THE NATIONAL INSTITUTES of Health (NIH) is an agency that is part of the U.S. Department of Health and Human Services; the NIH is the primary agency in the government of the United States that is responsible for biomedical research. The NIH is also one of the leading institutions for research in the world.
The NIH Web site stemcells.nih.gov has a wealth of information available to all regarding stem cell research; the site provides a great deal of information regarding basic stem cell background, the potential of stem cell research, federal funding opportunities, policy, and training. NIH publications that provide a comprehensive review of the progression of stem cell research are provided on the Web site, along with stem cell basics for those who would like a general overview of stem cells and their potential uses, as well as frequently asked questions regarding healthcare, research and policy, cell line availability, and funding, along with research regarding stem cells and disease and an extensive glossary of technical and scientific terms. The NIH site also provides links to current research, the stem cell registry, upcoming events regarding stem cell research, funding for research, training programs, and scientific literature. Databases are available for searching primary abstracts on stem cell literature; primary scientific literature about embryonic stem cell research and stem cell experimentation with regard to the treatment of disease is also provided on PubMED.
Stem cells have a remarkable capability to develop into many different cell types. Stem cells can divide infinitely to develop into other cells in the body. When stem cells divide into daughter cells, the daughter cell has the ability to either remain a stem cell or become a cell with more specialized cell functions, such as being a red blood cell or a brain cell. Three classes of stem cells exist: totipotent, multipotent, and pluripotent.
A fertilized egg can be considered totipotent; the potential of the mass is total and it can give rise to a multitude of cells within the body. Totipotency is the ability of a cell to divide and produce all of the undifferentiated cells within an organism. The growth and development of a living being is said to begin when a sperm fertilizes an egg and creates a single totipotent cell, the zygote. After fertilization, the cell begins to divide and produce other totipotent cells; these totipotent cells begin to specialize within a few days after fertilization. The totipotent cells specialize into pluripotent cells, which they develop into the tissues of the developing body. Pluripotent cells can further divide and specialize into multipotent cells, which produce cells of a particular function.
Multipotent cells, in contrast, can only give rise to a small number of cell types. For example, a hematopoietic cell, or a blood stem cell, can develop into several types of blood cells but cannot develop into liver cells or other types of cells; the differentiation of the cell is limited in scope. A multipotent blood cell can produce red and white blood cells, for example. At the end of cellular divisions during differentiation, the cells are terminally differentiated, meaning that they are considered to be devoted to that specific cellular function.
Pluripotent stem cells can give rise to any type of cell in the body except those needed to develop a fetus or adult because they lack the potential to support the extraembryonic tissue (e.g., the placenta). Pluripotent stem cells have the capability to differentiate into any of the three germ layers: the endoderm, the mesoderm, or the ectoderm. The endoderm consists of tissues and organs such as the lungs, the gastrointestinal tract and the stomach lining; the mesoderm consists of the blood, bone, and muscle; and the ectoderm consists of the nervous system and epidermal tissues. Pluripotent stem cells are isolated from embryos that are only several days old; cells from these stem cell lines can be cultured in the lab and grown without limit.
Stem cell lines can be grown in the laboratory and frozen for storage or for distribution to other researchers; these lines can provide an infinite amount of stem cells. A researcher can use the stem cell line indefinitely instead of having to isolate the stem cells again; this is other advantage of having a stem cell line. In the future, scientists hope to replace damaged genes with new ones by using stem cells to treat disease; scientists will also be able to use therapies to overcome the problems that are involved with immune rejection.
There are many ethical issues surrounding the use of both embryonic and adult stem cells; embryonic stem cells are controversial because the pro-life movement believes that human life becomes a human person at or shortly after conception. This mind-set contributes to the thought that the removal of stem cells from an embryo, which effectively kills the embryo, is technically equivalent to murdering a 70-year-old man or a 10-year-old girl. Regardless of the supposed health benefits, this position holds that even saving the lives of millions of people does not justify the killing of millions of other “humans.” The use of adult stem cells is generally much less disputed because the cells exist in humans and may be obtained without causing injury or death. Recently, they have been discovered in more locations in the human body and are becoming increasingly useful, but embryonic stem cells are far more differentiable and more plastic. The use of adult cells, however, does help to avoid the ethical issue because they are previously existing cells.
