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Basic Questions1. Why is stem cell research important? 1. Why is stem cell research important? Stem cell research holds great promise for relieving human disease and suffering. Because stem cells are the source of all tissues of the body, understanding how they develop and work will give us a fundamental understanding of human biology in health and in sickness. In addition, stem cells may be a renewable source of replacement cells that could be used to treat a variety of diseases and disabilities. Adult stem cells already have been used to develop effective treatments. For example, cancer patients who have repressed immune systems as a result of chemotherapy may receive a bone marrow transplant (BMT) that can regenerate the patient's blood and immune systems. BMTs have been successfully performed since 1970. Embryonic stem cell research, which only began in 1998, provides insight into the origin of disease and may lead to more effective treatments for serious human ailments such as juvenile diabetes, Parkinson's disease, ALS, cancer, heart failure and spinal cord injuries. Scientists believe research using these cells may answer fundamental questions about how specialized cells develop in an embryo and how they communicate and work together to form all the tissues and organs in the body. In addition, stem cell lines will be useful for testing the safety and effectiveness of new drugs. We don’t know how long it will take to find new treatments for any specific disease, but the research must continue. The very definition of research is to try new things and to explore the unknown. If we allowed uncertainty to stop research, we never would have developed blood transfusions, cardiac bypass surgery, insulin therapy for diabetes, kidney dialysis, antibiotics, organ transplants and so many other things that make our lives better and healthier. In the U.S. there are ongoing clinical trials using ESCs for spinal cord injury and a trial pending FDA approval for retinal stem cells. Stem cells are the foundation cells for every organ, tissue and cell in the body. They are like a blank microchip that can be programmed to perform particular tasks. Stem cells begin as undifferentiated or "blank" cells that, under proper conditions, develop into specialized cells, tissues and organs. In addition, stem cells can self-renew. They can divide and give rise to more stem cells. In theory, that means stem cells should never be depleted from a tissue. There are two primary types of stem cells: Embryonic stem cells that only exist during the first four through 14 days of embryonic development. Because they are unspecialized, but have the potential to form all cell types of the body, they are referred to as ‘pluripotent’ stem cells. After the embryonic stem cells change or specialize into a specific type of cell like a blood cell or skin cell, they are referred to as adult or ‘tissue-specific’ stem cells. They can only form a limited number of cell types corresponding with their tissue of origin and are called multipotent cells. Blood-forming stem cells can form all types of blood cells, while skin stem cells can form new skin cells. 3. How are stem cells different from other types of cells? All stem cells share two characteristics, 1) The ability to divide and grow into either more stem cells or into specialized cells for blood, nerves, etc. and 2) they can act as repair kits to fix cells damaged by disease or injury. When a stem cell divides, each so-called “daughter” cell has the potential to remain a stem cell or become a cell with a more specialized function, such as a muscle cell, a blood cell or a brain cell, according to the National Institutes of Health (NIH). Embryonic stem cells can become one of more than 200 specialized cells in the body, thus providing a potentially unlimited source of cells for medical and scientific purposes. They act as the body's own repair kit. The key is figuring out how to grow them in a controlled way and to make them take on the exact job needed. The hope is that someday they will help treat dozens of diseases and injuries. 5. How many types of stem cells are there? There are two basic types of stem cells, embryonic and adult. Embryonic stem cells (ESCs) are only found in four- to 14-day-old embryos. At this point the embryo is a microscopic cluster of about 150 cells called a blastocyst. Between 30 and 50 cells inside the blastocyst are stem cells. After the embryonic stems cells have changed or specialized, they are referred to as adult or tissue stem cells. There are many varieties of adult stem cells, including blood-forming stem cells, skin stem cells, muscle stem cells, nervous system stem cells, etc. Adult stem cells are found in specific body tissues and are also found in the umbilical cord. 6. Where do stem cells come from? Embryonic stem cells are from the inner cell mass of a blastocyst, which is a microscopic hollow ball of about 150 cells made up of an outer layer of cells that would form the placenta, a fluid filled cavity, and an inner cell mass containing cells that would form the embryo. Scientists isolate stem cells from embryos donated with informed consent of couples who have undergone in vitro fertilization (IVF). These embryos are no longer needed by the donor and would otherwise be discarded. Adult