Standardizing stem cell enumeration: A methodological comparison of single and dual flow cytometry platforms.

Abstract

Two flow cytometry methods are used for stem cell (CD34⁺) enumeration; single platform (SP) and dual platform (DP). While several studies reported comparable results, others suggested superiority of the SP method. This study evaluated variations between both methods using a modified workflow. A total of 54 fresh and thawed specimens, including mobilized peripheral blood, apheresis products, and umbilical cord blood, were analyzed using both methods. High concordance between SP and DP methods was observed for absolute viable CD34⁺ counts in fresh and thawed specimens (p = 0.088 and 0.427, respectively), as well as for CD34⁺ viability (p = 0.085 and 0.801). Absolute viable WBC counts were comparable between methods in thawed specimens (p = 0.124), whereas a modest statistical variation was observed in fresh specimen group (p = 0.039), largely influenced by umbilical cord blood samples. Variation in absolute viable CD34⁺ counts remained within clinically acceptable limits, with median variations of 2.4 for fresh and 1.4 for thawed samples. SP and DP methods demonstrated high concordance for absolute viable CD34⁺ enumeration and CD34⁺ viability in fresh and thawed specimens. Although a modest variation in viable WBC counts was observed in fresh samples, this did not affect CD34⁺ enumeration and remained clinically acceptable. While SP provides a standardized approach, the DP method offered greater gating flexibility, with fewer technical resources required, and was approximately 70% more cost-effective, supporting its use as a practical alternative in appropriate laboratory settings.