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Of Ovasomes and Parthenotes/Two other sources of pluripotent cells not using IVF clinic "left-overs"

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  • Of Ovasomes and Parthenotes/Two other sources of pluripotent cells not using IVF clinic "left-overs"

    "left-over" frozen embryos are not the most useful sources of pluripotent stem cells for therapy. Their major problem is that human embryonic stem cells will have the same tissue compatibility problems as other transplanted organs.

    What stem cells should be used for therapy? There are two types that have not been part of the debate. Pluripotent human stem cells for therapy developed from activated eggs and nuclear transplantation.

    Type 1: "Activated eggs" (Parthenotes)

    Human eggs are huge cells with the capacity to resume cell division without being fertilized by sperm. This occurs naturally in women, giving rise to dermoid cysts and teratomas. Women are born with about one million eggs. By the time they are 50 years old, the eggs have all died. Thus, about 20,000 eggs naturally die each year, in the ovary; she ovulates about a dozen.

    The challenge is to harness the capacity of the egg to start over, to give rise to new, pluripotent stem cells, once it is activated. This is a natural, obvious source of stem cells for ovulating women with serious diseases, such as diabetes and spinal cord injury, because they will not have the tissue rejection problems.

    Activation of human eggs for stem cells was first reported in 2001, (pdf article) but a continuous line of stem cells was not achieved. The research is ongoing in Bedford Stem Cell Research Laboratories with private funding; the research cannot be funded by federal dollars because of the moratorium on funding research on all "activated" human eggs.

    Parthenote stem cells were developed from a monkey egg in 2000 (pdf article), and have been shown to give rise to the same types of cells as stem cells derived from human embryos "left over" in fertility clinics. They are currently being used in several lines of research, including treating Parkinson's disease in monkeys.

    Type 2: Nuclear Transplant stem cells (Ovasomes: somatic ("body") cells from ("ova") eggs)

    Eggs have the remarkable capacity to "remodel" genetic information introduced into them, just like it "remodels" sperm at fertilization. This powerful capacity is not fully understood. It can erase the memory in the genes of a skin cell that made it a skin cell, and convert it back to a pluripotent stem cell. It does this without its own chromosomes. Then, when activated, the egg uses the new genetic information to divide into a line of stem cells genetically identical to the skin cell donor. Because this same basic technology led to cloning Dolly the sheep in 1997, there is fear it could lead to cloning a human. Such fears could be set aside by proper legislation to outlaw using nuclear transplantation technology to clone a human.

    Attempts to develop human nuclear transplant stem cells (ovasomes) were first reported in 2001, but the activated eggs stopped dividing, and stem cells did not develop (pdf article). In March, 2004, the first ovasomes (nuclear transplant stem cells) were developed in a laboratory in Korea (pdf article). The cells were shown to develop into all the same cell types as human embryonic stem cells and the monkey parthenote stem cells.

    Current status of research:

    Congress placed a moratorium on funding research on all forms of activated human eggs, including parthenotes and nuclear transplanted eggs, in 1996. President Bush extended the moratorium to include funding the derivation of stem cells from "left-over" human embryos in 2001.


    "We have lost so much time already" - Nancy Reagan

  • #2
    We (the public and scientists) are afflicted with a failure of imagination in America, an inability to visualize the possibilities. In many ways, the culture of science today is preventing that imagination from expressing itself. Students are constantly being chastised for not being "rigorous" enough when they speculate; the more advanced they are, the more they are chastised for speculation. In many ways, it is sad. I did not realize this until I started teaching undergraduate students and found them to be more imaginative than I am or dare to be. I did not permit myself to imagine, to loosen the corsets that years of NIH grants placed on my thinking, the pall of conservative thinking that NIH application demanded of scientist. If there is no evidence for something, it meant that it did not exist. The stem cell situation illustrates the paucity of our imagination so well.

    This article lists two potential sources of stem cells that were excluded from the debate. There are many more and I don't think that I am being unrigorous for proposing them. The following are some additional ways of creating stem cells.

    1. Genetic modification of cells. After all, a stem cell is just a cell that is expressing certain genes. Someday, we will be able to make any cell into a stem cell.

    2. Cell fusion. We now know that cells fuse with each other. The act of fertilization is when one cell fuses with another. More important, we know that stem cells fuse with other cells. We know that fetal cells that are infused into the blood of mothers gets into organs, perhaps fuse with cells, and then start behaving like stem cells.

    3. Cytoplasm determines the fate of cells. While we think that genes determine the fate of cells, some evidence suggest that it may be the other way around. We should have realized this from the cloning of Dolly. In somatic nuclear transfer, we thought that nucleus is "fooled" into thinking that it is an egg nucleus. In reality, it was not being "fooled" but was instead being told that it is in an egg. Well, instead of bring Mohammed to the mountain (i.e. the nucleus to the egg) why don't we take the mountain to Mohammed (i.e. put a somatic cell into a lot of egg cytoplasm). By the way, there is no reason why it has to be human egg cytoplasm. We can use bovine or even chicken cytoplasm, both plentifully available.



    • #3
      If a stem cell line were to be derived from one of these alternative sources today, would it be eligible for full NIH funding? No embryo has been destroyed so why not?
      "Oh yeah life goes on
      Long after the thrill of livin is gone"

      John Cougar Mellencamp


      • #4
        Mike, Any research that does not harm embryos or fetuses should be eligible for NIH funding. Wise.