This article from the Texas A&M newspaper describes the medical research with “knockout” mice, or mice that have a specific gene turned off. The University’s Texas Institute of Genomic Medicine , part of the College of Veterinary Medicine and Biomedical Sciences specializes in developing knockout mice strains using embryonic stem cells from mice embryos, which are then inserted into an early embryo, resulting in mice with some cells from the first, original blastocyst, and some from the embryonic stem cell line.
TIGM starts with frozen embryonic stem (ES) cells — cells taken from the early stage of a mouse embryo — containing the inactivated gene of interest. The ES cells then take six to eight weeks to thaw and expand. A highly-skilled microinjectionist then injects these cells into a protective cavity formed during embryogenesis, called a blastocyst, which is surgically placed in a recipient female mouse’s uterus. Twenty-one days later, the mouse gives birth.
But this litter will not have the mice the scientists desire. The mice from this litter, known as chimeras, contain a mixture of DNA from the mother and the ES cells. These mice then mate with chimeras and this second generation has potential for a mouse that contains the gene of interest from the original ES cells.
Of the mice that are born from this second litter, a maximum of 33 percent may have the same gene as the ES cells, and these are the knockout mice. More often than not, the litter yields no knockout mice, which then requires further mating and more time. (Read more: High-priced mice – The Battalion – Texas A&M.)
Note the problematic definition the author gives for “blastocyst.” The blastocyst is a stage of life of the embryo. It is the organism, itself.
This is not cloning, either, although the author implies that it is. Cloning is the production of an identical twin of the donor. The embryos produced by making chimeras are not identical to each other, much less an original donor.
Just imagine: the embryonic stem cells must first become germ cells – oocytes or sperm precursors – in that chimeric embryo. That’s the only cells that will effect the genes of the future baby mice.
The story goes on to explain that, hopefully, there will eventually be a male mouse whose sperm will contain the inactivated gene and which then can be used to impregnate female mice for the production of whole litters without the gene.
This is how ethical science is done, not through the destruction of humans at the embryonic stage.