A clone at last?
Panos Zavos wants to create a baby but is starting small, hoping to win respect.
By Nell Boyce
Panos Zavos, a fertility expert in Kentucky, reported in the online journal Reproductive BioMedicine that after practicing his cloning technique on cows' eggs, he has created a tiny, eight-cell human embryo. His brief paper is the only report of human cloning to appear in a science journal since Advanced Cell Technology said in November 2001 that it had produced three cloned embryos. ACT's embryos stopped dividing at the four-to-six-cell stage, leading some researchers to call the effort a failure. Zavos says his embryo was still growing when he froze it. And while ACT viewed cloned embryos as a source of life-saving stem cells, Zavos wants to make a baby.
A reproductive biologist who has studied male infertility, Zavos calls unproven cloning claims "garbage" and pledges "a very serious effort." He promises genetic evidence if his work at a secret lab succeeds. But other research reported last week suggests that his current technique may be a dead end. And some biologists criticized the journal's editor, test-tube baby pioneer Robert Edwards, for conferring scientific respectability on the report by publishing it even though it contains almost no technical details.
Still, the formal report is a first from any group aiming to clone babies. Zavos now plans to remove a cell or two from the embryo and test for genetic abnormalities. If it seems healthy, he plans to implant it in a surrogate mother. "We want to give this embryo a fair chance to implant and become a child," he says.
Monkey puzzle. Gerald Schatten of the University of Pittsburgh School of Medicine gives that long odds. While other cloned animals have become commonplace, Schatten's lab has tried for years to clone monkeys for research, without success. Now, in Science, his group explains why current cloning techniques may never succeed in monkeys--or presumably their primate cousins, humans.
Cloners usually start by taking an egg and removing its nucleus. Then they insert the genetic material of the individual they want to clone. Schatten tried this with hundreds of monkey eggs and got embryos that superficially "look terrific." But the embryos never produced pregnancies, and a peek inside showed why.
As a cell divides, the chromosomes copy themselves and line up in the middle of the original cell so they can be pulled apart into new cells. But in the monkey embryos, the chromosomes didn't split up properly. It turns out that in primates, proteins key to this choreography hang out near the egg's nucleus. Extracting the nucleus removes the proteins as well. Roger Pedersen of the University of Cambridge in England, who has tried to clone human embryos for stem-cell research, says Schatten's finding may explain "why there has been no documented success to date in achieving normal embryonic development" in human cloning.
If Schatten is right, a new technique his group is trying may offer an answer. They leave a monkey egg intact and insert both a sperm and the nucleus of the cell they want to clone. After the sperm fertilizes the egg, the proteins needed for chromosome partitioning spread out, so they are left behind later, when the egg and sperm nuclei are removed. "We're very encouraged already," says Schatten.
But if he succeeds, won't human cloners just adopt his methods? Schatten thinks cloning for making babies is "outrageous, immoral, unethical, unsafe, and should be illegal." The obvious question makes him sigh. "That," he says wearily, "certainly is not our purpose with this work."
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