14 Jul Science and ethics in the embryonic stem cell debate
The Medieval philosopher, Boethius, tackled the esoteric question of what is a human and came to the conclusion that “human is born of human”. There is a certain circular, facile truth in this conclusion that reminds one of the modern right-to-life refrain that “life begins at conception”—an argument that seems as unsatisfying as any argument that has been reduced to a cliché. It is repeated so often and so glibly that the basis of the argument goes unexamined and unchallenged.
This “life begins at conception” reasoning, leads to a casuistic rhetoric where harvesting embryonic stem cells (ESCs) from a five day old human embryo called a blastocyst, for the purpose of treating human ailments, is akin to killing a living adult in order to harvest his organs to transplant into someone else. But how do we cross the chasm of logic to believe that a blastocyst is the moral equivalent of an adult human? This is an unexamined and unspoken conclusion that looks very different in the light of modern biology.
Before exploring the premises underlying the right-to-life position let me acknowledge that at this point, some will ask, why revisit this debate? Haven’t embryonic stem cells been rendered unimportant in the face of the research success of adult stem cells and in view of the fact that we can now reprogram adult cells to become stem-like, thereby avoiding the destruction of embryos to harvest ESCs?
Not so fast.
The fact is that we are rapidly driving, some would say careening, toward the day when ESCs will be used to treat patients. Despite the exciting advances in stem cell alternatives, ESCs still play a role that adult and reprogrammed adult cells cannot supplant—yet.
The FDA recently approved the first ESC clinical trial to treat patients with spinal cord injuries. The California Institute for Regenerative Medicine that oversees the $3 billion stem cell investment that came out of Proposition 72 in 2004, recently awarded grants specifically for supporting research leading to FDA applications to use ESCs for experimental therapeutics. A medical doctor in India claims to have treated a quadriplegic with human ESCs, with modest results. Doctors in other countries make similar claims, raising the specter of unregulated “stem cell” tourism and unfettered treatment of patients with insufficiently tested ESC therapies—unregulated clinical trials in reality.
As we rapidly approach the era of stem cell therapy, or regenerative medicine, if in fact we are not already there, the debate over whether this technology represents a “brave new world” or a Faustian bargain will only intensify and I believe it will do so very soon. At the moment, this debate seems to be in a latent period due to the recent discovery that adult cells can be reprogrammed into stem cells. Opponents of ESC research hope that this advance will negate their ethical concerns about destroying human embryos in order to obtain stem cells. After all, if you can pluck a skin cell from someone’s arm, put it in a broth and, presto, pull a stem cell out, why would anyone need or want to do research with stem cells obtained from an embryo? But, the inconvenient truth behind these reprogrammed cells has not been fully explained. The fact is that they, too, have the potential to develop into persons. A scientist at Harvard recently reprogrammed a mature mouse blood cell into a stem cell and used it to derive a whole new mouse. Let us consider how this fact affects the whole stem cell debate.
Unpacking the right-to-life argument
I’ll begin by unpacking the right-to-life argument that “life begins at conception. It is abundantly clear that when a sperm fertilizes an egg cell, a cellular entity is created that can grow into a fully developed person. So, in a sense one can indeed claim that “life” begins at fertilization. But this argument assumes, and leaves unstated, that society is, therefore, obligated to give the same level of respect to a fertilized egg as it gives to an adult human.
Thus, the underlying ethical argument here really is not about “when life begins” (indeed there is no precise time where this happens—it is a process lasting a couple of days), but about when society is obligated to give full respect to human life. This is the essential ethical issue on which the whole debate should focus.
Let me illustrate the idea this way: We all agree that a living woman deserves our full moral consideration; society cannot legitimately take her life or deny her other life-related freedoms without good cause, such as committing a crime. On the other hand, neither a live dog nor a clearly dead human elicit the same level of consideration from society. This means that simply being alive, as in the case of the dog, or simply having a human body, as in the case of the corpse, do not provide a sufficient basis for assigning the full moral consideration that we give the woman. It follows that there is something inherent in the adult woman that we all readily recognize, but that we, equally readily, do not see in a live dog or a dead person, which tells us she deserves a greater level of moral respect. This inherent worth in the woman that we all innately recognize is the crux behind making sense of the embryonic stem cell debate.
