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The aldehyde dehydrogenase cord blood potency assay excludes early apoptotic cells
Author(s) -
Frändberg Sofia,
Li Susann,
Boreström Cecilia,
Holgersson Jan,
Palmqvist Lars
Publication year - 2018
Publication title -
transfusion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.045
H-Index - 132
eISSN - 1537-2995
pISSN - 0041-1132
DOI - 10.1111/trf.14570
Subject(s) - cord blood , cd34 , haematopoiesis , microbiology and biotechnology , aldehyde dehydrogenase , population , annexin , apoptosis , biology , stem cell , andrology , flow cytometry , viability assay , immunology , biochemistry , medicine , enzyme , environmental health
BACKGROUND Cord blood units (CBUs) are processed, frozen, and thawed before use in hematopoietic stem cell (HSC) transplantation. The manipulations affect HSC functionality, that is, induce apoptosis and reduce viability. HSC content, commonly expressed as CBU potency, that is, the expected ability of a CBU to restore hematopoiesis, is traditionally approximated through viable CD34+ cells and the colony‐forming unit (CFU) cell cultivation assay. Alternative approaches, for example, the aldehyde dehydrogenase (ALDH) enzyme‐based assay, are also forthcoming. We hypothesized that the ALDH assay might exclude apoptotic cells since it is based on enzyme activity. To investigate this, we designed a protocol for simultaneous staining of viable and apoptotic CD34+ and ALDH+ cells using 7‐aminoactinomycin (7‐AAD) and annexin V, in frozen‐thawed CBUs. Results were correlated with results from the colony‐forming unit–granulocyte/macrophage (CFU‐GM) assay. STUDY DESIGN AND METHODS Samples from 57 CBUs were thawed and simultaneously analyzed for CD34+ cells, ALDH+ cells, viability (7‐AAD), and apoptosis (annexin V) using flow cytometry. Enumeration of CFUs was also performed. RESULTS No nonviable and few apoptotic cells (mean 0.7%) were identified in the ALDH+ population compared to the viable CD34+ population (mean 3.6%). The total number of ALDH+ cells correlated better than viable CD34+ cells (r = 0. 72 vs. r = 0.66; p < 0.0001) with the results of the CFU assay. CONCLUSION The ALDH assay excludes nonviable and apoptotic cells, and therefore correlates better with CFU enumeration compared to the number of viable CD34+ cells. We propose that the ALDH assay might replace the CFU‐GM method in CBU potency measurements.