How Have Gene Therapy and Stem Cell Technology Changed the Face of Medicine - Coursework Example

January 15, 2009 How have Gene Therapy and Stem Cell Technology changed the face of Medicine? Introduction Medical science has come a long way primarily because its history has been marked by a string of revolutionary inventions and discoveries in the field. The development of medical science has enabled humankind to overcome and defeat many threats to physical and mental health. In its war against germs attacking the body, medical science devised the lethal weapon of antibiotics; in surgery it was anesthetics and a wide range of surgical equipment and procedure; in matters of the brain and the nervous system too, there have been breakthrough technologies such as micro-surgery; in its fight against cancer, medical science has deployed weapons such as radiotherapy and chemotherapy. Yet, there are still numerous diseases that medical science has not been able to fully bring under its control and effect reasonable cures. Cancer, Alzheimer’s, Parkinson’s along with lifestyle diseases such as diabetes, hypertension and even the common cold continue to evade credible understanding and cure. In the last two decades two new developments in the field of medical science – gene therapy and stem cell technology – have emerged as radically new perspectives or approach to understanding many hitherto unexplained medical conditions and in finally finding the elusive cures for what has been termed as incurable. In many ways, individually and put together, they hold the potential of revolutionizing medical science itself. Defining Gene Therapy Gene therapy involves the introduction of genetic material into a cell to treat disease. Many of the conditions treated in this way are genetic diseases that occur when genes malfunction (Yogendra, 2005). Genes can be used in many ways to fight diseases. One approach of gene therapy consists of first identifying the malfunctioning gene that is responsible for causing a disease and then supplying the patient or replacing the malfunctioning gene with a functioning or healthy copy. Genes are switched on or off to inhibit a disease-causing condition as the situation warrants. Genes are introduced to kill diseased cells such as cancer, to cut off the supply of blood in order to suppress tumour growth, or to stimulate the functioning of the immune system to attack specified types of disease-causing cells. Genes are therefore used as medicines in gene therapy (Centre for Genetics Education, 2007). Gene therapy basically introduces therapeutic material in the targeted malfunctioning cells. This makes the cells active again and thereby exerts the required therapeutic effect. In gene therapy, the gene is delivered to the affected cell by the use of ‘vectors’. The use of harmless viruses as vectors is one of the most promising methods used to deliver genes into the affected cells. In this method, the virus’s own genes are removed and replaced with working human genes. In some cases, such virus vectors are capable not only of delivering the genes into the cell but also of inserting the gene into the genetic makeup of the cell (Centre for Genetics Education, 2007). Once in place inside the cell, the gene is switched on and it starts instructing the cell make the protein that was either missing or altered. Stem cells have also been effectively used to deliver gene therapy. Stem cells are essentially immature cells that differentiate or develop into cells with different functions. In this method, stem cells are induced to make them accept new genes that can result in change of behaviour of the cells. The changed cells can effectively act to cure or put a stop to the progress of a disease. Human cells are of two types – germ cells and somatic cells. The germ cells are reproductive cells located in the male testes and the female ovaries are responsible for passing on of hereditary properties and characteristics from one generation to another. All the other cells in the body are known as somatic cells and do not have any hereditary implications. Genetic therapy usually target somatic cells, but in certain cases germ cell manipulations have also been attempted in tests and experiments in a bid to correct hereditary defects or diseases along generations. However, the only approved gene therapy so far is for a form of cancer, approved in China in the beginning of 2004. An immune deficiency condition known as adenosine deaminase was the first to be treated with gene therapy in the early 1990s. It was also the first condition for which therapeutic gene transfer into stems cells was attempted in the clinical area (Candotti, 2001). Defining Stem Cell Technology “Stem cells are cells that can divide to produce either cells like themselves (self-renewal), or cells of one or several specific differentiated types. Stem cells are not yet fully differentiated and therefore can reconstitute one or several types of tissues” (McLaren & Hermeren, 2000). Found in multi-cellular organisms, including human beings, stem cells have the potential of finding a variety of effective medical applications. The biggest promise of stem cell technology lies in the ability of stem cells to replicate themselves through the process of mitosis into desired specialized cell types. These cells can then be used to replace damaged or diseased cells in the human body thus providing a cure to the disease afflicting the cells. There are three different basic sources of stem cell: embryonic stem cells obtained from a very nascent embryo; embryonic germ cells obtained from somewhat more mature foetal tissue; and adult stem cells collected from mature tissues. Embryonic stem cells and embryonic germ cells hold greater potential for medical applications as they have the ability to be differentiated into virtually any cell