Enumeration of viable CD34+ cells by flow cytometry in blood, bone marrow and cord blood: results of a study of the novel BD™ stem cell enumeration kit

Abstract Background aims Enumeration of CD34+ cells in leukocyte-rich cell suspensions is important for clinical decision-making in stem cell transplantation. Single-platform flow cytometry assays offer the significant advantages of speed and reproducibility, and have therefore become the gold standard in stem cell enumeration. The clinical community has recently defined the need for stem cell enumeration kits that incorporate viability dyes. The purpose of this study was to evaluate a novel assay, BD Biosciences’ (BD) stem cell enumeration kit (SCE kit ), in relation to Beckman Coulter's (BC) commercially available BC Stem-Kit™. Methods Fresh/freeze-thawed samples from leukapheresis, bone marrow and cord blood, and fresh normal/mobilized blood, were analyzed with both assays (simultaneous detection of side/forward scatter and three fluorescence signals) on two flow cytometry platforms, BD FACSCanto II and BD FACSCalibur. Results Results from both assays were highly congruent, with an overall r2 ≥ 0.99 (all specimen types included), a linear correlation across all CD34+ cell frequencies and concentrations, and an almost ideal steepness of the trend line. Conclusions Both assays functioned reliably. Being based on single-platform International Society of Hematotherapy and Graft Engineering (ISHAGE) guidelines and similar staining methods, both assays essentially come to identical results. For most specimen types, the viability of CD34+ cells was equal to overall leukocyte viability. In summary, in the hands of an experienced technician, the BD™ SCE kit and the BC Stem-Kit are equivalent. The infrequent user might derive benefit from the fact that counting spheres are pre-pipetted into the Trucount tube for the SCE kit, making this assay less susceptible to pipetting inaccuracy.