Genetic mingling endorsed for dope testing

By The Associated Press

RENO, Nevada (Associated Press) — On a farm about six miles outsidethis gambling town, Jason Chamberlain looks over a flock of about 50 smellysheep, many of them possessing partially human livers, hearts, brains andother organs.The University of Nevada-Reno researcher talks matter-of-factly abouthis plans to euthanize one of the pregnant sheep in a nearby lab. He can’twait to examine the effects of the human cells he had injected into thefetus’ brain about two months ago.”It’s mice on a large scale,” Chamberlain says with a shrug.As strange as his work may sound, it falls firmly within the new ethicsguidelines the influential National Academies issued this past week forstem cell research.In fact, the Academies’ report endorses research that co-mingles humanand animal tissue as vital to ensuring that experimental drugs and newtissue replacement therapies are safe for people.Doctors have transplanted pig valves into human hearts for years, andscientists have injected human cells into lab animals for even longer.But the biological co-mingling of animal and human is now evolving intoeven more exotic and unsettling mixes of species, evoking the Greek mythof the monstrous chimera, which was part lion, part goat and part serpent.In the past two years, scientists have created pigs with human blood,fused rabbit eggs with human DNA and injected human stem cells to makeparalyzed mice walk.Particularly worrisome to some scientists are the nightmare scenariosthat could arise from the mixing of brain cells: What if a human mind somehowgot trapped inside a sheep’s head?The ”idea that human neuronal cells might participate in ‘higher order’brain functions in a nonhuman animal, however unlikely that may be, raisesconcerns that need to be considered,” the academies report warned.In January, an informal ethics committee at Stanford University endorseda proposal to create mice with brains nearly completely made of human braincells. Stem cell scientist Irving Weissman said his experiment could provideunparalleled insight into how the human brain develops and how degenerativebrain diseases like Parkinson’s progress.Stanford law professor Hank Greely, who chaired the ethics committee,said the board was satisfied that the size and shape of the mouse brainwould prevent the human cells from creating any traits of humanity. Justin case, Greely said, the committee recommended closely monitoring themice’s behavior and immediately killing any that display human-like behavior.The Academies’ report recommends that each institution involved in stemcell research create a formal, standing committee to specifically overseethe work, including experiments that mix human and animal cells.Weissman, who has already created mice with 1 percent human brain cells,said he has no immediate plans to make mostly human mouse brains, but wantedto get ethical clearance in any case. A formal Stanford committee thatoversees research at the university would also need to authorize the experiment.Few human-animal hybrids are as advanced as the sheep created by anotherstem cell scientist, Esmail Zanjani, and his team at the University ofNevada-Reno. They want to one day turn sheep into living factories forhuman organs and tissues and along the way create cutting-edge lab animalsto more effectively test experimental drugs.Zanjani is most optimistic about the sheep that grow partially humanlivers after human stem cells are injected into them while they are stillin the womb. Most of the adult sheep in his experiment contain about 10percent human liver cells, though a few have as much as 40 percent, Zanjanisaid.Because the human liver regenerates, the research raises the possibilityof transplanting partial organs into people whose livers are failing.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 andsheep cells, a tough task because the human cells aren’t clumped togetherbut are rather spread throughout the sheep’s liver.Zanjani and other stem cell scientists defend their research and insistthey 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 Agricultureis investigating the university over allegations made by another researcherthat the school mishandled its research sheep. Zanjani declined to commenton that matter, and university officials have stood by their practices.Allegations about the proper treatment of lab animals may take on strangenew 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’tuntil now be breached.Drawing ethical boundaries that no research appears to have crossedyet, the Academies recommend a prohibition on mixing human stem cells withembryos from monkeys and other primates. But even that policy recommendationisn’t tough enough for some researchers.”The boundary is going to push further into larger animals,” New YorkMedical College professor Stuart Newman said. ”That’s just asking fortrouble.”Newman and anti-biotechnology activist Jeremy Rifkin have been trackingthis issue for the last decade and were behind a rather creative assaulton both interspecies mixing and the government’s policy of patenting individualhuman 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 andchimp.The U.S. Patent and Trademark Office finally denied their applicationthis year, ruling that the proposed invention was too human: Constitutionalprohibitions against slavery prevents the patenting of people.Newman and Rifkin were delighted, since they never intended to createthe creature and instead wanted to use their application to protest whatthey see as science and commerce turning people into commodities.And that’s a point, Newman warns, that stem scientists are edging closerto every day: ”Once you are on the slope, you tend to move down it.”

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