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The Push to Label Genetically Engineered Foods
- Environmental Nutrition, June 2012
If you consume soy-containing products–ubiquitous on supermarket shelves–chances are you’ve eaten foods that contain genetically modified organisms (GMOs), also known as genetically engineered (GE.) According to the Grocery Manufacturers Association, about 80 percent of foods in the U.S. contain GMOs, such as corn and soy ingredients. Currently, there is no way you can know due to lack of required food labeling. However, consumers increasingly feel they have a right to know what is in the food they eat–particularly when it comes to GMOs; in a 2012 survey by the consumer research company The Mellman Group, 91 percent favored labeling.
What are GMOs? GMOs are created when the genetic material of an organism is modified in a way that does not occur in nature. It may be modified to create disease-or herbicide-resistant crops, or to include vitamins normally not found in the crop. Introduced commercially in 1996, the most common GMOs in the food supply are soy and corn. The U.S. Food and Drug Administration (FDA) reports no concern over the safety of GE foods and has taken a stance against labeling, alleging that the foods are basically the same as other foods and don’t pose any health risk. However, some health advocacy groups are concerned about potential health and environmental risks of GMOs. The consumer health advocacy organization Environmental Working Group, along with more than 500 other organizations representing healthcare, consumer advocates, farmers, businesses, environmentalists and more is pressuring the FDA to label GMOs via the Just Label It Campaign (www.justlabelit.org).
On the GMO labeling front GMO labeling is required in over 40 countries, but not in the U.S., though individual states, such as Connecticut and Vermont have introduced legislation calling for labeling. For example, California initiated grassroots efforts to advocate for labeling through a coalition called The Committee for the Right to Know, which submitted the California Right to Know Genetically Engineered Food Act in November 2011.
GMO-free foods. While we’re waiting for mandatory labeling, there are many ways you can avoid GMOs if you are so inclined. (See EIV’ s “Genetically Engineered Foods Update,” July 2010 for more information about the safety of GE foods.) You can limit them by avoiding processed foods–most GE crops are used for processed ingredients such as soybean oil and high fructose corn syrup–and purchasing organic products, which are not allowed to contain GMOs. And now, you can look for the Non-GMO Project-Verified seal on food labels, which indicates they are GMO-free. The Non-GMO Project, a nonprofit collaboration of manufacturers, retailers, distributors, and farmers that pro-motes informed choice, provides a third-party verification and labeling program (www.nongmoproject.org) for food products that do not contain any GMOs.
Full Text: COPYRIGHT 2012 Belvoir Media Group, LLC.
“The push to label genetically engineered foods.” Environmental Nutrition June 2012: 3. Gale Science In Context. Web. 20 Dec. 2012.
Title: Stem Cell Lines
Author(s): Susan Aldridge
Source: Biotechnology: In Context. Ed. Brenda Wilmoth Lerner and K. Lee Lerner. In Context Series Detroit: Gale, 2012. From Science In Context.
A stem cell is a primitive type of cell that can both self-renew and differentiate into a number of specific cell types, such as blood cells or neurons. Scientists work with stem cells in the form of stem cell lines, which are groups of stem cells with similar properties.
Creating a stem cell line starts with a sample of tissue from a part of the body known to harbor stem cells. It involves various cell culture and purification steps, and the resulting cell line is then sold to researchers or kept in a stem cell bank. Stem cells are of two kinds: embryonic and adult. Both have many potential therapeutic uses in the repair and renewal of the body, which is why the existence of different stem cell lines is important as a resource for work in stem cell therapies. However, the use of embryonic stem cells lines remains controversial, because a potential human life must be destroyed to create it. Therefore, work continues on adult stem cell lines, and there is much interest in induced pluripotent cells as an alternative to human embryonic stem cells.
Words to Know
Historical Background and Scientific Foundations
Advances in cell biology in the first half of the twentieth century enabled scientists to culture cells outside the body. The first significant cell line was derived in 1951 by George Gey (1899–1970) of Johns Hopkins School of Medicine. The HeLa cell line consists of cancer cells from tissue obtained from Henrietta Lacks (1920–1951), a patient who died of cervical cancer in that year. HeLa is not a stem cell line. Cancer cells can self-renew in a similar way to stem cells and are often called immortal, but they do not differentiate. HeLa cells continue to play an important role in medical research, and the establishment of the cell line was an important pointer to how stem cell lines might be developed. In the 1950s stem cells were identified in bone marrow, and the first bone marrow transplant took place in 1968. A further breakthrough occurred in 1998, when James Thompson (1958–) of the University of Wisconsin-Madison created the first human embryonic stem cell (hESC) line. In the early twenty-first century there are hundreds of different hESC and adult stem cell lines held in stem cell banks and laboratories around the world.
