Exploring the heterogeneity of the hematopoietic stem and progenitor cell pool in cord blood: simultaneous staining for side population, aldehyde dehydrogenase activity, and CD34 expression

Abstract

We show that simultaneous detection of the CD34, SP, and ALDH+ cells is clearly feasible using only small amounts of CB. In CB, ALDH+, and CD34+ cells are overlapping populations distinctly separated from the SP population. The difference in relation to the capacity for colony growth between ALDH+ and SP underlines that they define different cell populations.

The aldehyde dehydrogenase cord blood potency assay excludes early apoptotic cells

“…The results from our study together with previously published data, suggest that the ALDH assay might serve well as a surrogate for the CFU assay, both regarding the measurement of the number of HSCs in a particular CBU and also to appreciate the functionality of the cells pretransplant. Hence, we found no nonviable and very few apoptotic ALDH+ cells compared to the CD34+ cell fraction, indicating that very few ALDH+ cells compared to CD34+ cells were nonfunctional.…”

“…16 Also, as has been shown by Duggleby and colleagues, measurement of viable CD341 (CD341 7-AAD2) cells includes substantial fractions of early apoptotic cells (CD341 7-AAD2 annexin V1), and exclusion of these in measurements improves conformity with the functional CFU assay. 7 The results from our study together with previously published data, 6,10 suggest that the ALDH assay might serve well as a surrogate for the CFU assay, both regarding the measurement of the number of HSCs in a particular CBU and also to appreciate the functionality of the cells pretransplant. Hence, we found no nonviable and very few apoptotic ALDH1 cells compared to the CD341 cell fraction, indicating that very few ALDH1 cells compared to CD341 cells were nonfunctional.…”

“…The number of CFU‐GMs is yet the best predictor of neutrophil engraftment and overall survival of the recipient . However, the CFU assay is expensive, time consuming, and hard to standardize, highlighting the need for alternative approaches …”

“…5 However, the CFU assay is expensive, time consuming, and hard to standardize, highlighting the need for alternative approaches. 6 In 2012, Duggleby and colleagues 7 published results suggesting that exclusion of viable but apoptotic CD341 cells improved correlation between CD341 cells and CFU-GM, suggesting that analysis of viable, nonapoptotic CD341 cells could replace the CFU assay. Apoptotic cells exhibiting cell membrane phospholipid asymmetry were identified by annexin V and its binding to phosphatidylserine as assessed by flow cytometry.…”

Improving Quality and Potency Testing for Umbilical Cord Blood: A New Perspective

“…The CD34‐positive (CD34 + ) “stem cell marker” only detects a very small proportion of stem cells [17, 20, 21]; the majority of cells detected by CD34 are hematopoietic progenitor cells that play no role in the engraftment process [17]. Even aldehyde dehydrogenase, which has been considered a marker for stem cells [22], also correlates with CD34 + and GM‐CFU progenitor cells [23, 24]. Consequently, it is difficult to understand how the TNC count, viability, and CD34 content can be considered measures of purity let alone potency.…”