Key Step Toward Developing Embryonic Stem Cell Lines for Therapeutic Cloning
DURHAM, N.C., Jan. 17 /PRNewswire/ -- 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 today by the journal "Stem Cells."
(Logo: http://www.newscom.com/cgi-bin/prnh/20080117/CLTH022LOGO )
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."
The article, entitled "Development of Human Cloned Blastocysts Following
Somatic Cell Nuclear Transfer (SCNT) with Adult Fibroblasts," is available
online at: http://stemcells.alphamedpress.org/cgi/reprint/2007-0252v1.
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.
Contact: George Kendall: 919-680-0011, GKendall@alphamedpress.com.
SOURCE AlphaMed Press
George Kendall of AlphaMed Press, +1-919-680-0011, GKendall@alphamedpress.com
