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Cloning Research Stirs Discussion

By Ramy A. Arnaout
Senior Editor

It has been 17 days since scientists in Scotland announced they had succeeded in cloning a sheep, and the initial storm of publicity surrounding the event has begun to die down.

But the waves made by Dolly, the first animal to be cloned from adult genetic material, will not soon subside. Biologists and social scientists here and elsewhere will likely be discussing this discovery for a long time to come.

The experiment itself, by now, is old news. A team headed by Ian Wilmut, an embryologist at the Roslin Institute animal research center in Edinburgh, transplanted the genetic material of a cell from an adult ewe's mammary gland into an egg cell from another ewe after removing the egg's own genetic material.

The team let the egg divide and grow in a test tube and then implanted the young embryo into yet a third ewe, where it developed naturally into a baby sheep genetically identical to the first ewe.

Of course, what has generated all the excitement - and not a little discomfort - is that sheep and humans are not all that different from a biological standpoint, a fact that raises questions about whether cloning might soon be tried in humans.

Cloning itself is nothing new. Scientists have been cloning sheep and cattle from embryos' genetic material since the mid-1980s. The significance of Wilmut's experiment is that Dolly's genetic material came from an adult cell, not an embryo, and adult cells switch off most of the genes embryo cells use for growing an entire organism.

Before now, scientists thought that that off switch was permanent. Dolly seems to prove them wrong.

"The only explanation is that it's reversible," said Professor of Biology Rudolf Jaenisch, a developmental biologist who studies how this on/off switching works.

"I think the cloning of an entire mammal has shown me exactly how fast biology is moving ahead," said Sarah B. Tegen '97, a biology major and president of the Biology Undergraduate Students Association. "I had no real idea we were so close to this kind of accomplishment."

Scientific, ethical questions loom

"It is clearly the human implications that have people going," said Professor of Biology David E. Housman, who testified yesterday before the Massachusetts Senate Committee on Science and Technology on issues related to Wilmut's discovery.

The feat has led to talk of all sorts of scientific applications - like making parenthood possible to sterile couples, saving endangered species, or mass-producing medicinal drugs - in addition to Wilmut's goal of improving livestock. But it has also raised many fears among people who worry this technology could one day be used to clone humans.

Based on the current science, though, most of these dreams and fears are premature, say some MIT biologists.

One big problem is with efficiency of technique: It took nearly 300 failed attempts to produce the one live calf. "It seems to be very inefficient,"Jaenisch said. "Why is that?"

Cells in the body have a high rate of mutation that natural reproduction seems to reduce. Maybe using mammary cells - which are body, or somatic, cells - as genetic source material contributed to the high rate of abortion, Jaenisch said.

Whatever its cause, that problem has important ethical ramifications.

"You hear in the press that this technique could be used by a childless couple for a child, but there are serious scientific and ethical problems for that," said Jaenisch, who also testified before the Senate committee.

"If you think it's right to have to put up with all kinds of abortions until you get a [child]," he said, "that's an ethical problem."

And there are other problems involving human applications. The worst-case scenario is growing a clone as a human repair kit, Jaenisch said. Science fiction has long entertained the chilling idea of keeping clones as personalized organ donors. But "that is pretty repulsive for many people," Jaenisch said. Wilmut and many other scientists agree.

Still, there are many possible benefits that do not involve human experimentation. "Icould see some real big advantages," Jaenisch said. These include growing specific types of cells - marrow for leukemia patients, for example - in culture, that could later be used for transplants.

Science is still a ways away from being able to alter genes in cells like the one that made Dolly. Once that is possible, though, a whole new set of applications appear on the horizon.

It is within reason, for instance, to imagine raising pigs that had no immune systems, and therefore could be used for liver and other organ transplants without fear of organ rejection, Jaenisch said. Another possible application would be to insert genes into cows or sheep that would make their milk richer in certain proteins or life-saving drugs.

Overseeing technology difficult

But these possibilities also beg an important question: How can this new technology be guaranteed to be used safely and ethically? The hope, say scientists and students alike, seems to lie with both the government and scientists themselves.

Last week, President Clinton banned federal funding of human cloning research and further asked privately funded scientists to refrain from such research for the foreseeable future.

"I think the government and scientific communities are doing the right thing in staging a moratorium on human cloning until we better understand what is going on," Tegen said.

"This is the same thing that happened when recombinant DNA techniques were discovered in the 1970s," said Anna E. Lee '97, a former member of the Jaenisch lab. "A cooling off period should help us put things in perspective as well as give us the chance to figure out what is going one here."

"The issue for the public will continue to be human cloning and the emotional issues which this brings up," Housman said. Despite the public's distaste for pursuing this kind of research on people, "there can be no guarantees that such a direction will never be pursued by any scientists in any part of the world at any point in the future. A society-wide ban on the use of this methodology for human cloning is likely, and it is my hope that this ban will be adhered to in all parts of the world."

"I think we just need to be very careful about where the technology will take society," Lee said.

"Some technologies just aren't worth having in terms of their cultural and philosophical consequences," Lee said. "And Idefinitely don't think that we should allow a few scientists who are excited about technical details to guide us into this new era of genetic information. Most scientists Iknow just pay lip service to the ethical consequences of research."

But Housman remains hopeful. "We as scientists bear a duty to inform society as effectively as we can with respect to issues such as this one," he said.