Although there are interesting ethical issues surrounding the collection and use of somatic (adult) stem cells from aborted fetuses and umbilical cord blood, the most intense controversy to date has focused on the source of human embryonic stem (h ES) cells.
Four such approaches were identified as worthy of serious consideration: stem cells obtained from already-deceased embryos; stem cells obtained from living embryos by nondestructive biopsy; stem cells obtained from bioengineered embryo-like artifacts; and stem cells obtained from dedifferentiated somatic cells.
Each of these approaches sought to generate the functional equivalent of h ES cells derived from living blastocyst-stage embryos — pluripotent human stem cells that are genetically stable and long lived.
In response to this potentiality argument, supporters of stem cell research have questioned whether it is true that all potential human life must be realized in every case.
And even if the questionable assumption is granted that all potential life must be realized, it is simply false to claim that all early-stage embryos have the potential for complete human life, since many fertility clinic embryos are of poor quality and therefore not capable of producing a pregnancy, although they may yield stem cells. For instance, developmental biologists have estimated that as many as 75%–80% of all embryos created through intercourse alone fail to implant and are naturally lost, many because of genetic abnormalities.
Since this technique sought to preserve the ability of the donor to implant and develop to birth, it theoretically could allow for the banking of autologous h ES cell lines for children born from biopsied ex-corporeal embryos.
In the other study (), Alexander Meissner and Rudolf Jaenisch developed in mice a variation of somatic cell nuclear transfer (SCNT), a technique whereby the DNA of an unfertilized egg is replaced by the DNA of a somatic cell, by blocking the action of a gene (caudal type homeobox 2 [Cdx2]) that enables the developing embryo to implant into the uterus.Other sources of h ES cell research funding, notably state funding initiatives such as those in California, New York, and Massachusetts, began to emerge to help fill the void left by the Bush policy.In order to bypass the ethical controversy surrounding embryo destruction and to help advance stem cell science, the President’s Council on Bioethics recommended in 2005 that “alternative sources” of pluripotent stem cells be pursued that do not involve the destruction of or harm to human embryos ().Much of this controversy has been symptomatic of an ongoing public unease about the potential negative impacts of science on society.Since its inception, h ES cell research has tapped into underlying dystopian fears about human cloning, the commodification of human biological material, the mixing of human and animal species, and the hubristic quest for regenerative immortality ().Those who oppose embryonic stem cell research believe for religious or other personal reasons that all preimplantation embryos have a moral standing equal to all living persons, regardless of whether they are located in a fertility clinic dish or in a woman’s body.In this view, destroying preimplantation embryos during the course of research is akin to murder and therefore never acceptable, no matter how noble the aims of the research may be.h ES cells were first isolated and cultured in 1998 from embryos donated by couples no longer intending to use them for their own infertility treatment.From that point forward, h ES cell research has been steeped in ethical controversy.Two studies () published soon thereafter in Nature pursued two of the President’s Council’s suggested alternative stem cell sources — live embryo biopsy and bioengineered embryo-like artifacts.In one of these studies (), Robert Lanza and colleagues succeeded in deriving mouse embryonic stem cells from single blastomeres separated from eight-cell-stage mouse embryos.