After years of failure,
scientists have finally found a method to create embryonic stem cells without
destroying a fertilized embryo
For the first time, a team of scientists say they have successfully converted human skin cells into embryonic stem cells, a move that could help quiet the ethical debate surrounding stem cell research.
Researchers at Oregon Health & Science
University say they were able to implant the nucleus from a skin cell into a
donated human egg cell with its nucleus removed, creating an embryo-like cell
that has the genetic makeup of the patient who donated the skin cell.
Since 2007, scientists have had successes with the
procedure using monkeys and other mammals but not with human subjects.
"Every species is a little different
biologically," says Shoukrat Mitalipov, lead author of the study, which
was published Wednesday in Cell. "We've been using a good model in
primates, but we've now finally been able to optimize it in humans."
The embryonic stem cells created by Mitalipov can
be differentiated into many types of human cell, including nerve cells, liver
cells and heart cells. Scientists have suggested that stem cells may one day be
used to treat brain and nerve damage and diseases such as Parkinson's and
multiple sclerosis.
Mitalipov's method has several benefits over using
standard embryonic stem cells, which are created from fertilized eggs: Because
the cells contain a patient's genetic material, the body is unlikely to reject
the cells after implantation. The method also only uses a donor egg instead of
a donor embryo, which some anti-abortion advocates may be more willing to
tolerate ethically.
During monkey trials of the process, the team
attempted to implant the newly-created embryo-like cells into a female monkey
to see if it'd lead to a viable pregnancy.
"We never tried that in humans and it's not
our intention," he says. "But in monkeys we wanted to see if the
embryo was viable, but it wasn't. It's unlikely the technique we described
could be used for cloning."
Though Mitalipov is hopeful that his new method
will be more palatable for people ethically opposed to embryonic stem cell
research, he says it might raise new concerns.
"We believe there are big differences in the
methods. We're not destroying fertilized embryos," he says. "We think
it's more ethically acceptable, but you never know. Some people my say now
they're trying to use cloned embryos."
There have been several recent breakthroughs in
cell conversions. Last month, researchers in California were able to use stem cells
taken from an adult human's bone marrow and turn them into brain cells. But many
scientists agree that embryonic stem cells are likely the best cells to use for
therapies because they are "fresher" than adult stem cells.
When using adult stem cells, Mitalipov says that
newly-created cells still contain some signs of aging that have built up in a
cell's mitochondria, or power center.
"If you take a cell from a 90-year-old
patient, its battery is kind of drained. You could make new cells by
reprogramming it, but the energy is gone," he says. "The idea behind
using egg cells is that you're fully recharging the battery and making cells
that could probably live another 90 years. We're
taking you back to having young cells."
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