The Question of Human Cloning

Accustomed though we are to advances in medical technology, a 24 October 1993 news report that human embryos had been cloned astonished many persons. A New York Times story, "Researcher Clones Embryos of Humans in Fertility Effort," was the feature that Sunday morning in many newspapers throughout the country. Media coverage continued for several days, with debates about cloning on editorial pages, Nightline, and Larry King Live. Within a week the issue had faded from media consciousness, aided in part by Time and Newsweek stories that stressed the huge gap between die reported research and the Jurassic Park-type fears of cloned human beings that initially spurred national coverage. Bioethicists and law makers, however, must still contend with the ethical and policy issues that even limited cloning of humans presents. Should researchers be free to continue cloning research? May infertile couples and their physicians employ cloning to form families? Or should government prevent cloning research or discourage some or all of its later applications? As with many biomedical developments, these questions present a mix of issues that need careful sorting. They involve, among others, questions of the propriety of embryo research, the validity of deliberately creating twins, and the importance of nature versus nurture in forming human beings. They also raise slippery slope concerns: should otherwise seemingly valid uses of a new technique be stopped to prevent later undesirable uses from occurring? To address those issues we must first describe the cloning research that has touched off the furor and the concerns that it presents. Two Types of Cloning The research that put cloning on the public agenda was a long way from Huxleyian fantasies of identical babies, mass produced in laboratories, and did not involve cloning as conventionally understood at all. To clone means to create a genetic copy or replica. Perhaps due to science fiction fantasies, it has been assumed that cloning would occur by removing the nucleus from the cell of one person, placing it in an egg that has had its nucleus removed, and then implanting it in a laboratory incubator or a woman who would bring to term a child with the identical genetic characteristics of the person providing the cell nucleus. Although this procedure has worked with frogs, it has never succeeded with mammals and appears highly unlikely to be accomplished in even the mid-range future. If this form of cloning were possible, scientists could fabricate as many copies as one wished of any available human genome, subject only to the limits of uterine or artificial gestation. A second and more limited way to create clones is to split the cells or blastomeres of an early multicelled embryo before the cells have begun to differentiate. Because each blastomere at this stage is in theory totipotent (that is, capable of producing an entire organism itself), die separated cells can become new embryos, all of which which have the same genome. This form of cloning is now practiced to some extent in the cattle industry. Cloning by blastomere separation is limited to the number of cells that can be separated before cell differentiation, which destroys totipotency, occurs. The study that generated the recent interest in cloning involved a small but essential step toward cloning human beings by embryo splitting. Researchers at George Washington University Hospital in Washington, D.C., separated cells or blastomeres from seventeen two- to eight-celled preembryos and showed that, to a limited extent, they would divide and grow in culture. The cells had been obtained from polyspermic embryos that had no chance of implanting in the uterus and that ordinarily would have been discarded. The separated blastomeres were coated with an artificial zona pellucida and placed in the culture medium used for in vitro fertilization (IVF). The researchers obtained forty-eight blastomeres from the seventeen polyspermic embryos (eight two-cell, two three-cell, five four-cell, and two eight-cell), or theoretically forty-eight new totipotent embryos. …