Human cloning work moves away from the embryo, but the reasons aren’t moral.
A recent Nature News article (abstract only) reports on the advances in stem cell cloning published in the last week. After using 15,000 monkey eggs in years of work to create embryonic stem cells, Mitalipov of Oregon Health & Science University successfully transplanted a skin cell nucleus into an egg, resulting in a line of cells with the ability to become many different kinds of tissue. The same week, two different groups reported making stem cells without eggs, by inserting a small suite of four genes. Each group, Yamanato’s from Kyoto University and Thompon’s from University of Wisconsin, used a different subset of genes.
Pleuripotent stem cells, those with the capacity to mature into many specific tissues, are the grail of research into cures for many diseases, including Parkinsons, ALS, and type I diabetes. Biologists have been able to make cells immortal in culture for decades, and even induce them to make a limited number of tissues, but the immortalization process always involved the use of genes also known to be involved in many cancers. This time, there are no known cancer linkages to the genes used.
The shift away from embryonic stem cells is one of pure practicality. Even the biologist behind Dolly, the first cloned sheep, created by the transfer of a nucleus into an egg, is abandoning the embryonic approach. The problem is low yield. The success rate for nuclear transfer into eggs is about 0.7%. However, President Bush and the cultural right have taken credit for the advance with as much pride as if they’d held the pipettes in the laboratory themselves.