There is a lot of hype using the phrase "human embryonic stem cell", and it has been going on for many years. There is no such cell. The way this phrase has been used is to equate the cells of the early human embryo with "stem cells".
This is based on the premise that the early human embryonic cells are totipotent; that is, each of these cells can form the entire new individual, and, thus, will form its more than 200 tissues. In that sense they are labled as "stem cells". However, in the true sense of the word, a stem cell, by definition, is partially differentiated but not wholly so. Virtually every adult body tissue has its stem cells. They are there to replace lost cells and repair tissues. When properly stimulated a stem cell divides into two daughter cells, one into a differentiated pathway of its resident tissue and the other into the remaining stem cell pool. For example, virtually the entire lining of the digestive tract is replaced about every 8 days due to the activity of its stem cells. Some stem cells, particularly those in peripheral blood and bone marrow, when appropriately stimulated, demonstrate remarkable plasticity and can transform into other types of resident tissue cells.
The embryo is the term applied from fertilization to the end of the eighth week. No one knows if stem cells begin to appear during this time. It is reasonable to guess they do not. The term fetus is applied to development from the beginning of the ninth week to term. Undoubtedly, some stem cells begin to appear during this period. But, no one has done studies to show when or where.
The parlance of today's hescr equates the early human embryonic cells with stem cells. It is based on those cells being totipotent, as defined above. This condition has been demonstrated experimentally in lesser species. IVF (in-vitro fertilization) laboratories, in many cases, remove a single blastomere (cell) from a four or eight cell human embryo to check for certain genetic diseases. If the check is positive, the whole embryo is discarded, believing that all of the cells of that early embryo are exactly alike. If the check is negative, the remaining embryo is implanted into the fallopian tube and stimulated appropriately, and, presumably, brought to term.
Normally, 3 or 4 embryos are implanted. However, there is only a 15 to 20% success rate. No one really knows why out of 3 or 4 implanted, usually only one survives. Nevertheless, being brought to term is evidence that the remaining 3 or 7 cells of a given embryo are, indeed, totipotent and that the individuals born show no deficiency by the loss of one cell from the early embryo age.
The question arises, could the one cell removed from the early embryo have produced the entire development? No peer reviewed definitive evidence is at hand. However, there have been on-line reports from a specific fertility clinic that this has been the case.
The ethical objection to this procedure lies in the destruction of the extra healthy human embryos.
Thus, to claim that the zygote, or any totipotent embryonic cell, is a "stem cell" is a stretch and is inaccurate. To be sure, development from the zygote proceeds to the term infant, and beyond, and along the way differentiates the more than 200 different tissues of the body. What is desired in this effort to culture human embryonic stem cells (hesc) is to derive the real stem cells of a given tissue, but this is not what is happening. Unfortunately, when embryonic cells are cultured they want to differentiate, and so far this process cannot be stopped. When some cultured embryonic cells are injected into experimental mice, tumors are formed.
It is a laudable effort to culture cells from early embryonic cells because the controls over differentiation may become manifest, and we do not know what those controls are.
But, consider that during the normal differentiation of the more than 200 tissues of the human body the cells go through countless generations. During those processes from one generation to the next, chemicals such as stimulators, inhibitors, etc. are being passed back and forth from one cell to another, or from a group of cells to an adjacent group of cells, and maybe at some distance. Cells in culture are likely to bypass a great deal of these exchanges. What will be lost? No one knows.
Therefore, where does one start? First, animal model studies should be done. Second, the identification of true stem cells in a given tissue should be made. Those cells should be characterized. Third, once this has been done, the therapeutic value of those cells should be assessed. This may turn out to be the most difficult aspect of proposed stem cell research. It requires precise interjection (or injection) of the so-called stem cells into a diseased or damaged area of adult tissue. But, it may also require precise timing of the state of the injured or diseased tissue. Those mechanisms have not yet been elucidated.
On February 26th, 2006, the Sunday program "60 Minutes" reported on hescr. Two segments are worth commenting upon.
First, it was stated beating human cardiac muscle cells were obtained in culture from human embryonic "stem cells", and that they could be used to inject, or applied to, damaged heart for repair. The adult human heart tissue has no stem cells. The application of definitive "beating" human cardiac muscle cells would not be an example of stem cell research, and, further, would not be an easy procedure. There was no mention of the complications involved.
Second, as an example of the hopeful and future use of hesc, Ed Bradley, the host, gave an example of Batten's Disease, showing a child apparently suffering from this malady. This is a familial (genetic) disease resulting in severe mental retardation. It is difficult, if not impossible, to determine how stem cells could be used, in this case, therapeutically. If it would involve replacing damaged neurons, for example, how would the new neural networking be achieved? Nothing was said about any conceived therapeutic procedure.
Whenever therapeutic use of stem cells generated from human embryo sources is mentioned, very little, if anything, is said about the need for autologous stem cells. That is, the stem cells to be obtained must be generated from the same person (patient) in whom they are intended to be applied. Otherwise, the stem cells will be rejected.
To avoid rejection, a cloning procedure would have to be used. This would involve using the nucleus of an adult cell for the somatic cell nuclear transfer (scnt). These procedures are replete with problems, and, to date, have not shown any results encouraging the culture of stem cells.
