Despite ethical questions surrounding an American couple's recent announcement of their intention to become the world's first parents of a cloned baby, there are medical and scientific hurdles that may make this impossible even with the best of odds, experts on cloning technology told United Press International.
A couple identified only as "Bill" and "Kathy" announced Monday on CNN's "Connie Chung Tonight" that they, along with several other couples, would be implanted later this year with cloned human fetuses under the guidance of the controversial human cloning advocate Panayiotis Zavos.
"It would be dangerous or irresponsible for scientists to try to clone a human for reproductive purposes ... under any circumstances, by anyone," said Robert Lanza, vice president of medical and scientific development at Advanced Cell Technology Inc., of Worcester, Mass., which is developing therapeutic cloning techniques.
"It's like sending the mother and child up in a rocket, knowing it's going to blow up," Lanza said, noting scientists have yet to work out all the kinks in cloning technology and it "is still as much an art as a science."
Michele Boiani, a developmental biologist at the University of Pennsylvania in Philadelphia who researches cloning in mice, said cloning humans "is pure folly, completely crazy."
Lanza's and Boiani's fears are driven by the vast array of abnormalities and defects that have occurred in cloned animals. Among the species cloned so far, which include sheep, pigs, goats, mice and cattle, scientists have observed defects in the cardiovascular system, kidneys, liver and brain, lung failure at birth, diabetes, leg malformation and joint abnormalities.
These conditions occur with natural reproduction but they occur more often in cloned offspring, Lanza said.
"The vast majority of clones really are not healthy, and we don't even know why," Boiani said. A recent study conducted by Boiani and colleagues may explain part of the problem. The study found that genes crucial to development are not properly expressed in clones.
"I don't see any reason ... why it should be less risky to clone a human than to clone another species," Boiani said.
In addition, there are significant technical problems to overcome merely in creating a clone in the lab prior to implanting it into a mother's womb. This involves removing the DNA from a donor egg cell, replacing it with DNA from the mother and then growing the cell to the stage at which it is ready to be implanted into the mother's womb. The techniques required are sensitive and manipulations to them can result in defects in the offspring, Lanza said.
In their experiences with species already cloned, scientists have had plenty of opportunity to work out the bugs. Dolly the sheep, for example, was the result of 200 previously failed attempts.
"With humans we don't know what problems to anticipate in the long term," Lanza said. "You need to learn how to fine-tune each step in the process because you can run into many problems."
He noted cloning is very species specific, so even knowing how to do it in one species does not guarantee success in a different species. "Every species is formidable," Lanza said, pointing out it took the top cloning scientists two to three years to figure out how to clone a pig.
Boiani agreed, saying he knows how to clone mice but probably would fail if he tried to clone cows.
Both Lanza and Boiani agreed cloning success depends on the scientist's skill and experience. However, the couples seeking cloned babies are unlikely to have access to top researchers in the field because "no reputable scientist or company would touch this," Lanza said.
"Many people that want to clone a human being have never even cloned a mouse let alone a human," Lanza noted.
Zavos has said he will implant the clones in the couples at two clinics at undisclosed locations overseas. China may be the best source for that because scientists there are rumored to have successfully cloned human embryos, Lanza said.
Even if cloned human embryos are created successfully, the odds still are against further success, Lanza said. About 40 percent of the time, the embryos do not implant into the womb. Of those that do, only 10 percent to 20 percent will go to term and over 25 percent of these will not survive past birth, he said.
Cloning also may pose risks to the mother. In animals, there are a "very high number of spontaneous abortions," Lanza said. Massive hemorrhaging also is a possibility, he said.
Boiani said it would be necessary to implant several cloned fetuses into the mother's womb, some of which could die during the pregnancy. This "could cause infection in the mother so its really scary medicine," he said.
"I would never take the risk," he added.
