Japanese scientists have developed a process for
forming a chimeric embryo by planting a human stem cell into an animal
embryo, usually a pig. The organs would then mature inside the animal
until scientists harvest and transplant them into a human body.
Led by Professor Hiromitsu Nakauchi of the
University of Tokyo, they want to plant the embryo in a female pig's
womb, inducing pregnancy and creating a new-born pig with human organs
such as pancreas or liver. The organs would then mature inside the
hybrid offspring as it grows until it is slaughtered and scientists
harvest the organs and transplant them into a human body.
Creating the chimeric embryo is legal, but so far implanting it in an
animal's womb is not. Right now, a Japanese regulatory body is deciding
whether to lift the ban on implanting chimeric embryos in animals, and
these scientists are confident they could successfully grow a pig with
human organs within a year if they win approval.
Japan supports researches that have raised red flags in other countries,
such as its scientists’ plan to introduce a human stem cell (infant
cells that can develop into any part of the body) into the embryo of an
animal to create what is termed a "chimeric embryo"
that can be implanted into an animal's womb. That will then grow into a
perfect human organ, a kidney or even a heart, as the host animal
matures. Prof. Nakauchi's team has already succeeded in injecting stem
cells from rats into the embryos of mice that had been genetically
altered. “We can apply the same principles to human stem cells and pigs,
although the guidelines have not permitted us to do this yet,” he said.
There is little public opposition to research of this kind in Japan,
with domestic media coverage overwhelmingly positive, reflecting
relatively high levels of scientific literacy in the country. Until the
discovery of iPS cells (human “induced Pluripotent Stem” cell) several
years ago, the only way to obtain stem cells was to harvest them from human embryos.
This is controversial because it requires the destruction of the
embryo, a process to which religious conservatives, among others,
object.
Similar to embryonic stem cells, iPS cells are also capable of
developing into any cell in the body, but crucially their source
material is readily available. “We'll see if the experiment goes well,
but if we succeed in producing a human organ, the rest of the work
toward practical use would be done within five years,” Nakauchi told
AFP. He said creating kidney and human heart will be far more
complicated, but they are feasible. He and his team will initially breed
a pig with a human pancreas as it is a relatively easy organ to create,
and perfecting the technique will bring relief to millions of people
with diabetes.
Read more: http://www.digitaljournal.com/article/352815