Framing the Debates on Human Cloning and Human Embryonic Stem Cells: Pluripotent vs. TOTIPOTENT

Dianne N. Irving
Copyright July 23, 2005
Reproduced with Permission

Caution: not a single reference to "faith", "religion", or "fundamentalist beliefs" can be found in the following radically realistic article or in any of its references. Proceed at your own risk.

I. Introduction

The purpose of the following selected bibliography on human embryonic stem cells is to demonstrate and document that most of the cells of the early developing human embryo are totipotent, and to refute the current claim - from both sides of the aisles - that they are all pluripotent. The long-established scientific fact is that most of them are "totipotent" - not pluripotent. That means that they can not only produce "all of the cells, tissues and organs of the adult human being", but that they also have the inherent natural capacity to undergo regulation and to thereby be reverted to new living human embryos - to be used for both research and for reproductive purposes.

The obvious proof that most of these early human embryonic cells are totipotent is right before our collective eyes - in the empirical fact of "twinning". If twins are formed long before and even after 14-days - and they are - that could only happen if at least some of the cells of the early human embryo are totipotent - not pluripotent. Indeed, a third of natural human monozygotic "twinning" takes place from the 2-cell through the morula stage of early human development; two-thirds of such twinning takes place by the splitting of the human embryo at the blastocyst stage of development. That automatically means that the human embryonic "stem" cells from which these twins are derived are totipotent - not pluripotent. How has the current "confusion" about "pluripotent human embryonic stem cells" in the current popular literature come about?

II. Framing the Debates

The founding secular bioethics think-tank, the Hastings Center, has been in this game from the beginning, so the opening sentence to their recent mega supplemental report on "reprogenetics" ought to be taken seriously:

At the first of the discussions that led eventually to this report, a respected researcher-clinician in the world of reprogenetic medicine referred to his field as "one big embryo experiment."1 [Hastings Center Special Supplement 2003]

"One big embryo experiment" - exactly.

But how is this Big Embryo Experiment to be accomplished without incurring public outrage? Simple. Redefine the critical scientific terms and incorporate them across the academic fields so that the early human being at the embryonic stage "disappears". Or at least give the early human embryo a "reduced moral status" so that it can be "weighed and measured" against the rights and protections of real human beings. Frame the debates quickly though, before the public figures out what is going on. Indeed, as bioethics' recent history demonstrates, this was initially one of its main objectives.

And that is precisely what has been done for the last 40 years, taking advantage of the deplorable lack of solid scientific education of the average citizen and politician. The "framing" started in the late 1960's with the fake scientific term "pre-embryo" - even more seductive since it was coined here by two Roman Catholics - one a Jesuit priest, the other a frog embryologist from ... California. Before people could go to the library and check the term out in the readily available human embryology textbooks, the scientific field of human embryology itself began to be rewritten (and attempts continue to this day).

The term "pre-embryo" was then rapidly institutionalized by being incorporated into hundreds of state, national and international laws and regulations, in medical, law and graduate school curriculae, in seminary and journalism programs, in dictionaries, magazines, high school, college and university textbooks, etc. The politicization of science continues. Science is now done "democratically" by 'committees" - committees, councils and panels consisting, of course, of members who also lack sufficient scientific backgrounds in human embryology, or of scientists who just don't care.

In the early days of "framing", those in the know knew it was a fake term, but for various and sundry reasons used it anyway. It worked! They knew they could "get away with it" (as I overheard groups of researchers smirk on their way to testify at the latest NIH committee meetings and again before Congressional hearings!) - and they did. Indeed, the term flourished on both sides of the aisles.

We then experienced in rapid succession related "framings". Unborn human children were referred to as simply "products of your conception". Flagrantly defying all medical and scientific knowledge for over a hundred years, suddenly "pregnancy" was claimed to begin at implantation in the woman's womb rather than at fertilization in her fallopian tube; and "fetus" was defined as beginning at implantation rather than at 9 weeks post-fertilization - both formal "definitions" to be found in the 1981 OPRR federal regulations, IRB guidelines and various bioethics "reports". Before we knew it the term "pre-embryo" was successfully used to "justify" not only early abortion, but also the use of abortifacients, human embryo research, pre-implantation genetic diagnosis, and in vitro fertilization (IVF) research and "therapies". Anyone who defied the Framers or challenged their "framings" were successfully dismissed as "religious" zealots who want to force their "beliefs" down our secular throats. That worked too - especially in our pluralistic democratic multi-cultural society.

