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Artificial Wombs: Yosinori Kuwabara and his colleagues, working in a small
research laboratory at Juntendou University in Tokyo, are developing the
first operational artificial womb – a clear plastic tank the size of a bread
basket, filled with amniotic fluid stabilised at body temperature. For
the past several years, Kuwabara and his team have kept goat foetuses
alive and growing for up to 10 days by connecting their umbilical cords to
two machines that serve as a placenta, pumping in blood, oxygen, and
nutrients and disposing of waste products. While the plastic womb is
still only a prototype, Kuwabara predicts that a
fully functioning artificial womb capable of gestating a human foetus may be
a reality in less than six years. Scientists have created prototypes made out of cells
extracted from women’s bodies. Embryos successfully attached themselves
to the walls of these laboratory wombs and began to grow. . . . “We hope
to create complete artificial wombs using these techniques in a few years,”
said Dr Hung-Ching Liu of Cornell University’s Centre for Reproductive
Medicine and Infertility. . . . Liu and her colleagues grew layers of these
cells on scaffolds of biodegradable material which had been modelled into
shapes mirroring the interior of the uterus. . . . “Finally, we took embryos
left over from IVF programmes and put these into our laboratory engineered
tissue. The embryos attached themselves to the walls of our prototype wombs
and began to settle there.” The experiments were halted after six days.
However, Liu now plans to continue with this research and allow embryos to
grow in the artificial wombs for 14 days . . . “We will then see if the
embryos put down roots and veins into our artificial wombs’ walls, and
see if their cells differentiate into primitive organs and develop a
primitive placenta.” . . . “The next stage will involve experiments with
mice or dogs. If that works, we shall ask to take our work beyond the
14-day limit now imposed on such research.”
“The more stages of development you can study, the better
understanding you have,” said Stuart Newman, a scientist at New York Medical
College. But ethically, many reasons may exist for halting the growth of a
cloned human embryo. Some “people say gestate for a week, or two weeks
... but the technological imperative and the business imperative just roll
over any arbitrary boundary that people would like to set,” Newman said.
Under the new law in New Jersey, for example, cloned human embryos can
legally be placed in women for subsequent growth, but cannot result in
birth. The draft California ballot initiative says that cloned human embryos
would only be allowed “initially” to develop up to 12 days. Improved
technology, meanwhile, is allowing longer gestation of human embryos outside
the womb. . . . “This model would provide new avenues for testing new
drugs . . .” and could also grow tissue for possible transplants,
according to Hung-Ching Liu, the team's lead scientist. Four months ago, Japanese researchers . . . demonstrated a
way to grow human adult bone marrow stem cells into kidney tissue: by
putting the cells in embryonic rats. The embryos had gestated for nine to 10
days – in human terms, about four months. The researchers extracted them
from their mothers, injected the human cells into regions of the embryos
where kidneys were forming, and cultured the embryos in vitro for two days.
The researchers called this process “whole-embryo culture.” . . . The
embryos died, but the researchers removed the developing kidneys and
cultured them separately for another six days. They reported that “kidney
rudiments continued to grow.” . . . The authors called this “an in vitro
organ factory.” . . . Dr. Helen Liu . . . has grown artificial womb tissue
in the lab, put mouse embryos on it, and watched them implant and develop.
After a week, she moved some of them to the abdominal cavities of adult
mice. At 17 days - four days shy of full term - she took them all out....The
embryos in vivo, which had spent nearly half their gestation in vitro - and
none of it in a womb - seemed small but otherwise normal. . . . Put the two
technologies together, and you can grow organs in embryos without ever
implanting them in a womb....Artificial wombs erase the line
between in vitro embryos and implanted embryos. Whole-embryo organ culture
erases the line between therapeutic and reproductive cloning. Liu’s artificial womb is a surprisingly simple
construction. She created it after researching the making of artificial skin
and adapting those methods. First she and her co-workers mold a base, a
womb-shaped matrix of collagen and chondroitin, substances that are
biodegradable. Over time, they dissolve, leaving only the endometrial tissue
that is placed over the matrix. Each womb is shaped like a section of the
mammalian version it mimics: The artificial human mold is bowl-shaped; the
faux mouse womb is a doughnut-shaped section of a mouse’s tubular uterus. In
the beginning, Liu used endometrial cells donated by some of the clinic’s
female patients to grow human tissue. Then she added human embryos left over
from IVF treatments, donated by other patients. These zygotes implanted
and started to grow. But after they had gestated for 10 days, Liu ended
the experiments, well short of viability. Under current federal regulations,
two weeks is the limit for human fetal growth in the lab. “So we switched to
an animal model,” Liu says with a shrug. In 2002 she and her colleagues
started making mouse wombs and growing mouse embryos inside them. . . . Liu
thinks she and her team should have a viable mouse womb in 5 to 10 years. A
human model will take longer – “10 years, maybe, or a little more,” she
says, assuming that restrictions on fetal testing are lifted or eased. In 2002 Hung-Ching Liu, at Cornell University, in the
United States, announced that her team had successfully grown a sample of
cells from the lining of a human uterus and had used tissue engineering
technologies to shape them like a womb. When a fertilised human egg was
introduced into the womb, it implanted into the uterus wall as it would
in a natural pregnancy. The experiment was ceased at six days’ gestation
. . . . It is also feared that scientists involved in cloning could
continue their experiments without the need for surrogate mothers. |