Viewed in this way, the question with ESC research becomes this: does a blastocyst that was created by a human (through in vitro fertilization) and that lives in a petri dish and lacks a brain, personal history, personality or any recognizable human trait is the moral equivalent of a living adult human that enjoys all these attributes? Do we innately recognize something in the blastocyst, like we do in the woman, which compels us to assign full moral recognition to a five-day old sphere of cells that is no larger than a period at the end of a sentence?At this juncture, some will argue that the fertilized egg possesses a completely novel human genome that denotes a unique genetic human being, and that this makes it deserving of full moral consideration by society. But, this argument has this major problem; certainly, genetic makeup is necessary and sufficient for determining that an embryo is Homo sapien, but genetic makeup, no matter how unique, is not sufficient for determining moral standing. If it was, then skin cells, which have the same genes as the fertilized egg from which they came, should also have equal moral standing with the fertilized egg. It also could be argued here that an important difference between a fertilized egg and a skin cell is that the former has the “potential” to develop into a mature human person, while the latter does not. But there are problems of both semantics and logic with this contention. For instance, “potential” describes something that can, but has not yet come into being. In other words, to acknowledge that a fertilized egg has potential to become a person means that, in fact, it is not a person at that time.
Furthermore, it is not logical to assume that “potential” confers any a priori obligation–while I may have the “potential” to become President, that obligates no one to play “Hail to the Chief” when I enter a room. So, based on potential, there is no compelling reason to afford a blastocyst the same obligation we offer the adult woman.Conditional potential of stem cells to become people
It also is important to understand that a thing’s “potential” can be altered by circumstance. Thomas Aquinas, the great Catholic theologian and philosopher, made this argument about “potential” many years ago. He explained that for potential to be present, a thing must have the capability of realizing that potential. Thus, a piece of paper has the potential to be burned, because it is burnable. Conversely, a bucket of water does not have the potential to be burned because it is not capable of being burned.
Certainly we now know that water can be given the potential to burn, but only under specific electrolytic conditions that separate oxygen and hydrogen from the water molecules. So, the conditional circumstances in which water exists determine its potential to be burned.
In the laboratory, human ESCs are harvested from a blastocyst that has only lived in a tissue culture dish. As long as a blastocyst lives in the petri dish, it has zero potential to become a person. This can only happen if someone intentionally inserts it into the womb of a woman who has been hormonally manipulated to mimic pregnancy. Only after these human efforts, like the human efforts needed to make water burnable, can the tissue culture organism then acquire the potential to become a person.
From animal cloning, which is now a common practice, we know that under the proper conditions, we can reprogram adult cells back to an embryonic state where they acquire the ability to grow into an embryo and a fully functioning animal. Therefore, modern science tells us that, like a blastocyst that lives in a petri dish, a blood cell that lives in your veins has conditional potential to develop into a person. Since we do not confer any special moral status to a blood cell what then compels us to confer such status to the blastocyst that was created in a laboratory and that lives in a petri dish or frozen in a liquid nitrogen tank? After all, they both have similar conditional potential to become a person.
Thus, like genetics, “potential” is not a sufficient basis to compel us to confer the same moral status to a fertilized egg that we reserve for a living person.
How to know when to protect a developing embryo
It, admittedly, is very hard, if not impossible, to know when we ought to bestow full moral protection to a developing human embryo. But, I submit that we can know when the embryo does not enjoy the same consideration we give to an adult. To illustrate this point, consider this thought experiment—you walk past a building and see a fire raging inside. Moreover, you also see a man struggling to get off the floor and escape the conflagration. You see that he is lying next to a tank that you know contains thousands of frozen human embryos. What would you do if you only had time to make one trip into the burning building?
Most of us would opt to rescue the man indicating that we recognize a greater moral responsibility to one anonymous living adult person than we do to a tank full of nascent persons. Indeed, most of us would opt to rescue a dog before the tank of embryos. In other words, we do not innately view thousands of five-day old embryos as moral equivalents to a single fully formed person any more than we view a live dog as the moral equivalent of the woman. To do so, we have to conjure up a special respect for embryos that is based on the imperfect arguments discussed above.
Unfortunately, poor Boethius, a Christian, ran afoul of the Visigoth rulers of Rome and was executed in an especially gruesome way. They wrapped a rope around his head, inserted a stout stick and twisted it until his skull burst. I suspect that when the right-to-life community becomes aware of the ability of reprogrammed adult cells to become people, the debate will flare once again generating Boethian-sized headaches on both sides.
Recent columns by Steve Clark
- Steven S. Clark: Clinical research activity up significantly in 2008
- Steven S. Clark: More stem cell trial problems for Osiris Therapeutics
- Steven S. Clark: Slicing and dicing SBIR award data
- Steven S. Clark: The biotech industry: Promise vs reality
- Steven S. Clark: SBIR re-authorization update
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