Stem cells: the next cure? (Life/Tech Science: Stem Cells * Disease).Several years ago, brothers Blayke and Garrett LaRue desperately needed a miracle. The boys, ages 6 and 9 years, were born with a rare and lethal disorder of the immune system immune system Cells, cell products, organs, and structures of the body involved in the detection and destruction of foreign invaders, such as bacteria, viruses, and cancer cells. Immunity is based on the system's ability to launch a defense against such invaders. , the body's disease-fighting machinery. Their genetic (inherited) disease, known as "XLP XLP Xypoint Location Platform XLP X-Linked Lymphoproliferative Syndrome XLP Crosslinked Polyethylene XLP Extended Life Program XLP Literate Programming in XML XLP Extra Low Pulse ," afflicts I in every 10,000 babies; the standard treatment--replacing diseased bone marrow, or soft tissue inside bone that produces blood cells blood cells, n.pl the formed elements of the blood, including red cells (erythrocytes), white cells (leukocytes), and platelets (thrombocytes). blood cells See erythrocyte and leukocyte. Platelets are classed separately. , with healthy bone marrow--often fails. The boys' only alternative: a highly experimental-and--controversial treatment using stem cells stem cells, unspecialized human or animal cells that can produce mature specialized body cells and at the same time replicate themselves. Embryonic stem cells are derived from a blastocyst (the blastula typical of placental mammals; see embryo), which is very young . Did the revolutionary treatment save the LaRue brothers? What are stem cells, anyway? And if they're so beneficial, why have stem cells ignited a firestorm of controversy? Read this Q&A to find out. Q What is a stem cell stem cell In living organisms, an undifferentiated cell that can produce other cells that eventually make up specialized tissues and organs. There are two major types of stem cells, embryonic and adult. ? A: Each of your body's billions of cells originates from a single cell (zygote zygote: see reproduction. ) that forms when a sperm fertilizes an egg. How does a simple cell transform into a complex human being? The answer: stem cells--microscopic ball-like cells that form after the zygote divides several times (see diagram, p. 16). Stem cells have the potential to build and repair any one of your body's 200 cell types, including heart, blood, and skin cells. There are two major types of stem cells: embryonic and adult. Embryonic stem cells form about four days after the fertilization of sperm and egg. They multiply inside a hollow ball of cells called a blastocyst blastocyst /blas·to·cyst/ (-sist) the mammalian conceptus in the postmorula stage, consisting of an embryoblast (inner cell mass) and a thin trophoblast layer enclosing a blastocyst cavity. , which later develops into an embryo (an unborn child in the first eight weeks of growth). In this stage, stem cells are called pluripotent plu·rip·o·tent or plu·ri·po·ten·tial adj. 1. Capable of affecting more than one organ or tissue. 2. Not fixed as to potential development. Used of an embryonic cell. . That's because they can multiply without limit and have the potential to become any cell in the body. "It's like having a blob of clay that can be molded into any shape possible," says stem-cell scientist Brian Butcher at the Center for Gene Therapy at Tulane University in New Orleans, Louisiana. But embryonic stem cells don't remain in the body forever. Within a month, the cells receive thousands of signals from genes (units of hereditary information) and other cells that instruct them to differentiate, or grow into specialized body parts--like heart, muscle, or nerve tissue nerve tissue n. A highly differentiated tissue composed of nerve cells, nerve fibers, dendrites, and neuroglia. . "And once stem cells differentiate, they remain that type of cell for the rest of their lives," explains Butcher. Q What's an adult stem cell Adult stem cells are undifferentiated cells found throughout the body that divide to replenish dying cells and regenerate damaged tissues. Also known as somatic (from Greek Σωματικóς, of the body ? A: Stem cells are also found throughout the adult body--in the skin, brain, bone marrow, and blood. But unlike embryonic stem cells, "adult stem cells have limited potential to multiply and grow into other types of tissues," says researcher Laura Grabel at Wesleyan University in Middletown, Conn. That's because adult stem cells are already specialized to perform highly