A short primer on stem cells.

One day I received out of the blue an E-mail request from a local high school student for an E-mail “interview” on the topic of stem cells. He sent me the questions, I wrote my replies. I don’t know the student or how he got my name or contact information. I also don’t know what, if anything, he every did with my replies.

The topic isn’t exactly related to the Latin Mass, but that’s never stopped me from posting before. Thought you might be interested, here is how I answered his questions. - TC

First, some background material. Forgive me if you already know this stuff.

A stem cell differs from other cells in the body insofar as it (1) is unspecialized, and has the capacity of self renewal, and (2) has the capacity, under certain conditions (either natural and physiologic or artificial and laboratory-induced) to differentiate into “specialized” (or “mature”) cell types found in mature tissues and organs.

Stem cells come from two sources: embryos, and “adults” (these are more accurately called “somatic stem cells”, see below).

Embryonic stem cells are obtained from very early stage embryos, are undifferentiated, and are capable of differentiating into any cell type found in the body. That, after all, is why embryos have them. Note: embryonic stem cells are not “germ cells” (id est, “gametes”: eggs or sperm). Just to confuse things, there is a critter called an “embryonic germ cell”, beyond the limits of this discussion.

The embryos used in stem cell research are generally obtained as the left-overs from in vitro (“in the glass”, i. e., laboratory) fertilization procedures (the IVF process generates lots of “spares”). In a normal pregnancy, the 150 cell stage embryo (also called the “blastocyst” stage) would not yet have implanted in the mother’s uterus. Recall that fertilization takes place in the Fallopian tube, it takes a week more or less for the fertilized egg (zygote) to wander through the tube into the uterine cavity and implant. During this tubal “preimplantation” phase, the embryo is busy dividing from 1 to 2 to 4 to hundreds of cells, and it is at this blastocyst stage that the embryo pops out of the tube and implants. Thus, the blastocysts used in embryonic stem cell research are sometimes referred to as “preimplantation” embryos, because that is what they correspond to in vivo (in life). But make no mistake: a preimplantation embryo is an embryo nevertheless.

A “somatic cell” is a cell that is not a germ cell. Almost all of cells in me, and you, are somatic cells. Neither of us has any remaining embryonic stem cells (or so it is currently believed), but we both have “somatic (adult) stem cells”; cells found in small numbers in our bodies which have limited differentiation capacities.

A small point of terminology: From the time of conception to the end of the eight week, the developing human is called an embryo. From 8 weeks until birth, she is called a fetus. After birth, ask her parents what she is called. Thus, it is not strictly correct to say that embryonic stem cells are taken from fetuses. Embryonic stem cells are taken from embryos. Precision is important.

Now, the questions.

1. Stem cell research involving the use of fetuses (embryos) and the embryonic stem cells taken from them has been hotly debated, what are your thoughts on the morality there, do you think the pros outweigh the cons.

The allures of embryonic stem cells are these: (1) they are “pluripotent”, meaning they have the capacity to differentiate into any mature somatic cell type, and (2) they are more easily cultured and grown in the laboratory than are somatic stem cells, at least at this time.

To obtain embryonic stem cells, one must (1) produce an embryo, (2) allow the embryo to grow to a stage where stem cells can be identified (generally around 150 cells), and (3) destroy the embryo in order to obtain the stem cells. The morality of all this turns on the following two questions: (1) is the embryo human, and (2) if human, is it (more accurately, he or she) a person? This same question comes up with respect to abortion, cloning, in vitro fertilization, and a growing list of related topics.

The answer to the first question is easy: of course the human embryo is human, a separate, living, growing biological human being at the very earliest stages of development, for there is nothing else he, or she, can be. She is neither dead nor inanimate, and alive is the only remaining choice. She is a human being because she must be something (undefined is not a choice) and she is neither a banana nor an aardvark, and cannot possibly be either of those things or anything else. Her nature, her essence, her genetic code, her ancestry, her developmental potential, is human, nothing else. There is more to say, but the above will have to suffice for here: regardless of the means by which the embryo came into existence, once conceived, she is a living, growing, biological human being. Not a “potential” human being (that would make her undefined) but a human embryo, or, as they say, a human being with great potential. No one, other than some politicians and celebrities, seriously believes that the human embryo is not human.