stem cells can be found in small numbers in most of the tissues of the body. For example, blood stem cells are found in the bone marrow. But adult stem cells have not yet been found in some organs, for example the pancreas. Adult stem cells can also be obtained from other sources, for example, the umbilical cord of a newborn baby is a source of blood stem cells. Recently stem cells have also discovered in amniotic fluid, but research on these cells is at a very early stage. Since late 2007, cells with properties similar to embryonic stem cells, referred to as induced pluripotent stem (iPS) cells have been engineered from adult cells. Scientists were able to create iPS cells by treating adult cells with genes introduced by viruses. Using this process, adult cells were “induced” or reprogrammed to revert to a pluripotent or embryonic stem cell-like state. The iPS technology holds great promise for use in laboratory research, but much work must be done before iPS cells can be used for human treatments. Growing cells in a laboratory is known as cell culture. Stem cell lines can be developed two ways: Using embryonic stem cells and using iPS cells. Embryonic stem cells from the inner cell mass of a blastocyst (4 to 5 days after fertilization) are transferred into a plastic laboratory culture dish containing a liquid nutrient called culture medium and a feeder layer which releases nutrients into the culture medium. The cells divide and spread over the surface of the culture dish. After stem cells make copies of themselves or duplicate for several days, they crowd the dish. They are removed gently and distributed between several fresh culture dishes. This replating of the cells is repeated for many months and is called subculturing. After several weeks, those original 30 cells yield millions of embryonic stem cells. After these cells have proliferated in a cell culture for many or more months without differentiating – and have normal numbers of chromosomes – they are referred to as an embryonic stem cell line. They are then frozen and shared by researchers for their work. To develop an iPS cell line, adult cells -- often from skin cells -- are treated using the process described in Question 6 above. When they have reverted to an embryonic-like state, they are cultured using the same process as for embryonic stem cells. Stem cell lines are important because they provide a long-term supply of multiplying cells that can be shared among scientists for research and therapy development. 8. Why do scientists want to use stem cell lines? Once a stem cell line is established, essentially, it can grow indefinitely according to the National Institutes of Health (NIH). The researcher using the line will not have to go through the rigorous procedure necessary to isolate stem cells again. To conduct their research, scientists treat the stem cell lines, causing them to differentiate into the specialized cell types they need for their research. Studying stem cell lines carrying specific diseases or defects could facilitate the development of safer and more effective new drugs because scientists will be able to test new drugs on human cells bearing the exact defects that cause disease in patients. In addition, cell lines containing human disease mutations will allow scientists to study how cells change when they carry a disease. An often overlooked benefit of studying embryonic stem cells is that we currently have no good way of studying early human development. Researchers are able to watch both normal and damaged cells developing from their very earliest stage, helping them to understand the origin of inherited human diseases including birth defects, neurodegenerative diseases and cancer. 9. What are the benefits of studying embryonic stem cells? Embryonic stem cell research represents new hope for millions of Americans. Research on these cells has the potential to lead to new treatments for a range of serious human ailments, including diabetes, cancer, Parkinson's disease, Alzheimer's disease, ALS, heart disease, birth defects, spinal cord injury and burns. This extraordinary research is still in its infancy. Research on human embryonic stem cells only began in 1998, while research on adult stem cells has taken place for 50 years. No one can say how long it will take to find a cure for any specific disease using embryonic stem cells. Typically, biomedical research can take 10, 20, even 30 years to produce successful results. But the sooner the research starts, the sooner it can bring new insights and new treatments. There are currently FDA-approved clinical trials using ESCs for spinal cord injury. Another trial to repair damaged retinas is pending approval. 10. Why do some people oppose embryonic stem cell research? The Catholic Church is the largest of several conservative Christian organizations which oppose embryonic stem cell research because they believe that life begins as soon as an egg is fertilized. They maintain that embryonic stem cell research is wrong because harvesting these cells kills the living human embryo. The Catholic Church opposes most forms of in vitro fertilization and the direct destruction of human life for any purpose, including research [Source: Michigan Catholic Conference Focus, February 2005]. |
Basic Questions
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