stem cell.docx

Therapeutic Cloning When people think of the word cloning they are often hit with frightening images of duplicate human beings being created in somewhat of a mad scientist style experiment. In fact, many members of the public were outraged when Dolly the sheep resulted from a cloning experiment in Scotland. Therapeutic cloning, however, is entirely different and does not involve the creation of a perfectly copied human being. It is reproductive cloning that results in a copy of a specific human being. In therapeutic cloning, no sperm fertilisation is involved nor is there implantation into the uterus to create a child. How is Therapeutic Cloning Performed? Therapeutic cloning is another phrase for a procedure known as somatic cell nuclear transfer (SCNT). In this procedure, a researcher extracts the nucleus from an egg. The nucleus holds the genetic material for a human or laboratory animal. Scientists then take a somatic cell, which is any body cell other than an egg or sperm, and also extract the nucleus from this cell. In practical human applications, the somatic cell would be taken from a patient who requires a stem cell transplant to treat a health condition or disease. The nucleus that is extracted from the somatic cell in the patient is then inserted into the egg, which had its nucleus previously removed. In a very basic sense, its a procedure of substitution. The egg now contains the patients genetic material, or instructions. It is stimulated to divide and shortly thereafter forms a cluster of cells known as a blastocyst. This blastocyst has both an outer and inner layer of cells and it is the inner layer, called the inner cell mass that is rich in stem cells. The cells in the inner cell mass are isolated and then utilised to create embryonic stem cell lines, which are infused into the patient where they are ideally integrated into the tissues, imparting structure and function as needed. Benefits of Therapeutic Cloning A major benefit of therapeutic cloning is that the cells removed are pluripotent. Pluripotent cells can give rise to all cells in the body with the exception of the embryo. This means that pluripotent cells can potentially treat diseases in any body organ or tissue by replacing damaged and dysfunctional cells. Another distinct advantage to this type of therapy is that the risk of immunological rejection is alleviated because the patients own genetic material is used. If a cell line were created with cells from another individual, the patients body would be more likely to recognise the foreign proteins and then wage an attack on the transplanted cells. The ultimate consequence would be a rejected stem cell transplant. This is one of the major challenges of organ transplants, alongside the fact that there is a huge shortage of available organs for those who require the procedure. This means that therapeutic cloning has the potential to dramatically reduce the wait times for organ transplants as well as the immunological concerns associated with organ transplant therapy. Therapeutic cloning is also important to enhancing our understanding of stem cells and how they and other cells develop. This understanding can hopefully lead to new treatments or cures for some of the common diseases affecting people today. In addition, the procedure would allow for scientists to create stem cell therapies that are patient specific and perfectly matched for the patients medical condition. Problems with Therapeutic Cloning One problem with therapeutic cloning is that many attempts are often required to create a viable egg. The stability of the egg with the infused somatic nucleus is poor and it can require hundreds of attempts before success is attained. Therapeutic cloning does result in the destruction of an embryo after stem cells are extracted and this destruction has stirred controversy over the morality of the procedure. Some argue that the pros outweigh the cons with regards to treating disease whilst others have likened the destruction to an abortion. Still others state that this doesnt change the fact the embryo could potentially be a human being and so destruction of the embryo is no different than destruction of a human life. Because reproductive cloning does utilise SCNT as the primary step, there is also still fear that given our knowledge base to perform reproductive cloning, a scientist may attempt to move beyond therapeutic cloning to creation of a human being. To this date, no human being has been successfully cloned but the possibility of this occurring is a frightening one not only for the general public and policy makers, but also for most of the ethical scientific field. The majority of scientists are adamantly opposed to reproductive cloning and instead, support therapeutic cloning for treating disease. With policies and careful monitoring in place to ensure that therapeutic cloning is used responsibly, we can all benefit from the potential of this procedure to eventually treat, or perhaps one day cure, many diseases. Why Perform a Stem Cell Transplant? Although many people may think of a transplant to mean replacing a diseased organ with another one, such as in heart or liver transplants, stem cells have an important and often life saving use for treating disease. A stem cell transplant doesnt involve surgery in the same sense as an organ transplant and the procedure is simplistic in comparison. Its benefit, however, can be just as enormous. What is a Stem Cell Transplant? In basic terms, a stem cell transplant is the infusion of healthy cells to replace diseased or damaged ones. If successful, the healthy replacement stem cells will integrate into the body and give rise to more cells that can all take on the necessary functions for a specific tissue. Current Stem Cell Transplant Treatments There are current treatments that have shown success over the years and it is anticipated that the