A clinical trial in which stem cells
from women's fat are used to revamp their breasts is starting in Japan.
But some experts warn that such studies must proceed with caution.
Surgeons frequently
shuffle handfuls of fat from the hips up to the face for cosmetic reasons
- to smooth out wrinkles or cover up scars, for example. But they have
been wary of moving fat into the breasts.
In the 1980s, doctors found that
a proportion of grafted tissue tends to die and form hardened areas.
If fat has been transferred to the breast, these hardened areas can
show up on mammograms and might be mistaken for tumours. So using fat
to increase cup size is "kind of taboo", says plastic surgeon Adam Katz
of the University of Virginia, Charlottesville.
But Kotaro Yoshimura
of the University of Tokyo and his colleagues think they might be able
to avoid this problem by using a mix of fat cells and stem cells. The
stem cells may create fresh fat cells and coax blood vessels to grow
into and nurture the new tissue, says Yoshimura. This should boost tissue
survival.
Yoshimura
and his team carried out the procedure on their first patient on 21
January, and they plan to do 30 more operations after obtaining approval
from a review board. The women are undergoing the surgery for cosmetic
reasons.
During
the operation, the team suck fat cells from the woman's stomach or thigh.
By separating cells based on their density, the team enrich the slurry
for special stem cells that are able to generate new fat cells. They
then inject 300-400 millilitres of these stem cells mixed with normal
fat tissue into the woman's breasts.
More natural than silicone
Around 240,000 women
underwent breast augmentation in the United States in 2002. Most breast
enhancements are done by implanting packets of saline water. The use
of silicone implants is now restricted in the United States because
of concerns that they can leak, causing serious side effects. Around
a third of implants are removed within ten years because of complications.
Using a person's own
fat is an attractive alternative to these artificial implants because
it does not provoke the immune system and looks completely natural.
Also, women are rarely sorry to donate a few pounds of their own fat
to the cause. "There's no other tissue you can take that amount of,"
says Marc Hedrick of the University of California, Los Angeles, and
chief scientific officer for MacroPore Biosurgery in San Diego, California.
The idea of using stem
cells from fat isn't completely new. Two other groups have tried transplanting
fat stem cells to rejuvenate the faces of a small group of patients,
says Hedrick. Yoshimura's stem-cell trial is the biggest so far, he
adds.
Katz
says he would like to see more trials on animals and in other areas
of the human body before trying the technique on breasts. But Hedrick
is more optimistic: "There's a good shot that this will work," he says.
Hedrick believes that
fat stem cells will one day find a broader use in repairing heart muscle
and bone fractures and in other developing stem-cell therapies. But
it is not yet clear how to coax such cells into becoming muscle, bone
or blood, he says.
In
preparation for future therapies, MacroPore Biosurgery are already offering
people who have had liposuction the opportunity to bank their fat stem
cells. "I think it's crazy to throw them away," Hedrick says.
