Clinical Applicability of Newly Developed Image-based Cell Counter for Counting CD34＋ Cells: Comparison with Flow Cytometric Analysis

Abstract

Background: Flow cytometric analysis is the standard method for enumerating CD34＋ stem cells in hematopoietic stem cell transplantation. However, it has some limitations such as expensive instrumentation, high reagent costs, and discrepancies between technicians and laboratories. We compared counts of total nucleated cells (TNCs) and CD34＋ cells counts obtained from a flow cytometer with a newly-developed image based microscopic cell counter (ADAM II) to evaluate the possibility of clinical application of the ADAM II.Methods: We used 18 samples of circulating peripheral blood (PB) and waste tube fractions of peripheral blood stem cells (PBSCs) harvested by apheresis after G-CSF mobilization from adult volunteer donors. We assessed the reproducibility and linearity of the new procedure and compared the numbers of TNCs and viable CD34＋ cells determined with the ADAM II and two different flow cytometers (FACSCalibur, FACSCanto II).Results: Numbers of viable CD34＋ cells determined with the ADAM II were accurate over the expected range; the intra-assay coefficient of variation was ≤19.8%. Linearity was also satisfactory (R2=0.99). TNC counts obtained with the ADAM II were highly correlated with those obtained with the FACSCalibur (R2＞0.9841, P＜0.0001) and FACSCanto II (R2＞0.9620, P＜0.0001), as were the numbers of viable CD34＋ cells obtained with the ADAM II and the FACSCalibur and FACSCanto II (R2＞0.9911, P＜0.0001 and R2＞0.9791, P＜0.0001), respectively.Conclusion: The newly developed image-based microscopic cell counter (ADAM II) appears to be suitable for enumerating TNCs and viable CD34＋ cells.