Electronic volume, aldehyde dehydrogenase, and stem cell marker expression in cells from human peripheral blood apheresis samples

Abstract

Background: Over-expression of aldehyde dehydrogenase and other stem cell markers is characteristic of cells with tumorigenic potential in NOD/SCID mice. Most of these studies have focused on metastatic cells in bone marrow and on solid tumors. There are no studies on correlation of marker expression with ALDH1 expression in cells from human peripheral blood apheresis (HPC-A) samples. Methods: HPC-A samples from 44 patients were incubated with Aldefluor^® with or without the presence of aldehyde dehydrogenase inhibitor DEAB. Cells with high aldehyde dehydrogenase expression (ALDH1^bright) were analyzed for stem/progenitor markers CD34, CD90, CD117, and CD133. Electronic volume measured by Coulter principal in a Quanta flow analyzer was correlated with ALDH1 and marker expression. Results: In ALDH1^bright/SSC^low cells, 0.13% of the cells had CD34⁺ expression and three distinct populations were seen. Expression of CD90 was dim and the frequency of ALDH1^bright/SSC^low/CD90^dim cells amongst the nonlineage depleted samples was 0.04%. CD117^dim-bright expression was seen in 0.17% of the samples. Three distinct populations of cells with CD133 expression were seen in ALDH1^bright/SSC^low nonlineage depleted cells with a frequency of 0.28%. The ALDH1^bright/CD90^dim cells had the smallest mean electronic volume of 264.9 μm³ when compared with cells with CD34^bright expression (270.2 μm³) and ALDH1^dim/CD90^dim cells (223 μm³). Conclusions: ALDH1^bright/SSC^low cells show heterogeneity in expression of the four stem cell markers studied. The CD90 cells in both the ALDH1^bright and ALDH1^dim populations had the smallest mean electronic volume when compared with similar cells with CD117 expression. © 2010 Clinical Cytometry Society