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Adult Stem Cells vs Embryonic Stem Cells

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    Adult Stem Cells vs Embryonic Stem Cells

    Dr Young
    Australia is on the verge of legalising ESC Research. However some opinion writers are saying this is irrelevent as Adult Stem Cells have shown results whereas ESC have not. Could you please point me to the article where you disprove this perceptio.
    Thank you
    Philip Smith

    Philip, I just posted something but I am having trouble getting the posts to stick. In any case... I will write more later. Wise.


      Hi Smithpl,

      Here's a start:

      Opponents of embryonic stem cell research often argue that embryonic stem cell research is not necessary because adult stem cells from bone marrow or umbilical cord blood cells are already curing diseases, are more likely to cure diseases, and that adult stem cells would not be rejected by the immune system when transplanted. They are troubled by the cloning because they oppose creating an embryo in order to harvest its stem cells. Finally, they point out that current methods of collecting embryonic stem cells are inefficient and cloning embryonic stem cells may not be a practical method of producing cells for transplantation purposes. These arguments are partly true but are misleading and do not justify the current restrictions of human embryonic stem cell research. Let us consider some of the most frequently cited arguments for or against adult and embryonic stem cells.

      1. Are adult stem cells already curing diseases? Some opponents of embryonic stem cell research say that embryonic stem cells have never cured any condition while adult stem cells are already curing many diseases. Bone marrow and umbilical cord blood stem cells have been used for over two decades to treat blood-making (hematopoietic cells) disorders, such as sickle cell anemia, thalassemia, radiation or chemotherapy induced bone marrow damage, and autoimmune diseases. Bone marrow stem cell transplants may accelerate and improve healing from heart attacks (myocardial infarcts) or failing hearts (congestive heart failure). However, there is no credible evidence yet that bone marrow stem cells are replacing heart cells. Bone marrow cells may be releasing factors that help hearts heal faster. Neither bone marrow nor umbilical cord blood stem cells, or other types of adult stem cells, have cured neurological conditions, such as brain or spinal cord injury, amyotrophic lateral sclerosis, multiple sclerosis, Alzheimer's disease, Parkinson's disease, or non-neurological diseases such as diabetes, liver damage from hepatitis, and other currently incurable conditions. We do not know enough now to predict whether adult or embryonic stem cells would be better or which would be more effective.. Many animal studies have shown beneficial effects of embryonic stem cell treatments of animal models of diseases. Human embryonic stem cells have not yet been transplanted into humans. There are no restrictions on adult bone marrow or umbilical cord blood research at all while U.S. federal government signficantly restricts funding of human embryonic stem cell research.

      2. Do adult stem cells circumvent the problem of immune rejection? It is true that autologous grafts, i.e. adult stem cells taken from a person and transplanted into the same person, would not be rejected by the immune system. However, autologous grafts cannot be used for many conditions. First, autologous grafts are not useful for most genetic diseases. For example, there is no point in taking bone marrow from a person with a genetic disease such as sickle cell anemia or thalassemia and then transplanting these cells back into the same person. Heterologous grafts, i.e. transplant from one person to another, are necessary. Second, autologous bone marrow grafts cannot be used to treat many autoimmune diseases, such as multiple sclerosis, diabetes, lupus erythematosus, scleroderma, etc. The transplanted bone marrow will produce cells with the same autoimmune tendencies. Third, bone marrow transplants often cause graft-versus-host disease where the transplanted cells regard the host body as "foreign" and attack it. As much as 50% of heterologous bone marrow transplants cause graft-versus-host disease with a high mortality rate. Fourth, even closely matched heterologous bone marrow transplants require immunosuppression. Destroying the bone marrow usually does this. Finally, umbilical cord blood does not produce as much immune response or as severe graft-versus-host disease. Human embryonic stem cells, because they are immature, are even less immunogenic and do not produce graft-versus-host disease.

