“There was a big question mark whether
this was indeed possible.” — DIE TER EGLI
Cloning method
yields stem cells
By Tina Hesman Saey
Cloning technology has been used to
induce human eggs to reprogram adult
cells into a primitive embryonic-like
state. The accomplishment, reported
in the Oct. 6 Nature, may one day help
researchers develop a source of stem
cells that could be used to replace a
patient’s own faulty cells.
Scientists had previously shown
through cloning experiments that egg
cells from many different kinds of animals could perform the feat, but until
now there was no evidence that human
eggs could do it.
“There was a big question mark
whether this was indeed possible,” says
Dieter Egli, a researcher at the New York
Stem Cell Foundation.
Though promising from a research
perspective, the stem cells Egli and his
colleagues produced can’t be used to
treat patients.
“This is only partial success,” says
George Q. Daley, a stem cell researcher at
Children’s Hospital Boston and Harvard
Medical School, because the newly
created stem cells contain three sets of
chromosomes instead of the usual two.
The extra chromosomes come from
the egg. In animal cloning, researchers
remove the chromosome-containing
nucleus from the egg and replace it with
the nucleus from an adult cell. Something in the egg causes the adult cell to
revert back to its earliest primordial
stage so it acts like a fertilized egg and
creates an embryo.
But when researchers tried that
technique with human cells, it worked
only when the adult cell nuclei were
inserted into eggs that retained their
own nuclei. So the resulting embryonic
cells contained one set of chromosomes
from the egg and the normal two sets
from the adult cell.
Heart disease has its own clock
Broken timers in organs may act independently of brain
Vessels transplanted from normal mice into mice
with broken clocks were healthy (left). But vessels
from mice with broken clocks developed deposits
in normal mice (right, arrows show buildup).
By Tina Hesman Saey
Broken biological clocks in
blood vessels may contribute
to hardened arteries, even if
the main timer in the brain
works fine. The finding suggests that throwing off the
daily rhythms of the body’s
organs can have serious
health consequences.
It’s known that skimping on
sleep and working against the body’s natural daily, or circadian, rhythms can raise
the risk of illnesses such as heart disease
and diabetes. Scientists assumed that the
diseases resulted from malfunctions in a
master clock in the brain.
But recently, researchers have found
that the liver and other organs have
their own internal clocks. It hasn’t been
clear whether disrupting these clocks
could also contribute to disease, says
Satchidananda Panda, a circadian
rhythm researcher at the Salk Institute
for Biological Studies in La Jolla, Calif.
To investigate that question, vascular
biologist R. Daniel Rudic of the Georgia
Health Sciences University in Augusta
and colleagues transplanted blood vessels in mice. Putting vessels from normal
mice into mice with broken brain clocks
didn’t lead to problems, the team reports
online October 3 in the Proceedings of
the National Academy of Sciences. But
putting arteries from mice with broken
clocks into normal mice resulted in artery
hardening, indicating that diseases may
result from timing defects in the vessels
themselves, not the brain.
