stem cells that are also present in the marrow. To circumvent the problem of simultaneous severe damage to, and potential destruction of, normal blood stem cells in the bone marrow, the blood stem cells can be “harvested” (collected) and saved before melphalan is administered.
Figure 1. Blood vessel
Plasma
Platelets
© 2015 Slaybaugh Studios
Normal blood stem cells are collected from the patient or donor through a process called apheresis. The harvested normal Red blood cells blood stem cells are frozen at –80 degrees Celsius and can be stored indefinitely at that temperature. After the patient receives high-dose melphalan, White blood cells the frozen stem cells are defrosted and returned to the patient’s blood circulation by a process similar to blood transfusion. The stem cells pass from the circulating blood back into the bone marrow, where they divide and grow to repopulate, or “re-seed,” the normal bone marrow space. Approximately 36 to 48 hours after the melphalan is administered, the levels of melphalan in the blood and tissue are very low and do not harm the new stem cell growth. This whole process of harvest and re-infusion is called stem cell rescue, or stem cell transplant, because the stem cells “rescue” the bone marrow from the effects of the high-dose chemotherapy.
Types of stem cell transplant Autologous stem cell transplant (ASCT) “HDT with stem cell rescue” is the more accurate terminology. Stem cells are harvested from a patient with myeloma following initial therapy and re-infused after high-dose melphalan therapy has been administered. This is the most common type of stem cell transplant. The procedure can be performed once (single autologous transplant) or twice (double or tandem transplant), although tandem transplantation has become less common in the era of effective novel therapies. myeloma.org
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