First, and without links, I'd like to express my amazement that one or two articles about a brand new and unproven procedure can send Bushies into exalted self-righteousness over their perceived lack of the need for continued Embryonic Stem Cell Research. Suddenly, a promising but currently unusable breakthrough should make Embryonic Stem Cell studies a thing of the past. And yet, THOUSANDS of pages of research and scientific agreement on the process of Global Warming can be dismissed out of hand due to the financial considerations of his corporate donors. Whatever.
What we need to understand is that while this new stem cell research is PROMISING, it is in no way ready for prime time. It will not be saving people in the very near future, as the procedure is completely unsafe for use in humans at the current time. Also, even the scientists who produced the results(scroll down to first PDF)are saying that their findings should in no way hinder further research using Embryonic Stem Cells. Haven't seen that discussed on the news.
MORE --->
From the researchers themselves:
Media reports of these stem cell advances have enlivened the public's hopes of one day producing human iPS cells (induced pluripotent stem cells) from collected skin biopsies to generate patient-specific stem cells for disease research, drug development, and new cell-based therapies. Consequently, some policymakers and citizens might be tempted to jump to the conclusion that research on human embryonic stem cells (hES cells) is unnecessary in light of the emerging possibility of human iPS cell research. Indeed, this misguided impression could be further fueled by President Bush's latest stem cell bill veto, at which time he referred to these new stem cell studies as a galvanizing reason for his opposition to hES cell research and part of his motive for issuing an executive order to provide public funds for "alternative" forms of human stem cell research (Associated Press, 2007, Department of Health and Human Services, NIH, 2007).
However, it would be a serious mistake to conclude that recent developments in iPS cell research (or, for that matter, any other so-called "alternative" source of pluripotent stem cells) avert the need for ongoing research on hES cells. There are many important reasons why iPS cell research must be conducted hand in hand with hES cell research. In advancing these reasons we do not mean to imply that hES cell research is not of paramount importance in its own right. There are overwhelming scientific justifications for proceeding with hES cell research, which is precisely why it is important for the public to maintain a realistic perspective on iPS cell research vis-à-vis hES cell research.
Bush and the news channels are all over certain aspects of a new study out today that shows promise of developing pluripotent stem cells from skin tissue. Pluripotent stem cells are a basic building block from which all of the cells of the human embryo or adult may arise. "Pluri-" as in multiple, and "potent" as in producing powerful physical and chemical reactions. If a patients' own stem cells are not working properly, as with disease processes such as Leukemia, Lymphoma, and Multiple Myeloma, these cells need to be destroyed and replaced with healthy and effective stem cells. I work with hematological oncology patients, so I'll limit my focus to their situation. However, in the future, stem cells will be used to replace other malfunctioning cell lines such as the insulin producing cells of the pancreas whose failure results in Type I Diabetes, or the degenerative central nervous system cells which can lead to Parkinson's Disease.
First, a BRIEF overview of stem cell failure and transplant. Basically, when stem cells malfunction, they produce defective proteins which leads the body to produce cells which it is unable to use. If there is a genetic mutation in the stem cells of your bone marrow, then your marrow will produce blood cells that do not work as they should. In leukemia, ones bone marrow begins to produce immature, non-functioning white blood cells that do not act as white blood cells should (fighting infection, etc). The production of these useless cells depletes the protein building blocks within the body which are usually available to produce healthy cells. Not only do these ineffective cells deplete the body's resources, they tend to not die on schedule and therefore - literally and physically - crowd out an increasing number of healthy, effective cells.
A Stem Cell Transplant starts with finding a source for new stem cells once the defective stem cells are destroyed. With some patients, after some initial treatments, their own stem cells can be used. With others, the new stem cells must come from a healthy, matched donor. Stem cells can also come from Cord Blood, and potentially Embryonic Stem Cells or Stem Cells derived from Adults as this new study shows. Each method has its pros and cons, so the more treatment options available to the broad spectrum of patients out there, the better.