A researcher examines stem cell lines through a microscope, which are displayed on a computer screen.
The creation of a new adult stem cell line begins with a tissue biopsy from a niche in the body believed to harbor stem cells. Such niches exist in the bone marrow (a rich source of stem cells), skeletal muscle, blood, skin, liver, and even the brain. If an hESC cell line is being created, the source is usually a spare embryo from in vitro fertilization, donated by its parents with fully informed consent. A sample of tissue is taken for cell culture and the rest frozen for further cell line experiments. Cells are grown from this sample in an incubator on a nutrient medium containing glucose and amino acids under sterile conditions, with controlled temperature and pH. After around three weeks, many cells will have grown but they will not all be stem cells. The cell culture is mixed with a marker antibody that will tag surface marker proteins, which exist on stem cells but not on other types of cells.
Then the stem cells are separated from other cells using a cell sorter, which can identify the presence of the marker antibody. The next stage is to identify the differentiation properties of the stem cell. An embryonic stem cell is pluripotent, with the ability to differentiate into most of the cell types of the human body, whereas adult stem cells are multipotent and only able to differentiate into a limited range of cell types. For instance, mesenchymal stem cells, found in bone marrow, differentiate into bone, cartilage, and fat cells, but will not form any kind of blood cell. The stem cells progress through differentiation via a stage called a progenitor cell, which is then committed to form the range of final specific cell types. The cells are grown in plates containing a range of differentiation media, one for each possible cell type, and this allows the type of progenitor cell to be identified. These stem cell lines often are produced commercially by scientists who have the expertise to do so and then sold to laboratories around the world. It is common to establish a master cell bank, which is stored, while further production is undertaken using a working cell bank.
Impacts and Issues
Stem cell lines are a rich resource for potential cures for a variety of afflictions. Bone marrow transplants involving stem cells that differentiate into a range of blood cells have been used in the treatment of leukemia for many years. Treatments with stem cells to replace damaged heart muscle and worn cartilage in knee joints have been introduced more recently. Visually-impaired people have had their sight restored by retinal stem cells. Other stem cell treatments are in clinical trials: For example, patients at a hospital in Glasgow, Scotland, are receiving fetal-derived neural stem cells to treat brain damage caused by stroke. The first Food and Drug Administration (FDA)-approved trial of an hESC-derived therapy began in October 2010. The trial involves an oligodendrocyte progenitor created by the California-based biotech company Geron and is being tested on patients with spinal cord injuries.
However, there are technical and ethical issues surrounding the use of stem cell lines. Putting cells into a human body is very different from treating a patient with a drug. To date, no one is quite sure what the fate of a stem cell is when it enters the body, or what it actually does. At the very least, the cell line used to treat the patient should be guaranteed to be pure and well characterized. In the early days of developing cell lines, mouse cells had to be used as feeder cells, which raised the possibility of introducing some viral contamination. There has been a major shift towards producing cell lines with animal-free components.
The main ethical issue around stem cell lines arises when the cells are derived from human embryos. In 2001 President George W. Bush (1946–) declared that federal funding for work on hESCs would be restricted to work on existing cell lines. This move ensured that government would have no part in any research involving new embryos, even though these were created for IVF rather than for research purposes. There were said to be 64 such hESC cell lines in existence around the world. However, it turned out that some were contaminated and others were only at the research stage and not fully established. This left National Institutes of Health (NIH) researchers with only a limited number of cell lines available for research. President Barack Obama (1961–) lifted these restrictions in 2009, but there continues to be intense lobbying on both sides of the hESC debate.
Actor and Parkinson’s disease sufferer Michael J. Fox (2nd-L) addresses a news conference on stem cell research legislation with members of Congress, including Sen. Arlen Specter (R), R-PA; Congressman Mike Castle (2nd-R), R-DE; and Congresswoman Diana Degette (L), D-CO; on Capitol Hill in Washington on July 13, 2005. The news conference was called to urging Congress to pass a bill that would expand the number of stem cell lines available for federally-funded research.
Many opponents of hESC research argue that the same therapeutic benefits may be obtained by using adult stem cells. They would like to see research resources diverted away from hESCs and towards adult stem cells. To an extent, the NIH budget for 2011 reflects this view, with $358 million being given to adult stem cells and $126 million to hESCs. However, there is no guarantee that further research on adult stem cells will show them to be as useful as hESCs. According to the state of knowledge in the early 2010s, they are more limited in potential application because their differentiation range is narrower. There has been much interest, therefore, in induced pluripotent cells (iPSCs), which are adult stem cells treated so they act more like embryonic stem cells. So far, there is insufficient knowledge about iPSCs to state whether or not they are equivalent in potential to hESCs. They are certainly many years away from entering human clinical trials.
