CLONING: Pigs Cloned for the First Time - Brief Article

Applied Genetics News, April, 2000

he frch 5, 2000 was the birthday of five little pigs, all healthy, the first ever born as a result of nuclear transfer (cloning) using adult cells. PPL Therapeutics, Inc. (Roslin, Scotland EH25 9PP U.K.; Tel: 44 131 440 4777, Midlothian; Fax: 44 131 440 4888) is the proud parent (in addition to a certain sow) of the piglets, named Millie, Christa, Alexis, Carrel, and Dotcom.

DNA from blood samples taken from the piglets was shown in independent tests to be identical to DNA from the cells used to produce the piglets but clearly different from DNA taken from the surrogate mother. The DNA tests were carried out by Celera-AgGEN on coded samples. The cell samples had been provided to the testing company before the piglets were born. Nuclear transfer in pigs has proved to be more difficult than for other livestock, partly because pigs need a minimum number of viable fetuses to maintain pregnancy, whereas sheep and cows, for example, need only one.

The successful cloning opens the door to making modified pigs whose organs and cells can be successfully transplanted into humans--the nearest term solution to solving the worldwide organ shortage crisis. Pigs are the preferred species for xenotransplantation on scientific, practical and ethical grounds. Clinical trials could start in as little as four years and analysts believe the market could be worth six billion dollars for solid organs alone, with as much again possible from cellular therapies, for example, transplantable cells that produce insulin for treatment of diabetes.

PPL aims to produce a "knock-out" pig lacking the gene for alpha 1-3 gal transferase, an enzyme that adds a sugar to pig cell surfaces that is recognized as foreign by the human immune system. "All the known technical hurdles have been overcome," asserts Ron James, managing director of PPL. "An end to the chronic organ shortage is now in sight." Other companies developing genetically engineered pigs for the purpose of xenotransplantation include Nextran, Imutran, and Biotransplant (see following article).