Single Platform Enumeration of viable CD34+ Cells

PURPOSE This procedure gives instructions for enumeration of CD34 positive cells in peripheral blood, cord blood, bone marrow or apheresis product. POLICY • All specimens for CD34 analysis should be tested within 24 hours of collection. Samples stored overnight should be held at 4°C. • It is recommended that all specimens for CD34 analysis be tested with 7-AAD regardless of sample type or age, due to the variable presence of non-viable cells CLINICAL SIGNIFICANCE and INTERPRETATION The pluripotent stem cell responsible for long-term hematopoiesis resides in the CD34 positive cell compartment. True pluripotent stem cells along with CD34 positive progenitor cells are mobilized into the peripheral blood by high dose chemotherapy and/or cytokine treatment. In the autologous setting, harvesting these cells enables the clinician to treat cancer patients with higher doses of chemotherapy, causing total bone marrow ablation with the intention of ridding the body of cancerous cells. In the allogeneic setting, normal donors are the source of CD34 cells. Although individual patient response is variable, harvesting is normally performed 3 to 5 days after mobilization with G-CSF alone. If the CD34 absolute count in the peripheral blood is low (<10 x 106/L) the yield in the apheresis product will also be low. The target number of CD34 cells to be collected is 2-5 x 106/kg body weight. This number has been shown by others to be sufficient for long-term repopulation of bone marrow in cancer patients.