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Thread: could adult stem cell therapy cause cancer ?

  1. #31
    From what I'v read, Embryonic stem cells are the stem cells creating tumors.

    http://bluecrabboulevard.com/2006/10...m-cells-tumor/
    October 22, 2006

    A very disquieting news report that should really bother those who are strong proponents of embryonic stem cell research. It is very preliminary, but it is also very frightening.

    Steven Goldman and colleagues at the University of Rochester Medical Center in New York said human stem cells injected into rat brains turned into cells that looked like early tumors.

    Writing in the journal Nature Medicine, the researchers said the transplants clearly helped the rats, but some of the cells started growing in a way that could eventually lead to a tumor.

    Various types of cell transplants are being tried to treat Parkinson's disease, caused when dopamine-releasing cells die in the brain.

    This key neurotransmitter, or message-carrying chemical, is involved in movement and Parkinson's patients suffer muscle dysfunction that can often lead to paralysis. Drugs can slow the process for a while but there is no cure.

    The idea behind brain cell transplants is to replace the dead cells. Stem cells are considered particularly promising as they can be directed to form the precise desired tissue and do not trigger an immune response.

    Goldman's team used human embryonic stem cells. Taken from days-old embryos, these cells can form any kind of cell in the body. This batch had been cultured in substances aimed at making them become brain cells.

    Previous groups have tried to coax stem cells into becoming dopamine-releasing cells.

    Goldman's team apparently succeeded and transplanted them into the rats with an equivalent of Parkinson's damage. The animals did get better.

    But the grafted cells started to show areas that no longer consisted of dopamine-releasing neurons, but of dividing cells that had the potential to give rise to tumors.

    The researchers killed the rats and are very worried about the outcome they saw. This one ought to give a lot of people pause. There is a lot that is not at all understood here. It is really unfortunate that there is a political debate about science that appears to be not quite ready for prime time.
    UPDATE: Additional coverage in the Washington Post this morning:

    "The behavioral data validate the utility of the approach. But it also raises a cautionary flag and says we are not ready for prime time yet," said lead researcher Steven A. Goldman, a professor of neurology and neurosurgery at the University of Rochester Medical Center.

    Goldman said he suspected that with modest changes in technique, researchers will be able to keep the benefits of the treatment while eliminating or reducing the chances of getting the cancerlike growths. But he conceded that much more basic research would have to be done before scientists ? or regulators ? were likely to be convinced of the approach's safety.

  2. #32
    Dan,

    Human embryonic stem cells indeed can produce tumors called teratomas. Teratomas are tumors composed of many different kinds of cells (appropo of stem cells). Embryonic stem cells are the only stem cells that don't need other cells to create all the cells of the body. That is the way they were designed in the fertilized egg. But teratomas are not the most dangerous of tumors... although they grow and look awful (sometimes with hair on the inside), they do not invade into the surrounding tissues.

    You can substantially reduce or prevent tumor formation by treating the cells with retinoic acid (a differentiating agent). Steve Goldman deliberately did not pre-differentiate the embryonic stem cells as much or as far to prevent all tumor formation. There are now hundreds of scientists studying embryonic stem cells and how to differentiate them. I suspect that this will be a non-problem in the coming years.

    Wise.



    Quote Originally Posted by Dan194
    From what I'v read, Embryonic stem cells are the stem cells creating tumors.

    http://bluecrabboulevard.com/2006/10...m-cells-tumor/
    October 22, 2006

    A very disquieting news report that should really bother those who are strong proponents of embryonic stem cell research. It is very preliminary, but it is also very frightening.

    Steven Goldman and colleagues at the University of Rochester Medical Center in New York said human stem cells injected into rat brains turned into cells that looked like early tumors.

    Writing in the journal Nature Medicine, the researchers said the transplants clearly helped the rats, but some of the cells started growing in a way that could eventually lead to a tumor.

    Various types of cell transplants are being tried to treat Parkinson's disease, caused when dopamine-releasing cells die in the brain.

    This key neurotransmitter, or message-carrying chemical, is involved in movement and Parkinson's patients suffer muscle dysfunction that can often lead to paralysis. Drugs can slow the process for a while but there is no cure.

    The idea behind brain cell transplants is to replace the dead cells. Stem cells are considered particularly promising as they can be directed to form the precise desired tissue and do not trigger an immune response.

    Goldman's team used human embryonic stem cells. Taken from days-old embryos, these cells can form any kind of cell in the body. This batch had been cultured in substances aimed at making them become brain cells.

    Previous groups have tried to coax stem cells into becoming dopamine-releasing cells.

    Goldman's team apparently succeeded and transplanted them into the rats with an equivalent of Parkinson's damage. The animals did get better.

    But the grafted cells started to show areas that no longer consisted of dopamine-releasing neurons, but of dividing cells that had the potential to give rise to tumors.

    The researchers killed the rats and are very worried about the outcome they saw. This one ought to give a lot of people pause. There is a lot that is not at all understood here. It is really unfortunate that there is a political debate about science that appears to be not quite ready for prime time.
    UPDATE: Additional coverage in the Washington Post this morning:

    "The behavioral data validate the utility of the approach. But it also raises a cautionary flag and says we are not ready for prime time yet," said lead researcher Steven A. Goldman, a professor of neurology and neurosurgery at the University of Rochester Medical Center.

    Goldman said he suspected that with modest changes in technique, researchers will be able to keep the benefits of the treatment while eliminating or reducing the chances of getting the cancerlike growths. But he conceded that much more basic research would have to be done before scientists ? or regulators ? were likely to be convinced of the approach's safety.

  3. #33
    Maybe I should talk a bit about recent emerging information suggesting that adult stem cells play a role in cancer.

    A radical theory has emerged recently from stem cell research. This theory suggests that our bodies relegate the task of self-replication only to stem cells. Most other cells that differentiate can make other cells but not themselves. This makes sense because cells that produce other cells must be able sense a multitude of conditions that tell the cells if and when to make cells. A cell that can make many other cells and itself is potentially very dangerous.

    If you think about it, a stem cell must be remarkably sensitive to its environment. For example, if a stem cell produced fat cells in the spinal cord, our spinal cord would be in trouble because it doesn't need fat cells and, if it grows into a lipoma, it would cause paralysis. Maybe because of this, our central nervous system is bereft of most signals that stimulate stem cells to produce other kinds of cells. I think of the spinal cord as the Gobi Desert.

    The emerging theory is that many cancers grow by using circulating mesenchymal stem cells to produce more cancer cells. The cancer simply provides a niche for the stem cells to move into and the stem cells produce more cancer cells. This is quite a theory because it suggests a very different target for cancer therapy. Instead of aiming to kill tumor cells, one aims at disrupting the niche.

    Some cancers appear to secrete factors that attract stem cells. I recently saw a talk by an investigator who showed that stem cells preferentially "home" to cancers. I am very skeptical that stem cells can "home". After all, even if a cell knows where to go, it has no way of controlling where it goes once it is in the bloodstream. I will write more about this later.

    Wise.

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