September 5 1999
Egg cloning may let 70-year-olds become mothers
DOCTORS have discovered a way of manufacturing human eggs by using cloning technology, writes Lois Rogers.Lois Rogers
The Sunday Times
The eggs, after being fertilised in the laboratory, could be carried by surrogate mothers to create children.
The technology will give women the chance to become a genetic mother even in old age. Women of 70 or more will no longer be subject to the limitations of menopause in preventing them from having a child.
The reproduction experts have found they can reprogramme the DNA genetic blueprint from any living cell in a woman's body to make it behave like an unfertilised egg.
The nucleus of an immature egg cell from a donor is removed and replaced by the cell nucleus from a prospective genetic mother. Once the reconstituted egg is mature, it is fertilised and then incubated in the womb of a surrogate mother.
The technology, which would sweep away the queue of more than 1,000 childless women waiting for donor eggs, has been welcomed by British infertility specialists.
Zev Rosenwaks, who has pioneered the method with a team from Cornell Medical Centre, New York, plans to obtain immature ovarian tissue from donors to provide large numbers of potential egg cells for use as "envelopes".
In his first batch of 10 reconstituted human eggs, six were capable of maturing. In experiments involving 35 mice eggs, almost half matured.
Rosenwaks said: "We are primarily working with animals, but the work is also being pursued in humans. We have no human pregnancies yet."
The Human Fertilisation and Embryology Authority, which regulates infertility treatment in Britain, said the research would be unlikely to receive approval. Other specialists believe that pressure from childless women will lead to its acceptance.
Peter Brinsden, director of Bourn Hall, Cambridgeshire, one of Britain's largest infertility clinics, said: "Egg donation does not give women their own genetic child; this technology does. I would have no problem using it once it is established."
Although Bourn Hall does not treat women over 50, Brinsden expects older women to demand babies by the method. "A lot of women who have switched off as far as babies are concerned would have that urge reignited."
Although babies born from the technique would only be "half-cloned", there is concern that using "old" DNA from cells in the mother's body could mean that a newborn baby was the genetic age of its mother.
Early studies of Dolly the sheep, the first animal to be wholly cloned, suggest her cells are much older than her chronological age.
The announcement, at a conference in France, has also raised anxiety about the gathering pace of cloning technology before regulatory frameworks.
"I am instinctively uneasy about it," said Philip Hammond, the Conservative health spokesman. "We need legislation. If nature intended post-menopausal women to have babies, it would not have created the menopause."
Copyright 1999, Times Newspapers Ltd.