BODY & BRAIN
Stem cells help sterile mice grow eggs
Transplant success raises hope for human infertility treatments
BY LAUREL HAMERS
With an assist, an old mouse might be
able to make new eggs.
Sterilized female mice produced
healthy babies after receiving a transplant of egg-generating stem cells from
another mouse, researchers report online
May 18 in Molecular Therapy. If such a
procedure worked in humans — still a
distant prospect — it could help women
with early menopause or chemotherapy-induced infertility conceive.
These egg-generating cells are germline stem cells — precursors that become
eggs or sperm. While male germline stem
cells differentiate (or become specialized)
throughout a man’s life to produce sperm,
a woman’s are believed to differentiate
into a stockpile of eggs before she’s born.
Some recent studies have questioned
that conventional wisdom, though the
idea that germline stem cells still exist in
women after birth is controversial.
“It’s been a debate for many years,”
says Evelyn Telfer, a reproductive biolo-
gist at the University of Edinburgh.
Isolating germline stem cells and
coaxing them to become eggs has proven
tricky. Scientists have previously shown
that germline stem cells from mice can
turn into eggs in a petri dish. “The argu-
ment is whether these cells will do it in
the body normally,” Telfer says.
Developmental biologist Ji Wu of
Shanghai Jiao Tong University and colleagues took germline stem cells from the
ovaries of a 6-day-old mouse, grew them
in a petri dish and then transplanted
them into sterilized adult female mice’s
ovaries. The stem cells gradually moved
to a spot just under the ovary’s surface,
where they started turning into eggs.
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Five to eight weeks after the trans-
plant, those mice mated with males. Six
of the eight stem cell recipients became
pregnant and delivered healthy pups.
The results show that germline stem
cells can indeed restore fertility when
transplanted into other mice, Wu says.
The study also offers more evidence
that germline stem cells collected after a
female mammal is born can still turn into
viable eggs, Telfer says. But the stem cells
were from very young mice, she notes.
“Maybe a cleaner experiment would have
been to take them from an adult.” s
Germline stem cells (arrows, left) put into a
mouse’s ovary move toward the ovary’s edge
(arrow, right). The cells start to make a protein
that signals they’re becoming eggs.
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