You usually have stem cells from another person (a donor) in acute lymphoblastic leukaemia (ALL). This is called an allogeneic transplant or allograft.
You might have stem cells from:
- a brother or sister (sibling match)
- a person unrelated to you whose stem cells are similar to yours (matched unrelated donor or MUD)
- cord blood stem cells (umbilical cord)
Usually, the team collects stem cells from your donor’s bloodstream (peripheral blood stem cell harvest). But occasionally they collect the stem cells directly from the donor’s bone marrow.
You might have a stem cell transplant using stem cells from umbilical cord blood. Doctors take blood from the umbilical cord and placenta that is very rich in stem cells. The blood bank may give the donated stem cells to a person whose blood cells closely match the donated cells.
Cord transplants are mostly used for children because a smaller amount of cells are collected. You could have a stem cell transplant from 2 different umbilical cords. This is called a double cord transplant.
Finding a donor
Your doctor can test your brothers or sisters if you have them to see if they are a match. Or they can search national and international databases to try to find an unrelated match. They see how many particular proteins on the surface of the cells match yours. This is called tissue typing or HLA matching. HLA stands for human leucocyte antigen.
Having your own stem cells (autologous stem cell transplant)
You might have your own stem cells back after high dose treatment instead of using a donor’s. But this is rare for ALL. This is called an autologous stem cell transplant or autograft.
Stages of a donor stem cell transplant
Preparation and finding a donor
Your medical team look for and test possible donors.
To prepare you for your transplant, you have various tests. Closer to the time of the transplant you have a central line put in if you haven’t got one already. You might also need a feeding tube.
You may have chemotherapy before your high dose treatment.
Donor’s stem cell collection or harvest
Once your donor is found, the transplant team prepare them for their donation of stem cells.
Your donor has injections of a growth factor if they are going to have stem cells collected from their bloodstream (peripheral blood stem cell collection). The growth factor makes the stem cells in the bone marrow spill out into the bloodstream. When there are enough stem cells, the transplant team collects them from their bloodstream.
Your donor will need a general anaesthetic if they are having stem cells taken directly from their bone marrow. A doctor puts a needle into their hip bone to remove the bone marrow.
Your high dose treatment and having your donor’s cells
When a donor is found, you have high dose treatment also called conditioning treatment. This involves having high dose chemotherapy. You might also have whole body radiotherapy or a targeted cancer drug, or both.
You then have the donor's stem cells through a drip into your bloodstream.
Blood count recovery
The stem cells find their way to your bone marrow where they start to make blood cells. This recovery of blood cells is called engraftment.
Blood count recovery depends on the type of transplant you have. It can take around 2 weeks to see some blood count recovery with peripheral blood stem cells, 3 weeks with bone marrow stem cells and about 4 weeks with cord blood stem cells.