Cloning May Cause Long-Term Health Problems

In February 1997, researchers in Scotland made history when they reported that they had successfully cloned a sheep with DNA from a mammary cell of an adult ewe. Before Dolly, many scientists believed it would be impossible to make a clone with DNA taken from an adult cell because it would require that the cell's genes be reprogrammed back to the naive embryonic state. The birth of Dolly raised the possibility that adult human beings could be used to make genetically identical clones of themselves, a prospect that raises many troubling ethical issues. But in this week's Lancet, French researcher Jean-Paul Renard and co-workers report that a cow cloned with DNA from an adult cell may have died because of errors in its DNA's genetic reprogramming. Although there have been many reports of clones dying during pregnancy or shortly after birth, this is the first report that indicates that cloning may have long-term harmful effects on the clone.

The researchers took an ear cell from a healthy adult cow, itself a clone made from embryonic cell DNA, and used it to create a new clone. Six weeks after birth of the calf, there was a sudden, dramatic fall in its red blood cell counts. The calf died a week later. A post-mortem showed that the lymphoid tissues—spleen, thymus, and lymph nodes—had not developed normally.

Harry Griffin, at the Roslin Institute (Edinburgh, Scotland), where Dolly was created, told BBC News Online: "This reinforces the point we have made repeatedly in response to speculation about human cloning. No-one should be contemplating the cloning of a human being using technology which is at a very early stage of development and the mechanisms of which we understand very little."

For more information: Jean-Paul Renard, Unite de Biologie du Developpement, Laboratoire de Biologie Cellulaire et Moleculaire, Institut National de la Recherche Agronomique, 78352, Jouy-en-Josas, France. Tel: +33 34652594. Fax: +33 134652677. Email ranard@biotec.j.