Guilt-free pluripotent stem cells?
"Much ado about nothing" could describe the recent hype and flurry of news reports about an "ethical" way to get stem cells out of a human embryo without harming that embryo. Scientists have proposed pulling off one of the eight cells of an early embryo in order to create stem cells, while allowing the seven remaining cells to continue developing into a baby.
On first hearing, the proposal sounds attractive to many. Scientists from a small biotech company called Advanced Cell Technology published a paper in the journal Nature in August 2006, describing the technique. They implied that they had done the procedure and that the embryos they used for biopsy had survived. Following public scrutiny of their claims, however, it came to light that none of the 16 embryos they operated on actually ended up surviving. Importantly, even if the experiment had worked, and even if all the embryos had survived, the approach would still sputter and stall in ethical terms because young humans would end up being directly subjugated and violated in laboratory settings, in order to mine their desirable cells and parts. The quest for "guilt-free stem cells" is certainly a good one, but the so-called "embryo biopsy" approach to generating embryonic stem cells fails to deliver. More importantly, other new techniques which rely either on "de-differentiation" or on the use of "germ cells" offer genuinely novel ways to get stem cells without any ethical objections at all.
The "embryo biopsy" approach fails to deliver because of at least four serious moral objections:
1) A non-therapeutic intervention is performed on a human embryo. At least 10 percent of its body mass is removed for research, not for purposes of treating that specific embryo-patient for a known medical condition. The embryo is instead employed as a starting source for harvestable raw materials, in a gesture that reduces young humans to commodities or manipulable products.
2) Embryonic humans should not be generated in laboratory glassware. They do not belong inside test tubes or Petri dishes. The only fitting home for human embryos is in the warmth and shelter of their mother's womb, not in the open lights of the laboratory where they can be prodded, invaded and violated.
3) In order to get the single cell that is removed out of the embryo to turn into a stem cell, scientists have to "coat" it with a layer of human embryonic stem cells (taken from another, previously destroyed, human embryo). Thus, the procedure still relies on the prior destruction of young humans.
4) The extracted single cell may itself be totipotent, that is to say, it may be a new human being, now able to grow into an adult on its own. Early embryos are so flexible that occasionally when a cell breaks off from them, an identical twin can form. While this can certainly occur at the two- and four-cell stage of the embryo, it may even be possible at the eight-cell stage, though there is ongoing debate about this question.
A fifth problem could also be mentioned, namely that the remaining seven cells of the embryo may not necessarily grow to produce a perfectly healthy baby as is commonly assumed. Many babies have been born after a procedure called preimplantation genetic diagnosis (PGD), where a single cell is removed from the embryo for genetic testing. When testing indicates that the embryo is not affected by a genetic disease, it can be implanted into its mother to grow. What remains unclear is whether babies born after PGD testing are really as healthy as those born without PGD testing. Long-term follow-up studies have not been carried out on these PGD children, so it certainly premature at this time to argue that removing one of the eight cells of an embryo has no future effects on that individual.
Can pluripotent stem cells (the most highly flexible variety), be obtained from sources other than human embryos, and without crossing any moral lines? Absolutely. There are an expanding number of ways to derive such cells. For example, in March of 2006, German scientists published a paper in the journal Nature describing a new way to derive pluripotent stem cells. They removed special cells, called germ cells, from the testicles of mice, and transmuted them into pluripotent stem cells. Shortly afterwards, a biotech company in California called PrimeCell Therapeutics reported the same results in humans. No embryos were required at any point in the process.
Another example: In August of 2006, scientists from Japan published results in the journal Cell indicating that by adding a combination of four different protein factors to adult mouse cells, they could change them into pluripotent stem cells. This kind of direct conversion of adult cells into embryonic-type cells is called "dedifferentiation" or "reprogramming," and is a very promising direction for future research. These kinds of novel approaches do not depend upon the destruction of young humans. Another important source for obtaining pluripotent stem cells would be from certain mature body tissues including the bone marrow and the umbilical cord. Normally, stem cells from bone marrow and umbilical cord are not pluripotent, but multipotent (somewhat restricted in their possibilities for differentiation). However a growing number of researchers are finding that there may be a rare subpopulation of genuinely pluripotent cells that are also present in these adult sources. That is to say, stem cells as flexible as the ones that come from embryos may be naturally present at very low levels in bone marrow and umbilical cord, or at least may be derivable from such sources.
All of us are embryos who have grown up. Such embryos should not be destroyed, exploited or otherwise strip-mined for scientific purposes. We can all support those forms of stem cell research, including pluripotent stem cell research, which do not depend on such degrading practices against the youngest members of our species. Remarkable scientific progress is being made every day in developing alternative, ethically acceptable approaches to pluripotent stem cell research. The argument that we must offer up young humans on the altar of scientific sacrifice, while always objectionable in moral terms, is becoming continually less tenable in medical terms as well.
Father Tadeusz Pacholczyk, Ph.D. earned his doctorate in neuroscience from Yale and did post-doctoral work at Harvard. He is a priest of the diocese of Fall River and serves as the director of education at The National Catholic Bioethics Center in Philadelphia.