- WEDNESDAY, July 9 (HealthDay News) — Scientists say they have
finally succeeded in developing human embryonic stem cells earlier in the
development stage of a blastomere, or a 4-cell stage embryo, so the whole
embryo is not destroyed.

The development, expected to be presented Wednesday at the European
Society of Human Reproduction & Embryology annual conference in
Barcelona, may make stem cell research easier to conduct by not raising as
many ethical concerns, the researchers added.

“Previously, scientists have been able to derive hESC [human embryonic
stem cell] lines at the 8-cell stage,” Hilde Van de Velde of the Vrije
Universiteit Brussel, Brussels, Belgium, said in a news release issued by
the society, “but success rates were variable, and it was necessary to
culture them by mixing with established hESC lines. We have been able to
derive hESCs at an earlier stage of embryonic development, and without the
need for co-culture with established hESC lines. Now we have derived a
second hESC from one cell of a 4-cell stage embryo. Given the complex
nature of earlier attempts, we were pleased that we could develop a
technique that seemed simple and was also reproducible.”

Blastomeres form in the early stages of embryonic development when
important changes occur: inner cells become the fetus, and outer cells
change into trophoblast, the outermost layer of the embryo that hooks into
the uterus and becomes a feeding tube for the developing egg.

Working with mature eggs donated by couples undergoing in vitro
fertilization, researchers split three 4-cell stage embryos into a dozen
single blastomeres. They then allowed them to grow in vitro and cultured
them using conventional methods for hESC derivation. From these 12, one
resulted in a stable hESC line, including one that scientists determined
was pluripotent, or derived from the inner cells at the blastocyst stage,
just as most other established hESC lines are.

“Now we will try to derive four hESC lines from the same embryo in
order to compare the potency capacity of all four cells,” Van de Velde
said.

The work could have major ramifications for pre-implantation genetic
diagnosis (PGD), by enabling the biopsy of one cell from a 4-cell stage
embryo. This would let the remaining three cells grow into a blastocyst
(five-day embryo) that could be implanted into the uterus and develop into
a healthy baby.

“Currently, PGD is performed at the 8-cell stage, when one or two cells
are removed; others have derived stable hESC lines at this stage but with
low efficiency. If hESC derivation at the 4-cell stage turns out to be
more efficient then at the 8-cell stage, we might consider changing our
PGD policy,” Van de Velde said.

The public mostly favors stem cell research, according to another
researcher scheduled to speak at the conference.

According to the online survey of almost 600 people, more than 78
percent disagreed or strongly disagreed with the statement “I believe that
it is morally wrong to use embryonic stem cells for research.” A similar
majority also disagreed with the statement “I believe that it is morally
wrong to use embryonic stem cells for medical treatment.”

“We found no difference between male and female attitudes towards using
hESCs for research, but when it came to medical treatment, men showed
significantly more support than women,” survey researcher Jaclyn Friedman,
a clinical embryologist at Reproductive Biology Associates in Atlanta,
said in a news release from the society. “We found no significant
differences when we looked at particular age groups, but a higher level
education of respondents correlated with greater support for the use of
hESCs, both in research and medical treatment. There were no important
differences among regions of the world …”

“Our study shows that public, patient, and scientific opinion is very
much in favor of both stem cell research and the therapeutic use of stem
cells in medical treatment. This is different from the perceived equal
distribution for and against hESC use reported in the news media,” she
said.

More information

The National Institutes of Health has more about stem
cells.