PEOPLE whose lungs are damaged by diseases such as emphysema may one day have
their lungs patched up with replacement tissue. Researchers in London said last
week that they had for the first time created lung cells out of mouse embryonic
stem cells鈥攁 primitive type of cell found in embryos that can become any
other cell in the body.
Anne Bishop and her colleagues from the Imperial College Centre for Tissue
Engineering in London, took some stem cells from a mouse embryo and left them to
grow into clusters known as embryoid bodies. They then continued to grow these
clusters in a standard medium which promotes the growth and maintenance of the
epithelial cells lining the surface of the lungs.
After a few days, the growing cells began to differentiate into specialised
types of cells. Some of them looked just like the cells lining the alveoli in
the lungs. Bishop told a stem cell meeting at London鈥檚 Chelsea and Westminster
Hospital that studies of the cells鈥� membrane proteins and their gene expression
confirmed their resemblance to alveolar cells.
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The team now wants to work out exactly what it was in the growth medium that
favoured the development of the alveolar cells. If they can figure out the right
conditions, they might be able to persuade all the embryonic stem cells to turn
into alveolar cells. Bishop cautions that her results are preliminary. She is
preparing a paper for publication.
If researchers could grow and develop human stem cells in the same way, they
could inject alveolar cells into diseased lungs, where they would replace
damaged tissue. Alternatively, doctors might simply inject the relevant growth
factors, so that lungs regenerate themselves. Studies in rats suggest that such
regeneration is possible.
With this kind of approach doctors could treat disorders that affect the
alveoli, such as lung fibrosis and chronic obstructive pulmonary disease. In the
long term, it might even be possible to grow and replace whole chunks of lung by
growing the cells in a three-dimensional matrix.
Robin Lovell-Badge, a stem cell researcher at the National Institute for
Medical Research in London, says that to his knowledge, lung cells haven鈥檛 been
created from stem cells before, except in whole animals. 鈥淚t鈥檚 one case where
use of embryonic stem cells is particularly exciting,鈥� he says.