      3. Are adult stem cells safer than embryonic stem cells for treatment of neurological disorders? Autologous transplants are very attractive for treating non-genetic diseases. For example, they would be an ideal treatment for traumatic brain and spinal cord injury, Parkinson's disease, stroke, and non-genetic conditions. However, heterologous transplants may be required for genetic conditions such Alzheimer's disease or amyotrophic lateral sclerosis. Even when bone marrow cells are carefully matched for histocompatibility, prolonged immune suppression may be required for engraftment. If selected stem cells are transplanted, particularly into brain or spinal cord, graft-vs. host disease would be unlikely. On the other hand, bone marrow transplants have a high complication rate, with a 20-50% incidence of graft-versus-host disease and 20-30% mortality rates. For these reasons, heterologous bone marrow transplants are seldom carried out except for life-threatening conditions. In contrast, embryonic stem cell transplants may not require as much or as prolonged immunosuppression because they do not express as many immunogenic proteins. Cloned embryonic stem cells that are genetically matched for the person should pose even less immunogenic risk.

      4. Do embryonic stem cells cause tumors? There are some claims that embryonic stem cells are more likely to cause tumors. All cells have the potential to cause tumors, particularly if they are grown for long periods in culture. Prolonged culturing increases the risk of malignant transformation of the cells. Immaturity of cells also may increase the likelihood of tumor formation. Some stem cells will not respond to all tissue factors and may produce the wrong type of cells, too many cells, or cells that transgress tissue boundaries. Cells with any of these three behaviors would be called a tumor. Because embryonic stem cells are often grown for long periods of time in culture, they have more of an opportunity to undergo malignant transformation. Because embryonic stem cells are immature compared to adult stem cells, they may not possess receptors to all tissue factors. However, much evidence now suggests that embryonic stem cells can be matured and pre-differentiated in culture before transplantation and that such cells are unlikely to produce tumors. This is a risk but not an insurmountable risk.

      5. Are adult stem cells more likely to result in cures for diseases than embryonic stem cells? Adult bone marrow or umbilical cord blood stem cells have been used to treat hematopoietic disorders for over 20 years. As pointed out above, heterologous bone marrow grafts may cause serious complications and are currently only used under the most dire circumstances. Umbilical cord blood transfusions show promise and presents less risk but appear to be less effective. Although some scientists have claimed that bone marrow mesenchymal stem cells can be induced to produce neurons and other cells under certain circumstances, their ability to do so is limited and substantial manipulation of the cells is required. In contrast, embryonic stem cells readily produce all types of cells, including neurons, insulin-producing cells, muscle, skin, and heart cells, both in culture and after transplantation. Embryonic stem cells also grow faster in culture and can be easily modified to produce specific cells with specific functions. We are perhaps expecting too much from adult stem cells when we transplant them into different tissues and expect them to fix disparate problems such as replacing insulin-producing cells, promote regeneration, remyelinate axons, repair heart tissues, and restore function to diverse organs. From this perspective, embryonic stem cells possess a significant advantage over adult stem cells. Because they grow indefinitely in culture, they can be produced in large numbers and be optimized to have more predictable and beneficial behavior after transplantation. At the present, we don't know which is more likely to result in cures for diseases.

      6. Is cloning necessary for embryonic stem cells to be used for transplantation? In biology, cloning means simply to produce cells with the same genes. Cellular cloning unfortunately has been associated with "reproductive cloning" or production of an individual with the same genes. One method of cloning embryonic stem cells is to transfer a nucleus into an egg and then trick the egg into producing stem cells. Called somatic cell nuclear transfer (SCNT), this method produces stem cells that have the same genes as the transferred nucleus. This method of cloning stem cells is currently inefficient, requiring dozens of eggs. In my opinion, cloning is not necessary for embryonic stem cells to be used for therapy. Doctors have successfully transplanted cells (blood) and organs (kidney, heart, liver, pancreas) for many decades without cloning. If the stem cells are carefully matched for histocompatibility genes (HLA) and immunosuppressive therapies are used, the cells will engraft. It is also possible to develop embryonic stem cell lines that express a limited set of histocompatibility antigens that would match 90% of people. Finally, immune rejection is not necessarily bad. The immune system eliminates cancer or excess cells. We may want the immune system to eliminate the cells after they have finished their work. In any case, much work needs to be done on cloning before it can be used clinically. For example, I don't think that it would be harmful to have 3-year moratorium on cloning of human embryonic stem cells but allow animal and human embryonic stem cell research to go forward. On the other hand, a ban of SCNT would be a serious mistake because it is a general technique that is important for many other clinical applications.

