| NEW YORK, April 28
NEW YORK, April 28 And now there are three: in
the wake of announcements from laboratories in Oregon and
California that they had created human embryos by cloning cells
of living people, a lab in New York announced on Monday that it
had done that and more.
In addition to cloning the cells of a woman with diabetes,
producing embryos and stem cells that are her perfect genetic
matches, scientists got the stem cells to differentiate into
cells able to secrete insulin.
That raised hopes for realizing a long-held dream of stem
cell research, namely, creating patient-specific replacement
cells for people with diabetes, Parkinson's disease, heart
failure and other devastating conditions. But it also suggested
that what the Catholic Church and other right-to-life advocates
have long warned of - scientists creating human embryos to order
- could be imminent.
The trio of successes "increases the likelihood that human
embryos will be produced to generate therapy for a specific
individual," said bioethicist Insoo Hyun of Case Western Reserve
University School of Medicine in Cleveland. And "the creation of
more human embryos for scientific experiments is certain."
The accelerating progress in embryonic stem cell research
began last May. Scientists, led by Shoukhrat Mitalipov of Oregon
Health & Science University, reported they had created healthy,
early-stage human embryos - hollow balls of about 150 cells - by
fusing ova with cells from a fetus, in one experiment, and an
infant in another.
Earlier this month, scientists at the CHA Stem Cell
Institute in Seoul, South Korea, announced they had managed the
same feat with skin cells from two adult men.
In each case, scientists used a version of the technique
that created the sheep Dolly in 1996, the first clone of an
adult mammal. Called somatic cell nuclear transfer (SCNT), the
recipe calls for removing the nuclear DNA from an ovum, fusing
it with a cell from a living person, and stimulating each ovum
to begin dividing and multiplying. The resulting embryo includes
stem cells that can differentiate into any human cell type.
While that sounds simple enough, immense technical hurdles
kept scientists from achieving human SCNT over more than a
decade of attempts. Now that they have a reliable recipe,
including the right nutrients to sustain the eggs and the right
timing to start it dividing, they have "a reproducible, reliable
way to create patient-specific stem cells" via cloning, said Dr.
Robert Lanza, chief scientific officer of Advanced Cell
Technology and co-author of the CHA paper.
In the latest study, published online in Nature, scientists
led by Dieter Egli of the privately-funded New York Stem Cell
Foundation Research Institute derived insulin-making "beta
cells" from the embryos they cloned from a 32-year-old with
type-1 diabetes, an autoimmune disease in which the immune
system attacks beta cells. Beta cells do not function in that
incurable form of diabetes, often known as juvenile diabetes,
which is treated with insulin.
The beta cells produce as much insulin as those in a healthy
human pancreas, Egli said. When transplanted into lab mice, the
cells functioned normally, making insulin in response to
Egli has no plans to transplant stem-cell-derived beta cells
into patients with type 1-diabetes, in large part because the
new cells will meet the same fate as the patient's native beta
For one thing, in type-1 diabetes the immune system chews up
beta cells, so the same fate could await cells transplanted into
a diabetic, Egli said.
One of the most important uses of the newly created beta
cells will therefore be for research, not therapy, said
biologist Douglas Melton of the Harvard Stem Cell Institute, who
was not involved in the study.
A key research imperative, experts said, is animal
experiments to compare the therapeutic potential of cloned
embryonic stem cells with stem cells made by "reprogramming"
adult cells. This technique does not create or require human
embryos, and so was hailed as a way to have stem-cell research
without the ethical baggage.
It turns out that some cells produced this way self-destruct
or die young, however, suggesting that the embryonic kind will
be necessary after all.
That has resurrected a debate that flared in 2001, when U.S.
President George W. Bush declared that federal funds could not
be used to create human embryos for research. Existing stem cell
lines, or IVF embryos, were therefore used.
But with the creation of patient-specific stem cells now
scientific reality, there will likely be greater scientific
interest in creating human embryos for research, returning the
moral debate to the front burner.
"They are cloning human embryos and killing them for their
cells," biologist David Prentice of the pro-life Family Research
Council said. "There should be much more outrage."
(Reporting by Sharon Begley; Editing by Julie Steenhuysen and