therapies will be further refined to improve success rates. Cancer Cancer, particularly leukaemia, is an important disease for stem cell transplants; bone and peripheral blood stem cell transplants have been used for decades. A patient receives chemotherapy or radiation treatment to destroy the cancer cells but unfortunately, healthy cells are also damaged. A stem cell transplant can replace the lost and damaged cells with fresh, functioning ones, which can then provide the red blood cells, white blood cells and platelets that are important to metabolism, clotting and immunity. The other benefit of this treatment is that the newly formed white blood cells can further improve immune function such that they destroy any remaining cancer cells in the marrow. Aplastic Anaemia Aplastic anaemia is a condition that is not cancerous but rather, involves a reduction in the production of blood cells by the bone marrow. A stem cell transplant can replace the dysfunctional marrow with new functioning stem cells. These stem cells then travel from the bloodstream to the marrow where ideally, they begin to work properly and produce healthy working blood cells. Potential Future Transplant Treatments Success has already been shown in studies with stem cell transplants for a variety of diseases but more research is required before these can be performed regularly. Some of the diseases that could benefit from stem cell transplants are: Parkinsons disease - replacing destroyed brain cells with healthy ones. Type I diabetes - providing viable functioning stem cells for the pancreas. Retinal diseases - transplanting stem cells to replace those in the retina that have been damaged by disease.What Are The Risks? Stem cell transplants still have several risks associated with the procedure. Some people will find they experience few issues while others may require consistent monitoring and repeated hospital stays. Some of the complications that can occur with a stem cell transplant are: Damage to organs or blood vessels Graft versus host disease DeathThus, although some people will experience few complications, others may find they suffer from short and long-term problems associated with a stem cell transplant. The success varies widely and it is impossible to predict who will experience side effects and to what degree they will occur. In most cases, the benefits of stem cell transplants will likely outweigh the risk of complications and these techniques can truly be life-saving for conditions such as leukaemia and aplastic anaemia. It is hoped and anticipated that future research can yield successful therapies for a broader range of diseases. Peripheral Blood Stem Cell Harvestperipheral blood stem cell harvest is a technique used to restore a persons blood cells after they have been damaged by chemotherapy or radiation. The procedure is often used to treat patients with either leukaemia or lymphoma cancer. Because the chemotherapy or radiation treatment damages healthy cells alongside cancer cells a patient requires a viable source of blood-forming cells. Stem cells are able to generate the white blood cells, platelets and red blood cells that are important for functions such as oxygen transport, clotting and immunity.What Types Are There?There are three types of transplants that may be performed for a peripheral harvest: Autologous: a patient receives his or her own stem cells. Allogeneic: a patient receives stem cells from someone else-either a relative or an unrelated donor. Syngeneic: a patient receives stem cells from an identical twin.How Are The Peripheral Blood Stem Cells Obtained?The stem cells utilised in this procedure are obtained from the bloodstream in a process called apheresis. In the preceding week before apheresis is performed, a donor receives drugs to increase the number of stem cells in his or her bloodstream. During apheresis, the donors blood is removed, usually through the arm, and it flows through a machine that removes the stem cells. The blood then flows back to the donor while the extracted stem cells are then frozen until they are transferred to the recipient. The process usually lasts approximately five hours. How Are Peripheral Blood Stem Cells Given To The Patient?The patient is treated with either radiation or strong cancer drugs, before receiving stem cells through an intravenous line. After the stem cells are transplanted into the patient, they move from the bloodstream to the bone marrow. It is here that they produce healthy white blood cells, red blood cells and platelets. The process is called engraftment and it generally occurs over the two to four weeks following stem cell transplantation. Physicians will follow a patients progress by observing blood counts on a regular basis to ensure that the engraftment is successful. A complete recovery is much more long-term, however, and immune functioning can take months to years before it is fully recovered. Sometimes, bone marrow aspiration is performed, where a physician samples a small amount of bone marrow to provide a detailed assessment of the patients progress.Advantages of Peripheral Blood Stem Cell HarvestAlthough traditionally, all stem cell transplants that were initially performed were bone marrow transplants, peripheral blood stem cell transplants are now commonly used. It is often the case that more stem cells can be harvested from peripheral blood as opposed to bone marrow. In addition, the procedure for extracting cells from the donor is less taxing and complicated than a bone marrow stem cell harvest. Even more beneficial is the fact that the recipients blood count tends to replenish much more quickly in comparison with a bone marrow harvest. Therapies such as peripheral blood stem cell harvests are often life-saving. For those who have suffered from cancer or know someone who has battled the disease, stem cell treatments have provided a better chance of remission from