2 Cloning Studies Could Mute Critics’ Safety Fears

When the House of Representatives approved a broad ban on human cloning this summer, some lawmakers argued for the measure on grounds that the procedure was clearly unsafe. In animals, they said, cloning produced unhealthy babies, “crippling deformities” and “horror stories.”

Now that argument against cloning may be crumbling.

In separate announcements, two companies that have cloned dozens of cattle are about to report that the animals, if they survive birth, mature into adulthood and remain healthy at rates comparable to those of non-cloned cattle.

Although a huge number of clones still die in the womb, both companies say their experiences show that cloning methods are continually improving and that fears of birth defects may be overstated, at least in cattle.

Conclusions about one animal species may not be meaningful for another, and hardly anyone says cloning is safe enough to attempt to produce a child. But the two reports could force opponents of human cloning to rely on the argument that it is immoral or unnatural, rather than unsafe.

A small number of groups, including the American Society for Reproductive Medicine, say they oppose human cloning primarily on safety grounds and would have to reevaluate their opposition in the light of new data.

“The battle against cloning so far has been won on safety concerns,” said Arthur Caplan, a University of Pennsylvania bioethicist. “If you start to diminish the safety concerns, then the ethics will have to carry that much more weight.” The Senate is expected to consider the cloning ban early next year.

The new reports also may lend optimism to some researchers’ hopes of using cloning to produce replacement cells and tissues for patients. The reports come as the National Research Council begins a study Tuesday of whether cloned and genetically altered animals can be used safely to produce food and pharmaceuticals. The study was requested by the Food and Drug Administration.

Survival Rates Compare With In Vitro Numbers

Concerns about cloning’s safety have arisen amid laboratory reports of animals born with unusual problems, such as lung abnormalities, heart defects and misfiring immune systems. The problems have seemed unpredictable, possibly the result of random genetic mutations that arise during the cloning process.

In one study to be published in the Nov. 30 issue of the journal Science, the Massachusetts biotechnology company Advanced Cell Technology Inc. reports on 30 cattle produced by cloning in the last four years. Six of the 30 died shortly after birth, and the 24 others have successfully grown to adulthood--at least 1 year old.

That means 80% of the cloned cattle survived to adulthood, compared with an 84% to 87% survival rate for cattle born through in vitro fertilization, a common reproductive technique that is widely considered safe, said Dr. Robert Lanza, a company official.

Of the 24 surviving cattle, the report says, all showed normal results in tests of blood chemistry, immune systems and physical condition, such as temperature and respiratory rate.

“We ran literally every medical test that’s available. . . . We didn’t observe any of the genetic defects or immune deficiencies that have been reported in the popular press” and by other scientific teams, Lanza said.

The second report will be presented Tuesday at the National Research Council meeting by Infigen Inc. of Wisconsin. The report has not been accepted for publication by a peer-reviewed journal, which generally is required for data to gain the highest level of credibility among scientists.

Michael Bishop, Infigen’s president, said 85% of cloned cattle that survived birth grew to adulthood.

The company compared the health of about 100 cloned cattle of at least 2 years old with that of non-cloned cattle. “Were they sicker? They were not,” Bishop said. “Did they require any extra management and care versus the non-cloned? No, they did not.” He said growth rates and reproductive capacity were similar, as well.

But both companies said that an overwhelming number of their attempts at cloning failed, with animals often dying in the womb.

Cloning produces offspring that are genetic duplicates of a single parent. In traditional reproduction, by contrast, genes from two parents, carried by egg and sperm, are commingled to form a unique offspring.

Clones Have Traits of Only 1 Parent

In cloning, scientists start with a cell from an adult animal, often a skin or cheek cell. They place that cell inside an egg cell that has been stripped of its own genetic material. When the process works, it produces an embryo that has genes from only one adult.

The embryo is then transferred to a surrogate mother and carried to term.

Advanced Cell Technology said it created 496 blastocysts, or very young embryos, to get the 30 cloned animals that survived through birth. Most of the cloned embryos never produced a pregnancy after being transferred to a surrogate mother. Others died because they did not attach properly to the mother’s uterus, Lanza said.

Some scientists said it would take far more detailed genetic studies to determine whether the surviving animals were truly healthy.

Rudolph Jaenisch, a cloning expert at MIT, has said that he does not believe that a “normal” clone has ever been born and that all clones likely have some kind of defect, many of them subtle.

Jaenisch said tests on cloned animals so far have not been sophisticated enough to find those defects. To do so would require studies of individual genes in the cloned animals--a significant task in cattle, because their genes have not been well documented.

Jaenisch said the Advanced Cell Technology results were “reassuring,” but he called the tests “crude” measures of the animals’ health. Subtle genetic defects might not be detected in the biochemistry of a cow, he said, but they could be obvious and devastating in a human clone.

Bishop said Infigen had begun sophisticated gene testing, tracking the activity of 5,200 genes in cloned cattle and comparing them to non-cloned animals. The technique allows the company to predict which cloned embryos are likely to thrive and which are not, he said.

In addition, the company has studied gene activity to help it adjust the nutrient baths used to grow embryos before they are transferred to a surrogate mother. This has allowed the company to cut down on failures, Bishop said.

“We’re definitely getting better,” he said.

Lanza said Advanced Cell Technology also was improving its techniques. He said researchers had learned how to care for cloned animals immediately after birth to improve their chances of survival.

The new reports could become important in the National Research Council study of cloned and genetically modified animals used in food or pharmaceutical production.

The FDA’s Center for Veterinary Medicine requested the study because companies are using the two techniques to create food animals that grow faster or produce more meat. In addition, several companies have added genes to cows and goats so that they create proteins in their milk that can be used as drugs.

In Congress, there is broad support for a law to prohibit cloning as a technique to produce children. But significant disagreements exist concerning whether to ban cloning as a tool of medical research as well.

Some scientists hope they can use cloning to create heart, brain, pancreas and other tissues for patients whose own tissues are failing.

The technique would produce tissues that are genetically identical to those of the patient, which in theory would eliminate the problem that develops when a patient’s body sees transplanted material as “foreign” and refuses to accept it.

The House measure would criminalize human cloning for any purpose. It was approved July 31 on a 265-162 vote.

Prospects in the Senate are unclear. In the past, several senators have said cloning should remain legal as a tool of medical research and treatment.