But eventually the term "pre-embryo" was formally rejected by the international nomenclature committee on human embryology - thus requiring the Framers to come up with a long string of "pre-embryo substitutes" in order to continue confusing everyone - especially when attention was diverted to issues involving human cloning, human embryonic stem cell research, human genetic engineering, and "regenerative medicine". The continuing list of "pre-embryo substitutes" includes: "therapeutic" vs. "reproductive" cloning; "cloning" vs. "stem cell research"; "ball of cells" vs. "organism", and "activated or reconstructed egg" vs. "single-cell zygote", etc. And these "pre-embryo substitutes" are working too.

III. Latest "Pre-Embryo Substitute": "pluripotent" vs. "totipotent"

The latest "pre-embryo substitute" on the block is "pluripotent" vs. "totipotent". That is, the cells (or blastomeres) of the early developing human embryo are "pluripotent" rather than "totipotent" - the point of the Framers being that these "pluripotent" cells could never ever naturally revert to new human organisms - human beings. Why? Because these human embryonic cells are too "differentiated" now - they can only give way to more cells, tissues and organs - never revert to new human embryos. They are simply needed for basic research and "stem cell therapies". Not to worry.

But the "pluripotent" claim is not true, and is refuted by the accurate objective scientific facts. Most of the cells of the early developing human embryo - both in vivo and in vitro, whether derived from sexual or asexual reproduction - are totipotent, not pluripotent. And that means that they can not only produce all of the cells, tissues and organs of the adult human being, but also that IF IF IF separated from the whole human embryo they have the natural capacity to be regulated and reverted back to new human embryos - for use in whatever project happens to be around at the time. Again, the proof is right before our collective eyes - in the empirical fact of "twinning". If twins are formed - and they are - that could only happen if at least some of the cells of the early human embryo were totipotent. "Twinning = totipotent".

This magnifies the ethical objection of killing already living "surplus" IVF-produced human embryos considerably -- to one of purposefully producing vats-full of living human embryos by "twinning" and other cloning techniques for research and for reproductive purposes. The Framers just call them "immortal human embryonic stem cell lines" instead.

IV. More Confusion

And so the term "pluripotent" is now featured as the very major premise in statements about "alternative methods", "regenerative medicine" and even research studies and bioethics "courses" across the fields, on both sides of the aisles - well on its way to being immortalized and institutionalized by the Framers. And it is working too, resulting in the desired confusion, contradictions and adherents as needed.

For example, all four of the current proposals for "alternative sources of human embryonic stem cells" (among other concerns) assume as their major premise that these stem cells are pluripotent,2 rather than totipotent. No questions asked. Thus whatever is being claimed for these "pluripotent" stem cells is actually true for totipotent stem cells instead! Confusing?

Even when it is officially acknowledged that the cells of the early developing human embryo are mostly really totipotent, the line is conveniently drawn at the blastocyst stage with the claim that the cells from the inner cell mass of the blastocyst (supposedly the only "serious" source of human embryonic stem cells) are pluripotent - not totipotent - and therefore their use can be sanctioned and funded by the federal government. As Dr. Skirboll, NIH associate director for science policy, "explained" recently:

"An egg is fertilized by sperm. From that fertilization, an embryo begins to form; a group of cells begins to divide, producing totipotent cells, or totally potent cells. What we mean by that is: totipotent cells each have the potential to develop into a fetus and a baby. Soon the totipotent cells begin to differentiate, on their way to becoming the complex organism that human beings are. Next, a blastocyst is formed from the totipotent cells. It is from the inner cell mass of this blastocyst structure that so-called "pluripotent" cells can be extracted. Pluripotent, or 'plural potent' cells are capable of becoming almost all cells of the human body. However, unlike totipotent cells, pluripotent cells cannot develop into humans. This distinction between totipotent cells and pluripotent cells is very important, Skirboll pointed out. Because pluripotent cells can never develop into a human, the HHS Office of General Counsel has determined that federal agencies may legally fund research using pluripotent stem cells."3 (emphases added)

Indeed, "the distinction between totipotent and pluripotent cells is very important". And obviously these earliest of human embryonic cells could be twinned precisely because they are totipotent. But why then does NIH's Skirboll stop her accurate scientific explanation at the blastocyst stage? It is well known that many of these cells from the ICM are totipotent - the scientific explanation of most natural monozygotic twinning in humans. Could it be to assuage the public who have been led to believe that the only "human embryonic cells" of interest are those derived from the inner cell mass of the human blastocyst, and that they are all pluripotent, not totipotent? But then how would Skirboll explain human monozygotic twinning at the blastocyst stage?

