PARTS of a woman鈥檚 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.
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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鈥檚 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. 鈥淭his graft may not last,鈥� 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鈥檚
unlikely to be used in that way. 午夜福利1000集合y women would have to decide in their
twenties to have an ovary surgically removed and frozen. 鈥淭he public is
enamoured with `natural鈥�,鈥� says Soules. 鈥淭his is an unnatural way to stay
natural. I can鈥檛 see it ever being applied.鈥�
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鈥檚, are
trying to incubate immature human eggs in mice to use in IVF.