Stem Cells





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 come 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 traditionally 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. The most promising discovery with umbilical cord blood is the lower risk associated with GVHD than traditional bone marrow transplants.
GVHD carries the biggest potential for complications in patients following bone marrow stem cell transplantation. Cord blood stem cells significantly lower a patients chance of this rejection of newly implanted cells. If a recipient of a stem cell transplant receives cells from a donor who does not match their tissue-type the result could be death. Families who have a history of disease should consider saving their babies cord blood. The banked cord blood can be instrumental in treating a blood disease or rebuilding a weakened immune system. Donated bone marrow is still the most prevalent in stem cell transplants although it is much more difficult to harvest.
New research reveals that cord blood from both matched and unmatched donors is successful when transplanted. With the discovery that cord blood stem cells have the ability to engraft with a non-matched donor, recipients are given hope in a shorter waiting process that doesn’t necessarily involve exact matching. HLA typing is done at the time of collection, which decreases the search time for a suitable recipient. There are six major HLA genes. The production of HLA proteins takes place on chromosome six. There is only a 25% chance that siblings will provide suitable donor stem cells to each other based on the matchings of theses HLA genes.





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