The second question, is the embryo a person, is more complicated: what, exactly, is a person? The follow-on question is this: Is a person the same thing as a human? A digression is necessary.

Prior to 1865, some identifiable groups of humans in the US did not have full legal protections: although they were generally acknowledged as humans, they were nevertheless considered chattel and could be bought, sold, and generally treated as a piece of property. These humans were known as slaves. Interestingly, under some circumstances these articles of property could challenge their status as property in court, and that is exactly what one article of property known as Dred Scott did. Scott’s case made its way all the way to the Supreme Court of the United States and, in 1857, the Supreme Court issued its decision that yes, indeed, there were identifiable groups of humans who did not have full rights and protections under the law. “A negro,” the decision went, “whose ancestors were imported into the United States and sold as slaves … could not be an American citizen, and therefore had no standing to sue in federal court.” There was more to the decision, of course, but the upshot was that a particular, identifiable group of humans did not have full rights and protections under the law.

Subsequent to the Civil War, the “Reconstruction Amendments” (1865-1870) were passed. The 13th abolished slavery, thus rendering slaves citizens and not chattel. The 14th amendment covered citizens’ (and non-citizens’) legal rights and protections. The 15th extended voting rights to African-American men. It is in the 14th Amendment that the personhood issue develops: in general terms, a “person” in a legal sense is a being – organic or otherwise – that has rights and protections and liabilities under the law.

During the interregnum of 1870-1973, legal “personhood” and membership in the human race were legally (if not always in actual fact) regarded as more or less synonymous. (“Corporate personhood” does not concern us here.) It is important to note that we are not now discussing “citizenship” as such, but general legal rights and protections, of which citizenship is one, but not the only, element. Not all humans were, or are, US citizens, but all humans have (or had) protections and at least some rights under the law.

In 1973 the question was raised again: are there identifiable groups of humans to whom full legal protections do not apply? In this instance the question was raised not regarding African-Americans but the group known as unborn children – embryos and fetuses – and whether it was legal to abort them which, of course, renders them dead. The Supreme Court of the United States again answered yes, as it had in Scott v. Sanford. In Roe v. Wade, the Court ruled that a fetus could be aborted for any reason, or no reason at all, in the first trimester. Later Supreme Court decisions extended this to term: a fetus could be aborted for any reason, or no reason at all, up to the moment of birth. This places the abortion laws in the US among the most permissive on the planet; only China is more permissive by permitting infanticide.

Justice Harry Blackmun, writing for the majority in Roe, said “If this suggestion of personhood is established, the appellant’s case, of course, collapses, for the fetus’ right to life would then be guaranteed specifically by the (14th) Amendment.” And that, as the Justice well knew, was, and is, the heart of the matter. If the fetus is a legal person, you can’t just kill him, and so Justice Blackmun along with the majority of the Supreme Court declared the fetus (and embryo) to be unpersons. And there the situation has resided for the past 45 years: in these United States, there exists a group of living biological human beings – unborn children, or fetuses, if you will - who are not considered persons under the law. With the development of in vitro fertilization (IVF) procedures in the 1970’s we add a related group, embryos created not by the usual means but external to the mother’s body. Same question, though: are these IVF embryos persons?

This question of the relationship between humanity and personhood has been with us always, in all times, all places, all cultures and civilizations. In a sense, the situation in the US between 1870 and 1973 was a radical departure from historical norms: what the Supreme Court did in 1973 was to return us to what has been standard throughout history: separating the biological class of “human” from the legal class of “person”. Persons and humans overlap somewhat, but they are not the same. Some humans are not persons, and some persons are not humans.

So. Is personhood – legal, and/or moral – synonymous with “biological human being”? There’s only two possible answers (indeed, it really is that simple): Yes, or No.

If the answer is yes, then that means all biological human beings including the embryo (whether in a uterus or a plastic dish) have basic legal protections, and the most basic of these is the right to life, meaning to not have one’s life ended arbitrarily. (Noto bene: Capital punishment is not part of this discussion. The question of whether one can, by his own criminal action, forfeit his right to life is a separate question.)

If the answer is no, then the immediate follow on question is this: which biological lives are worthy of being considered persons, and who decides?

