- "Splice"-like hybrids have been banned in Ohio, Arizona and elsewhere.
- Scientists say the research could cure cancer, HIV, diabetes, other deadly diseases.
- Opponents worry about the moral issues of combining animal and human cells.
Dren, the half-human, half-animal hybrid set to terrorize Adrien Brody and Sarah Polley in the new movie "Splice," is pure science fiction, but politicians across the country aren't taking any chances.
In the last month Ohio and Arizona have both passed laws forbidding research of animal human hybrids.
Proponents of the laws fear Dren-like creations and object morally to the combining human and animal cells. But scientists say the research could lead to cure for AIDS, immunize people against cancer, or grow replacement organs.
The potential for medical cures or advances is huge, said Esmail Zanjani, a scientist at the University of Nevada Reno who has created sheep that produce livers that are up to 20 percent human.
"But just because we can do something doesn't mean we should," said Zanjani. "We need to have a full discussion with the public," about this kind of research.
In a recent interview, "Splice" director Vincenzo Natali said that his inspiration for "Splice" was the earmouse, a 1995 experiment where scientists grew a large, human-shaped ear from cow cells grown on the back of a hairless mouse.
Despite the fact that no human cells were used in the ear mouse (the scientists placed cow cells on a polymer shaped like the human ear), the research sparked controversy and raised hopes that replacement organs would soon be available.
Since then research into animal human hybrids, or chimeras (after the lion, goat, and snake creature from Greek mythology) has exploded. Over the last 15 years scientists have created sheep with human livers and pancreas cells, mice with human immune systems, and many other combinations of human and animal cells.
None of the modern chimeras look like something out of Dr. Moreau's menagerie. They look like normal animals. The difference is on the inside.
The blood flowing through their veins could be human. The liver or kidneys could contain discrete human liver or kidney cells. These are not transgenic animals, said Zanjani. They are discrete cells, either animal or human. The DNA is not mixed.
If a human had, say, hepatitis, and their liver was dying, scientists could extract liver cells from that person, insert them into a developing sheep, and then harvest a human liver, made from a person's own cells (to reduce the chance of organ rejection), and replace the old liver.
Infected cells can't fight off an infection, whether it is HIV or some other disease. But if uninfected human stem cells were placed in an animal's body, scientists could train those cells to recognize and fight off the infection.
Once they are ready, the cells would be harvested from the animal and introduced back into the original human's body. There the retrained immune cells would fight off the infection.
The same technique could work for cancer, said Jeffery Platt, a scientist at the University of Michigan exploring this very scenario.
Millions of lives could be saved using human-animal hybrids, say scientists, but some people have strong moral objections to mixing human and animal cells. Earlier this week the Ohio Senate passed Senate Bill 243, which prohibits "the creation, transportation, or receipt of a human-animal hybrid, the transfer of a nonhuman embryo into a human womb, and the transfer of a human embryo into a nonhuman womb."
Anyone who violates the new law could spend five years in prison and face up to a quarter million dollars in fines. Other states, including Louisiana, Oklahoma, and Arizona have also banned research into chimeras.
National governments have also stepped in. The United Kingdom approved chimera research in 2008, when it granted a Newcastle University stem cell scientist Lyle Armstrong a permit to use cow eggs filled with human DNA to develop therapies for Parkinson's disease and stroke victims. (All cow DNA would be removed before the human DNA would be inserted.)
Canada bans all chimera research, but the Human-Animal Hybrid Prohibition Act of 2009 failed to pass the U.S. Congress.
Fears about new technology are nothing new, said Platt; the advent of railroads sparked controversy about how fast the human body was meant to travel. Nor are they unnatural; people fear what they don't know. But the potential of chimera research to save millions of lives should also be added to the equation.
"Where it becomes a problem is if government responses with undue constraints that are not justified," said Platt.