As part of myeloma treatment, transplant refers to the infusion or administration of blood stem cells. It is therefore called a stem cell transplant or “SCT.” In the past the stem cells were obtained directly from the bone marrow. Now, growth factors are used to stimulate the release of stem cells from the bone marrow into the blood stream (peripheral blood). These peripheral blood stem cells are then collected or what is called harvested, meaning collected and set aside for use within the next few days or weeks or set aside, keep in the freezer and used at some much later date which can be years in the future.
Transplant or infusion of blood stem cells is used to rescue the bone marrow after the administration of very high dose chemotherapy such as with melphalan. The treatment is the high dose melphalan. The stem cell transplant is to repopulate or re-grow blood stem cells in the bone marrow since they have also been wiped out by the high dose melphalan.
Although this may sound like, and is, a delicate procedure, the details have been worked out over more than 2 decades now. The procedure is currently very safe when a patient’s own stem cells are used as the replacement cells: called autologous stem cell transplant (ASCT).
When stem cells are used from another source, such as a family member, this is called either a syngeneic transplant (if the family member is a matched twin) or an allogeneic transplant if another individual is involved (allotransplant or mini-allotransplant) if lower dose chemotherapy used.