1 Stem Cells: Cures For The Future Cancer, heart disease, diabetes, Alzheimer’s, Parkinson’s, HIV/AIDS, multiple sclerosis, lung diseases, and spinal injuries. These words are synonymous with pain and suffering but a new hope on the horizon has the potential to change that. Imagine a single cell, not just any cell but a cell that could develop into any other type of cell in the human body, a master cell. This cell could replace damaged and diseased cells in order to heal the human body. A master cell does exist. It is called a stem cell. Human stem cells have sparked a new revolution in medicine, the rise of regenerative medicine. These cells are able to become any type of cell in the human body ranging from muscle cells to nerve cells and anywhere in between. Stem cells have limitless possibilities. “Cell-replacement therapies based on stem cell lines will render obsolete many current drug and medical interventions” (Green 1: 2). The debate on stem cells is not scientific but moral and ethical, especially when pertaining to embryonic stem cells, which either come from In Vitro fertilization clinics or aborted embryos. The two main ethical problems that oppose stem cell research are cloning and embryonic stem cells. “…Obstacles result from the fact that, of the three sources of stem cells, human embryos are the most promising” (1: 2). With an understanding of stem cells and treatments derived from that understanding, mankind will improve the quality of life; however, with the new cures, treatments, and possibilities that accompany stem cells there must also come great responsibility and care in order to maximize the gains from stem cells. Not all stem cells are created equally. Stem cells are generally cells with the ability to become or produce specialized cells’ but there are many different types of stem cells. The National Institutes of Health defines stem cells as “Cells with the ability to divide for indefinite periods in culture and to give rise to specialized cells” (Natl. Inst. of Health 2). These master
2 cells can give rise to other types of cells and are able to multiply for a long time. Two of these are adult stem cells and embryonic stem cells. Stem cells that are present in the human body since childhood are adult stem cells. An adult stem cell is “An undifferentiated cell found in a differentiated tissue that can renew itself and (with certain limitations) differentiate to yield all the specialized cell types of the tissue from which it originated” (1). This means that adult stem cells are found in tissues that can regenerate themselves but can only produce more of the same tissue, like the liver. While adult stem cells can produce many other types of cells, they only produce the types of tissue associated with the tissue they originate. “These cells are “multipotent”, meaning they are able to produce a range of related tissues, such as the differing types of blood system cells” (Green 1: 2). Adult stem cells can be gathered from the brain, bone marrow, blood vessels, skin, and the liver. In addition, some of these adult stem cells can be collected from a living person. One example are ADAS cells, stem cells that come from fat. “For the first time, stem cells purified from fat have been used to heal an injury in a living animal… In mouse experiments that so-called Adipose-Derived Adult Stromal (ADAS) cells purified from a rodent's belly fat could be coaxed to heal a skull fracture too large to mend by itself” (Cohen 1). ADAS cells are fat stem cells, which are a form of adult stem cells, and have been used in mice to heal bone fractures. “If the same technique works in humans, these cells could be coaxed to mend broken bones and correct other defects in tens of thousands of surgical procedures each year in which bone grafts and prosthetics are now necessary” (1). A treatment developed from these cells could not only render current treatments obsolete but also cut down the time it takes the bone to heal from a fracture. “ADAS cells grow seven times faster than the bone marrow cells in the laboratory. And it is relatively easy to harvest more than a litre of fat tissue, even from patients who are not obese. Bone marrow is much less plentiful and must be removed in a painful surgical procedure” (1). Added benefits
