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Clone human embryos not monkey embryos

Research published today in the scientific journal Nature reports the first successful cloning of primates, and derivation of embryonic stem cells. This announcement brings us a significant step closer to therapeutic cloning in humans.

The team at Oregon Health and State University used somatic cell nuclear transfer in Rhesus monkeys, the same technique that was used to create Dolly the sheep in 1997, the first cloned animal. Nuclear material from cultured monkey skin cells was extracted and then injected into eggs that had previously had their nuclei (containing genetic material) removed. From over 300 eggs, 35 primitive embryos were created, out of which two embryonic stem cell lines were created.

It has taken ten years since the first report of animal cloning for successful cloning in primates. It has proven technically more difficult in primates than in other species, and some have speculated that cloning in primates might be impossible. Three years ago a Korean group famously claimed to have produced embryonic stem cells from cloned human embryos, a result that turned out to have been faked. This time around, medical journals have been more cautious, delaying publication of the US team’s report until they had an independent group confirm their results.

Therapeutic cloning holds enormous medical potential. It has the potential to create cells perfectly matched to an individual, allowing replacement of damaged or diseased tissue without problems of rejection by the body’s immune system. Examples of illnesses that might be treated with embryonic stem cells include Parkinson’s disease or Alzheimer’s disease.

The news of this breakthrough will be greeted with concern in some quarters. Opponents of cloning are likely to point to the necessity of creating cloned human embryos if a similar technique is to be tried in humans. They may also raise the possibility of live births from cloned human embryos (reproductive cloning). There are substantial ethical differences between these two types of cloning, though the debate often fails to distinguish between the two. However it is unlikely that opponents of cloning will object to the research in the Rhesus monkeys per se.

Yet it is important to understand why the creation of cloned human embryos would be problematic when the creation of monkey embryos is not. When we distinguish between cases on ethical grounds we need to do so on ethically relevant criteria. There are differences between humans and monkeys, such as our use of language, or our cognitive capacity, though it is not clear why these features should justify different treatment. There are miniscule differences between a clump cells belonging to a primitive monkey embryo, and a clump of cells belonging to a human embryo.

We cannot draw attention merely to the membership of some group, and say that we are justified in treating that group differently unless we can say why group membership is relevant. If we treat some people differently merely on the basis of being part of a different race, we can be accused of racism. Treating primates differently merely on the grounds that they belong to a different species is a similar form of discrimination, which has been labelled ‘speciesism’.

In fact there are good reasons to think that it would be preferable to perform research working to create human embryonic stem cell lines rather than cloned monkey embryos and monkey stem cell lines. Unlike the rhesus monkeys, human egg donors are able to understand procedures that they are undergoing, and consent to the procedure and to research using their eggs. Research using cloned human embryos is more likely than research in monkeys to produce results that will have actual clinical benefit. And the therapies that result from such research are likely to be used to benefit humans (it seems unlikely that rhesus monkeys will ever benefit from therapeutic cloning).

There remain significant hurdles before therapeutic cloning will actually be clinically useful. However perhaps it is time to stop work on cloning monkey embryos, and focus on the generation of cloned human cell lines.

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