An anonymous reader quotes a report from The Guardian: Scientists say growing human organs inside animals could not only increase supply, but also offer the possibility of genetically tailoring the organs to be compatible with the immune system of the patient receiving them, by using the patient's own cells in the procedure, removing the possibility of rejection. "Even today the best matched organs, except if they come from identical twins, don't last very long because with time the immune system continuously is attacking them," said Dr Pablo Ross from the University of California, Davis, who is part of the team working towards growing human organs in other species. Ross added that if it does become possible to grow human organs inside other species, it might be that organ transplants become a possibility beyond critical conditions.
Ross and colleagues have recently reported a major breakthrough for our own species, revealing they were able to introduce human stem cells into early pig embryos, producing embryos for which about one in every 100,000 cells were human. These chimeras -- a term adopted from Greek mythology -- were only allowed to develop for 28 days. Now, at this week's meeting of the American Association for the Advancement of Science in Austin, Texas, the team have announced that they have managed a similar feat with sheep embryos, achieving an even higher ratio of human to animal cells. "About one in 10,000 cells in these sheep embryos are human," said Ross. The team are currently allowed to let the chimeric embryos develop for 28 days, 21 of which are in the sheep. While that might be sufficient to see the development of the missing organ when human cells are eventually combined with the genetically modified embryo, Dr Hiro Nakauchi of Stanford University, who is part of the team, said a longer experiment, perhaps up to 70 days, would be more convincing, although that would require additional permission from institutional review boards.
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