3 from this kind of treatment are that ADAS cells can be generated faster and obtained easier than bone marrow, which is also a type of adult stem cell found at the core of bones. The most versatile and less differentiated, less specialized, stem cells come from human embryos. “…ES [Embryonic Stem] cells, derived from the inner cell mass of the blastocyst-stage embryos [a fertilized egg about a week after conception]. These pluripontent [able to produce every type of cell] cells are the most ubiquitous of all [stem cells]” (Green 1: 3). ES cells are the mothers of all cells. They are completely blank and scientists think that they can be “nudged” into becoming any type of cell in the human body (1: 3). By learning the secrets of the ES cell scientist can produce all types of tissue for use in regenerative medicine and for testing of new drugs. Issues regarding stem cell research rise from the fact that of the three sources of stem cells, human embryos are the most promising (1: 2). Their potential lies in that they are the most undifferentiated of all stem cells and therefore the most appealing. In Vitro fertilization clinics are a prime source of stem cells. “Until very recently the vast majority of stem cells used in research came from discarded (or excess) embryos stored at In Vitro fertilization clinics” (Reaves 2). In Vitro fertilization, or IVF, clinics create excess embryos while they provide their service. “In IVF, several hundred eggs are fertilized in a petri dish. 5 days after fertilization (approximately the time at which an embryo fertilized in the womb would implant in the uterus), a few of these ‘blastocyst’ embryos are transferred into the mother’s womb. If the transfer is successful (i.e. the embryo implants into the uterus) then the rest of the embryos are discarded” (Gilbert RA100). Those excess embryos are usually destroyed; however, they can be used for Embryonic Stem, or ES, cell research. “British infertility clinics in the course of performing their legally mandated duty of discarding 3300 unwanted or unclaimed embryos, are reported to have thawed and administered a few drops of alcohol to each embryo before incinerating them” (Green 2: 1). The unwanted embryos at IVF clinics will be destroyed
4 regardless whether they are used for ES cell research. This source of ES cells has no ties to abortion. In fact, it is the opposite because IVF clinics help people with fertility problems, which stem cells could help cure also. “Presuming that at least initially such stem cells will likely come from discarded embryos from IVF clinics, then research or no research the embryos will be destroyed” (Green 2: 1). IVF clinics are a great potential source of stem cells that must be explored in order to further research. Many oppose all stem cell research based on one source of ES cells, aborted fetuses. “In the most controversial method, scientist can also pull stem cells from aborted fetuses, first asking for signed consent from a patient who’d previously (and independently) decided to terminate their pregnancy” (Reaves 2). This is done most like an organ donor program. It is not an open door for scientists, or anyone, to encourage abortion. While this method of obtaining ES cells can be performed, it is not usual. “One misconception is that ES cells are derived from aborted fetuses. The practice of abortion has no relationship, direct or indirect, to ES cells. All (without exception) ES cell lines are derived from 5-day embryos (blastocyst) that were voluntarily donated by couples undergoing In Vitro Fertilization (IVF) and would otherwise be discarded.” (Gilbert RA100) What is more, the stem cells that come from aborted fetuses have differentiated somewhat, their stem cells have begun to specialize, and as a result are not as flexible as those obtained from IVF clinics when the embryo is about a week old. “Embryonic stem cells are pluripontent, able to give rise to all tissue type, although recent research suggest that their usefulness in cell replacement therapies might be limited because they have already begun to take on some specific characteristics of their reproductive function” (Green 1: 3). Contrary to popular belief, the ideal stem cell does not come from a fetus that has already developed. In fact, the ideal stem cell comes from the inner cell mass of about a week old embryo called a blastocyst, which is a mass of cells not a developed baby. A developed fetus is not the ideal
