Abstract 12
Introduction
The current gold standard for cord blood unit (CBU) potency assessment, the colony‐forming unit assay (CFU), shows significant variability between laboratories and results in a substantial delay before product release. We recently developed a rapid flow cytometry assay based on the measurement of intracellular STAT5 phosphorylation in CD34+ cord blood stem cells in response to IL‐3 stimulation and completed a full method validation of this IL‐3‐pSTAT5 assay.
Objective
In partnership with the BEST Collaborative group and worldwide participants from public cord blood banks and stem cells labs, a multicenter blinded study was conducted to provide an international testing ground for the assay, to evaluate its inter‐laboratory reliability, and to obtain constructive feedback from expert users.
Methods
Ten CBU samples cryopreserved in tubes and all necessary reagents were sent to 15 participating sites. Of the ten samples, eight were from potent CBUs (normal) and two from units subjected to extreme warming events (abnormal). Participants were asked to execute the protocol and submit their results.
Results
Thirteen of 15 participants returned results. All normal samples were correctly identified by each participant, except for one sample from one participant. Of the two abnormal samples, one was correctly identified by all participants and one was correctly identified by 7 of 10 participants. The coefficient of variation (CV) of normal samples between all participants was 8.9% with an intraclass correlation coefficient (ICC) of 0.8871.
Discussion
All participants completed the study without any major issue and without prior training other than the provided protocol and video. Sample normality identification is satisfactory and coherent with our validation results. The CV between participants is also satisfactory, especially for a CBU potency assay using flow, given that both this type of assay and this method are known for their high variability. While there are some important milestones yet to be achieved with the IL‐3‐pSTAT5 assay, this study is an important step toward the implementation of the assay, which could have a significant impact on the time before release of CBUs and, therefore, serving the patient's best interest.