Stem Cell Collection – University of Utah Internal …

A bone marrow transplant is done by transferring stem cells from one person to another. Stem cells can either be collected from the circulating cells in the blood (the peripheral system) or from the bone marrow.

Hematopoietic stem cells, or progenitor cells, are the very young or immature cells from which all blood cells are produced. The stem cells are formed in the bone marrow (the spongy cavity in the center of large bones). Each stem cell receives chemical signals that direct it to become a red cell, one of several kinds of white cell, or a small cluster of platelets. This growth process occurs in the bone marrow space, and normally only mature cells are released into the peripheral blood stream.

Hematopoietic stem cells may be harvested directly from the bone marrow, or collected from peripheral blood after the stem cells are mobilized from the bone marrow. The choice is determined by a number of factors such as the patients stage and type of disease, the treatment plan, or the donors age.

Peripheral blood stem cells are collected by apheresis, a process in which the donor is connected to a special cell separation machine via a needle inserted in the vein. Blood is taken from one vein and is circulated though the machine which removes the stem cells and returns the remaining blood and plasma back to the donor through another needle inserted into the opposite arm. Several sessions may be required to collect enough stem cells to ensure a chance of successful engraftment in the recipient.

Bone marrow harvesting involves collecting stem cells with a needle placed into the soft center of the bone, the marrow. Most sites used for bone marrow harvesting are located in the hip bones and the sternum. The procedure takes place in the operating room. The donor will be anesthetized during the harvest and will not feel the needle. In recovery, the donor may experience some pain in the areas where the needle was inserted.

Autologous donors are treated with appropriate therapy by their oncology doctor, and then referred to the bone marrow transplant program for evaluation and collection. Allogeneic donors, when needed, are identified by tissue typing and matching with the recipients tissue type.

A workup is done on all donors to assess their health status. The routine workup includes a physical examination, health history questions, blood tests, chest x-ray, and electrocardiogram (EKG). Regulations require that stem cell donors be tested for the same infections diseases as any other blood donor. These tests are for hepatitis, HIV (AIDS), Human T-cell leukemia (HTLV), syphilis, and other viral diseases such as cytomegalovirus, herpes, and West Nile. A sample from the donor must be tested within 30 days of each collection. The results are reviewed by the transplant physician, and the donor is given the opportunity to discuss the workup and ask questions prior to giving consent for the stem cell collection. The donor is then scheduled for mobilization and collection.

Mobilization, or priming, is the process used to stimulate the donors marrow to produce extra stem cells and release them into the peripheral blood. This is done by giving injections or shots of a growth factor called Neupogen or G-CSF. Autologous donors may receive a combination of chemotherapy plus growth factor, or growth factor alone. Allogeneic donors receive growth factor only. Priming is required for peripheral stem cell collections and generally not used for bone marrow harvest collections.

Autologous donors may have a widely variable response to priming. When chemotherapy plus growth factor is used, the last day of chemotherapy is called day 1, Neupogen shots start on day 6, and the average time to begin collection is day 1012. However, a longer time or additional growth factors may be required for adequate mobilization. Priming with growth factor alone is usually done for 4 days and collections begin on day 5.

The priming for allogeneic donors is usually scheduled to coincide with the recipients treatment so that the collections occur when the patient is ready to receive the stem cells. The donor receives G-CSF for 3 or 4 days, depending upon the patients treatment plan, prior to start of collection on day 4 or 5.

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Stem Cell Collection - University of Utah Internal ...