Bioethicists, long involved in advocating human embryo research of any and all kinds, help to foster confusion by self-contradictory remarks even within the same breath:

Whatever the odds may have been in 1995, recent PSC [pluripotent stem cells] research dramatically improves the odds that using human embryos as a source of PSCs will lead to major scientific and clinical benefits. Regaldo (1998) usefully reviewed PSC research. PSCs have the potential to develop into several (but not all) of the various cells in the body. PSCs are more specialized than the totipotent cells in the human blastocyst, each of which can develop into a total individual. A few researchers, with private support, have labored long to isolate, culture, and nurture human PSCs to grow into various types of cells (e.g., neural, muscle, heart, blood). Reports from two of these investigators (Shamblott et al., 1998, Thomson et al., 1998) published in November dramatically changed the context for debate about embryo research. Building on earlier work with PSCs isolated from embryos of rhesus monkeys and marmosets, James Thomson and a team from the University of Wisconsin, Madison, derived human PSCs from the inner cell masses of excess embryos donated for research with the consent of infertile couples treated by IVF.4 (emphases added)

How could Fletcher claim first that all of the cells from the inner cell mass (ICM) of the human blastocyst are pluripotent, and then claim that pluripotent cells in the human blastocyst can revert to new embryos (twin)? Not only are totipotent cells now defined as pluripotent, but pluripotent cells are defined as totipotent! Which is it?

Even in the face of empirically known and acknowledged natural monozygotic twinning, the assertion by influential bioethics groups that the cells of the inner cell mass of the blastocyst are only pluripotent continue:

"Unlike an adult stem cell, a human fertilized egg is totipotent, meaning it has the potential to create all the specialized cells that make up a human being, as well as the intrauterine support structure necessary for fetal development. After approximately four days (and several cycles of cell division) the totipotent cells begin to specialize into a blastocyst. The outer layer of cells will go on to form support structures like the placenta. The inner cell mass will become the fetus. These cells are called pluripotent stem cells, because while they can form virtually every type of cell in the human body they cannot give rise to the cells necessary to support fetal development. Until about day 14, the inner cell mass has the potential to split, forming identical twins (in rare instances, they continue to split, forming identical triplets or quadruplets.)5 (emphases added)

How can pluripotent stem cells produce twins when by definition they can't? And so we observe the gradual institutionalization of yet another "pre-embryo substitute". The new living and very real human embryos that could realistically result by regulating these early totipotent human embryonic "stem" cells must be figments of our imaginations. Not to worry.

V. What's at Stake?

What's at stake? Essentially the early developing human embryo is linguistically "disappearing" once again - thus absent from any and all considerations. The tip of the ice berg of the "pluripotent human embryonic stem cell" confusion includes the deceptive production of vast amounts of living human embryos for use and commercialization in: "regenerative medicine" (both research and "therapies"); human cloning and other human genetic engineering research; nanotechnology research and development requiring human "fragments"; the production of wayward and dangerous "mutagens"; and IVF basic research and "infertility treatments" at IVF centers. Of special concern is the fact that now "IVF surplus embryos" includes those produced by cloning and genetic engineering, and that women will be simply used as guinea pigs to "test" these experimental and alternative "entities" or "balls of cells". And needless to say, such IVF research protected by continuous "framing" and the total lack of regulations, laws or inspections could easily include the clandestine production of human embryos for biological, chemical and nuclear warfare purposes - but who's to know? Not even the government? One Big Embryo Experiment indeed. And One Big Clinical Trial needed to empirically prove it.

VI. Why the Deception?

As you read slowly through the references on totipotency below, the reason for much of the "confusion" and the "contradictions" will become crystal clear. The issue of totipotency is inherently bound up with many other controversial issues as well - issues that many would prefer were not raised in the public square. Like the domino effect, allowing one deception to be exposed exposes all the rest. Just for starters, you will notice in these references that:

1. Contra the "California science" of those like Irving Weissman, Michael West, the National Academy of Sciences, etc., the immediate product of sexual and of asexual human reproduction is a single-cell human organism - a human being, an embryo -- not just a "cell". The whole human embryo at the blastocyst stage is a human organism, not just a "ball of cells". Thus we are really looking at human cloning on a huge scale, not just "stem cell research".

2. Most of the cells of the early human embryo are totipotent, or a mixture of totipotent and pluripotent. The term "totipotent" itself indicates a range of totipotency rather than any single constant potency during early development. Yet cells within that range are all naturally capable of reverting to new embryos in vivo, and this reversion can be artificially accomplished in vitro as well. For example, even though the totipotency of a cell of a 3-cell human embryo is high (because its DNA has not differentiated extensively yet) compared to the totipotency of a cell from the inner cell mass of a blastocyst stage human embryo (because its DNA is more differentiated), both cells are still capable of reverting to new embryos because they are totipotent - not pluripotent. This is not to say that totipotent cells are embryos. Of course they aren't. They are still just cells, not organisms. But it is to say that human totipotent cells have a natural inherent capacity to be transformed into new human organisms - human beings -- even without outside intervention.