- Bongso, Ariff, and Eng Hin Lee, eds. Stem Cells: From Bench to Bedside, 2nd ed. Hackensack, NJ: World Scientific, 2010.
- Freshney, R. Ian, G. Stacey, and Jonathan M. Auerbach, eds. Culture of Human Stem Cells. Hoboken, NJ: Wiley-Interscience, 2007.
- Gottweis, Herbert, Brian Salter, and Cathy Waldby. The Global Politics of Human Embryonic Stem Cell Science: Regenerative Medicine in Transition. New York: Palgrave Macmillan, 2009.
- Korobkin, Russell, and Stephen R. Munzer. Stem Cell Century: Law and Policy for a Breakthrough Technology. New Haven, CT: Yale University Press, 2007.
- Masters, J. R. W., Bernhard Palsson, and James A. Thomson, eds. Embryonic Stem Cells. New York: Springer, 2007.
- National Research Council (U.S.), Institute of Medicine (U.S.), and National Academies Press (U.S.). The National Academies’ Guidelines for Human Embryonic Stem Cell Research. Washington, DC: National Academies Press, 2007.
- New Zealand Ministry of Health. Guidelines on Using Cells from Established Human Embryonic Stem Cell Lines for Research: Discussion Document. Wellington, New Zealand: Ministry of Health, 2005.
- Shi, Yanhong, and Dennis Owen Clegg, eds. Stem Cell Research and Therapeutics. Dordrecht, The Netherlands: Springer, 2008.
- Turksen, Kursad, ed. Human Embryonic Stem Cell Protocols, 2nd ed. New York, NY: Humana Press, 2010.
- Wagner, Viqi, ed. Biomedical Ethics. Detroit: Greenhaven Press, 2008.
- Waldby, Cathy, and Robert Mitchell. Tissue Economies: Blood, Organs, and Cell Lines in Late Capitalism. Durham, NC: Duke University Press, 2006.
- Hanna, Kathi E. “Cloning/Embryonic Stem Cells.” National Human Genome Research Institute, April 2006. http://www.genome.gov/10004765 (accessed November 3, 2011).
- Harris, Gardiner. “U.S. Judge Rules Against Obama’s Stem Cell Policy.” The New York Times, August 23, 2010. http://www.nytimes.com/2010/08/24/health/policy/24stem.html (accessed December 31, 2011).
- “Stem Cell Information: National Institutes of Health Guidelines on Human Stem Cell Research.” National Institutes of Health, U.S. Department of Health and Human Services, 2011. http://stemcells.nih.gov/policy/2009guidelines.htm (accessed November 3, 2011).
- Source Citation (MLA 7th Edition)
- Aldridge, Susan. “Stem Cell Lines.” Biotechnology: In Context. Ed. Brenda Wilmoth Lerner and K. Lee Lerner. Detroit: Gale, 2012. In Context Series. Science In Context. Web. 11 Feb. 2013. http://go.galegroup.com/ps/i.do?id=GALE%7CTUPNKZ905476787&v=2.1&u=nysl_we_smhs&it=r&p=GPS&sw=w
- Gale Document Number: GALE|TUPNKZ905476787
Source Number 3
Title: Stem cells and stem cell research
Source: World of Anatomy and Physiology. Gale, 2002. From Science In Context.
Stem cells are undifferentiated cells that can give rise to diverse types of differentiated (specialized) cell lines. Stem cells are further classified into three groups: embryonic stem cells, embryonic germ cells, and adult stem cells.
Because they are undifferentiated (not yet specialized into cells that form muscle, nerve, or other types of tissue), stem cells hold unique promise for potential use in wide variety of medical treatments. Researchers are actively investigating whether stem cells may serve as a source of tissues needed for transplantation and investigation continues into several stem cell-based therapies. For example, use of stem cells to create transplantable tissues would be of great clinical significance because there is a chronic shortage of donor organs and tissue suitable for transplantation.
The use of stem cells derived from embryonic tissue remains controversial in some parts of the world, and is opposed by some religious groups.