      7. Are embryonic stem cells practical? At the present, we do not have enough cells from any source that can be used to treat millions of people. For example, the world supply of umbilical cord blood is about 200,000 units. This is barely sufficient to satisfy the needs of 12,000 pediatric patients who need umbilical cord stem cells every year to treat their hematopoietic disorders. Although many laboratories have been trying for decades to grow stem cells from bone marrow, umbilical cord, placental, and other postnatal sources of stem cells, no reliable method is available to produce sufficient diversity and amounts of bone marrow or umbilical cord stem cells to treat millions of people. If any stem cell turned out to be useful for any of the major diseases, we do not have enough cells to treat even a tiny fraction of the people. Because they grow indefinitely in culture, embryonic stem cells provide a possible inexhaustible supply of stem cells that can treat millions of people. A cell bank with several thousand lines of human embryonic stem cells, for example, would be very helpful to satisfy current therapeutic and research needs.

      8. What other ways can human embryonic stem cells help cure diseases? Opponents of embryonic stem cell research seldom mention one important use of human embryonic stem cells. An embryonic stem cell line derived from a person with a genetic disease would be a very powerful tool to study that genetic disease. For example, if we had an embryonic stem cell lines from somebody with Alzheimer's, amyotrophic lateral sclerosis, Huntington's disease, diabetes, rheumatic arthritis, lupus erythematosus, etc. the cells can be used to assess mechanisms and treatments. At the present, we have to use animal models or human cadaver materials. Availability of human embryonic stem cell lines will allow large-scale screening of drugs and other treatments. Finally, many parents who use in vitro fertilization methods may have specific genetic conditions causing infertility. Eggs from infertility clinics may provide insight into genetic causes of infertility. Last but not least, the availability of such human disease-specific stem cell lines should reduce use of animals for studying human disease.

      In summary, adult bone marrow and umbilical cord blood stem cells have long been used to treat hematopoietic disorders. Obtaining stem cells from one part of the body and transplanting to another would circumvent immune rejection but most genetic diseases cannot be treated with such transplants. Bone marrow grafts tend to be immunogenic and cause graft-versus-host disease where transplanted immune cells attack the host. Human umbilical cord blood transplants are less immunogenic and cause less serious graft-versus-host disease. Human embryonic stem cells are even less immunogenic and do not cause graft-versus host disease. Stem cells may produce tumors after transplantation if they do not respond to all tissue factors, produce the wrong type or numbers of cells that do not respect tissue boundaries. All cells have some potential for malignant transformation. Differentiating stem cells in culture before transplantation reduces the risk of tumors. Cloning should produce genetically matched stem cells but we have much work to do before cloning can be applied clinically. Doctors have been transplanting cells and organs for many years without cloning. Embryonic stem cell research should go forward, even without cloning. We do not now have an adequate stem cell supply to treat even a small fraction of people who may benefit from stem cell therapies. Embryonic stem cells can be grown indefinitely to treat millions of people. Human embryonic stem cell lines obtained from people with specific genetic diseases will greatly accelerate research on many genetic diseases, including infertility, and will reduce the use of animals. Thus, it is important not to close the door on human embryonic stem cell research.
      Why are embryonic stem cells important?