specific functions in your body. For example, skin stem cells replenish and repair cells found only in your skin. Researchers are trying to "teach" adult stem cells to behave more like embryonic stem cells. Last year, UCLA UCLA University of California at Los Angeles UCLA University Center for Learning Assistance (Illinois State University) UCLA University of Carrollton, TX and Lower Addison, TX scientists coaxed stem cells plucked from human fat tissue into becoming bone and muscle cells. The cells are now being tested in animals to see if they grow and function. Q Why should I care about stem cells? A: Many scientists think stem cells may be the most promising "miracle" in medicine's future. For example, due to their morphing powers, stem cells might one day help a bum victim grow new skin, a quadriplegic quadriplegic /quad·ri·ple·gic/ (-ple´jik) 1. of, pertaining to, or characterized by quadriplegia. 2. an individual with quadriplegia. (person with paralyzed par·a·lyze tr.v. par·a·lyzed, par·a·lyz·ing, par·a·lyz·es 1. To affect with paralysis; cause to be paralytic. 2. To make unable to move or act: paralyzed by fear. arms and legs) regain limb control, or a head-injury victim grow new brain cells. Stem cells may also be the greatest hope for some of the world's more incurable diseases: diabetes, heart disease, Alzheimer's, and Parkinson's. "The list goes on and on," says Butcher. "Within the next decade we have the potential to treat just about any disease there is." However, the promise of stem-cell research is hampered by controversy: The harvesting process destroys the embryo, which would otherwise grow into a baby. Some opponents think research should be limited only to adult stem cells, which don't require embryonic destruction. That's why, for example, if experiments succeed on adult fat cells, they could prove to be an abundant and less controversial stem-cell source than human embryos. Q Can stem cells really cure human disease? A: To date, most stem-cell research has been conducted in animals--rats, mice, and monkeys. However, some experiments have been successfully conducted in humans. For example, Dr. E. Richard Stiehm at UCLA used adult stem cells to treat the LaRue brothers' immune disorder. First, Stiehm harvested flesh stem cells from the blood of an umbilical cord umbilical cord (ŭmbĭl`ĭkəl), cordlike structure about 22 in. (56 cm) long in the pregnant human female, extending from the abdominal wall of the fetus to the placenta. , a tube about 24 inches (60 cm) in length that channels nutrients from a mother to a fetus and is discarded after birth. The umbilical cord is rich in adult stem cells specifically instructed to build white blood cells White blood cells A group of several cell types that occur in the bloodstream and are essential for a properly functioning immune system. Mentioned in: Abscess Incision & Drainage, Bone Marrow Transplantation, Complement Deficiencies , which the boys needed to repair their ailing immune systems. He then grew the cells in a petri dish pe·tri dish n. A shallow circular dish with a loose-fitting cover, used to culture bacteria or other microorganisms. Petri dish a shallow, circular, glass or disposable plastic dish used to grow bacteria on solid media such as agar. and later injected them into Blayke and Garrett, where they migrated to and replaced damaged cells in the bone marrow. "It's like transplanting another baby's healthy immune system into a sick child's body," says Stiehm. Last April, he declared the brothers' immune-system disorder cured. About 500 people a year now receive similar stem-cell transplants. Q What is a stem cell "line"? A: A stem-cell "line" is a colony of millions of identical cells sharing the same DNA DNA: see nucleic acid. DNA or deoxyribonucleic acid One of two types of nucleic acid (the other is RNA); a complex organic compound found in all living cells and many viruses. It is the chemical substance of genes. (double-stranded molecules that store genetic information). Scientists need and use stem cell lines to conduct thousands of experiments. To generate a line, scientists extract a sample of stem cells from a living source, then store the cells in a nutrient-rich environment that keeps them from differentiating. Cells then "expand" or multiply in vitro in vitro /in vi·tro/ (in ve´tro) [L.] within a glass; observable in a test tube; in an artificial environment. in vi·tro adj. In an artificial environment outside a living organism. (in a petri dish) to form a cluster of millions of stem