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On Human Cloning
Rudolf Jaenisch

Dr. Rudolf Jaenisch is a founding member of the Whitehead Institute for Biomedical Research and a professor of biology at MIT. He recently spoke out strongly against human cloning in Washington as part of a National Academy of Sciences panel convened to discuss human cloning technology. One of the pioneers of transgenic science (gene transfer to create mouse models of human disease), Jaenisch is currently using cloned mice to study how a genome from an adult cell is reprogrammed to create a new organism.

NOVA: Is human cloning sound science?

Jaenisch: Human cloning is totally flawed. It's bad science. That is, if there is any science in it at all. I don't think there is any science in it. Scientists have not had any experience with human cloning. For cloning activists to announce that they have the experience necessary to clone a human is wishful thinking on their part and any evidence they may cite as proof of their experience is, in truth, distorted evidence taken from animal cloning research.

Human cloning is totally flawed. It's bad science.

On the other hand, the science that has been done to clone mammalian animals is generally good science. We are in the very early stages of understanding what happens with cloning in animal subjects. What we know is that it works very inefficiently. Most die before birth, while some survive until birth and then die a few days or weeks after birth. Only a few percent make it to adulthood, and most of those that do are abnormal in some way. They may grow abnormally large, suffer respiratory problems, or have heart and circulatory abnormalities. Humans are mammals, so we can predict a similar effect in human clones. There's no reason to think it would be any other way with humans. In fact, to try to clone humans, especially now when we know only a little about cloning, could potentially be a disaster.

NOVA: You said cloning research in animals is generally good science. What are we learning from it?

Jaenisch: The cloning research on animals that is being done is good science and some of it is even very good science. Through this research, we're beginning to understand what's wrong with cloning. The hypothesis—and there's good evidence of this—is that the major problem lies in the reprogramming of the genome in the cloned subject. For example, Dolly, the first cloned mammal, was derived from a mammary gland cell nucleus. The somatic donor nucleus, i.e., the nucleus of a mammary gland cell, has activated genes important for mammary gland function, for example milk production. But the mammary gland cell does not have activated genes for embryonic development because they are not needed for mammary function. For cloning to succeed, the silent, or turned off, embryonic genes of the donor cell need to be activated and the active milk-specific genes need to be silenced. This process is complicated, and we know very little right now about how such reprogramming works. In my lab, we are trying to learn more about it.

There is no way to predict whether a given clone will develop into a normal or abnormal animal.

Many scientists believe, although there is some controversy, that if this reprogramming doesn't occur correctly, the animal will be abnormal in some way. The real problem that we have discovered is that there might be apparently normal clones running around that seem fine which are really not normal, because development is not halted by a few irregular genes. It's only when key genes are irregular that the clone will die, but it may survive to birth and beyond despite irregular activation of many non-key genes. So far, we have no method for screening out abnormal embryos. There is no way to predict whether a given clone will develop into a normal or abnormal animal. Likewise, there is no way at present to predict whether a human clone will turn out to be a normal or abnormal individual.

NOVA: What would happen if clones with abnormal genes were running around?

Jaenisch: Well, there might be animals with different phenotypes running around. We have seen this in cloned mice and sheep already: Many become fat in old age. We don't know why exactly this would happen, but the best hypothesis would be that it is because the activity of some metabolic genes is not correctly regulated for some reason. We are beginning to grasp how big the problem is. That's the state of the science of animal cloning. At this very fragmentary stage of understanding, to propose to do human cloning when no science has been done whatsoever is preposterous. Is there any good research on human cloning being done? No. Are there any responsible scientists doing this? No. Are these cloning activists even competent scientists? No, they're not. So with all of these unknowns, with these people at this stage proposing to do human cloning is ludicrous. It's irresponsible. It's dangerous. They should not do it. They claim they understand the science. I don't believe they do.

NOVA: Do you think that advocates of human cloning—scientists and non-scientists alike—have good intentions?

Proposing to do human cloning is ludicrous. It's irresponsible. It's dangerous.

