Chimeras sound like something out of a science fiction movie, a fusion of human and animal cells to create something in-between.
But they're real.
Scientists say they're not interested in creating "Goat Boy," the half-man, half-goat character from a few seasons back on "Saturday Night Live." Instead, they say chimeras could help them develop cures and treatments for a host of human afflictions.
For Sen. Sam Brownback, R-Kan., though, such creatures represent an unacceptable blurring of what makes humans human. The Kansas Republican is sponsoring the "Human Chimera Prohibition Act of 2005" in the Senate.
"From the moral perspective, to create a human that is less than fully human or to create an animal that possesses particularly unique human aspects should be a serious concern for all of humankind," Brownback said in a written statement to the Journal-World.
Brownback's stance against chimeras isn't surprising; in recent years the senator has become one of the most prominent national conservative voices at the juncture of science and morality, leading efforts to restrict cloning and embryonic stem cell research.
His insistence that moral considerations should guide research decisions has drawn the attention - and, often, the ire - of the nation's leading scientists. Brownback's name is prominent in the July issue of Scientific American, which has a special report on the stem cell debate.
"He's someone that a lot of people listen to, he's an effective speaker," John Rennie, editor-in-chief of Scientific American, told the Journal-World. "He speaks to a large part of the constituency on the political right that is worried about some of these things."
Humans have been using parts of animals for medical and scientific purposes for decades. Heart valves from pigs are used to fix damaged human hearts, for example. Brownback is not opposed to these kinds of efforts.
In 1988, though, Stanford University biologist Irving Weissman, along with colleagues, created a mouse with a fully human immune system to study AIDS. The field of "chimerical research" was born, and has progressed mostly quietly since.
"You've now got an animal that's now a little bit humanized, in that sense," Rennie said, adding: "That's useful, because you can study how HIV acts inside these kinds of animals."
The field has recently taken on a new prominence, though, with the emergence of stem cell research. Scientists hope that some day they will be able to use the highly adaptable stem cells to treat Alzheimer's and other illnesses, including diabetes, Parkinson's, heart disease and multiple sclerosis.
Those treatments will need testing, however. Scientists say chimeras are an opportunity to test those techniques on human systems - before testing them on actual humans.
"You can do a lot in a petri dish : you can do a lot of research that looks at cells outside an animal or a human," said Marcia Nielsen, assistant to the executive vice chancellor for health policy at University of Kansas Hospital. "But at some point, you run into limitations, and you need to understand how these therapies work in an animal before we try it in a human."
Brownback says chimeras could prove dangerous to humanity by providing some animal diseases an opportunity to adapt and attack humans.
"Public health concerns such as an increasing number of infections moving from animal populations into humans -like the Avian Bird Flu or SARS -should lead us to place limits on chimeras," he said.
"That is certainly something people worry about," Rennie said. "That's not a worry unique to chimeras or stem cells."
In late April, the National Academy of Sciences issued ethical guidelines regarding stem cell research recommending that chimeras generally be permitted. But it also called for some restrictions.
"My sense is, I think most scientists - certainly the responsible scientists - recognize you would want some limitations on this work," Rennie said.
The guidelines would ban:
¢ combining human cells with those of humanlike primates, such as monkeys.
¢ putting animal cells into human embryos.
¢ allowing human-animal chimeras to breed.
"Almost nobody likes the idea of trying to breed one type of creature inside another type of creature," Rennie said. "Nobody wants to see a human embryo growing inside a chimpanzee or goat. It would almost certainly be a fatal, unethical, inhuman type of experiment."
Nielsen said the academy's guidelines would curb abuses of chimerical research. Any scientist who crosses the ethical lines, she said, would probably lose funding and be blackballed from the scientific community.
"We've got a long and successful history of scientists regulating science," said Nielsen, who said KU was not currently doing chimerical research.
Brian Hart, a Brownback spokesman, said the senator was skeptical about the effectiveness of the guidelines.
"They're really more like suggestions," Hart said.
Not against science
Brownback's efforts - on chimeras, cloning and stem cells - have angered Weissman, the Stanford biologist. In the July Scientific American, Weissman compared Brownback and Rep. Dave Weldon, R-Fla., to Trofim Lysenko, a Soviet whose combination of ideology and bad science hurt that country's research efforts for decades.
But Brownback and his supporters say he isn't against science. Rather, he's against efforts that undermine the sanctity and dignity of human life, and he considers embryos - which scientists consider a rich source of stem cells - to be included in that life.
Brownback is an avid supporter of the National Cord Blood Bank, which preserves umbilical cords as a source of stem cells without taking even nascent human life. And KU research officials are careful to state that while they might disagree with Brownback on the issue of chimeras, they work well with him on other scientific issues.
"I have always supported good science that is both ethical and that results in real treatments for real people," Brownback said.
In the meantime, chimerical research continues. A Nevada scientist has created sheep with human cells integrated throughout their bodies, and Weissman reportedly envisions creating a mouse with humanized brain tissue.
Such creations will inevitably spark a visceral reaction among some members of the public, Rennie acknowledged.
"People vary in what they're comfortable with," he said. "It's always a challenge, in a democratic society like ours, in how you set reasonable limitations."
Brownback, at least, figures the federal government has a role in setting those limitations.
"This is an issue that's directly related to the future of humanity," he said, "so it's one worth addressing."