July 14, 2004

Washington, D.C.


Congressional Testimony of

Prof. Irving Weissman, M.D.


My name is Irving Weissman, Director of the Stanford Cancer and Stem Cell Institute. I am a stem-cell biologist. My labs purified blood-forming stem cells from mouse and man, and isolated human brain-forming stem cells. Blood forming stem cells regenerate the blood and immune system after nuclear exposure, or high-dose cancer therapies.  I Co-founded Cellerant, Inc., to transplant human blood-forming stem cells to regenerate the blood in these patients and to replace genetically defective blood systems, such as Sickle Cell Anemia and autoimmune diseases, with healthy stem cells. We have shown in diabetic mice that a stem-cell transplant from a genetically resistant donor permanently blocks the autoimmune reaction that kills insulin-producing cells. Such stem-cell transplants also block autoimmune reactions in models of Multiple Sclerosis and Lupus.  And stem-cell transplanted hosts can for life accept tissue, organ, or cell transplants from the stem cell donor without any anti-rejection drugs.


I also Co-founded Stem Cells, Inc., to treat neurodegenerative diseases by transplanting brain stem cells. The company has promising data in treating mice that have a fatal childhood neurodegenerative disease, and spinal-cord injury, or a variety of demyelinating diseases. We are also currently testing these cells in a mouse model of human Alzheimer’s Disease with a Montana lab. In all of these tests, only small numbers of purified stem cells are required to give lifelong and robust tissue regeneration.


I do not have any connection with any commercial entity in the area of, embryonic stem cells or nuclear transfer-produced pluripotent stem cells.  While I am a strong advocate of adult tissue stem-cell approaches, I am also the strongest critic of unproven stem-cell discoveries. You have heard from advocates that claim that one kind of tissue stem cell easily and robustly can turn into any adult tissue. I was especially excited when there were claims that blood-forming stem cells could regenerate the heart, or muscles, or brain, or insulin-producing islets. But when we tested this notion directly, blood and bone-marrow stem cells only made blood, and did not regenerate any of those injured tissues.   


What about Embryonic Stem Cells (ES) (from IVF clinics), and Nuclear Transfer (NT) stem cells? The current ES cells allowed for Gov’t.-funded research by President Bush are important in studying human developmental biology, but cannot tell us about human inherited diseases or be used in transplant therapies. NT stem cells are made, for example, by taking a skin cell, putting it in an egg lacking chromosomes, and stimulating it to divide to form a blastocyst stage that can give rise to pluripotent stem-cell lines. NT stem-cell lines develop every cell type in the body. We can do it in mice.  If the skin cell comes from a donor with the ‘bubble boy’ immunodeficiency, the stem cell line has that disease. If it comes from a cancer stem cell, say a melanoma, the stem-cell line redevelops the melanoma. Perhaps even cells from a complex inherited disorder, like Lou Gehrig’s Disease, will make stem-cell lines that undergo motor-neuron degeneration in the lab.


There is something in common with virtually all human genetic diseases, and all human cancers -- although we are finding out which genes seem to be involved, we don’t know in which cells and how the disease develops. But to find treatments and cures that is just what we must know. Finally, there is a promising field publicly called therapeutic cloning, where you start with a cell taken from you, to make a cell line that is transplantable to you. That field is just beginning, but has enormous therapeutic potential.


So we come to the problem.  It would certainly be of great medical benefit to open these ‘platform technologies’ by NT to produce pre-defined stem cell lines. Imagine if we had and could distribute to the best and the brightest, a juvenile diabetes stem-cell line, or a Lou Gehrig’s Disease stem-cell line. Today, the best and the brightest in the US cannot receive or use such cell lines. It doesn’t make senses to me. What makes even less sense is the bill proposed to criminalize all aspects of producing, studying, and even developing treatments using the NT stem-cell technology. If this turns out to be like the recombinant DNA example, which we regulated rather than banned, tens of thousands of human lives are at stake. In my view, whoever of you acts to ban this research is responsible for the lives it could save.


Banning research for an ideology is just not the American way. It’s more like Russia, which in the 1930’s banned Darwinian genetics in favor of Lamarckian approaches espoused by Stalin’s advisor, Lysenko. We all know what happened there. Some scientists were fired and jailed, and others, like Muller and Dobzhansky, immigrated to the US to set up America as a world leader.  For at least 50 years, Russia didn’t produce any advances in genetics; their crops failed; and no Russian geneticist emerged. The biotechnology industry passed them by, and patients in Russia suffered.


I beg you to think hard about what you do before you enact the first ideological ban of biomedical research in the history of the United States. Separate the issues and ban the reproductive cloning of humans, which needs to be done to protect the patients; pass a real stem-cell research bill that funds and regulates this kind of research. Don’t put us on the sidelines while we read of advances in South Korea, the United Kingdom, Singapore, Israel, or China.


I thank you for your attention.