The first direct study of the lifespan of cloned animals, carried out by a research team at the National Institute for Infectious Diseases in Tokyo, suggests that cloning leads to premature death.

The cloning technique involves replacing a nucleus of an ovum with a nucleus from a donor cell. Frequently these nuclear transfer embryos miscarry or fail to develop. Some clones die post-parturition. To date, many scientists have argued that the surviving clones have the capacity to be perfectly healthy, normal animals.

The latest research suggests that even apparently healthy clones may suffer from unpredictable defects in the long term. Scientists suspect an immune system defect is the key to early deaths of
clones.

In Tokyo, Atsuo Ogura’s team cloned 12 male mice from a testis cell and compared them with seven males from natural matings. The clones, all active and healthy, initially thrived. By 800 days (26 months), 10 of the clones had died from liver failure and pneumonia, in comparison to one of the seven control animals.

The precise cause of death is yet to be isolated, as dead clones exhibited high rates of cancer, liver disease and pneumonia. Consistently low levels of antibody production in clones suggest a disorder of the immune system. The experiment will be repeated with more animals as the research team attempts to pinpoint the cause of death.

The team regards these preliminary results as a warning about attempts to clone human beings: “The possible long-term effects of cloning, as well as the high incidence of spontaneous abortion and abnormal birth of cloned animals, give cause for concern about attempts to clone animals for reproductive purposes,” reports the team.

Their research is published the journal Nature Genetics (February 2002). On February 16, headlines across the globe announced the arrival of the world’s first cloned cat, christened Cc. Brought into existence by a team at Texas A & University, Cc’s creation was financially backed by US businessman and philanthropist, John Sperling. According to the journal Nature, the newly arrived kitten “was vigorous at birth and appears to be completely normal”.

by Sonia Vasquez (Complements of The Veterinarian, Mar 2002).