Stem cell origins and types
All cells in the human body, including specialized cells, such as neurons, cardiac muscle cells, and skin cells, are descended from stem cells in the early-stage embryo termed a blastocyst. A blastocyst is a hollow sphere of cells, smaller than the period at the end of a sentence, which is formed within three to five days of the fertilization of an egg cell by a sperm cell. The term embryo is popularly used to refer to blastocysts, although scientists usually reserve this term for later stages of development where human anatomy has begun to appear. The cells in the inner cell mass of the blastocyst can be isolated and are termed embryonic stem cells. Embryonic stem cells are cultured cells originally collected from the inner cell mass of an embryo at the blastocyst stage of development (four days after fertilization). Embryonic germ cells are derived from the fetal gonads, which arise later in fetal development.
Both embryonic stem cells and embryonic germ cells are pluripotent, which means that they can produce daughter cells that are able to differentiate into all of the various tissues and organs of the body that are derived from primary embryonic tissue types (i.e., the endoderm, ectoderm, and mesoderm).
The adult body also contains adult stem cells that can produce a more limited range of final cell types. Adult stem cells maintain and repair tissues in the living organism. Adult hematopoietic (blood-forming) stem cells derived from bone marrow have been employed in transplants for 40 years. In each healthy person, about two million red blood cells are produced from adult stem cells in bone marrow every second.
Generations of cultured cells in which cells are provided a means to live, grow, and replicate is termed a cell line.
Embryonic stem cell research in the early twenty-first century has been marked by improved scientific understanding of the mechanisms that trigger differentiation of embryonic stem cells into various specialized tissue types.
Ethical and Legal Limitations to Research
For research purposes, embryonic stem cells are primarily derived from leftover products of in vitro fertilization procedures. Embryonic germ cells from later gestational age fetuses have been obtained from fetal tissues resulting from elective termination of pregnancy or spontaneous fetal death. Some people object to the use of embryos for research purposes.
Several countries around the world have various laws regulating cell technologies, including cloning and stem cell research. However, the most controversial debates have taken place in the United States. Restrictions on the use of human fetuses and fetal tissue in scientific research formally date to an initial ban in 1974. In 1995, President William Jefferson Clinton (1946-) signed into law a measure banning federal funding for research involving most human embryonic tissue.
In 1998, American developmental biologist James A. Thomson (1958-) was first able to isolate and extract human embryonic stem cells from blastocysts. Although the possibility of using stem cells to treat various diseases and injuries excited physicians and scientists, it also fueled religious and ethical controversy over the use of cells derived from embryonic tissue.
In 2001, President George W. Bush (1946-) issued an order banning federal funding of research using human embryonic stem cells on new stem cell lines. Research was allowed to continue on approximately 60 stem cell lines already in existence, and the ban did not prohibit embryonic stem cell research using other sources of funding. However, most medical research in the United States–especially research requiring advanced cell culture techniques and equipment–is federally funded. As a result of the ban, research was restricted or terminated. Some researchers moved their work to other countries. The majority of experts contended that some of the existing cell lines were not usable for needed areas of research. Moreover, more lines would be needed to conduct the level and scope of research anticipated to result in significant medical advances.
In response to the federal restrictions, some U.S. states tried to independently fund stem cell research. In 2004, California residents voted to spend three billion dollars of state money to fund stem cell research.
In January 2009, shortly after the inauguration of President Barack Obama (1961-), the U.S. Food and Drug Administration (FDA) approved the first-ever phase 1 clinical trial in human patients of a therapy for recent spinal-cord injuries based on human embryonic stem cells. Severe spinal-cord injuries, which occur at the rate of at least 10,000 per year in the United States alone, cannot heal naturally because nerve cells in the central nervous system do not divide to produce new nerve cells.
In March 2009, President Obama issued an executive order removing President George W. Bush’s ban on federal funding for human embryonic stem cell research using most cell lines. President Obama left the details of the new federal policy to be set by scientists working for the National Institutes of Health (NIH).
In July 2009, NIH guidelines were released that require stem cell lines used in federally funded research be derived from excess embryos at in vitro fertilization clinics. Clear written consent, among other requirements, must be obtained from embryo donors. As of April 2012, NIH has approved at least fifty-three stem cell lines for use in research receiving federal funding. Legal controversies continue and have resulted in conflicting rulings, including temporary stays of research for more than 450 stem cell research projects. In May 2011, the U.S. Court of Appeals for the District of Columbia rescinded an injunction that effectively had prohibited renewed federal funding for embryonic stem cell research projects approved by the National Institutes of Health. Both critics and proponents of such funding assert that Court’s ruling allows the Obama administration to proceed with its plan to broadly increase federal funding for stem cell research.
