The cloned pigs. The genetic structure is more similar to humans than that of sheep * Scientists in Japan: soon we will clone cats too. Researchers: Replication of pigs
15/3/2000
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An important step towards the genetic production of organs for transplantation
After Dolly the sheep, it was the pigs' turn: five cloned pigs were born on March 5 at a farm in the US, after their mother's body was injected with a cloned egg. This was announced by the company PPL Therapeutics, which also assisted in the replication of Dolly. The scientists of the company, which is based in Scotland, said that in duplicating the pigs - Millie, Christa, Alexis, Carl and Dotcom - they used the same technique that was successfully tried on sheep. According to them, the importance of the success in their latest project is that the genetic structure of pigs is more similar to that of humans, than the genetic structure of sheep. That is why they believe that the reproduction of pigs is an important step on the way to the genetic production of organs for transplantation.
The people of the company added that in the next step they plan to develop pigs, in whose genetic structure changes will be introduced that will prevent the fear of rejection of the transplanted organ by the human body. The announcement published yesterday renewed in Britain the controversy surrounding the question of transplanting animal organs into humans.
Atim-Reuters reports: Japanese scientists are preparing to create the world's first cloned cat as early as June. The Kyodo news agency stated that scientists at Yamaguchi University in eastern Japan announced that they had succeeded in developing in vitro a cloned egg from a cell of a dead cat embryo, and that the egg is ready for implantation in the uterus of a cat.
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by Tamara Traubman
The Scottish company that cloned Dolly the sheep announced yesterday the first success in cloning pigs, animals that are particularly difficult to clone. The company, PPL Therapeutics, intends to repeat the cloning despite objections from some ethicists and animal rights activists. The next step, she announced, will be the genetic engineering of pig organs so that they are suitable for transplantation into humans. The company aims to create a pool of organs for transplantation, which the human immune system will not reject, as is the case with transplants today.
The five pigs - Millie, Christa, Alexis, Carl and Dotcom - were born healthy on the 5th of March. The cloning method is similar to the one in which Dolly was cloned three years ago. In this method, DNA is transferred from a cell of an adult pig to an egg taken from another pig, which is implanted in a third pig, which serves as a surrogate mother. The uniqueness of the process is that it does not involve a male sperm cell.
Ron James, CEO of PP-L, said in an interview with "Haaretz" that the DNA test of the piglets revealed that their DNA is different from that of the surrogate mother and similar to that of the mother's cells from which the piglets were created. According to him, PFIL also gave DNA samples to a private American company, which confirmed the results of the test, proving that the pigs were indeed cloned.
James did not say which cell the DNA used in the current clone was taken from (in Dolly's case, it was an udder cell). The company's spokesman, Philip Dennis, told "Haaretz" that the researchers intend to publish, "when the time comes," the results of their research in the scientific journal "Nature
In order to adapt the pig's organs to transplant into humans, PFIL scientists will create pigs in which the action of the gene responsible for producing an enzyme called gal transferase alpha 1-3, which causes the human immune system to react acutely to reject the foreign transplant, will be deactivated. Two competing companies have already succeeded in creating such pigs, but not their clone.
According to Dennis, the company intends to start clinical trials on humans within four years. Analysts consulted by the company estimated the market value of whole organs from pigs (such as heart, kidney or liver) at $6 billion. The market value of cell transplants (such as nerve cells or pancreas) reaches a similar amount.
The technology is still in a very early stage, and it is not entirely clear if there is any risk in it. Because of this, to date transgenic pig organs have only been transplanted into a few hundred patients. Most of the transplants were of skin or pancreas, or were done in patients who were treated with a kind of external dialysis devices, which purify the blood with the use of pig kidney, liver or spleen cells.
As in the case of Dolly, the announcement of the pig cloning also raised ethical questions concerning human cloning. To the cloning of the pigs was also added an acute reservation that has accompanied the idea of transplanting pig organs into humans since its inception: the fear that diseases and viruses of pigs will jump over the "species barrier" and pass to humans. Such new diseases may be difficult to cure, such as the AIDS virus, which, according to one hypothesis, passed to humans from monkeys. But the largest study to date, published late last year, showed that the main virus that researchers feared (called PERV) did not attack the transplants or cause morbidity.
According to the accepted estimate, in Israel about a thousand patients are waiting for organ transplants. Donations from humans cannot meet the global shortage of organs for transplantation. Using pig organs, which are relatively easy to genetically engineer and suitable for the human body, is considered a good solution to the problem. "Transplantation of organs from pigs can literally save lives," says Dr. Yaakov Lavie, director of the heart transplant unit at the Sheba Medical Center. According to him, following the study published last year, the British Ministry of Health has already given "approval in principle" to perform a heart transplant from a pig, and also in the Israeli Ministry of Health "the tone is optimistic".
Millennium's Millie and her sisters
Even before the piglets were born, says Philip Dennis, a spokesman for the PFIL Therapeutics company, the researchers decided that one of them would be called Millie, after the new millennium.
The second is named Christa, as a tribute to Dr. Christian Bernard, who performed the first heart transplant in the world. Alexis and Carl are named after Dr. Alexis Carl, who is considered the father of organ transplants. Dotcom's name stemmed from an inside joke by PHI employees.
{Appeared in Haaretz newspaper, 15/3/2000{
Clone / partial list
Medulla to protein for stroke treatment
* March 24, .'97 Scottish researchers announced the cloning of Dolly the sheep, the first mammal cloned from adult mammalian cells.
* July .'98 researchers from Hawi University successfully cloned 50 mice from three generations of cloned mice.
* August .'98 Scientists from New Zealand cloned a species of cows in danger of extinction.
* April .'99 researchers from Taft University cloned goats. The genetic refresher has been engineered so that it is possible to extract from their milk a protein that helps in the treatment of heart attacks and strokes.
* January 2000 American researchers announced that they had cloned a rhesus cell for the first time, using a cloning technique called "cell splitting". That same month, a Japanese-American team announced that they had created four calves, cloned from the skin cells of a bull's balance (as opposed to Dolly, who was cloned from an udder cell).
Tamara Traubman
{Appeared in Haaretz newspaper, 15/3/2000{
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