stem cells :: essays research papers

  Ã‚  Ã‚  Ã‚  Ã‚  After a typical delivery the umbilical cord and the blood within it is discarded. Now researchers have discovered that this blood contains valuable stem cells which can be used in the treatment of several blood disorders. Stem cells are simply undeveloped cells that develop into platelets or red and white blood cells. Stem cells will continue to produce blood cells for an indefinite period of time after transplantation. Until the discovery of stem cells in umbilical cord blood and placentas, bone marrow stem cells were the primary means available to those in need of a transplant. The harvesting process for bone marrow stem cells involves anesthesia, and major surgery with a collection time of up to four hours. Cord blood stem cells can be harvested directly from the already detached umbilical cord and placenta in about five minutes, with no pain, anesthesia, or patient risk. There are two types of cells used in stem cell transplantation. Haemopoietic stem cells co me from umbilical cord blood. Bone marrow stem cells are known as autologous. Stem cell transplants are necessary after a patient has undergone a radical treatment such as chemotherapy. While these treatments destroy unhealthy cancerous cells, they also destroy otherwise healthy cells that are needed to maintain a strong immune system. Stem cells from cord blood transplants typically fail for one of two reasons. The first occurs if chemotherapy fails to kill the pre-existing tumor, and the second if the newly introduced graft becomes infiltrated with tumor cells. Stem cells from umbilical cord blood do have a few downsides. First, the available collectable volume is not typically enough to reestablish an adult immune system. Most adults and older children are not suitable for cord blood transplantation. Also, there is not enough blood to create a reserve in case of unsuccessful engraftment. Only small amounts of blood can be obtained from umbilical cords, so recipients are tradition ally children who require fewer stem cells than adults. One advantage of cord blood is that it does contain significant numbers of stem cells that can be stored indefinitely. It also poses no medical risks to the donor, and has a low graft-versus-host-disease (GVHD) threat even when combined with a non-matched donor. Minority children stand to gain the most benefits from umbilical cord blood (UCB) because there is such a small reserve of donated minority blood and exact matches aren’t always necessary with cord blood.