lungs severely damaged by incurable diseases such as cancer," said Professor Polak, who has herself undergone a heart-and-lung transplant.
There is a huge shortage of organs for transplant medicine and some operations ultimately fail because the body's immune system rejects "foreign" tissues from an unrelated donor.
However, stem cells offer the prospect of repairing damaged tissues in situ without the need for organ transplants and if the stem cells can be cloned from the same patient there will be no need to take tissue-rejection drugs.
Another possibility is to use embryonic stem cells to build artificial organs in the laboratory using biological "scaffolds". Although this is far more complex than repairing damaged tissue, some scientists believe it may be a realistic possibility for some of the simpler organs of the body.
Anne Bishop, one of the scientists who led the study, which is published in the journal Tissue Engineering, said that repairing damaged lungs would probably be possible before scientists were capable of building them artificially in the laboratory. "Although it will be some years before we are able to build actual human lungs for transplantation, this is a major step towards deriving cells that could be used to repair damaged lungs," Dr Bishop said.
The scientists hope to develop the technique to treat patients with acute respiratory distress syndrome, a condition where the cells lining the lungs fall off. By injecting fresh cells into the lung the scientists may be able to repopulate the vital lining of the organ.
Professor Stephen Spiro, professor of respiratory medicine at University College London and a spokesman for the British Lung Foundation, warned that although the work was very important it was still in its early stages.
People suffering from acute respiratory distress syndrome had damaged air sacks, the tiny, air-filled ends of the lungs where gas exchange between the blood and the atmosphere took place, Professor Spiro said.
"It's always been a huge challenge to replace the damaged air sacks in acute respiratory distress syndrome. Maybe these cells will be the beginning of something," he said.
The Imperial College study was funded by the Medical Research Council and will be developed commercially by NovaThera, a company spun off by the college.
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