In addition to their possible clinical applications, embryonic stem cells may be useful in other fields of research. These cells represent a very early stage of development about which scientists know relatively little. Close observation in the laboratory offers the possibility of a better understanding of normal development, as well as the opportunity to investigate factors that cause abnormal development. Some researchers have suggested that embryonic stem cells might be used in gene therapy, a technique that replaces a defective gene with healthy copies of the gene. The idea here is that investigators could create a population of engineered embryonic stem cells containing a known, functional gene. The cells could then function as vectors to transfer the gene into target tissues. Once in place, the cells would hopefully become part of the target tissues, begin to replicate, and restore lost function. Initial studies in mice confirmed that the idea is feasible. Investigators in Spain incorporated an insulin gene into mouse embryonic stem cells. After demonstrating the production of insulin in vitro, the cells were injected into the spleens of diabetic mice that subsequently showed evidence of disease reversal.
Recent Research Advances
In 2007 and 2008, two groups of researchers working independently published studies showing that it is possible to create stem cells from normal adult cells. Using techniques of cellular reprogramming, insertion of a few select genes into extracted human cells returned the cells to an embryonic state capable of following a new developmental path. Researchers were able to create induced pluripotent stem cells (iPS) from adult epidermal cells (skin cells) by injecting the skin cells with retroviruses carrying genes that code for four proteins key to the de-differentiation process needed to create stem cells from adult cells. Because the researchers did not destroy human embryos, these new methods may offered a potential solution to ethical concerns about sources of stem cells for medical research and clinical treatments.
In 2008, a research team working with mouse cells was able to convert cell types directly from one type to another without reverting cells to an embryonic stem cell state. In March 2009, researchers announced that they had created pluripotent stem cells from normal adult skin cells that showed far less ability to cause the post-transplantation cancers previously associated with stem cells produced from adult cells.
In September 2010, researchers under the direction of Derrick J. Rossi at Children’s Hospital in Boston published experimental results in the journal Cell Stem Cell heralding a significant breakthrough in cell technology by allowing the production of pluripotent stem cells from adult epidermal cells (skin cells) without the higher risk of tumor formation. Using messenger ribonucleic acid (mRNA-) based technology, the research team was able to produce stem cells with the same developmental potential as stem cells derived from embryos, but with significantly reduced risks of subsequent tumor formation when the induced stem cells re-differentiate into various tissue types.
In contrast to injecting genes using retroviruses, the Rossi research team approach relies on the use of mRNA molecules to induce adult skin cells to become stem cells and to also control the subsequent stem cell re-differentiation process into muscle cells (and potentially other tissue types). The deoxyribonucleic acid (DNA) in genes–which, in humans, is located on chromosomes in the cell nucleus–serves as the template for the creation of mRNA molecules. The sequence of adenine (A), guanine (G), thymine (T), and cytosine (C) nucleotides in DNA serves as a template for the precise construction of an mRNA molecule, with a complimentary sequence of nucleotides, with uracil (U) replacing thymine as complimentary to adenine (A) in RNA, and guanine (G) complimentary to cytosine (C). Accordingly, a sequence designated ATTCGG in DNA is transcribed into a UAAGCC sequence in mRNA. In the eukaryotic cells (cells with a nucleus surrounded by a nuclear membrane) found in humans, mRNA molecules (often described as mRNA segments) then carry the genetic code out of the cell nucleus to the protein assembly organelles located in the cell cytoplasm. Formation of mRNA is called transcription, and the subsequent formation of proteins that determine and regulate cell structure and function is called translation. Proteins are produced by translating the genetic instructions transcribed into the structure of the mRNA molecule. The use of mRNA by Rossi’s team allowed the direct production of the key transformation proteins needed to induce the stem cell state without the need to introduce new genetic material. The stem cells produced did not show the high rates of tumor formation associated with stem cells produced using genes introduced via retroviruses.
In February 2011, French doctors announced the birth of the first “designer baby” (also referred to as a “saviour sibling”). The baby was the product of in vitro (literally, “in glass,” referring to in the laboratory) procedures designed to select for or against selected genetic characteristics. During the in vitro embryo selection phase, multiple embryos were examined to ensure that the embryo selected for implantation and development did not carry the gene for beta thalassemia, a genetic disorder results in severe and often lethal anemia. Stem cells were harvested from fetal umbilical cord stem cells that will be used to treat sibling suffering from beta thalassemia.
Source Citation (MLA 7th Edition)
“Stem cells and stem cell research.” World of Anatomy and Physiology. Gale, 2002. Science In Context. Web. 11 Feb. 2013.
Gale Document Number: GALE|CV2430500388