Cloning Twist Clouds Ethical Complexities
Scientists attending the April 2003 Human Genome Organization meeting in Cancun, Mexico claimed that a new technique could overcome ethical and safety objections to reproductive cloning.1 This technique would involve the creation of a cloned human embryo, from whom embryonic stem (ES) cells would be extracted and stimulated to develop into presumably healthy sperm or eggs (a process known as gametogenesis). The sperm or eggs could then be fused, via in vitro fertilization, with gametes from the spouse of the person who was cloned, allowing infertile couples to have their own genetically-related (but not cloned) children. The original cloned embryo would not survive the process of stem cell extraction. Nevertheless, bioethicists interviewed for an online article in the journal Nature agreed that the procedure would remove many of the ethical objections to reproductive cloning.
Though the procedure was presented as a possibility, rather than as having already been accomplished, some early support for its feasibility was reported a month later in the journal Science. Researchers there documented the spontaneous production of mouse oocytes from ES cells grown in culture dishes,2 a development hailed as "an ethical earthquake" by Arthur Caplan of the University of Pennsylvania.3 However, while these oocytes have many of the properties of mouse eggs, it is still not clear if they can be fertilized or if they will give rise to healthy offspring. Neither is it clear if human ES cells have the same properties. Nevertheless, this approach is being viewed as a way to overcome the ethical and financial difficulties of obtaining human eggs for cloning and in vitro fertilization.
Apart from the fact that most of these "developments" are merely speculative, the fanfare that has surrounded them fails to recognize that the procedure actually does very little to allay ethical concerns. One bioethicist interviewed for the online Nature article claimed that the proposed technique would satisfy the desires of most infertile couples seeking reproductive cloning because they "don't want a clone--just a baby." Yet the report acknowledges that the procedure would begin with the cloning of a human embryo, who would then be destroyed in the stem cell extraction process. Rather than overcoming concerns about human cloning, couples using this technique would be responsible not only for cloning human embryos, but also for destroying them. Yet bioethicists continue to claim that this procedure would circumvent many ethical objections.
The online Nature report also claims that this new technique would be much safer, allaying ethical concerns about the harm cloning may cause. The high rate of failure and damage following cloning, or somatic cell nuclear transfer (SCNT), has been attributed to a phenomenon known as "epigenetic reprogramming." As eggs and sperm mature naturally, the genes that they contain are reprogrammed to the "settings" normally needed for the development of a healthy embryo. But when an adult somatic nucleus is transferred into an enucleated egg, the genetic reprogramming must occur much faster than it typically does, making the process highly prone to errors. The claim in the online Nature article is that these errors will be avoided by the newly proposed technique. However, this assumes that the ES cells produced by SCNT do not contain these errors, or that they will not interfere with the subsequent development of gametes produced from these cells. This assumption is questionable given studies showing that cloned embryos have gene regulation patterns that are much more similar to those of the donor somatic cells than to non-cloned embryos.4 Furthermore, the inability to successfully clone monkeys has been attributed to the loss of proteins that are essential for normal chromosomal development.5 Such proteins are lost when enucleated eggs are prepared for use in the cloning process, a difficulty which may impact the cloning of all primates, including humans. The newly proposed procedure will still require this problematic step.
In summary, then, the technical and ethical problems posed by human cloning are not likely to be overcome by this new technique. Mammalian cloning remains an experimental and dangerous practice, and because the new procedure still involves human cloning it is no less ethically problematic. To the contrary, it is actually more so, since the cloned embryos who are created would be destroyed and the embryos who are given a chance at life might suffer harmful side-effects due to the ES cells from which they originated having been subjected to several experimental procedures.
This new procedure, then, combines all the ethical problems of human "reproductive" cloning (in which the birth of a cloned baby is intended) with those of so-called "therapeutic" cloning (in which embryos are destroyed for their stem cells) and then adds new concerns over the potential harm to babies that might result from the intense manipulation of ES cells, gametes, and embryos. In an attempt to "satisfy the desires" of those seeking to have children, the potential babies will have to survive the risks imposed by SCNT, ES cell harvesting, induced gametogenesis, and in vitro fertilization. The proposal displays a wanton disregard for nascent human life by claiming that destruction of human embryos is a way to overcome the ethical problems with cloning. It's about time that the cloning technofix was exposed for the technological house of cards it is--before it comes crashing down upon infertile couples and their potential children whom it is likely to harm the most.
2 Huber, K., et al. "Derivation of Oocytes from Mouse Embryonic Stem Cells in Science 2003;300:1251-6.
3 Vogel, G. "Oocytes Spontaneously Generated" in Science 2003;300:721.
4 Kang, Y.-K., et al. "Limited Demethylation Leaves Mosaic-Type Methylation States in Cloned Bovine Pre-Implantation Embryos" in EMBO J. 2002;21:1092-1100.
5 Simerly, C., et al. "Molecular Correlates of Primate Nuclear Transfer Failures" in Science. 2003;300:297