type. Adult cell types can however be differentiated into a narrower range of stem cells. With the ability to cultivate stem cells in vitro, artificial culturing of human stem cells could offer new insights into the development of cells and tissues that could not be observed directly in the human embryo or comprehended through clinical observation of animal models. Research on stem cells could shed more light on basic development biology and lead to better understanding of genetic problems such as abnormal births, pregnancy loss and infertility. Such studies could also provide answers to the complex processes of normal and abnormal human development. Stem cell technology could help in studying a wide range of human diseases on animal models. Animal stem cells, especially embryonic stem cells could be engineered to incorporated human mutated genes associated with particular diseases, and then transferred to the experimental specimen animals. If the treated animal manifests the same pathology of the human disease, then the human gene is not only identified as the root cause of the disease, but the strategy also provides a animal model of the human disease for conducting intensive research and further experimentations. Research based on this approach has been underway in the case of incurable diseases such as Alzheimer’s. Stem cells hold high promise for pharmacology, especially in rapid screening of a wide range of chemicals used in the production of medicines and other biomedical products. Stems cells provide a way to study the effect of drugs under trial on pure populations of specific differentiated cells. It could therefore be effective in sorting out medicinal products with negative or contrary effects at the cell level. As has already been mentioned, stem cells could be used as vectors for the delivery of gene therapy. There are several reasons why stem cells could be the ideal vectors in gene therapy. Since stem cells replicate or regenerate by themselves, the need for repeated gene therapy could be reduced or eliminated. Potential Application of Gene Therapy and Stem Cell Technology Though gene therapy and stem cell technology has not been approved for treatment on human patients except for the single case of a form of cancer in China, extensive experiments including clinical trials on animal specimen and even human beings have been carried out employing both the approaches individually or even together. This however does not imply that limited type of stem cell and gene therapy are not in use. Caner patients who undergo high dosage of chemotherapy or radiation therapy are often given a type of bone marrow transplant which is akin to stem cell transplant. The stem cells in the bone marrow replicate and give rise to red and white blood cells along with platelets thus replenishing the damaged tissue of the patient. In a procedure which can be viewed as the precursor of gene therapy, orthopaedic surgeons are already replacing damaged bone and are successfully transplanting cartilage and tendons. Donated bone or bone allograft has already been used in orthopaedic surgery. Ligament allograft has also been used in sports-related injuries to replace ligament in the knee (new-medical.net, 2004). Orthopaedics Orthopaedics is an area of medical science that gene therapy and stem cell technology hold special significance. A novel form of adult stem cell therapy could not only relieve the sufferings of patients who require the classical ‘autograft’ technique for fractures that refuses to heal properly, but could also prove to be a much less painful but more reliable form of treatment. In such cases, doctors have tried replacing ‘autograft’ with stem cell therapy with encouraging results. In certain cases, doctors have also experimented with transplanting adult donor stem cells to reduce the pain and risk of obtaining stem cells from the patient. Dr. Jimenez, one of only a handful of surgeons in the world performing the investigational surgery comments: "The beauty of these adult stem cells is that they can turn into almost any kind of cell, including bone cells and vascular cells. The surgeries weve conducted thus far have had promising results, and to-date, the patients are doing well." (new-medical.net, 2004) The University of Texas, MD Anderson Cancer Research has reported that they have found a new way to use stem cells as vector to deliver gene-based therapy to fight malignant bone tumours in paediatric patients. Studies on mice give strong indications that such a gene therapy could be used to directly target the tumour and thus avoid harrowing systemic toxicity from chemotherapy in children (MD Anderson News Release, 2008). Matters of the Heart Heart disease has been a leading cause of death not only in the United States but also in many other developing and developed nations of the world. According to a study conducted by the American Heart Association, the results of which was published in its journal Circulation Research it has been found that patients with specific types of muscular dystrophy could be able to maintain a healthy life with partial gene therapy or stem cell therapy. Patients with such muscular dystrophy have a gene mutation that disrupts the production of a specific protein. This leads to severe muscular degeneration resulting in severe heart disease and death. "In gene therapy, mutated genes are replaced with healthy genes. In stem cell therapy, diseased cells are replaced with healthy cells. However, in these gene and stem cell therapies, it is not feasible to fix every cell in the heart." (ScienceDaily, 2007) The same research has now found that a heart can function almost normally even with fifty percent of its tissues or cells intact. This finding implies that gene therapy and stem cell technology could be effectively used to treat ailing hearts. Cystic