Ethical issues regarding stem cell research consider the moral results of using stem cell technology. Legal issues require a unique fusion of researchers, scientists, policy makers, and the public to decide how government will be involved in the scientific arena: funding, technology regulation, and so forth. Social issues entail the effect of technology on society and public issues.
Stem cell research is inextricably linked to public policy; this fundamental bond will continue to grow, and so it is important to make the public and legislators more aware of research developments and clinical applications of stem cells.
On August 9, 2001, President George W. Bush announced that federal funds could be awarded for researching using human embryonic stem cells (hESCs) only if certain strict criteria were met. The law stated that the derivation process of destroying the embryo had to initiate before August 9, 2001; furthermore, the stem cells had to be derived from an embryo that was created solely for reproductive purposes and was no longer needed; then, informed consent had to be obtained for the donation of the embryo, and the donation could not involve any financial stimulus.
According to the NIH Stem Cell Registry, the NIH has consulted with the investigators who have derived the cells from federally funded hESCs. States may pass laws to permit hESC research using state funds only; Congress has not to date passed a law that bans states this right, and so a state may pay for hESC research that is not eligible for federal funding.
President Bush signed a law on August 9, 2001, banning the use of federal funding for research done on any new embryonic stem cell lines and restricting the funding to what he claimed were “60 preexisting genetically diverse stem cell lines.” Dissenters immediately began to call him out on this figure. The director of the National Institutes of Health informed Congress that only 11 such stem cell lines are readily available for research fitting Bush’s restrictions, and that all of these lines are potentially contaminated by viruses from mouse feeder cells. As a result of these funding restrictions, new research is being thwarted and essentially choked. Although researchers at Johns Hopkins have since discovered a method of developing cell lines using human feeder cells, they cannot proceed with federal funding because the method still does not qualify under Bush’s policy. The policy has stalled the progress of stem cell research throughout the United States.
HESCs are believed to have a much greater developmental potential than adult stem cells; hESCs are pluripotent, meaning that they have the ability to give rise to cells found in nearly all tissues of the developing embryo. Conversely, adult stem cells are thought to be multipotent, meaning that their development is restricted to specific types of cells. Adult stem cells are less controversial and are much easier to acquire, but much more potential lies within the functionality of the hESCs.
Several advancements and experiments in stem cell research have been made at the NIH, specifically with relation to medicine and techniques. In 2007 heart cells derived from hESCs helped to restore rat heart function, a major advancement in cardiovascular research. Scientists hope to repair and replace damaged heart muscle cells with stem cells in the future. In the laboratory of C. E. Murry, NIH-funded investigators developed a novel technique to create a large number of heart muscle cells from hESCs. Improved heart function was examined in rat hearts, which offers great promise for the effective treatment of human heart disease.
Other advancements in stem cell research have been equally exciting; for example, researchers were able to isolate adult stem cells for the first time in tendons, procedures were developed to differentiate between stem cells lines and the development of hESCs for different types of neurons, tissue-matched human stem cells were created without cloning, olfactory stem cells were identified in mammals, hair follicles were regenerated in mice, hESCs developed into lung tissue, adult stem cells were able to develop into skeletal muscle, nonembryonic human stem cells were matured in the rat spinal cord, stem cells responsible for pancreatic cancer were identified, and stem cells were generated in amniotic fluid.
Many people question the effectiveness of hESCs; scientists have only been performing experiments with hESC since about 1998. When federal funds that supported hESC research were limited with President Bush’s decision on federal funding in 2001, academic researchers suffered: Almost all researchers depend on federal funding to support their laboratory experiments. Because of the federal fund restrictions, however, scientists have only recently begun to develop stem cells and conduct experimentation. Although hESCs are believed to have great potential for the advancement of medicine, extensive research is still necessary to offer therapies for disease and therapy. Hematopoietic stem cells (HSCs) are blood-forming stem cells in bone marrow. At present, these stem cells are the only type of stem cell that is conventionally used to treat human disease; for example, doctors have been using the HSCs of bone marrow for bone marrow transplants for over 40 years.
Although the potential of adult stem cells has been tested and observed in the treatment of other types of human disease (such as kidney cancer), the studies have only involved a limited number of subjects (patients), and not enough experimentation has been conducted to extensively use stem cells for treating human disease. Nonetheless, the unique properties of hESCs offer great potential in the understanding of embryonic development, disease, cancer, and biomedical engineering.
Clinical Trials Within U.S.: Blind Process; Federal Government Policies; Regulations Overview; Stem Cells, Bush Ruling; United States.
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