Brussels, 02 Jul 2004
The use of reproductive cloning techniques in mice has a greater likelihood of resulting in developmental abnormalities than more conventional methods of assisted reproduction, scientists have told a conference in Germany.
The finding adds to the evidence that reproductive cloning can have dangerous side effects, and has led to renewed calls for a ban on applying the technique to humans.
The research was carried out by researchers from Cornell University in New York, US, who fertilised 68 mouse eggs using both cloning and conventional assisted reproduction techniques (ART). They observed that far fewer of the cloned embryos reached the blastocyst stage, and those that did showed signs of abnormal patterns of genetic development.
Presenting his team's results to the European society on human reproduction and embryology (ESHRE) conference in Berlin, Dr Takumi Takeuchi said: 'We found significantly impaired development in the cloned embryos compared with those derived from more conventional ART [...] and this has made us more convinced that reproductive cloning is unsafe and should not be applied to humans.'
ESHER executive director Dr Andre van Steirteghem told the BBC: 'There is absolutely general agreement that reproductive cloning should be banned. It's clear from all the available experiments that it's much too dangerous.'
Meanwhile, the conference also heard from a group of scientists reporting an apparent breakthrough in the treatment of Parkinson's disease in rats using human embryonic stem cells.
The team from Hadassah University Hospital in Jerusalem manipulated stem cells from a cloned embryo to create special neurons that are absent in patients suffering from the degenerative brain disease. These were then implanted into the brains of rats with Parkinson's, the first time that human stem cells have been used in animals.
The researchers found that the symptoms of Parkinson's in rats, such as a tendency to turn constantly when moving, were significantly reduced following the transplant.
Benjamin Reubinoff told the conference: 'This study shows for the first time that human embryonic stem cell-developed neural precursors can include partial functional recovery in an experimental model of Parkinson's disease. We believe these observations are encouraging, and set the stage for future development that may eventually allow the use of embryonic stem cells for the treatment of Parkinson's disease.'
However, while many experts at the conference welcomed the results, others also warned that the long term effects of the procedure on the rats needed to be studied further.
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