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Study Reports Successful Cloning Of Human Embryo Using Adult DNA
A California research team has
become the first to report, and painstakingly document, the cloning of a
human embryo using donated oocytes (egg cells) and DNA from the cells of an
adult donor. The study was published online by the journal "Stem
Cells."
The experiments, using a technique called somatic cell nuclear transfer
(SCNT), provide key steps toward the development of patient-specific
embryonic stem cells for use in developing new treatments for conditions
such as Alzheimer's disease, Parkinson's disease, and spinal cord injury,
among others. The lead author was Andrew J. French, Ph.D., of Stemagen
Corp., a private company headquartered in La Jolla, Calif.
In the experiments, the researchers removed the nuclei of mature
oocytes from healthy young women who had previously donated eggs for
successful infertility treatments. The SCNT technique was then used to
insert DNA from an adult male donor into the oocytes. The DNA was derived
from a type of cell called fibroblasts, obtained from skin biopsies.
Subsequently, several of the reconstructed oocytes continued to develop
as normal embryos, to the blastocyst stage. Extensive and carefully
documented genetic tests were performed to confirm the genetic identity of
the cloned embryos. In three embryos, tests showed the same DNA as the male
fibroblast donor.
In one of the three cases, additional tests showed that the embryo had
another type of DNA, called mitochondrial DNA, from both the female oocyte
donor and the male DNA donor.
Mitochondrial DNA testing is viewed as an essential proof of successful
human cloning -- particularly after previous fabricated reports from a
South Korean research group. Amidst this background of controversy, the
researchers took extraordinary steps to ensure that their experiments were
properly conducted and documented. These included approval by an
independent review board and confirmation of the genetic results by an
independent laboratory, among other steps.
The ability to generate stem cells using the patient's own DNA holds
great promise for the treatment of currently incurable degenerative
diseases, as well as for cell-based drug discovery. Previous studies
reporting the development of cloned human embryos have used embryonic stem
cells as the DNA donors.
"This study demonstrates, for the first time, that SCNT can be utilized
to generate cloned human blastocysts using differentiated adult donor
nuclei remodeled and reprogrammed by human oocytes," the researchers write.
They believe that some key technical factors contributed to their
successful results, including the use of freshly donated oocytes from
successful egg donors.
While the study is an important step toward the development of stem
cells for therapeutic cloning, much more research will be needed to confirm
and extend the results. Dr. French comments, "The data we present are not
in any way the final word on this topic, but, we anticipate, just one of
many publications from a variety of researchers who will use a variety of
methods to conduct and analyze similar experiments."
Dr. Miodrag Stojkovic, Co-Editor of "Stem Cells," comments: "These
researchers have for the first time developed cloned embryos up to
blastocyst stage using adult somatic [skin] cells as donor cells. This is a
key advance in the development of patient-specific stem cell lines for
therapeutic and drug development purposes. Although these results are
preliminary since no stem cell lines have been derived from the cloned
embryos, this may now be attempted."
About AlphaMed Press
AlphaMed Press publishes the internationally renowned journals, "Stem
Cells" and "The Oncologist." "Stem Cells," now in its 26th year, is the
oldest and one of the world's top-tier peer-reviewed monthly journals in
the fast-paced area of stem cells and regenerative medicine. "The
Oncologist," in its 13th year, is a premier peer-reviewed monthly journal
dedicated to physicians entrusted with the care of cancer patients. View
AlphaMed Press journals at http://www.alphamedpress.org.
AlphaMed Press
http://www.alphamedpress.org
Studiul Rapoarte de succes clonare umanã Embryo Utilizarea adulþi a ADN-ului - Study Reports Successful Cloning Of Human Embryo Using Adult DNA - articole medicale engleza - startsanatate