Researchers find easier way to make stem cells
By Maggie Fox, Health and Science Editor Sun Oct 12, 1:03 PM ET
WASHINGTON (Reuters) - Researchers trying to find ways to transform ordinary
skin cells into powerful stem cells said on Sunday they found a shortcut by
"sprinkling" a chemical onto the cells.
Adding the chemical allowed the team at the Harvard Stem Cell Institute in
Massachusetts to use just two genes to transform ordinary human skin cells into
more powerful induced pluripotent stem cells or iPS cells.
"This study demonstrates there's a possibility that instead of using genes and
viruses to reprogram cells, one can use chemicals," said Dr. Doug Melton, who
directed the study published in the journal Nature Biotechnology.
Melton said Danwei Huangfu, a postdoctoral researcher in his lab, developed the
new method.
"The exciting thing about Danwei's work is you can see for the first time that
you could sprinkle chemicals on cells and make stem cells," Melton, a Howard
Hughes Medical Institute Investigator, said in a statement.
Stem cells are the body's master cells, giving rise to all the tissues, organs
and blood. Embryonic stem cells are considered the most powerful kinds of stem
cells, as they have the potential to give rise to any type of tissue.
Doctors hope to someday use them to transform medicine. Melton, for instance,
wants to find a way to regenerate the pancreatic cells destroyed in type 1
diabetes and perhaps cure that disease.
INSERTING GENES
But pluripotent stem cells such as the embryonic cells are difficult to make,
requiring the use of an embryo or cloning technology. Many people also object to
their use, and several countries, including the United States, limit funding for
such experiments.
In the past year, several teams of scientists have reported finding a handful of
genes that can transform ordinary skin cells into iPS cells, which look and act
like embryonic stem cells.
To get these genes into the cells, they have had to use retroviruses, which
integrate their own genetic material into the cells they infect. This can be
dangerous and can cause tumors and perhaps other effects.
Last month U.S. researchers did the same thing using a harmless virus called an
adenovirus, but the method was not efficient. And last week, Shinya Yamanaka of
Kyoto University in Japan, who discovered iPS cells in mice, used a loop of
genetic material called a plasmid to reformat the cells.
Huangfu tried treating the cells first with valproic acid. After she did this,
it only took two of the four usual genes to reprogram the cells into iPS cells,
she reported.
This is good because the other two genes usually needed can promote cancer.
The Melton team used retroviruses to carry the two genes in but suggest they
might not be necessary.
"These results support the possibility of reprogramming through purely chemical
means, which would make therapeutic use of reprogrammed cells safer and more
practical," they wrote in their report.
Huangfu said the valproic acid unraveled the chromatin -- the physical structure
of the chromosomes -- making it possible to get in and alter the DNA more
easily.
"We may need two types of chemicals, one to loosen the chromatin structure, and
one to reprogram. We are looking for that reprogramming chemical, and it should
be possible to find it eventually," she said.
(Editing by Eric Walsh)