The only rational answer is to assert that all biological human life, from the moment of conception to the moment of natural death, is worthy of the status of personhood. That does not mean that all lives have equal rights – neither a fetus nor a high school student can vote – but it does mean that all of those flavors of human life have the right to basic protections, the most basic of which is right to their own lives. Otherwise, personhood is decided merely by whomever happens to have political power at the moment.

From this I hope it’s obvious that the “pros”, if any, to embryonic stem cell research do not outweigh the “cons”, anymore than the “pros” of slave labor on plantations in the south (and there were pros to this) would outweigh the cons of the institution of slavery and its degrading effect on humanity.*

2. How viable or useful are stem cells taken from adults?

Tremendously useful. The most common stem cell transplant procedure is bone marrow transplantation (BMT), first performed in 1955 (Stem cell transplantation is not new!!!) The stem cells from an adult donor (or, these days, umbilical cord blood, but still considered “somatic” or adult stem cells) are harvested, and then infused into the patient where they colonized the patient’s marrow and regenerate his capacity for hematopoiesis (the process of making red cells and white cells).

Bone marrow transplantation is part of therapeutic regimens for a huge list of malignant and non-malignant (but severe) diagnoses. The stem cells may be derived from the donor himself (autologous transplant) or a different person (allogeneic transplant, this includes umbilical cord stem cells).

3. Are there any adverse side effects that are possible to occur when using stem cell therapy?

Absolutely. Using BMT as the example, there are a list of adverse events, some severe and others less so. Detailed discussion of these is way beyond the scope of this session, suffice it to say that the most serious risks involve some form of rejection (most commonly graft vs. host disease; note that this would only be seen in the allogeneic BMT) and graft failure. Conversely, BMT is only considered as a therapy in the case of serious and lethal diseases, so it is a risk/benefit analysis. Most BMT patients do better than they would have without the BMT.

4. Stem cells are predicted to be able to do miraculous things in the future, at the current rate of research, how long do you think that will take? (When I say miraculous things I mean things like preventing or undoing Alzheimer's or something like that)

Most of the mainstream media claims are hyperbole, and I’m not interested in hyperbole. Although I think there will be benefits with the further development of somatic stem cell transplant procedures (embryonic stem cell research is morally inadmissible due to the necessary destruction of human embryos), what these future benefits will be remains to be determined.

5. Could research into making adult stem cells more fruitful be worthwhile?

Absolutely. To repeat, the only stem cell therapies currently in clinical use are somatic stem cell transplants, mostly BMTs. One area of great interest is “reprogramming” somatic (adult) stem cells to behave in a more pluripotential manner, similar to embryonic stem cells. These are known as “induced pluripotent stem cells” (IPSCs) and, at least in theory, do not have the moral problems associated with embryonic stem cells, and many theoretical benefits over “conventional” stem cells, such as mitigation of the graft rejection problems (because one could use the patient’s own stem cells as substrate for the IPSCs.) This is a big topic.

In wrapping this up, it is well to remember these points:

1. Currently, all of the stem cell therapies in existence use adult stem cells, mostly the hematopoietic stem cells of BMTs. These therapies are widely used, of proven utility, and under constant development and improvement. They are not without possibly serious risk, but remember we’re talking about serious diseases here.

2. There is a lot of room for growth and development regarding the use of somatic stem cells. The IPSCs are one example, there are others.

3. Currently there are no therapies utilizing embryonic stem cells, and there are none on the near horizon, regardless of the bubbling and seething in the media.

4. Embryonic stem cells involve the destruction of human embryos, which is morally inadmissible. That is my view, of course, but it is a view which is very defensible. The fact that we as a nation have already granted the legal antecedents (it is legal to destroy embryos and fetuses in the womb, so why not create and then destroy embryos for research and medical purposes) in no way invalidates the arguments against the practice. When slavery was legal (and supported as settled law by the Supreme Court), the arguments against it were still valid.

* Food for thought: When one creates an embryo in vivo and grows it in the laboratory, how long does one allow it to continue growing? There is not (to my knowledge) any legislation regarding this in the US, although general practice is to not allow IVF embryos to grow beyond the blastocyst stage. In the UK, however, there are, in fact, laws about this. It is illegal for a lab to grow an embryo beyond the blastocyst stage (although, like in the US, growth may be arrested by cryopreservation). This creates the interesting situation where, in British law, there is a defined group of human beings – actively growing IVF blastocysts – whom it is illegal not to kill.

And then, we have this from Reuters.