A Moral Way To Obtain Embryonic Stem-cells - or is it?

Santorum-Specter Bill S-2754, is promoted as a moral way to obtain embryonic stem cells. Let’s see what is involved.

Normal Embryogenesis:Stage 1: Involves one ovum and 300 million sperms.
Fertilization begins when the sperm enters the ovum and it ends with the creation of the zygote/embryo.The process takes about 24 hours.
The sperm penetrates the zona pellucida of the ovum and binds to receptor proteins in the zona. The process takes about 20 minutes. The neuclei of the ovum and the sperm fuse and when fusion is complete, fertilization is ended culminating in creation of a zygote/embryo.

Stage 2:
The zygote/embryo now begins to cleave, each division forming two cells called blastomeres. The first cell division begins a series of divisions with each division occurring approx every 20 hours. Each blastomere within the zona pellucida becomes smaller and smaller with each subsequent division . When cell division has generated about 16 cells, the zygote / embryo is called a morula/embryo. It now leaves the Fallopian tube and enters the uterine cavity, 3-4 days after fertilization.

Stage 3:
The morula /embryo continues cell division and within the resulting mass of cells a cavity called a blastocele is formed. Cells flatten and compact on the inside of the cavity while the outer zona pellucida remains the same size. The structure is now called a blastocyst. The presence of a blastocyst indicates that two cell types have appeared – the embryoblast cells forming the inner cell mass of approx.30 cells on the inside of the blastocele and the trophoblast cells forming the outer cell mass on its outside. From the embryoblast collection of cells the embryo continues its development. Within this collection of embryoblasts are found the embryonal stem cells. The trophoblast cells go on to develop the placenta.
With fertilization, a new entity appears that is directed by an intrinsic teleological process towards formation of an adult person. This process of formation is a continuum: no single moment can be found in which a substantial change occurs, a change that allows us to speak of a human being only after this moment and not before.

Neuclear-Transfer Embryogenesis - Cloning:

In regular cloning an adult body cell - a skin cell in most cases - and a woman’s ovum are taken. The neucleus is removed from the ovum, discarded and replaced by the neucleus of the skin cell. The result is a cell with a full complement of chromosomes, a cell that is alive and that constitutes a cloned cell, an embryo. Since human cells are used, the embryo has to be accepted as human, as a human person. After the neuclear transfer to the ovum cytoplasm, a genetic readjustment or reprogramming has to occur, mediated by elements within the ovum cytoplasm. Growth, development, and maturation of the embryo then proceeds in a manner identical to that which occurs in a normal pregnancy.

Traditional Embryonic Stem-cell Harvesting:

Embryos from IVF are taken at the blastocyst stage at 4-5 days old.
Human embryonic stem cells are isolated by transferring the inner cell mass of 30 cells onto a culture dish containing culture medium. The cells divide and spread over the surface of the dish. Over the course of several days, the cells of the inner cell mass proliferate and begin to crowd the culture dish. They are gently removed and plated onto several fresh culture dishes. The process of replating the cells is repeated many times and for many months and is called subculturing. After 6 months or more, the original 30 cells of the inner cell mass yield millions of embryonic stem cells.
Embryonic stem cells that have proliferated in cell culture for six or more months without differentiating, are pluripotent and appear genetically normal and are referred to as an embryonic stem cell line .
As long as these cells in culture are grown under certain conditions, they can remain undifferentiated/ unspecialized. But if they are allowed to clump together, they form embryoid bodies and begin to differentiate spontaneously. They can form muscle cells, nerve cells, and many other cell types.
To generate cultures of specific types of differentiated cells – e.g. heart, blood or nerve cells - scientists change the composition of the culture medium, alter the surface of the culture dish or modify the cells by inserting specific genes. They have established some basic protocols for the directed differentiation of embryonic stem cells into some specific cell types. It is hoped that the resulting differentiated cells may be used to treat certain diseases at some time in the future.

Cell Potency:

Totipotency:
This refers to the ability of a single cell to express the full genome in the cells to which it gives rise by cell division. Thus fertilized eggs (zygotes) are totipotent because they produce a population of differentiated cells forming an entire organism, whereas under normal circumstances , human skin cells for example, are not totipotent, because, in culture, they divide to produce only more skin cells and not nerve, muscle or other end-stage cells. Totipotency is the ability of all living cells potentially to regenerate whole new individuals. The problem is how to trigger them to do it. All living cells have the necessary information but not the trigger to change the development. Totipotent cells specialize into pluripotent cells that can give rise to most, but not all, of the tissues necessary for fetal development.
Totipotent cells also are able to differentiate into cells of the placenta.

