Mouse embryonic stem cells coloured with fluorescent dye

Credit: Wikipedia

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TOKYO: Mouse embryos have been cloned from unfertilised eggs by Japanese scientists, an advance that could help resolve the heated ethical debate about stem cell research.

The find raises the prospect that the process could be used for human eggs that would otherwise go to waste during IVF.

Advocates say research involving embryonic stem cells – cells that can develop into various organs or nerves – can save lives by finding cures for diseases such as cancer and diabetes.

But the research has provoked a furore among religious conservatives, who argue that it destroys a human life – albeit one at its earliest stage of development. President George W. Bush has banned all federal funding for stem cell studies in the United States, the world's biggest research hub.

One proposed alternative has been to use unfertilised human eggs, but this presents the major obstacle of trying to persuade healthy women to undergo the painful process of donating eggs.

Now, a Japanese team claims to have found a potential future solution. It performed in-vitro fertilisation (IVF) with mice and found that egg cells that failed to be fertilised could be used to make cloned embryonic stem cells.

"If we can use [human] egg cells that would have been dumped, then the problem of finding donors will be solved," said Teruhiko Wakayama, who led the study at the Japanese government-backed Riken research foundation.

"Before our findings, it was believed that only fresh eggs could be used. But if incompetent eggs [from IVF] can be cloned, then scientists could be given eggs that failed to be fertilised and would have been abandoned in fertility clinics," said Wakayama. The study is published in the US scientific journal Current Biology.

Japan, the world’s largest funder of research after the United States, has few restrictions on stem cell research. And in Washington, Democratic lawmakers have been pushing to lift restrictions on stem cell research since they took control of Congress in January from Bush's largely anti-abortion Republicans.

Experts believe the use of unfertilised, cloned eggs - if replicated in humans - could ease ethical concerns, although it would be unlikely to eradicate all opposition.

"Fertilised eggs in particular are regarded as the beginning of human life in certain religions, namely Catholicism, so destroying them for the sake of medicine can be controversial," said Ryuichi Ida, a professor of international law and biology at Kyoto University in western Japan.

"But if unfertilised eggs can be used without ethical problems such as physically hurting donor women, that's probably less sinful than using fertilised eggs," he said.

"And yet, we cannot escape the question of whether it is morally okay to use any human egg cells, which are one stage ahead of being fertilised egg cells," Ida said.

Some scientists also caution that there is still a long way to go before Wakayama's research can be turned to practical use.

"I think Doctor Wakayama's research is scientifically interesting, but there is a fundamental problem," said Motoya Katsuki, president of Japan's National Institute of Basic Biology. "Scientists have never succeeded in creating a [fully-functioning] cloned organ,” Katsuki said, we’re therefore a long way off from having to worry about the ethical issues.

Another concern on the ethical front is the risk, however remote, that cloned stem cells could grow into cloned human beings - one of the ultimate taboos for religious conservatives. Wakayama insisted that his cloned embryonic stem cells did not turn into cloned mice, and were unlikely to even have that capability.

But Norio Nakatsuji, president of the Institute for Frontier Medical Sciences at Kyoto University, warned that nothing was impossible in the long term. "Theoretically speaking, you can't say that cloned mice will never be created from a cloned stem cell," Nakatsuji said. "You can never tell, because science progresses with every new discovery."