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Hope on ice

作者:伏莘    发布时间:2019-03-07 03:02:14    

By Alison Motluk in Toronto PARTS of a woman’s ovary that had been removed and frozen have been successfully transplanted back into her body. The operation offers hope for women who become sterile during cancer treatment, and may someday lead to the reversal of menopause. But some experts doubt that the procedure will ever be widely used. Roger Gosden of the University of Leeds had previously transplanted frozen ovarian tissue back into sheep and pigs, which later bred. But until February this year, no one had successfully carried out the operation on a woman. Most women who freeze their ovarian tissue are suffering from cancer, and doctors are wary of transplanting potentially cancerous material. But a 29-year-old American woman, Margaret Lloyd-Hart, provided the perfect test. She had one ovary removed due to a cyst and the second because her periods were irregular. With no ovaries, she began to suffer many symptoms common among postmenopausal women, including exhaustion. But she had taken the precaution of having her second ovary frozen and then approached Gosden to have it reimplanted. In order to be preserved cryogenically, an ovary must first be sliced into strips just millimetres wide. The thawed fragments have to be woven together before re-implantation. The surgeon who carried out the procedure, Kutluk Oktay of the New York Methodist Hospital, devised a way of weaving the fragments onto a framework that dissolved after the transplant. Gosden and Oktay say Lloyd-Hart’s transplant appears to be developing a blood supply. Stimulated by hormones, the transplanted tissue even produced an ovarian follicle, the precursor to an egg, they told a meeting of the American Society for Reproductive Medicine in Toronto this week. Although some reports have claimed that the technique can reverse the menopause, the researchers are more circumspect. “This graft may not last,” says Oktay. Menopause is a complex process, and no one knows what triggers it. And even if the technique could reverse the menopause, Michael Soules, a reproductive biologist at the University of Washington in Seattle, believes it’s unlikely to be used in that way. Healthy women would have to decide in their twenties to have an ovary surgically removed and frozen. “The public is enamoured with `natural’,” says Soules. “This is an unnatural way to stay natural. I can’t see it ever being applied.” Soules adds that the long-term success of this operation even in young women such as Lloyd-Hart is in doubt. The operation might help young women with cancer whose treatment leaves them infertile. But other procedures may prevail. Other labs, including Soules’s,

 

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