As a result of the process, two embryos were created that survived for only a few hours, and then stopped developing
By Tamara Traubman, Haaretz
Cloning of human embryonic cells
Scientists in the US have created a genetic duplication of a human embryo. Genetic duplication (cloning) is a process that makes it possible to create copies of animals that are genetically identical to each other. The controversial technology has been tried so far in animals, but this is the first time that scientists have also applied it to humans. As a result of the process, two embryos were created that survived for only a few hours, and then stopped developing.
The cloning was done in the laboratories of Advanced Cell Technology, an American biotechnology company based in Massachusetts. In an official announcement published by the company, one of the researchers, Dr. Robert Lanza, said that it was not their intention to create an embryo and grow it until it becomes an adult. According to him, the experiment was carried out as part of a series of experiments aimed at creating cloned embryos for the purpose of producing embryonic stem cells - the body's source cells - which are Only in embryos and capable of turning into any of the types of cells in the body. In this way, the researchers hope, for example, they will be able to transplant new cells into the pancreas of diabetic patients to produce insulin instead of those destroyed by the disease.
Cloning is done by transferring a skin cell taken from donors into an egg taken from a woman, and its genetic material has been removed. The genes from the cell inserted into the egg directed the development of the cloned embryo. Each of the cloned embryos is a genetic copy of the person who donated the skin cell. His parents, therefore, are the mother who donated the egg and the man or woman who donated the cell.
The identity of the people who donated the skin cells is kept secret. Only one of them is willing to be exposed - Judson Summerville, a 40-year-old doctor from Texas. Summerville is paralyzed from the chest down, as a result of a car accident, and has been confined to a wheelchair for years.
But scientists not affiliated with the American company expressed lack of enthusiasm for the experiment. Prof. Yosef Itzkovitz, who is involved in stem cell research at the Rambam Hospital, pointed out the fact that one of the embryos survived only to a stage where it consists of four cells, and the other embryo only survived to the stage of 6 cells.
"The scientific significance of this experiment is very limited," said Prof. Itzkovits. According to him, the fact that the embryos did not continue to develop "means that there was no normal development here, but a reaction of the egg to the injection of the cell itself." He defined the publication of the research as "an advance notice, designed to attract attention and achieve publicity".
Eduardo Matrani, a professor of developmental biology at the Hebrew University, did not express much enthusiasm for the research either. However, he pointed out that the fact that in the current experiment the researchers were unable to create a cloned embryo and make it develop to a more advanced stage should not be seen as evidence that human embryos cannot be cloned. "If they managed to do it in mice and sheep, there is no reason why they won't be able to do it in humans as well. It's just a matter of time," he said.
"The main thing here is the very experience, the fact that this is the first time that someone broke the taboo and tried to apply the cloning to humans as well," said Prof. Hermona Sorek, a molecular biologist at the Hebrew University. She referred to the results of the experiment as "one more step on the way to harnessing cloning for the purpose of producing stem cells for medical purposes", and added that this "underscores the need for reference to the achievement on the part of the legislative bodies".
The first time a mammal was cloned from an adult cell was about four years ago, when Scottish scientists created the famous cloned sheep Dolly. It has since become clear that it is very difficult to create cloned animals; Most of them die during birth or shortly after. The cloned animals that survive usually suffer from many problems, including genetic defects.
In March of this year, two doctors from the United States and Italy announced their intention to create by 2002 the first cloned human. Following the announcement, some of the leading scientists in the field of cloning appeared before committees of the US Department of Health and the US National Academy of Sciences, and testified about the dangers of the method. They claimed that most of the cloned animals die before birth or shortly after, and those that survive suffer from many problems. According to them, given the risk The higher, human cloning would be an immoral act.
In an article published yesterday in the scientific journal "Journal of Regenerative Medicine", the researchers clarified that they "support restrictions on cloning for reproductive purposes until the insurance and moral issues are resolved."
In fact, social scientists have been secretly working on the human cloning project since the beginning of the year. According to them, before starting the experiment, they consulted with an ethics committee they had established. Although the committee was appointed by the company, some of the leading experts in the US on bioethics matters sit on it, such as Dr. Ronald Green, director of the College of Drama's Institute of Ethics.
In one of the series of experiments, the researchers tried a technology known as "virgin reproduction". With this method, the egg is made to start dividing and multiplying, as if it were a normal embryo. This is done without the use of a sperm or a donor cell, but with the help of chemicals that change the biochemical actions in the egg, causing it to behave as if a sperm had fertilized it. Although mature eggs and sperm have only half of the genetic material in the cells of the body, the eggs lose half of their genetic material at a relatively late stage in their maturation process. If they get them activated before this stage, they will still have a full gene set.
The researchers used 22 eggs. After five days, six eggs have developed into a tiny body known as a blastocyst. At this stage in the development of the embryo - which usually occurs at the age of 6-5 days - the embryo has about 200-100 cells, and it looks like a hollow ball. This ball contains an "inner cell mass", from which the embryonic stem cells are produced. However, in the blastocysts obtained in the experiment, no internal cell mass was seen - which makes them worthless in terms of the possibility of using them for medical applications.
Researchers have so far been able to induce virgin reproduction in mammals such as mice and rabbits, but not in humans. Nevertheless, Lanza says that the method has great potential, because "it is unlikely that stem cells from such a source will be rejected after transplantation, because they will be similar to the patient's cells. Such cells may also raise fewer moral dilemmas in the eyes of some people than stem cells produced from cloned embryos."
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