Stem cells Stem cells are ‘generic’ cells that develop into particular types of cells. So they may become nerve cells, muscle cells, blood cells… in fact, any cell in the body! Stem cells divide over and over to produce new cells.
Stem cells, bone marrow and blood cells One of the main places you find stem cells is in bone marrow. Stem cells in bone marrow produce new blood cells to replace those that have died. When the cells are mature they are released into the bloodstream. A ‘bone marrow’ donation is really a donation of stem cells. Bone marrow is found in the cavities inside the long and flat bones of the body.
Leukaemia Leukaemia is a form of cancer. • In the most common forms of leukaemia, one abnormal white blood cell continuously replicates (clones) itself. These abnormal white blood cells do not function properly: • They do not fight infections • They inhibit the production of other blood cells and platelets For some people, a bone marrow transplant can be a life-saver.
Transplants save lives Bone marrow transplants not only save the lives of leukaemia patients. They can also save the lives of those suffering from: • illnesses where the immune system does not function properly such as aplastic anaemia(where the bone marrow stops making enough blood cells) • rare genetic diseases such as osteopetrosis (where bones harden and become dense and bone marrow does not develop properly) • all kinds of cancers(where healthy stem cells have been damaged during treatments to destroy cancer cells)
Stem cell (“bone marrow”) donation There are three ways to collect stem cells from a donor: • Bone marrowA donor has a small operation under general anesthetic. • Circulating bloodA donor’s circulating stem cells are boosted with a special drug. Then they are connected to a cell separator machine, which collects the stem cells and returns the rest of the blood to the donor. • Cord bloodSelected hospitals offer new mothers the chance to donate the blood that remains in the placenta and umbilical cord after their baby’s birth.
Advantages / disadvantages for patients • Advantages: • Cord blood: • hasn’t been exposed to environment so less likely to contain viral infection; • requires less stringent matching; • once collected is banked and can be readily available at short notice. • Bone marrow and circulating blood: • tend to have a greater number of stem cells in the donation, so tend to be accepted into the patient’s body more quickly. • Disadvantages • Cord blood: • tends to have less stem cells in the donation. • Bone marrow and circulating blood: • finding a match and arranging a donation can take weeks, or months (this is time the patient may not have).
Finding a match • A bone marrow donor needs to be a close ‘tissue type’ match with the recipient • You can tell what someone’s tissue type by testing their blood • Tissue type is inherited but only 30% of donors are found from within a patient’s family • Patients are most likely to find a match from within their own ethnic community • So donors from all ethnic backgrounds are needed