Apheresis units of stem cells used for transplantation in cancer patients do not all have the same potency. Does your collection center measure up?
Stem cell transplantation (SCT) restores hematopoietic systems damaged as a consequence of radiation/chemotherapy in cancer patients. Often times, health professionals collect and cryopreserve patients' autologous (their own) stem cells before undergoing cancer treatment. Other times, allogeneic (non-self) donors may provide the stem cells. We have also discussed using cord blood for SCT.
SCT is a procedure that carries high risks. Science continues to evaluate all parameters that affect SCT outcome so as to reduce those risks. One important consideration is the “potency” of the apheresis unit.
Apheresis is an outpatient blood donation procedure. First, patients receive a daily drug dose for a few days to “mobilize”, their stem cells from the marrow into peripheral blood. On “collection day,” blood from the donor is passed through a machine to separate out components. The peripheral blood mononuclear cell (PBMC) component is collected while everything else is infused back into the donor.
PBMC contains a small percentage of cells that express the CD34 cell surface protein. Stem cells and blood progenitor cells are contained within this CD34+ fraction. Therefore, the CD34+ cell count determines the “potency” of the apheresis unit and how well a patient will respond to SCT.
SCT with >5 million CD34+ cells/kg body weight results in excellent outcome for the patient. But how can one predict if an apheresis collection will deliver the required yield? In medical practice, the CD34 cell count in a donor's peripheral blood is taken to be the best indicator of when to start apheresis after mobilization. However, not all centers have access to the CD34 assay, which is specialized and costly.
Could a parameter from the complete blood count (CBC) assay be used instead as a predictive factor for apheresis yield? CBC is inexpensive and readily available at all centers.
A retrospective study was performed using data from 113 pediatric patients diagnosed with a dozen different cancers. CBC results collected up to 24 hr before apheresis were compared to the CD34+ yield upon apheresis.
There was a statistically significant difference between types of cancer diagnoses and CD34+ yield. However, there was no correlation between CD34+ yield and any of the CBC data, such as leukocyte count, hemoglobin level, platelet count, neutrophil count, lymphocyte count, or immature granulocyte count.
We at HemaCare are proud that our leukopheresis procedure allows for a cell-rich, superior product. We provide apheresis units for clinical use, manufacturing, and research. Our controlled and consistent collections enable quality assurance for our clients. We provide state-of-the-art services that include immunophenotyping, flow cytometry, and CD34+ assays.
- Garcia MP, Farias MG, Júnior CGdC. Analysis of predictive factors of complete blood count for a high-yield hematopoietic stem cell apheresis collection. J Mol Pathophysiol. 2014; 3(4): 47-51.