Types of stem cells Essays - Biology, Stem Cells, Biotechnology

Types of stem cells Not all stem cells come from an early embryo. In fact, we have stem cells in our bodies all our lives. One way to think about stem cells is to divide them into three categories: Embryonic stem cells: grown in the laboratory from cells found in the early embryo Tissue stem cells: found in our bodies all our lives Induced pluripotent stem cells, or reprogrammed' stem cells: similar to embryonic stem cells but made from adult specialized cells using a laboratory technique discovered in 2006 Embryonic stem cells : Embryonic stem cells (ESCs) cells have unlimited potential to produce specialized cells of the body, which suggests enormous possibilities for disease research and for providing new therapies. Human ESCs were first grown in the lab in 1998. Recently, human ESCs that meet the strict quality requirements for use in patients have been produced. These clinical grade' human ESCs have been approved for use in a very small number of early clinical trials. One example is a clinical trial carried out by The London Project to Cure Blindness , using ESCs to produce a particular type of eye cell for treatment of patients with age-related macular degeneration. The biotechnology company ACT is also using human ESCs to make cells for patients with an eye disease: Stargardt's macular dystrophy. Current challenges facing ESC research include ethical considerations and the need to ensure that ESCs fully differentiate into the required specialized cells before transplantation into patients. If the initial clinical trials are successful in terms of safety and patient benefit, ESC research may soon begin to deliver its first clinical applications. [1] Tissue stem cells : Many tissues in the human body are maintained and repaired throughout life by stem cells. These tissue stem cells are very different from embryonic stem cells. Blood and skin stem cells : Stem cell therapy has been in routine use since the 1970s! Bone marrow transplants are able to replace a patient's diseased blood system for life, thanks to the properties of blood stem cells . Many thousands of patients benefit from this kind of treatment every year, although some do suffer from complications: the donor's immune cells sometimes attack the patient's tissues (graft-versus-host disease or GVHD) and there is a risk of infection during the treatment because the patient's own bone marrow cells must be killed with chemotherapy before the transplant can take place. Skin stem cells have been used since the 1980s to grow sheets of new skin in the lab for severe burn patients. However, the new skin has no hair follicles, sweat glands or sebaceous (oil) glands, so the technique is far from perfect and further research is needed to improve it. Currently, the technique is mainly used to save the lives of patients who have third degree burns over very large areas of their bodies and is only carried out in a few clinical centers. Cord blood stem cells : Cord blood stem cells can be harvested from the umbilical cord of a baby after birth. The cells can be frozen (cryopreserved') in cell banks and are currently used to treat children with cancerous blood disorders such as leukemia, as well as genetic blood diseases like Fanconi anemia. Treatment of adults has so far been more challenging but adults have been successfully treated with double cord transplants. The most commonly held view is that success in adults is restricted by the number of cells that can be obtained from one umbilical cord, but immune response may also play a role. One advantage of cord blood transplants is that they appear to be less likely than conventional bone marrow transplants to be rejected by the immune system, or to result in a reaction such as Graft versus Host Disease . Nevertheless, cord blood must still be matched to the patient to be successful. There are limitations to the types of disease that can be treated: cord blood stem cells can only be used to make new blood cells for blood disease therapies. Although some studies have suggested cord blood may contain stem cells that can produce other types of specialized cells not related to the blood, none of this research has