5 source of ES cells because beyond the first week the ES cell begins to differentiate inside the womb further than the sought after cells. These differentiated cells are less flexible than the younger cells and therefore less appealing for research involving ES cells. A major issue concerning ES stem cells regards the classification of ES cells, “are [embryonic stem cells] morally protectable entities [human beings] or are they more like other disposable tissues gleaned from the human body?” (Green 1: 3). This ethical dilemma centers mainly on abortion but effects ES cells because they are derived from human embryos. “No one denies that early embryos lack sensory organs or tissues. They cannot suffer pain. Their moral worth, if any, resides in their potential for further development” (Green 2: 1). Furthermore, embryos stored in IV clinics lack the potential that a fetus inside a womb has. The left over embryos no longer have the ability to become human. In 1999, DHHS [the U.S. Department of Health & Human Services] announced that it intended to fund research on human ES cells derived from embryos remaining after infertility treatments. This decision was based on an interpretation “that human embryonic stem cells are not a human embryo within the statutory definition” because “the cells do not have the capacity to develop into a human being even if transferred to the uterus, thus their destruction in the course of research would not constitute the destruction of an embryo. (Natl. Human Genome Research Inst. 4) The embryos that were left over from infertility treatments cannot develop beyond a mass of cells, and certainly not into a human being. Another controversy in stem cell research is cloning. “The term cloning is used by scientists to describe many different processes that involve making duplicates of biological material. In most cases, isolated genes or cells are duplicated for scientific study, and no new animal results” (Natl. Human Genome Research Inst. 1). Usually, cloning is used to duplicate
6 genes and cells for study, not to create whole, complex entities. There is a fear of cloning based on the idea of “genetic determinism”, that genes alone will entirely determine the individual and clones will be exact copies (Natl. Human Genome Research Inst. 2). This fear is false because even a clone will not be an exact copy of an individual because genes unaided do not define a person. For a clone to be exact, he would have to experience the same, physical and mental, development as the original. “ES cells also could be derived from embryos created through somatic cell nuclear transfer, or cloning. In fact, several scientist believed that deriving ES cells in this manner is the most promising approach to developing treatments because the condition of …[IVF] embryos over time is questionable and this type of cloning could overcome graft-host responses if resulting therapies were developed from the recipient’s own DNA” (Natl. Human Genome Research Inst. 4). Such cloning would never yield a human, but instead, customized tissue for the regenerative treatment, which would eliminate the risk of rejection by the patient of the treatment. A third common misconception is that either derivation or the intended use of ES cells involves the cloning of a human being… What is referred to as ‘Reproductive cloning’ implies that egg is able to develop to a blastocyst, which is then implanted into the womb of a recipient mother who brings to term an individual genetically identical to the original donor… ‘Therapeutic cloning’ refers to the process of deriving such cells from blastocyst, which destroys the cloned human embryo before it develops beyond the blastocyst stage. (Gilbert RA100) Therapeutic cloning of ES cells involves the cloning of ES cells, not a full human being. In the process, the blastocyst is destroyed for its inner mass, which contains the needed ES cells. An ES cell without the rest of the blastocyst can never become a human being.
7 Stem cells are a major scientific break through. These new findings in science do not offer false hope. They do not offer proven hope either, because it is, in fact, a new discovery. Stem cells and their cure just offer hope. Hope with great potential and that is why it is crucial that stem cells are thoroughly investigated. ES cell research holds many possibilities and much potential. “There are essentially three categories of medical promise from ES cell research. First, researching the requirements for ES cells to differentiate into various tissues will provide a wealth of valuable information about early human development” (Gilbert RA100). With this new information scientist can figure how and why early diseases in humans, such as genetic disorders and birth defects, develop which can lead to more cures. “ES cells also provide potential to test drugs in freshly differentiated cells of different tissue types to more closely resemble the human condition” (Gilbert RA100). Tissues derived from ES cells can test drugs better for humans than other animal models. The beauty of stem cells are their flexibility to become any cell in the human body, even the highly specialized reproductive sperm and egg cells, which in turn can create more stem cells. This is the foundation of regenerative medicine. Regenerative medicine could repair cells