I have been informed of a recent debate held at Princeton University on April 19th, 2006, courtesy of Professor Robert George, a Professor of Politics at Princeton. This debate was on stem cell research after an airing of a student-produced "documentary" film on the subject. On the one side were Professor Lee Silver, a Molecular Biologist, Shirley Tilghman, President of Princeton University, and Professor Peter Singer, bioethicist. On the other side were Professor Robert George and his Research Assistant, Ryan Anderson. I reproduce a few selected comments below from Silver and Tilghman to show that the current arguments in favor of human embryonic stem cell research have not evolved from nonsense to common sense, or even to factual knowledge. I put the comments by Silver and Tilghman in quotes, followed by my rebuttals in bold.
Silver: "Well, my personal opinion is that an embryo is not a human being. That an embryo is a group of cells. That later on during development it gets fuzzy. I don't know when the human being begins. But that before implantation its's perfectly clear that you have a group of cells that has no semblance of unique humanness. So, that's what I believe. Now, I don't think that I should foist my belief on others. But what I do what others to understand (sic) is the theological basis for having other kinds of beliefs."
Silver is a Professor of Molecular Biology. But, it is clear he knows virtually nothing about Human Embryology, not even that which most high school students know. The embryo is just "a group of cells"? The unique quality of a human being begins with fertilization. A lot of biology is going on during the act of fertilization, and from that moment on, which is "unique" to the human specie. He states: "an embryo is not a human being". In the 1930s Adolph Hitler declared that Jews, Gypsies, Slavs, and others, were not human beings. This was his concept of "untermenschen" (subhumans) and gave rise to the axiom: "Lebens unwerten leben" (lives unworthy of life). Is Silver being arbitrary? Read on.
Tilghman: "In the case of the stem cell debate, I would say that you have on two sides of the issue very different views about the moral rights of a small ball of cells (my emphasis), that arise from a fertilized egg, that get from a single cell to 64 cells, and at that point is a blastocyst - this is how we refer to them in science. And the question is, does that ball of cells, in your belief, deserve the same rights and privileges, and protection under the law, as an embryo, as a fetus, as a newborn, as an adult. And that's not a scientific question. That is a moral question, on which people can differ."
President Tilghman was a Professor of Molecular Biology, and suffers from the same deficiencies as Silver. It is amazing to me that someone like her can rise to the position as President of a major University with so little facts of biology, which was part of her field of research. First and foremost, her characterization of the early human embryo as a "small ball of cells" clearly implies her fascination with size. Does she see "small" people as less human than big people? Further, she (and Silver) do not understand the fact of "The Continuum". Such terms as zygote, morula, blastula, blastocyst (all of which are terms applied to the embryo), and fetus, are of value only in the taxonomic sense. All of development is a CONTINUUM. The terms simply enable embryologists to talk to one another. Each advancing moment blends into the next advancing moment, and each moment of development gets its significance from the immediately previous moment. Tilghman claims that "rights" of an embryo or fetus is a "moral question". The truth is that Tilghman is engaging in moral relativism, leading directly to a political question.
What she and Silver do not understand is that the SCIENTIFIC value of any age of life, from fertilization to death - whenever that may occur - is equivalent. That is because all of the characteristics of life are forever changing, albeit at different rates at different times: size, form, content, function, appearance, etc.
Silver: "My own view, which is not well formed, I don't know where to draw the line. My own view would say 1) it's very difficult to draw such lines, and 2) societies somehow, sometimes have to draw what are arbitrary (my emphasis) lines, and 3) I look at the abortion debate as an issue of a woman's right to decide what to do with her body."
Well, well, well. Silver finally admits to it. He is being ARBITRARY. So, the argument is reduced to: who has the bigger hammer! Even the Supreme Court has been arbitrary, as we have known since Roe vs. Wade. The factual knowledge of Human Embryology be damned, as Silver and Tilghman have implied. They can ignore the facts, reduce the argument to one of "religious beliefs", engage in blather and weaseling with pomposity because, ultimately, they can rely on their big "hammer" - Roe vs. Wade (and Doe vs. Bolton), which they have done.
Human embryonic stem cell research is being widely promoted today, and some prestigious Universities have been headlined as in the forefront of that research, but with few, if any, encouraging results. As a scientist I do not dismiss possibilities of eventual success of stem cell research in three areas: 1) knowledge of the controls of differentiation of the body tissues, 2) eventual culture and harvesting of true stem cells, and 3) therapeutic applications of true stem cells.
However, there is virtually no public analysis of the proper methodology to obtain any of the three goals. Just reflect upon the comments of Silver and Tilghman. They are the popular advocates for hesc research. If a judgement were to be made today based on their supportive statements justifying hescr, we should all pack up and go home. Yet, we are faced with such propects as California Proposition 71, in which 3 billion dollars of tax money will go to support hesc research. Other states have followed suit, and North Carolina is poised to commit millions of dollars for similar research. It is difficult to predict the outcome of this research. But, one thing is certain: human embryologists are not being consulted. Therefore, the public is not being well informed.