      Here's more:

      What is the difference between embryonic and adult stem cells?

      Why the SCI Community should continue to press on the ESC issue


        Thank you seneca and Dr Young
        Philip Smith


          Dr Wise,
          what do you think about this email that i got from Manipal hospital INdia
          I had a discussion with the stem cell lab group. They will be happy to
          provide this therapy, if the accept the procedure and costs
          associated with it. We use Mesenchymal stemcell bone marrow. so you need to
          stay here for at least 4-6weeks. Initially we harvest cells from bone
          marrow and culture the cells and give 2 doses of therapy at an interval
          of 2 weeks.

          We are not sure about the results at present and we cannot assure any
          kind of guarantee of recovery. Since there is no other alternative "
          treatment, this l therapy appears to be very hopeful.


            ESCR opponents will 1. promote ASC, 2. promote ESC alternatives

            Originally posted by smithpl
            Dr Young
            Australia is on the verge of legalising ESC Research. However some opinion writers are saying this is irrelevent as Adult Stem Cells have shown results whereas ESC have not. Could you please point me to the article where you disprove this perception.
            Thank you
            Philip Smith
            Philip beware that when their arguments favoring ASC's are proven to be more religious based than scientific, the ESCR opponents will try to convince us that there are "ethical" ways to derive ESC type cells. This has led to a variety of "decoy" bills in the US. ( Now that the US is on the verge of passing a bill allowing federal funding of ESCR from fertilized egg cells left over from In Vitro Fertilization clinics which are routinely discarded anyway)


            Stem Cell& Diabetes& Advocacy& Spinal Cord Injury& Parkinson's Disease25 Aug 2005 04:30 am
            The Truth About Embryonic Stem Cell Alternatives

            Executive Summary: There aren’t any.

            The first potential alternative is a promising breakthrough in the biotech world of stem cell research with the news that Harvard scientists reported taking skincells to generate embryonic stem cells.
            Researcher Kevin Eggan and his colleagues achieved this
            dramatic medical advance by fusing individual adult skin cells and bone
            cells to embryonic cells.
            However Eggan estimates it may be as much as ten years before this method can be used in treatment. His complete report appeared in the journal Science on-line on August 22.
            Additionally in a New York Times article, it is reported that scientists would need to uncover how to reprogram the chromosomes of the cellĀ“s nucleus. The fused cells may have twice the number of chromosomes of the original cell, thus the cell may not survive.
            This simply doesn’t help in any way with the current requirements of stem cells for treating diseases like Parkinson’s, diabetes, Multiple Sclerosis, heart disease, spinal cord injuries etc.
            “We are right where we always were,” said Sen. Tom Harkin, D-Iowa, a co-sponsor of the bill with Sen. Arlen Specter, R-Pa., on Monday after having read of the Harvard research.
            The second alternative is cordblood-derived-embryonic like stem cells or CBE’s. They are better than adult stem cells but the newfound CBEs are nowhere as versatile as human embryonic stem cells.
            In short embryonic stem cells currently do not have any alternatives in treatment of life-threatening diseases.

            You may also like to read:

            Human Cloning: The Final Frontier
            Scientists Discover Flexible Stem Cells in Placenta
            Stem Cell Bill: The Real Story
            As Stem-Cell Bill Languishes, so are the Ill and Dying
            Bartle's bill in Missouri aims to throttle stem cell research
            Majority of Americans back Embryonic Stem Cell Research
            Stem Cell Trigger Identified for Growing Human Organ Tissue Using Embryonic Stem Cells
            Breakthrough Study paves way for Stem Cell Research Overcoming Ethical Issues
            India could Lead in Stem Cell Technology
            "Embryonic Stem Cells Are A Medical Milestone Seen Only Every 100 Years" - Dr. Hans Keirstead
            Last edited by Faye; 24 Feb 2006, 10:42 AM.


              Here is some news from Australia from today; Link