within organs that drugs and surgery cannot fix by replacing cells that are damaged beyond repair. “…Because stem cells are undifferentiated, they aren’t committed to becoming a liver cell, say, or a blood cell, scientist may be able to prompt them to become whatever type of cell is needed” (Reaves 2). Stem cells could cure diabetes by differentiating them into beta-islet cells that produce insulin. They could also cure Parkinson’s disease by differentiating them into dopamine-producing cells, the absence of which causes Parkinson’s (Green 1: 2). “Also on the distant horizon lies the possibility of new cardiac tissue for heart attack victims, replacement blood and marrow cells for those who have undergone…therapy for cancer, new skin tissue for burn victims, bone for those suffering from severe fractures or
8 osteoporosis, and so on” (1: 2). Stem cells have the potential to ease the suffering of many who are in pain. Future research on stem cells may reveal new sources of stem cells. It may also reveal new techniques and treatments using stem cells. The necessity to destroy embryos for research may even vanish with further research and development. The ability of stem cells to differentiate into other types of tissue is undeniable. Now the mystery holding back stem cell cures is the mechanism that makes them differentiate into other cells; more narrowly, the obscurity that shrouds the mechanism that controls which type of cell the stem cell becomes. Regeneration is a natural process. Richard J. Gross, a developmental scientist observed, “If there were no regeneration there would be no life. If everything regenerated there would be no death” (Parson 13). Everything in nature has some sort of regeneration, whether it is the human liver or an amphibian limb. Everything has regeneration but with varying degrees. With an understanding of stem cells and treatments derived from that understanding, mankind will improve the quality of life. Stem cell research does not equal abortion. It does not endorse the cloning of humans. Stem cells will make drug testing more accurate and safe. It will reveal the mysteries of genetic diseases and help the understanding of not only the human body but also life. They will also give rise to new treatments and regenerative medicine. However, with the new cures, treatments, and possibilities that accompany stem cells there must also come great responsibility and care in order to maximize the gains from stem cells. “Moral reasoning must always be in conversation with human experience” (Green 1: 4). This means that people should use judgment and common sense in order to make informed decisions about stem cells. The pending success of stem cell cures will change the world and how mankind perceives itself. The only sure way to find out where stem cells will take humankind is to continue research, monitor the results and act accordingly. For stem cells, the possibilities are endless. It is now a matter of
9 how mankind will handle this new discovery and where it will lead. As more is learned about stem cells and new technologies and treatments are developed it is undoubtedly certain that humans will face new challenges, choices, and opportunities. Science and possibly the destiny of mankind are at a crossroad. It is not the first or the last. People must learn the facts and make decisions that will define mankind.
10 Works Cited Cohen, Philip. “Fat Stem Cells Heal Broken Skulls”. NewScientist.com. 13 April 2004. 17 April 2006. <http://www.newscientist.com/news/news.jsp?id=ns99994873. Gilbert, M. David. “The Future of Human Embryonic Stem Cell Research: Addressing Ethical Conflict With Responsible Scientific Research”. Med Sci Monit. 10(5). 1 May 2004. RA99-103. 17 April 2006. <http://www.MEDSCIMONIT.com/pub/vol_10/no_5/4448.pdf Green, M. Ronald. “The Stem-Cell Debate”. Part 1. NOVA Online "Life's Greatest Miracle". Comp. Lexi Krock. November 2001. 17 April 2006. <http://www.pbs.org/wgbh/nova/miracle/stemcells.html. ---. “The Stem-Cell Debate”. Part 2. NOVA Online "Life's Greatest Miracle". Comp. Lexi Krock. November 2001. 17 April 2006. <http://www.pbs.org/wgbh/nova/miracle/stemcells2.html. National Human Genome Research Institute. Cloning/Embryonic Stem Cells. By Kathi E. Hanna, M.S., Ph.D. October 2004. 17 April 2006. <http://www.genome.gov/10004765. Parson, B. Ann. The Proteus Effect. Washington, D.C.: Joseph Henry Press. 2004 Reaves, Jessica. “The Great Debate Over Stem Cell Research”. Time. 17 April 2006. <http://www.time.com/time/health/article/0,8599,167245,00.html. National Institutes of Health. Glossary [Stem Cell Information]. 10 June 2004. 17 April 2006. <http://stemcells.nih.gov/info/glossary.asp.