Radiation and chemotherapy are used to destroy, as completely as possible, the defective bone marrow stem cells within a patient with a blood based, hematological cancer. It is imperative to replace the stem cells ASAP so that the patient's body is vulnerable for the least possible amount of time - this is why appropriate stem cells must be available before the bone marrow is eradicated. The window between the ablation of a patient's bone marrow and the engraftment of the new stem cells is the most vulnerable time. During these weeks, medical support must be available to fight infection (insufficient white blood cells), support cellular oxygenation (insufficient red blood cells), and ensure proper healing (insufficient platelet levels). Certain drugs, such as GCSF, are used to push the body to more quickly produce a new immune system from the transplanted stem cells.
The closer that newly transfused stem cells' proteins match the proteins on the cells of their recipient, the more likely they are to produce a healthy and stable balance within the body. Some patients are able to receive an Autologous Stem Cell Transplant, in which their own stem cells are harvested prior to ablation and reintroduced into the body. Others require outside sources. The recipient's body may fail to utilize the new stem cells in some cases - no engraftment means that the stem cells failed to begin producing effective cells. If there is a problem with the protein matching beforehand, the engrafted bone marrow may begin to produce new white blood cells that actually attack the body cells of the recipient. This is known as Graft Versus Host Disease - or GVHD. The engrafted Immune System views the cells of the host as invasive, unrecognized, foreign cells and begins to attack and destroy them. This is why you cannot receive just any old blood type when you need a transfusion - if the cells are marked with "foreign" proteins, an attack is initiated to rid the body of invasion. With GVHD, this can be mild and ongoing, or this can prove fatal.
When a patients own cells are used to replenish the depleted marrow, there is ALMOST no chance for GVHD (I've seen it twice in 8 years). With donated cells, we do our best to crossmatch surface proteins, then hope for the best. Often, siblings provide the closest match, with identical twins being the absolute best case scenario (they get their own category - syngeneic transplant). At this point, Embryonic Stem Cells have proven to be heartier in the lab AND to provide a broader range of potential cellular differentiation, but ARE donor cells, so more likely to cause GVHD. Adult Stem Cells are less well understood, and more difficult to reproduce in the lab, but could potentially be created from the patient's own cells thus reducing the chances of both rejection and GVHD.
SO THEN! Why cautious optimism and not an OVERJOYED rejection of "baby-killing" research? For one thing, the methods used to force the differentiation of the Adult Stem Cells utilizes retroviruses to insert components into the cells. Retroviruses insert themselves into a host's nucleus and cause viral DNA to be reproduced instead of proteins useful to the body of the host. HIV is a retrovirus. While is it interesting that retroviruses can be used to force differentiation of Adult Stem Cells, there is no WAY that we could allow these tainted cells to be introduced into the human body.
Yamanaka’s work, published online today (Nov. 20) by the journal Cell, involves using four factors — including cancer genes — that are inserted into human adult skin cells using retroviruses. It was only last summer that he, Konrad Hochedlinger of HSCI and the Massachusetts General Hospital Center for Regenerative Medicine, and Rudolph Jaenisch, of the Whitehead Institute and MIT, independently and simultaneously reported doing the same thing using mouse skin cells. Because the method involves the use of cancer genes and retroviruses — which can turn on cancer genes — there is general agreement that such cells could not be used to treat patients.
Hochedlinger, who last summer published a study similar to Yamanaka’s mouse study, said of Yamanaka’s latest report, "We have to get rid of the viruses. We don’t want retroviruses in the cells. They could activate oncogenes, or be turned on inappropriately in mature cells and cause cancer." Hochedlinger cautioned that "there are still major hurdles that need to be overcome before thinking about replacing human embryonic stem cells with these cells."
Another potential problem - no one knows what the life span of adult stem cells will be. While cells divide into identical sister cells, there ARE sub-cellular aspects caused by the age of the cell which may lead to diminishing returns. This is one of the potential reasons that Dolly, the cloned sheep, lived such a brief life. The cells from which her body was derived were "older", and carried a lessened shelf life from TRUE embryonic cells. But I won't go into that right now... ;)