Jaenisch: I doubt it. Just hearing them and knowing them I think they are totally irresponsible. I don't know if they are after money or if they are after fame or why they spout this nonsense, because it is obvious to everybody in the scientific community that it shouldn't be done. It just startles me.

NOVA: Do you differentiate between reproductive human cloning and therapeutic cloning?

Jaenisch: Therapeutic cloning is a very different kettle. To do therapeutic cloning one would also transfer a somatic nucleus into an enucleated oocyte to create a cloned embryo, but instead of implanting this embryo one would transfer it to a petri dish to develop into an embryonic stem cell. This embryonic stem cell could be used for therapeutic purposes, for example, as a source for generating many different body cell types—nerve cells, heart muscle cells or pancreas cells that could be used to treat Parkinson's, cardiac diseases, or diabetes in the donor. These cells could be used for extremely important research on these diseases. We know that these cloned cells behave totally normally, so they could be used for tissue transplantation. They wouldn't be rejected because they would be immunologically identical to the donor. I don't think that therapeutic cloning causes a major ethical problem, much less of a problem than using a fertilized embryo to derive an embryonic stem cell line to do research.

NOVA: Recently the U.S. House of Representatives voted 265 to 162 to ban reproductive cloning and cloning for medical research. How do you take this news?

Therapeutic cloning has enormous potential. So to throw these two things out in the same motion is very unfortunate.

Jaenisch: It was a terrible decision. It was a decision based on ignorance, I think. I can understand why they want to ban reproductive cloning. It makes perfect sense to me, and I think it is the only way to stop these hack scientists. But therapeutic cloning, as I said, is a very different issue, and it has enormous potential. So to throw these two things out in the same motion is very unfortunate. I think it will impede research and its potential application to a great extent.

NOVA: Therapeutic cloning is legal in Britain. Are we going to fall behind Britain and other countries in which it is legal if we ban cloning here?

Jaenisch: Yes we are. We are going to fall very seriously behind. So scientists who can't do this kind of research will leave the country and do it somewhere else. And companies will leave too. I think Britain's law, which is very good, should serve as an example. Britain's legislation is very clear about what's criminal and what isn't.

NOVA: What would it take to persuade you, now or in the future, that human cloning is a good idea?

Jaenisch: At this point, nothing could persuade me. The very first step is to determine that cloning is safe in animals. So far it is not. Without that I think we can't proceed and we shouldn't proceed. We don't even have to talk about human cloning right now.

NOVA: Some advocates of reproductive cloning research have classified cloning as a basic human right, that it is our choice to use our own genes however we want to. They've even gone so far as to suggest that human cloning technology could be used to replace a couple's deceased child with a clone. How do you respond to this?

The scientific evidence is very clear about human cloning: Don't do it.

Jaenisch: I think this is a totally ridiculous argument. This is one of the worst potential applications of cloning research. No one can take that seriously.

The only serious argument is a childless couple—a couple that cannot have a child through normal means—having a child, I suppose. But I feel very uncomfortable with this scenario as well. In this case, what you do is that you fulfill the desire of a person to have a child by creating a being very different from just a regular child who comes from two normal parents. He or she might have serious problems or abnormalities stemming from a lack of human genetic identity. Also, the cause of infertility may often be genetic. Cloning of such an infertile individual would create a cloned person who would have the same defect and could only reproduce by the same means: Cloning.

NOVA: Are your concerns about human reproductive cloning more about the potentially flawed science behind it or the ethics of the issue?

Jaenisch: At the moment, the scientific basis of the argument, or lack thereof, overwhelms any other consideration, such as the ethical issues. The ethical concerns are in the future, and at the moment they don't play a role in this debate, especially from my vantage point as a scientist. When we get to a point where it even makes sense, scientifically, to think about the ethics of reproductive cloning in humans, then we can start thinking about ethics. Right now the scientific evidence is sufficient, and it is very clear about human cloning: Don't do it.

Interview conducted by Lexi Krock, editorial assistant of NOVA Online

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