Scientists create animals that are part-human

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Harvesting human organs from sheep
Few human-animal hybrids are as advanced as the sheep created by another stem cell scientist, Esmail Zanjani, and his team at the University of Nevada-Reno. They want to one day turn sheep into living factories for human organs and tissues and along the way create cutting-edge lab animals to more effectively test experimental drugs.

Zanjani is most optimistic about the sheep that grow partially human livers after human stem cells are injected into them while they are still in the womb. Most of the adult sheep in his experiment contain about 10 percent human liver cells, though a few have as much as 40 percent, Zanjani said.

Because the human liver regenerates, the research raises the possibility of transplanting partial organs into people whose livers are failing.

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Zanjani must first ensure no animal diseases would be passed on to patients. He also must find an efficient way to completely separate the human and sheep cells, a tough task because the human cells aren’t clumped together but are rather spread throughout the sheep’s liver.

Zanjani and other stem cell scientists defend their research and insist they aren’t creating monsters — or anything remotely human.

“We haven’t seen them act as anything but sheep,” Zanjani said.

Zanjani’s goals are many years from being realized.

He’s also had trouble raising funds, and the U.S. Department of Agriculture is investigating the university over allegations made by another researcher that the school mishandled its research sheep. Zanjani declined to comment on that matter, and university officials have stood by their practices.

Allegations about the proper treatment of lab animals may take on strange new meanings as scientists work their way up the evolutionary chart. First, human stem cells were injected into bacteria, then mice and now sheep. Such research blurs biological divisions between species that couldn’t until now be breached.

Combining monkeys and people
Drawing ethical boundaries that no research appears to have crossed yet, the Academies recommend a prohibition on mixing human stem cells with embryos from monkeys and other primates. But even that policy recommendation isn’t tough enough for some researchers.

“The boundary is going to push further into larger animals,” New York Medical College professor Stuart Newman said. “That’s just asking for trouble.”

Newman and anti-biotechnology activist Jeremy Rifkin have been tracking this issue for the last decade and were behind a rather creative assault on both interspecies mixing and the government’s policy of patenting individual human genes and other living matter.

Years ago, the two applied for a patent for what they called a “humanzee,” a hypothetical — but very possible — creation that was half human and chimp.

The U.S. Patent and Trademark Office finally denied their application this year, ruling that the proposed invention was too human: Constitutional prohibitions against slavery prevents the patenting of people.

Newman and Rifkin were delighted, since they never intended to create the creature and instead wanted to use their application to protest what they see as science and commerce turning people into commodities.

And that’s a point, Newman warns, that stem scientists are edging closer to every day: “Once you are on the slope, you tend to move down it.”

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