3 Once a cell is pluripotent, multipotent, or unipotent it cannot automatically revert to a new embryo unless outside forces intervene - such as in artificial cloning in vitro.

4. The term "totipotent" does not only mean that a cell can produce "all the cells, tissues and organs of the later adult human being" (as with the single-cell human organism or zygote immediately produced sexually or asexually). It also means that if one (or more) of these cells separate from or break off of the whole developing organism it could possibly have its DNA "reprogrammed" (demethylated) back to that of a single-cell zygote, resulting in a new living individual human organism. To provide only the first part of the definition and leave out the second part of the definition is quite deceptive and confusing. [One of the major natural biological mechanisms involved in this reprogramming is called "regulation", quoted directly in some of the human embryology references below.]

By contrast, the term "pluripotent" implies that, under normal conditions, the cell is not capable of undergoing regulation and being reprogrammed back to a new zygote - even if it were to be separated from the whole organism of which it is a part. Most of the cells (blastomeres) of the early developing human embryo before implantation are totipotent - not pluripotent. Many of the cells of the early developing human embryo after implantation are also totipotent - not pluripotent.

5. The totipotent single-cell human organism produced either sexually or asexually is at Stage 1 of the Carnegie Stages of Early Human Development (see endnote 9). The individual cells (blastomeres) of the same early developing human organism at the 2-cell, 3-cell, 4-cell, 5-cell, 6-cell, 7-cell, and 8+-cell (morula, Stage 2) are also totipotent - not pluipotent. Many of the cells of the inner cell mass of the "free" and of the implanted blastocyst (3-7 days, Stages 3 and 4 respectively), as well as the primitive germ line cells (beginning as early as the blastocyst stage) are also totipotent. That is, any of these cells, if separated from the whole human organism, could possibly be reprogrammed back to a new single-cell zygote - a new human being.

6. Precisely because these cells are totipotent -- not pluripotent -- and could undergo regulation, "twinning" can take place, resulting in new individual living human organisms. This can take place naturally in vivo, or artificially in vitro - e.g., by mechanically teasing the blastomeres apart (called "blastomere separation") or splitting the blastocyst in half (called "blastocyst splitting) - as is done in IVF (called "embryo multiplication", a form of "cloning"). Both blastomere separation and blastocyst splitting (twinning) are now performed in IVF centers as "infertility treatments".

7. "Twinning" is one of several different kinds of cloning techniques.

8. Because these early human embryonic cells are also diploid (contain "46" nuclear chromosomes), they can also be cloned by nuclear transfer.

9. Embryonic cells in the inner cell mass (ICM) of the blastocyst are also totipotent6 - not pluripotent -- and therefore can be cloned by "twinning". Because these cells are diploid, they can also be cloned by nuclear transfer.

10. Embryonic germ line cells are also totipotent7 - not pluripotent -- and therefore can be cloned by "twinning". Because these cells are diploid,8 they can also be cloned by nuclear transfer.

11. Historically, cloning by twinning and by nuclear transfer is not new.

12. Cloning by nuclear transfer does not result in a "genetically identical" embryo because the mitochondrial DNA of the donor cell is not transferred, and the mitochondrial DNA of the enucleated oocyte remains in the cloned embryo.

VII. Think "Twinning"!

When you get confused by the deceptive and contradictory claims about totipotency and pluripotency, think "twinning". It's a great reality check. Clearly, if monozygotic twinning takes place almost immediately after fertilization or cloning, and even after 14-days, then at least some of those cells are totipotent - not pluripotent - and they have been regulated to revert to new embryos. Otherwise twinning could not take place. Given the mere quantity of recent confusing and deceptive documents on human embryonic stem cell research, it might be prudent for readers to automatically substitute the term "totipotent" every time the term "pluripotent" is used, and only then evaluate the various statements and documents.

VIII. Resources:

The following selected bibliography on "totipotency" represents another tip of another iceberg. Only a few of the thousands of items that came up on both PubMed (NIH) and Google searches are included here. The final reference list would be prohibitively long. But even these few references should make it clear to the reader that most of the cells of the early developing human embryo are totipotent - not pluripotent as often claimed. Since the real experts on this issue are human embryologists, I have listed direct quotations from human embryology textbooks first, followed by other scientific and professional resources, as well as popular sites. These people, fortunately, are not confused at all:

Next Page: IX: Selected Bigliography on the Totipotency
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