"Biologically, scientifically, the entities we're creating are not an individual," West said. "They're only cellular life, they're not a human life."
ACT scientists cloned the human embryo using a technique known as "somatic cell nuclear transfer." It's the same method that was used to successfully clone the first large animal, a sheep named Dolly, and is now the standard procedure used for cloning cattle, sheep, pigs, and mice.
ACT scientists created the cloned embryo by taking an unfertilized human egg and removing the nucleusthe compartment that contains the chromosomes and genetic material. The original nucleus was replaced with the nucleus of an adult skin cell or cumulus cell, which is a non-reproductive cell from the ovary.
Because human reproduction requires a combination of genetic material from both the mother and the father, the nucleus of a human egg has only half the genetic material required to make an embryo.
In the cloning procedure, however, the replacement nucleus comes from a mature skin or cumulus cell, which carries a complete set of chromosomes. As a result, the modified egg is able to divide as though it had been fertilized by the father's sperm.
The embryothe small ball of cells that forms as the egg dividesis a clone of the cell that donated the nucleus.
In the ACT cloning procedures, 19 eggs were given a new nucleus. Three began dividing and producing embryo clones; each of the eggs divided two to three times. Two embryos grew to four cells, and one reached six cells before dying.
All the embryos died before reaching the 32- to 64-cell stage, when embryonic stem cells are usually collected.
Lanza and his colleagues published their research in the online journal e-Biomed: Journal of Regenerative Medicine. The journal article also reports a second method used to create an embryo directly from the egg itself. The researchers have also published an account of their work in Scientific American.
Scientists who favor cloning technology believe that in the future, people could have their own healthy cells cloned to create a genetically matched "fix-it kit" of cells that could be used to treat a number of diseases without the threat of immune rejection.
Many scientists are interested in using somatic cell nuclear transfer technology to produce stem cells. Berg said he is "one hundred percent in favor of the procedure." But the work done by ACT, he contended, does little to advance progress toward that goal.
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