Scientists are using a new stem-cell technique that may someday revolutionize care for disorders as diverse as diabetes,
Alzheimer’s disease and muscular dystrophy.
Discovered by the Japanese scientist Shinya Yamanaka, the method creates stem cells without using
and destroying human embryos. By studying cells created from people with inherited disorders,
scientists are observing, in ways never before possible, how diseases progress and react to treatments, said Doug Melton,
a Harvard University researcher.
"This is the breakthrough the stem-cell field has been waiting for," said
Beth Seidenberg, a partner at Kleiner Perkins Caufield & Byers, the Menlo Park, Calif.-based venture-capital
firm that helped start Google Inc.
Unlike embryonic cells, the cells created using the Yamanaka method opened
a path to test drugs for genetic diseases, Seidenberg said.
The approach used in a study conducted at the Gladstone Institute in San Francisco is being adopted
by labs in the United States, Europe and Asia and helped persuade GlaxoSmithKline Plc to invest $25 million
in a joint venture with the Harvard Stem Cell Institute.
Since human embryonic stem cells were first isolated in a laboratory in 1998, they have fired
the imagination of doctors, scientists and patients, who envision a day when new tissues or body parts
might be grown to replace diseased ones. The cells are pluripotent, meaning they can be turned into any other type of cell,
such as those that make up skin, nerves or neurons.
Embryonic cells also stir controversy. Obtaining them destroys the embryos they come from, placing
the research along the same ethical fault line as abortion. Former President George W. Bush limited federal
support for the science-a policy overturned this month by his successor, Barack Obama.
While politicians and citizens debated the morality
of using embryonic cells, Yamanaka, a professor at Kyoto University in Kyoto, Japan, developed a technology
that may make the argument moot. Yamanaka, who has two daughters, started his effort 10 years ago, after
peering at a tiny embryo through a microscope and reflecting that it might form a child if it weren’t
used to make stem cells, he said in an interview.
"I saw that if we could make pluripotent stem cells without using human embryos, that would
be ideal," he said.
In 2006, he scored his first success. Using a virus to insert four genes into the skin cells of mice, he started a process
that returned the cells to a primordial state able to form any other cell in the body. Yamanaka named them induced pluripotent
stem, or IPS, cells. The next year, he repeated the feat with human cells.
Yamanaka and researchers elsewhere are now racing to find better ways to achieve the same effect.
They would like to get rid of the virus, which can cause the genes to lodge permanently in the structure
of the cell and may trigger the growth of tumors.
Yamanaka’s technique exploits a basic fact of human biology-that every cell in a person contains
the genetic instructions that set that person’s traits, from hair color to inherited disease. By taking
skin cells from a person with a disease and turning them into cells in the heart, brain or pancreas that
are affected by a genetic disease, researchers can experiment with disorders at their earliest stages,
Melton of Harvard said.
IPS cells are now being created in laboratories because making them is far simpler than getting cells from embryos, said Jeanne
Loring, founding director of the Center for Regenerative Medicine, part of the Scripps Research Institute in La Jolla, Calif.
"Every stem-cell researcher I know has
made about a dozen," Loring said.
She estimates that researchers have made 300 different so-called lines of IPS cells, a number that may double this year. Each
line is a colony of cells descended from the first ones made. Scientists keep them alive in culture and the cells keep replicating.