Fibrosis Cystic Fibrosis is a fatal genetic disorder common in Caucasians and is caused by the mutation of a gene in epithelial cells that line the airways to the lungs. Cystic Fibrosis causes frequent infections in the airways ultimately leading to the death of the patient. A report in the Proceedings of the National Academy of Sciences (PNAS) suggests that patients with cystic fibrosis could be treated with their own stem cells that have genetically manipulated. "Our results provide proof of principle that a cell-based therapy using marrow stromal stem cells is both a feasible and promising clinical approach. We plan to further investigate its potential and are hopeful that we can perform a small clinical trial within the next two to three years." (Kolls, 2004) Diabetes and other Chronic, Degenerative and Acute Diseases The economic and psychological implications of gene therapy and stem cell technology application for treatment of chronic, degenerative and acute diseases are enormous. In the United States "it has been estimated that up to 128 million people suffer from such diseases; thus, virtually every citizen is effected directly or indirectly. The total costs of treating diabetes, for example is approaching $100 billion in the United States alone." (Chapman, et. al. 1999) Stem Cell technology and Gene therapy could provide the answers to such degenerative and lifestyle diseases. In children with Type I diabetes, the pancreas stops producing the insulin needed to break down glucose. It has now been found that stem cells transplanted in such patients can be instructed to differentiate into a particular type of cell that could in turn produce the required insulin. Similarly Alzheimer’s disease is caused when cells that are responsible for the production of certain neurotransmitters die. In Parkinson’s disease, nerve cells that produce the chemical dopamine die. Even in spinal chord injury, brain tumor and strokes, different types of cells stops functioning or die. "Perhaps the only hope for treating such individuals comes from the potential to create new nerve tissue restoring function from pluripotent stem cells" (Chapman, et. al., 1999) Fighting HIV Even in the case of HIV which threatens to overrun the world, gene therapy or stem cell technology hold the potential to provide effective means to control the disease and treat patients effectively. As early as in 2006, researchers in the University of Pennsylvania conducted a clinical trial in which a disabled version of he HIV virus itself was used as a vector to deliver added genetic material to reduce or stabilize HIV levels in the blood of patients by blocking HIV reproduction. Genetic treatment together with stem cell technology could therefore provide an alternative to antiretroviral drugs for the treatment of AIDS (BBC News, 2006). Conclusion Genetic Therapy and Stem Cell Technology has the potential of eventually enabling medical science to grow life in the form of organs. This raises some interesting ethical concerns. Many feel that the freedom to create or manipulate living organs and life should be the exclusive preserve of the Almighty. Human beings should restrain themselves from tinkering with something that they are yet to fully comprehend. This has been the reason why genetic therapy and stem cell technology have been approached rather cautiously by a majority in the fraternity of medical sciences. Nevertheless there is no doubt that both these approaches hold the potential to change the face of medical science and make the quality of life much better for humankind. This could be turned into a practical reality as we begin to acquire a more holistic and complete knowledge of life and the living. Works Cited -01 BBC News, HIV gene therapy ‘shows promise’, November 6, 2006, http://news.bbc.co.uk/2/hi/health/6120042.stm Accessed January 18, 2009. Candotti, F., Gene therapy for immunodeficiency, 2001, Current Allergy and Asthma Reports, 1(5):407-415 Centre for Genetics Education, Gene Therapy, Fact Sheet, Australian Genetics Resource Book, 2007, p. 26 Chapman, A., R., Frankel, M., S., Garfinkel, M., S., Stem Cell Research and Applications, Monitoring the Frontiers of Biomedical Research, November 1999, American Association for the Advancement of Science and Institute for Civil Society. Kolls, J., K., professor of pediatrics, immunology and molecular genetics and biochemistry at the University of Pittsburgh School of Medicine and chief, Division of Pediatric Pulmonology and Laboratory of Lung Immunolgy and Host Defense at Children’s Hospital of Pittsburgh in Innovations Report, Forum for Science, Industry and Business, December 21, 2004, http://www.innovations-report.com/html/reports/life_sciences/report-38120.htmlhttp://www.innovations-report.com/html/reports/life_sciences/report-38120.html Accessed January 10, 2009 McLaren, A., Hermeren, G., Opinion of the European Group on Ethics in Science in Science and New Technologies to the European Commission, 2000, European Commission. MD Anderson News Release, Stem Cells deliver Gene Therapy to Bone Tumours in Preclinical Tests, August 12, 2008 http://www.mdanderson.org/departments/newsroom/display.cfm?id=3f960a50-319d-4bfd-99b67086e82711f0&method=displayfull&pn=00c8a30f-c468-11d4-80fb00508b603a14 Accessed January 12, 2009 news-medical.net, Stem cells, gene therapy, and allograft applications show promise for treating orthopaedic conditions, March 23, 2006 http://www.news-medical.net/?id=16826 Accessed January 15, 2009 ScienceDaily, Gene, Stem Cell Therapy only needs to be 50 percent effective to create a healthy Heart, November 2, 2007, http://www.sciencedaily.com/releases/2007/10/071031114315.htm Accessed January 17, 2009. Yogendra, S., Gene Therapy, Postnote, Parliamentary Office of Science and Technology, 7 Millbank, London SW1P 3JA, June, 2005, p. 3 Read More