Hematopoietic stem cell (HSC) harvest apheresis is a special form of leukapheresis used to collect cells from the peripheral blood that can be used in bone marrow transplant.
UC San Diego Health System operates the largest HSC collection facility in San Diego County. The HSC harvest apheresis program is accredited by numerous organizations including the Foundation for the Accreditation of Cellular Therapy, the American Association of Blood Banks, the State of California and the U.S. Food and Drug Administration (FDA).
What are hematopoietic stem cells (HSCs)?
There are various types of stem cells. Hematopoietic stem cells, unlike embryonic stem cells, can be collected from the peripheral blood by apheresis. HSC are the progenitor cells that give rise to all the components of the bone marrow and immune system, including red blood cells, white blood cells and blood platelets.
What is HSC harvest apheresis used to treat?
Hematopoietic stem cell harvest apheresis is now the primary method for obtaining the cells that are transplanted in the procedure called bone marrow transplantation. This is used in the treatment of various types of leukemia, lymphoma and other cancers, and occasionally for certain genetic diseases that lead to anemia or immune deficiency.
As the name suggests, bone marrow transplant (BMT) originally required placing a needle into the interior of a bone to obtain these cells. Nowadays, in more than 90 percent of cases, equivalent cells can be collected from the bloodstream by HSC harvest apheresis, avoiding the painful and more complex procedure of bone marrow aspiration.
The HSC can be obtained from matched volunteers (often family members) for “allogeneic” BMT, or from patients themselves for “autologous” BMT. The apheresis procedures continue daily until the quantity of HSCs obtained has reached a predetermined target, which is the amount needed to subsequently reconstitute the patient's bone marrow and immune system.
Once sufficient HSCs are in the storage freezer, the patient undergoes chemotherapy in high enough doses to kill cancer cells. This will also wipe out their bone marrow and immune system, but is done in the secure knowledge that afterwards the patient can receive back their stored HSCs. After the HSC are given back by transfusion, the cells migrate to the bone marrow and begin the process of creating new blood cells, thereby rebuilding the bone marrow and immune system.
HSC cell harvest apheresis process
Before the hematopoietic stem cell collection, you may receive injections of growth factors to increase the number of peripheral stem cells in the blood. On the day that the blood cell count has reached a sufficient level, blood is removed through a needle or catheter and circulated into a blood cell separator machine.
The blood is separated and mononuclear white blood cells and peripheral blood stem cells are transferred to a collection bag. They are saved and frozen. The other blood components (plasma, red blood cells, platelets) circulate back to the patient through a return needle. One or two HSC harvests are usually sufficient to obtain enough cells from normal allogeneic donors, but in autologous cases some patients may have to undergo three, four or more daily apheresis procedures.
Potential side effects
HSC harvest apheresis is a safe procedure with a few possible side effects. You may have discomfort at the needle site and occasional light-headedness during treatment. A nurse will check on you regularly during treatment and a physician will be onsite.