Reading aloud Scottish researchers first cloned pigs out of an adult sow using the dolly method. According to the research institute PPL Therapeutics in Edinburgh, five healthy cloned piglets were born on March 5 in the US. The researchers hope for a breakthrough in the transplantation of animal organs to humans. The PPL-affiliated Roslin Institute had already presented to the world in February 1997 the seven-month-old sheep Dolly, the first mammal cloned from a body cell. The identical piglets Millie, Christa, Alexis, Carrel and Dotcom saw the light of day in Blacksburg, Virginia. Under the direction of PPL director Ron James, the cloned ova had been planted in a pig research facility. The US government is involved in financing the cloning project.

Scientists call the production of identical living organisms biotechnical methods as cloning. This is possible with plants, animals and humans. In the case of the sheep Dolly Scottish researchers had first reproduced a mature mammal. Human cloning is banned in Germany and many other countries.

For this purpose, the genetic material from the "adult" and differentiated cell of an animal is first restored to a state in which it can take over any function in the body. For this, the researchers "starve" the cells. Thereafter, the genetic material is transplanted into the pitted, unfertilized egg cell of a second animal. In a special nutrient solution then grows the embryo, which is finally discharged by a third animal. The resulting animal resembles his gene donor.

In animal breeding, cloning has been done for a long time by changes in the embryo. From the cells that emerge from the first divisions of the fertilized egg, each can develop into a complete animal. If these cells are artificially separated, similar progeny are produced - as is the case naturally with monozygotic twins. A US researcher had already cloned human embryos in this way in 1993, but they did not use a woman. display

In the case of the cloned piglets, the researchers used the cell nucleus of a full-grown cell in a previously seeded egg cell. This was then discharged by a mother. They did not want to specify from which body cell the pigs were cloned.

The birth of the cloned piglets opens the possibility of breeding genetically modified pigs, which could be used to transplant animal organs into humans (xenotransplantation), James said on Tuesday. He hopes that clinical trials with humans could begin in four years. Until then, it should be achieved through genetic modifications that pig organs such as heart, liver or kidneys are not rejected by the human body. Also, the researchers hope for a breakthrough in the breeding of insulin-producing cells that can be implanted in diabetes patients.

James does not see any ethical problems. Pigs are best for xenotransplantation for "scientific and ethical reasons, " he said. Only in this way could the global shortage of donor organs be remedied in the long term. According to the Institute, the market for organs is currently estimated at six billion dollars (twelve billion marks).

The names of the piglets were selected by the US scientists. The firstborn animal was christened after the new millennium "Millie". Christa is to commemorate the South African heart transplant surgeon after Christian Barnard. Alexis and Carrell were named after Dr. Named after Alexis Carrell, who received the Nobel Prize for Medicine in 1912. Dotcom, according to James, is a concession to the current wave of success of Internet companies.

Steffi Hentzelt and dpa

© science.de

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