An allogeneic transplant uses stem cells from a donor. The donor must closely match the patient's human leukocyte antigen (HLA) tissue type.
Stem cells may be collected from different types of donors:
- A sibling. This donor is called a matched related donor (MRD).
- A matched unrelated donor (MUD). A worldwide registry called the National Marrow Donor Program (NMDP) http://marrow.org/Home.aspx coordinates and oversees donations from unrelated donors.
- Cord blood. If a patient does not have a related or unrelated matched donor, they may be able to use cord blood. Stem cells are collected and stored from a newborn infant's placenta or umbilical cord after birth. These cells are kept frozen (cyropreserved) in an umbilical cord blood bank and are readily available.
Finding the Best Donor
It is very important to find the best donor for the recipient. Finding the best donor will lower the recipient's chances of developing graft-versus-host disease (GVHD). GVHD occurs when the immune cells given from the donor recognize the patient as foreign and attack the patient's tissues.
The best donors are identified using a test called human leukocyte antigen (HLA) testing. HLAs are proteins on the surface of most cells in the body. The proteins help the body tell the difference between normal cells and foreign cells.
Genes that produce HLA proteins are inherited by an individual. A person has a 1 in 4 chance of inheriting the same HLA pattern as his or her parents. Therefore, siblings that have the same parents have a 25% chance of inheriting the same pattern. If this occurs, the brother or sister can be identified as the best donor.
Once the donor is identified, the patient's doctors will determine the best source of stem cells from the donor—either the donor's bone marrow or peripheral blood. The donor's bone marrow levels or peripheral blood stem cell levels are back to normal within 4-6 weeks.
Types of Stem Cell Donation
There are two methods of donation: peripheral blood stem cell (PBSC) and bone marrow. The patient's doctor chooses the donation method that is best for the patient.
- PBSC donation: This procedure is non-surgical. It takes place at an outpatient hospital unit or at a blood center.
- Before the stem cell collection, the donor receives injections that increase the number of stem cells in the peripheral bloodstream.
- The donor's blood is then removed through a needle in the arm. This procedure is called leukopheresis or apheresis. During this process the donor's cells are passed through a machine that separates out and collects the stem cells, or blood-forming cells.
- The rest of the cells are returned to the donor.
- Bone marrow donation: This is a surgical procedure and must take place at a hospital.
- The donor receives anesthesia so no pain is experienced.
- The physician collects the stem cells from the donor's bone marrow through a needle.
- The liquid bone marrow is drawn through the needle from the pelvic bone.
The Transplant Process
Preparative Transplant Regimen
All transplant patients are placed on drugs that suppress the immune system to avoid the donor's cells rejecting their host. Depending on your transplant regimen, you will receive high doses of chemotherapy and/or Total Body Irradiation (TBI). These will destroy your disease and prepare your marrow for new stem cells. Unfortunately, these two therapies not only destroy the cancerous cells, they will also harm other healthy cells in you bone marrow.
Immunosupressive drugs are given to weaken your immune system in order to prevent and control graft versus host disease (GVHD). GVHD is caused when the donor’s immune system (graft) attacks your body’s own tissues (host) because the new cells from the donor do not recognize the tissues and organs of your body.
After your chemotherapy and/or TBI treatment, the bone marrow or stem cells will be infused.
The day of infusion of stem cells is referred to as Day 0. You will hear all days prior to your transplant referred to as a negative days. For example, you may receive chemotherapy/TBI on Day -6 through -1. All days post-transplant are considered positive. This time can vary from day +12 to day +18.
The infusion of stem cells will be much like a blood transfusion. The stem cell technician will thaw the frozen stem cells, and your nurse will administer them.
The new stem cells will migrate from the bloodstream to the bone marrow spaces. From here, the transplanted stem cells will begin to create new cells. This process is called engraftment. We will do lab tests on your blood often to see if you have engrafted.
Your immune system will be very weak at this point. Expect to be placed on several preventive medications during this period, such as antibiotics, antivirals, and antifungals. Your nurse will check your temperature often for fever, as fever is a sign of infection.
In the days after transplant, patients usually experience side effects from chemotherapy:
- Mouth sores
You will receive instruction and education on ways to prevent some of these side effects, as well as ways to help minimize them.
Engraftment means that the stem cells have started producing their own white blood cells, red blood cells, and platelets. After your transplant, we continually do tests to see how many neutrophils, a type of white blood cell, are in your blood. This test is called an absolute neutrophil count (ANC). When your ANC is more than 500 for three consecutive days, engraftment has occurred.
Engraftment date varies from person to person and depends on the kind of transplant that you had. Once you have engrafted, your health care team will start taking away some of your preventive medications.
If you have been staying in the hospital, you will be discharged when your health care team determines you are well enough. You will still be in recovery, however. You are still at risk of infection, and you will need a caregiver to help you at home 24 hours every day for at least 100 days after your transplant.
Most patients after discharge will continue to struggle with infections, nausea, diarrhea, or problems with graft-vs-host disease. The BMT outpatient clinic and home health care agency can provide additional IV medications, blood transfusions, and fluids as indicated after discharge. You may also need to be re-admitted to the BMT inpatient also.
100 Days after Transplant
We will do lab tests 100 days after transplant. This is called your day +100 workup. This workup will tell us if you are ready to have immunosuppressive medications tapered. The workup will also tell us whether you can return home if you have been temporarily staying in the Salt Lake area.
Once BMT physicians have determined that you are stable, you may return to your local or referring oncologist for care.
You will no longer be required to have a 24-hour caregiver, but you are still at risk of infection. Good hand washing and wearing your BMT mask in crowds is required.
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