cells. To keep them fresh for research, the cells are then frozen. But, explains Grabel, "it's not always easy to make a stem-cell line, particularly from a human embryo." Like humans, each cell line has different characteristics--some may grow better, while others may do a better job at becoming nerve cells or liver cells. Some may need special nutrients to multiply. Last August, President Bush announced he would allow the government to fund research on human embryonic stem cells--but limited the research to 60 existing colonies of cells created before his announcement date. He won't permit federal funding of research using stem cells derived from new embryos. That poses a problem, Grabel says: "Scientists still don't know Don't know (DK, DKed) "Don't know the trade." A Street expression used whenever one party lacks knowledge of a trade or receives conflicting instructions from the other party. a lot about these 60 embryonic stem-cell lines, because most of the research has been done by the private sector." The cell lines available for federal research are divided among just 10 companies and universities. And that could prove to be a major roadblock for medical research--especially if the cell lines are in poor condition. "Do we have all the stem-cell lines we need for all the research we want to accomplish in the future? Probably not," says Grabel. [ILLUSTRATION OMITTED] Cross-Curricular Connection Language Arts: Research another controversial breakthrough or discovery in science. Write an essay on how it has changed the world. Have the changes been beneficial or detrimental? Why? Did You Know? * In 1998, biologist James Thompson at the University of Wisconsin became the first scientist to grow embryonic stem cells in a laboratory. * An increasing number of new mothers are paying more than $1,300 to have their stem-cell rich umbilical-cord blood frozen at minus 400 [degrees] F for potential future medical use. * Factory chicken farms hope to clone billions of chickens each year using stem cells. The clones would grow at the same rate, have the same amount of meat, and taste the same. National Science Education Standards The National Science Education Standards (NSES) are a set of guidelines for the science education in primary and secondary schools in the United States, as established by the National Research Council in 1996. Grades 5-8: structure and functions in living systems * reproduction and heredity heredity, transmission from generation to generation through the process of reproduction in plants and animals of factors which cause the offspring to resemble their parents. That like begets like has been a maxim since ancient times. * science and technology in society Grades 9-12: the cell * the molecular basis of heredity * science and technology in local, national, and global challenges Resources "Cellular Divide," by Sharon Begley, Newsweek, July 9, 2001. "U.S. Approves Labs With Stem Cells for Federal Use," by Nicholas Wade, The New Dark Times, Aug. 27, 2001. The National Institutes of Health's stem-cell primer: www.nih.gov/news/stemcell/primer.htm Directions: Match word(s) in the left column with the correct phrase in the right column. -- 1. zygote -- 2. gene -- 3. pluripotent -- 4. differentiate -- 5. umbilical cord -- 6. blastocyst -- 7. in vitro a. hollow ball of embryonic stem cells b. capable of giving rise to most of the body's tissue types c. cell formed when sperm fertilizes an egg d. to grow inside a laboratory dish e. unit of hereditary information f. nutrients pass through this tube between mother and fetus; rich source of stem cells g. to grow into specialized body parts RELATED ARTICLE: How Stem Cells Grow Body Parts A step-by-step look at the process 1 DEVELOPMENT A fertilized fer·til·ize v. fer·til·ized, fer·til·iz·ing, fer·til·iz·es v.tr. 1. To cause the fertilization of (an ovum, for example). 