The first step in planning for an allogeneic transplant is to find a suitable donor. This is done through the process of Human Leukocyte Antigen (HLA) Typing. People often assume that if their blood type matches, then their HLA types much match, but this is not the case. HLA typing is a molecular laboratory test done off of a blood sample that looks at DNA structure. Since you receive DNA from your parents we look first at any siblings you may have since it is likely (a one in four chance) that you would match one of them. If not, or if you have no siblings, there are unrelated donor registries that can be searched to find potential HLA matched donors.
Sibling donor typing will be facilitated through the transplant coordinator a plan to come to our hospital or clinic to have blood drawn. For siblings living outside the Denver metro area, there are kits for the testing. The cost of the HLA typing itself will be covered by the transplant recipient’s insurance, if a blood draw is required of a physician's office or clinic that draws the blood will be the responsibility of the donor.
Sibling typing is done in two stages. If you and your sibling match after the first level of molecular typing is complete, we will have a second level of molecular typing performed on the original sample. No additional blood will need to be obtained to do this. It is only after this second level that we can truly identify a donor. If your sibling does not match you at the first level, they will not be a suitable candidate to be your donor and therefore no further testing will be done.
If we find that no siblings match, there is always the option of an unrelated donor. Since we will have your typing complete, we will run a preliminary search of the National Marrow Donor Program unrelated donor registry. This is free of charge and gives us an idea of the potential availability of an unrelated donor. If this is the route chosen, we look more in depth at donors on the registry and have samples of their blood sent to our laboratory to confirm HLA typing.
Once a donor has been found for you whether it is related or unrelated, each donor goes through a health history and physical and has comprehensive lab work done to assess their suitability to be a donor. At times the findings from this workup will make a person NOT eligible to donate. Some of the findings include the presence of hepatitis, HIV, blood disorders, etc.
The actual donation process for the related donor requires that he/she be in Denver for 7-10 days. This depends on whether the physician wants to use blood stem cells or marrow stem cells for the transplant. Marrow stem cells are obtained during a surgical procedure under general anesthesia where the marrow cells are “harvested” from the pelvic bones. Blood stem cells are collected by a process called apheresis. For this, the donor undergoes a series of daily Neupogen injections to make the stem cells move from the bone marrow out into the blood stream to be collected by the apheresis process.
Apheresis is the procedure used to collect stem cells from the peripheral blood. This takes place at P/SL Medical Center. The Collection of stem cells takes 1-2 days for approximately 4 hours each morning from 7:00 a.m. to 11:00 a.m. A physician or advanced practice provider will see donors each day prior to being connected to the apheresis machine (cell separating machine). As a donor, your blood will be withdrawn from an intravenous catheter (IV) placed in one of your arms. It is circulated through the machine, which will separate out the stem cells and return the remaining blood back to you via a second IV in your other arm. There is only a small amount of your blood (a little over one cup) in the separator machine at any given time.
There are very few side effects associated with this procedure. The main side effects are:
- Numbness/tingling of the fingers or toes
- Numbness/tingling of the skin, especially the lips
- Feeling very cold
- Muscle cramps
All of theses symptoms can be a sign of low calcium in your blood. This is due to Citrate, a calcium-binding substance used during the collection of your stem cells to prevent your blood from clotting while it is circulating through the machine. We encourage you to eat breakfast prior to donating. If you eat calcium-rich foods such as milk, yogurt, or cheese, some of the symptoms mentioned may be prevented. Alert the apheresis staff if you experience any of the above symptoms or have any other concerns.
During the time you are undergoing apheresis, daily lab tests are done to count the number of stem cells collected. Each patient has a target goal of stem cells to collect from the donor. It may take more than one day to attain this goal. The apheresis staff will notify donors when the target goal has been met. The ideal number of stem cells for transplant is 2 million.
Donated stem cells are most often given to the recipient on the same day they are collected from the donor. Fresh stem cells are viable for 48 hours. In the event that all of the collected stem cells are not needed, the excess cells will be cryopreserved for possible future use.