Pluripotency:
Pluripotent cells have the potency to develop into the primitive layers of the developing fetus – the endoderm, the mesoderm and the ectoderm.
From the endoderm develops the stomach, intestinal tract and the lungs.
From the mesoderm develops the muscle cells, bone cells, bone marrow and blood cells and the urogenital tract.
From the ectoderm develops the epidermal tissues and the nervous system.
Pluripotent cells can eventually specialize into any bodily tissue but cannot themselves develop into a human being.
Pluripotent cells undergo further specialization into multipotent cells.

Multipotency:
Multipotent cells are committed to give rise to cells that have a particular function for example. multipotent marrow stem cells that give rise to red cells, white cells and platelets of the blood.

Unipotency:
Unipotent cells are stem cells that can differentiate into only one type of tissue or cell type. Skin cells are the best example.The unipotent cell has the unique property of self-renewal, a feature that distinguishes it from non-stem cells.
In recent experiments, scientists have been able to persuade marrow stem cells to behave like neurons or brain cells and there is continuing research to see if it is possible to make multipotent cells into pluripotent cells.

Altered Neuclear Transfer Embryogenesis (ANT)
Prior to the OAR procedure, scientists were experimenting with cloned cells in a procedure called ANT - altered neuclear transfer. This was proposed by Dr Hurlbut. Prior to neuclear transfer they were disabling a gene in the skin cell neucleus that in the embryo would code for a developmentally-important protein that regulates gene expression in the nucleus. It appears that the gene being disabled codes for formation of the placenta from trophoblast cells. Obviously without a placenta, the embryo formed would not be able to develop or survive because of lack of effective nutrition.
This created but disabled embryo developed normally until the blastocyst stage which is reached 4-6 days after neuclear transfer. Because of the gene disabling, the blastocyst had a disorganised, disabled outer layer while the inner layer of cells which contains the stem cells was normal. These stem cells were removed and used as embryonic stem cells.

Oocyte-Assisted Reprogramming. (OAR)
Since there was much opposition to the ANT procedure of creating and disabling an embryo, a new approach was conceived by Hurlbut and applied to mouse models by Meissner and Jaenisch. – the OAR procedure.or oocyte-assisted reprogramming.
Senate bill S-2754 promoted this procedure.
This new approach is essentially a case of cloning where genetic engineering over-expresses a protein called NANOG normally present in the transferred skin neucleus. NANOG has been shown in mice to promote and maintain pluripotency and prevent differentiation into different cell maturity levels.
NANOG is a transscription factor critically involved in the self-renewal of undifferentiated embryonic cells. It maintains pluripotency. Scientists have yet to identify the signal that turns NANOG on, early in an embryo’s existence. .
Proponents claim that the presence of NANOG and re-programming factors in the ovum cytoplasm causes the neucleus of the entity produced by altered nuclear transfer, to undergo retrogressive de-differentiation from the unipotent, differentiated state of the skin neucleus, to an immature multi-potent state, and then to an even more immature pluripotent state. They claim that it will never reach the ultimately-immature totipotent stage where the cell has the potentiality to differentiate into all final end-stage cells. Proponents claim further that such pluripotent stem cells can never constitute an embryo as they would be unable to produce all the end-stage, specific, differentiated cells needed to constitute a human body . No embryo is created during this entire procedure, they claim, since the cells never reach the totipotent stage. Finding proof for this hypothesis is the crux of the problem. There is no proof for this claim and it remains a hypothesis thus far.
Experience with mouse embryos shows that NANOG normally functions within a certain developmental context. Its expression outside this context will not lead to stem cells but instead will lead to a grossly-defective embryo that quickly dies or to a totally unaffected normal embryo which continues to develop..

Questions:
Will we not require more assurance that the OAR procedure can indeed produce cells that are not human embryos. Can we simply assume that over-expression of NANOG and genetic reprogramming in the transferred skin neucleus would indeed lead to a non-embryo entity that would be able to proceed along the usual path of development and be able to generate a form of non-embryo ‘blastocyst’ from which stem cells could eventually be derived? As yet there seems to be no scientific assurance that it would.

Can we assume that absence of totipotency implies absence of embryo formation?

Since up to the formation of the ‘blastocyst’ in OAR, the created entity must go through developmental stages that are indistinguishable from those of normal embryogenesis, are we not creating a cloned embryo and interfering with its true development. Are we not interfering unjustifiably with a living human embryo?

Where will all the womens’ ova come from? Might the practice not lead to trafficking in human ova?. Will ovum extraction procedures not place donor women at surgical risk?.