the disease. Further research into new treatments as well as improving older ones will ensure that we stay on the path to a cure for cancer.New Harvesting Techniquesharvesting techniques are crucial to successful stem cell research because they provide greater opportunities to treat diseases in a more unique case-by-case basis. They also provide ways to overcome challenges with current techniques as well as extending stem cell therapies to diseases that may otherwise have been untreatable by current therapies. Perhaps even more important they offer a possible solution to the ethical conundrum that continues to plague stem cell research. Altered Nuclear TransferAltered nuclear transfer (ANT) may make it feasible for stem cells to be removed from embryos without destroying the embryo itself in the process. This could offer a way out of the current ethical dilemmas surrounding embryonic stem cell research. Normally, embryonic stem cells have been obtained by growing a human embryo into a cluster of cells that contain an inner cell mass. It is the inner cell mass that is abundant in the embryonic stem cells; after this inner cell mass is removed, the embryo is ultimately destroyed. Traditionally, embryonic stem cells were harvested by destroying the human embryo in a process called somatic cell nuclear transfer (SCNT). A somatic cell is simply a body cell that is neither an egg nor a sperm cell. In this procedure, the nucleus is removed from a somatic cell and it is then implanted into a donor egg that first had its nucleus removed. The egg cell is essentially fooled into thinking it has been fertilized. It has its own DNA and after stimulation, it divides just as a normally fertilized egg would, before forming an embryo. Cells from the inner cell mass are extracted and cultured to provide embryonic stem cells but the technique destroys the embryo. This process has, of course, generated much debate because the embryo could potentially have become a living person.ANT, however, prevents an embryo from actually being created. The nucleus of the somatic cell is altered, or genetically reprogrammed, prior to being transferred into the egg. The alteration consequence is that the somatic cell DNA still produces stem cells but does not generate an embryo.Blastomere ExtractionThis technique is one potential way around the ethical concerns that result from the destruction of an embryo. It is performed on a two-day old embryo, following the division of the fertilized egg into eight blastomeres, or cells. Previously, the techniques used for harvesting involving the derivation of embryonic stem cells at a later developmental stage, when the embryo is made up of approximately 150 cells. When these cells were harvested, the embryo was destroyed. It was found that embryonic stem cells could be extracted from blastomeres, which thus avoids the destruction of the embryo. The cell could be triggered to divide and the resulting stem cells could still be used for research and disease treatment.Further strengthening the research for this technique is the fact that in fertility clinics, the blastomere is already often removed for diagnostic tests to detect genetic abnormalities. The embryo, now with only seven blastomeres can still be implanted into the mother, assuming no defect has been found. These embryos then grow into healthy babies. Neither ANT nor blastomere extraction are perfect techniques but they do appease many of the ethical concerns surrounding stem cells and can pave the way for new techniques that may one day treat a disease that afflicts you or a loved one. The Challenges of Stem Cell TherapyStem cell therapy encompasses new technologies and therapies that aim to replace damaged cells with healthy new ones. Cells may be dysfunctional due to any number of reasons such as genetics, disease, injury or aging. Currently, stem cells offer the potential to treat cancer, Parkinsons disease, spinal cord injuries and diabetes, among other serious diseases. Unfortunately, there are several challenges faced by researchers that must be overcome before stem cell therapies can become a successful reality for those suffering from disease. Researchers do expect to eventually move beyond these challenges but the unfortunate reality is that those suffering from disease often have little time to wait for treatment.Identifying Stem Cells in Adult TissuesA major difficulty that scientists continue to encounter is the identification of stem cells in adult tissues. These tissues contain many different types of cells and an attempt to locate the often scarce numbers of stem cells in tissues that could contain thousands of different cells is difficult at best. The research involved is complex and even after cells are isolated, the process to successfully trigger differentiation into the desired cell type is another challenge for researchers. This requires an understanding of stem cell control and regulation that has yet to be fully gained. In addition, researchers must also use the correct laboratory medium, or solution, to coax the growth and this has proven to be difficult.Stem Cell IntegrationIf scientists do manage to identify, isolate and trigger the appropriate differentiate of stem cells, the cells still must be implanted into the patient and accepted among the native body cells. This success is therefore dependent on effective integration into the patients body systems and other cells. For example, if cardiac cells are implanted, they must be able to beat in sync with the patients own heart cells. For a patient who suffers from a neural based disease, any neural cells must integrate into the complicated network of natural neural cells if they are to effectively function and replace damaged cells. Immunological Rejection Immunological rejection is a major barrier to successful stem cell transplants. When a patients immune system views the transplanted cells as