New Technique allows Primate Cloning

In a ground breaking experiment scientists have created cloned embryos from an adult monkey. This could lead to the successful cloning of human embryos for stem-cell therapies.

Mark Henderson, reporting in The Times, writes about the success in the United States that is the first proof that viable primate cloning is possible. It had been thought by some experts that the procedure would be too technically demanding to make it possible.

Possible Applications

More work must be done before this technique could be used in Human cloning, but this breakthrough suggests that it will be possible to use the DNA of living humans to clone embryos and derive working stem cells from them. The possible uses of Embryonic Stem Cells are to treat diseases such as Parkinson’s and diabetes without fear of rejection by the body’s immune system. The cells also have the potential to be used in studies of these diseases and could lead to new treatments.

Since the birth of Dolly the Sheep in 1997, therapeutic cloning has been a aim for medical research. However, initial hope was dampened by the technical difficulties that presented themselves in primate cloning.

Previous Experiments

Experiments in the past have seen success in the cloning of monkey embryos, but this is the first time that the clones have survived long enough for stem cells to be extracted. Attempts to implant them in the womb have also resulted in failure.

Widespread excitement over cloning was generated in 2005 when a South Korean team claimed to have cloned a human embryo. It later emerged that much of the study had been fabricated. A British Team has already managed to clone a human embryo, but this died almost immediately. These failed attempts had led many scientists to conclude that therapeutic cloning was too difficult to ever be practical.

Shoukhrat Mitalipov, of the Oregon National Primate Research Centre, led the group that created two colonies of Embryonic Stem cells from the cloned embryos using the DNA of an adult male rhesus macaque monkey called Semos, his name is taken from the ape god in the film Planet of the Apes.

Nuclei were removed from Semo’s skin cells and inserted into 304 eggs taken from 14 different female monkeys. The success of this experiment has been attributed to new techniques developed for handling the eggs during the nuclear transfer process.

Independent Verification

The results of this experiment were first announced at a conference in Cairns, Australia, in June. The research has now been subject to peer review and was published in the journal Nature.

Nature took a rare step in commissioning an independent assessment of Professor Mitalipov's results before agreeing to publish them. This is due in part to the extreme scepticism that claims about cloning have been met with since the Woo Suk Hwang, the Korean scientist faked supposedly pioneering human research.

The analysis by David Cram, Bi Song and Alan Trounson of Monash University in Melbourne, has lain to rest any suspicion that the two Embryonic Stem cell lines were not true clones of Semos. “Proof of concept for creating somatic cell nuclear transfer primate stem cells is now firmly established,” they concluded.

It is still too early too to use this technique in human cloning due to the low success rate of 0.7 per cent and the shortage of human eggs that are available for such research. This also means that it would not be a practical method of cloning human embryos for reproductive purposes.

The breakthrough, however, does suggest that human therapeutic cloning may be possible in future. It also adds weight to a call from a UN expert panel this week for an international ban on reproductive cloning, as the results of this experiment arguably make this more plausible. 

Responses

The Times records the following responses:

The group in Oregon are to be congratulated on this achievement. The ability to produce embryo stem cells from cloned human embryos would create entirely new opportunities to study inherited diseases.  Ian Wilmut, of the University of Edinburgh, who led the team that cloned Dolly the sheep

This puts us one important step closer to developing patient-specific ES cell lines, not only for possible therapies in the future but for drug discovery and research into serious diseases. Publishing the independent verification simultaneously was a judicious move, which will put to rest the doubts that would otherwise exist post-Hwang and gives scientists immediate confidence to pursue this line of research.  Anna Krassowska, research manager of the UK Stem Cell Foundation

The paper is not only the best but also by far the most useful work to date showing that it is possible to carry out the cloning procedure and to obtain ES cell lines in primates. The overall success rate of 0.7 per cent is still too low to be used in human studies, especially given the difficulty in obtaining eggs for research. Unless there is some other way to improve the methods then it may well still be necessary to use eggs from other species in combination with human somatic cells, to obtain cytoplasmic hybrid embryos, which can then be used to derive the essentially human ES cell lines. So, although we still await a reliable method for deriving patient-specific human ES cell lines, the work is a very exciting and large step in the right direction.  Robin Lovell-Badge, of the National Institute for Medical Research

Source news article:

The Times, First Cloning of Monkey Embryo raises hope of a great leap in medial science , Thursday 15th November 2007

There have been 0 replies to this Article. + Post your comment here.