2. egg divides and multiplies, becoming a blastocyst: a core of embryonic stem cells surrounded by a protective cell wall. [ILLUSTRATION OMITTED] 2 REMOVAL The stem cells are removed and placed in cultures, where the cells multiply and begin to differentiate. [ILLUSTRATION OMITTED] 3 DIFFERENTIATION Communicating through a system of chemical signals and receptors, the cells begin developing into the body's specialized tissue types. [ILLUSTRATION OMITTED] 4 RESULTS The tissue types occur in three groups: Mesoderm mesoderm, in biology, middle layer of tissue formed in the gastrula stage of the developing embryo. At the end of the blastula stage, cells of the embryo are arranged in the form of a hollow ball. Forms the core tissues of the body, including bone, muscle, cartilage, heart, and blood cells. Ectoderm ectoderm, layer of cells that covers the surface of an animal embryo after the process of gastrulation has occurred. This outer layer, together with the endoderm, or inner layer, is present in all early embryos. Develops into many of the most specialized tissues, including the central nervous system, eyes, and hair. Endoderm endoderm (ĕn`dədûrm'), in biology, inner layer of tissue formed in the gastrula stage of the developing embryo. At the end of the blastula stage, cells of the embryo are arranged in the form of a hollow ball. Ultimately forms the lining of the digestive and respiratory tracts, along with the lining of several glands. [ILLUSTRATION OMITTED] Medical "miracle": Stem cells can repair most tissue types. SKIN CELLS Skin cells, or basal cells (mag: x65), can be grown to help burn victims. [ILLUSTRATION OMITTED] NERVE CELLS Freshly grown nerve cells, or neurons (mag: x7,500), can replace cells damaged by spinal-cord injuries. [ILLUSTRATION OMITTED] HEART-MUSCLE CELLS Lab-grown heart muscle cells (mag: x5,050) may cure heart disease. [ILLUSTRATION OMITTED] Juan Velasco and Jim McManus/The New York New York, state, United States New York, Middle Atlantic state of the United States. It is bordered by Vermont, Massachusetts, Connecticut, and the Atlantic Ocean (E), New Jersey and Pennsylvania (S), Lakes Erie and Ontario and the Canadian province of Times RELATED ARTICLE: Debate is Stem-Cell Research Ethical? Stem cells hold great promise--and have triggered a fierce debate. Read both views, then discuss in class: What do you think, and why? YES When I was 22 years old, I was diagnosed with diabetes. Now I must give myself daily insulin injections to control my blood-sugar level or risk future complications like blindness, limb amputation amputation (ăm'pyətā`shən), removal of all or part of a limb or other body part. Although amputation has been practiced for centuries, the development of sophisticated techniques for treatment and prevention of infection has greatly , and heart disease. Stem cells from embryos have the potential to improve my life, and the lives of millions of others suffering from a wide range of potentially deadly diseases, such as muscular dystrophy muscular dystrophy (dĭs`trōfē), any of several inherited diseases characterized by progressive wasting of the skeletal muscles. There are five main forms of the disease. , cancer, and Alzheimer's, or spinal-cord injuries. Stem cells may be the best--and, in some cases, the only--hope to cure diseases that now kill thousands daily. Stem cells can also be taken from adults, but they're not as flexible as stem cells derived from embryos, which can turn into every kind of human cell. Embryonic stem cells come from frozen embryos that are left over from in-vitro fertilization, an infertility treatment that generates many excess embryos. There are about 100,000 frozen embryos in the U.S. slated for destruction or to be left frozen indefinitely. I believe the ethical choice is to use them to save lives. --Lawrence Soler Chairman, Coalition for the Advancement of Medical Research NO The primary rule of medicine says: "First, do no harm" Doctors have always insisted that research be permitted on human beings only when the subjects give their consent and the research can benefit them. We should not allow experiments on human beings unable to give their consent. When scientists discovered that embryonic stem cells could perhaps be used to develop cures for various diseases, there was tremendous pressure to experiment with them. The ethical problem is that embryos must be destroyed in order to get the cells. It's always wrong to destroy innocent human beings. It doesn't matter at which stage of development these human beings are. All of us were embryos at one time. Besides, embryos do not need to be destroyed to proceed with stem-cell research. Some kinds of stem cells can be obtained from babies or adults without doing them harm. Very beneficial treatments have already been developed using these cells. --John M. Haas President, National Catholic Bioethics Center The National Catholic Bioethics Center is a research center located in Philadelphia. Established in 1972, its mission is promoting and safeguarding the dignity of the human person. [1] The chairman of the Board of Directors is the Most Reverend Robert C. |
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