The Scottish creators of Dolly, the sheep cloned from the genetic material of an adult sheep, have now produced a lamb which carries a human gene in every cell in its body. Genetic researchers worldwide are hailing the news as a 'breakthrough,' ushering in an era when animals might become 'living factories' producing hormones, compounds, and organs which could save human lives.
Once fetal sheep cells (which are more easily manipulated than cells from mature animals) were obtained, new genes -- at least one of them human -- were added to the sheep DNA within the laboratory setting. Scientists then replaced the genetic material of a sheep's ovum with that of the manipulated fetal cell. Once this new material was in place, the egg was inserted in a ewe's uterus. The pregnancy resulted in Polly, whose every cell contains the newly introduced human gene. Polly, born two weeks ago, is just the first of three such lambs created by the Scottish scientists. Two other lambs carrying the human gene were born earlier this week.
The Scottish methodology is seen by experts as a vast improvement on previous attempts at cross-species genetic engineering. The dominant method in the past involved the injection of alien genes into a newly fertilized egg, and subsequent implantation of the resultant embryo into a uterus. Scientists could then only hope that the added genes took their place within the embryo's multiplying cells.
Practical medical applications of the new technology may arrive relatively soon. The Scottish researchers are currently working on the creation of cloned sheep which can produce human alpha-1-antitrypsin, a blood protein useful in the treatment of cystic fibrosis. Another project under consideration is the placement of human genes in sheep to produce blood-clotting factors for use by hemophiliacs.
After the news about Dolly, most geneticists believed the creation of an animal like Polly was a logical next step. However, the speed at which the breakthrough occurred caught many experts by surprise. After Dolly, everyone would have predicted this," Silver said, "but they were saying it would happen in 5 or 10 years." He said the next step may be even more revolutionary. All of this can be passed over to human beings. Genetic engineering of human beings is now really on the horizon.
I am fearful of what this research can and will lead to.
The New York Times (July 25, 1997)