Education Corner

Stem Cells Transplantation

Stem cell transplant is the infusion, or injection, of healthy stem cells into your body to replace damaged or diseased stem cells. It may be necessary when:

  • Your bone marrow stops working and doesn't produce enough healthy stem cells.
  • High-dose chemotherapy or radiation therapy is given in the treatment of blood disorders such as leukemia, lymphoma or multiple myeloma.
  • Your body needed to make enough healthy blood cells and reduce your risk of life-threatening infections, anemia and bleeding.

Stem cell transplants can use cells from your own body (autologous stem cell transplant), from a donor (allogeneic stem cell transplant) or from an identical twin (syngeneic transplant).

Stem cells that turn into blood cells are called hematopoietic stem cells (HSCs). They are capable to develop into:

  1. red blood cells that carry oxygen
  2. white blood cells that fight infection
  3. platelets that help blood clotting

Hematopoietic stem cells can be found in bone marrow, the peripheral blood and/or the umbilical cord blood of newborn babies.

Types of Transplants

The two main types of stem cell transplants are autologous and allogeneic.

Autologous HSCs transplantation.

With this type of transplant, patients act as their own donor. That is, a patient who is about to undergo cancer treatment will have his or her own stem cells removed (harvested) or have cryopreserved his or her umbilical cord blood right after birth, and frozen for later use. After the child receives chemotherapy and/or radiation, the stem cells are thawed and put back into the child's body. Transplantation may be done once or many times, depending on the need. Sometimes doctors will use high doses of chemotherapy during treatment (kill as many cancer cells as possible) if they know a patient will be getting a stem cell transplant soon after.

Allogeneic HSCs transplantation.

With an allogeneic transplant, the stem cells come from a donor whose cells are considered a "match" for the patient. The process of finding a match is called HLA (human leukocyte antigen) typing. HLA is a protein on the surface of blood cells. Basically, the more "HLA markers" a child and the potential donor have in common, the greater the chance that the transplant will be successful.

Unlike autologous transplantation, there is a risk of a patient's body rejecting the donated cells. Donor cells can make immune cells that attack the recipient's body. This condition is called graft-versus-host disease (GvHD), and can be serious. Most cases are successfully treated with steroids and other medications.

Sources of HSCs

Three different sources of hematopoietic stem cells:

  1. Peripheral blood stem cells are harvested bloodstream.
  2. Bone marrow stem cells are collected from the donor's hip bone through a surgical procedure.
  3. Cord blood stem cells are collected immediately after a child is born.

Transplant itself will be done through infusion and healthy stem cells will be introduced to the patient's body. After the infusion, the patient will be watched very closely to make sure the new stem cells are settling into the marrow and beginning to manufacture new blood cells (engraftment). For allogenic transplantation, doctors will watch for any signs of GvHD in patients. During Engraftment (it usually take 1-6 weeks), patients will receive medicines to promote engraftment and prevent GvHD and rejection.

Recovery

Patients who receive stem cell transplants have a high risk of infection because during transplant is grafting, their immune systems are weakened and unable to fight bacteria and other germs that enter the body. Due to these risks, a patient who's had a stem cell transplant will not be released from the hospital until doctors are sure the transplant has successfully.