What is Engraftment?

The Definition of Engraftment and What is Happening in Your Stem Cell Transplant

Neural stem cell culture. Credit: Riccardo Cassiani-Ingoni / Getty Images

Engraftment in stem cell transplantation is when your body accepts the transplanted bone marrow or stem cells and they begin to produce new blood cells and immune system cells. It is a step in a successful stem cell transplant.

What Happens During Stem Cell or Bone Marrow Transplant?

Blood cancers may be treated by killing your bone marrow and stem cells with radiation or chemotherapy to destroy the cancerous cells.

People with other types of cancer may also need a stem cell transplant because of the effects of radiation or chemotherapy. These treatments can have the side effect of damaging their bone marrow and stem cells, and if the damage is too extensive, a transplant is needed to restore the function of their bone marrow. Other people may need a marrow transplant due to accidental exposure to radiation or chemicals or other conditions that damage their bone marrow.

During stem cell transplantation, the bone marrow of the recipient is damaged by chemotherapy with or without radiation therapy to the point where it can no longer function. It is rendered unable to produce healthy red blood cells, platelets or white blood cells. In fact, the damage is so severe that the patient will die unless their marrow function is restored by an infusion of stem cells, either from a donor, or the patient's own cells that were previously collected and stored.

Once the donated stem cells are infused into the recipient, they find their way into the marrow space in the bones. When they are in place and begin to reproduce, engraftment occurs. The stem cells will create a new hematopoietic and immune system for the recipient.

What is Happening During Engraftment?

The stem cells or marrow is given as an intravenous transfusion.

The stem cells and bone marrow cells natually find their way into the bone marrow. It takes about two to four weeks before they begin to produce new blood cells. These include red blood cells, white blood cells and platelets. Once production begins, engraftment is said to have occurred.

Your complete blood count will be checked frequently to monitor whether engraftment is happening. A slow and steady increase in blood cell counts indicates that engraftment is occurring. Early on in the process, the complete blood cell count will show a rise in white blood cells and a shift from predominantly lymphocytes to neutrophils.

It can take months to as much as one to two years for a complete recovery of immune function after engraftment. It usually occurs faster for autologous transplants than for donor transplants. You will have blood tests to ensure the cells being produced are new cells rather than the cancer cells returning. You may also have a bone marrow aspiration to check on how the new marrow is working.

The final endpoint is a fully functioning bone marrow producing normal cell lines for red blood cells, white blood cells and platelets, including all of the different types of white cells - lymphocytes, granulocytes and monocytes.


McAdams, F., Burgunder, M. “Transplant Course” in Ezzone, S. ed. (2004) Hematopoietic Stem Cell transplantation: A Manual for Nursing Practice. Oncology Nursing Society: Pittsburg, PA.

Cutler, C. “Bone Marrow Transplantation” in Stern, T., Sekeres, M. eds (2004) Facing Cancer. McGraw-Hill: New York.

Blood-Forming Stem Cell Transplants , National Cancer Institute, August 12, 2013.

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