Rapid comparative immunophenotyping of human mesenchymal stromal cells by a modified fluorescent cell barcoding flow cytometric assay.

Flow cytometry immunophenotyping is a sensitive technique allowing rapid characterization of single cells within heterogeneous populations, but it includes several subjective steps during sample analysis that impact the development of standardized methodology. Proposed strategies to overcome these limitations include fluorescent cell barcoding (FCB), which facilitates multiplexed sample evaluation with increased data reproducibility whilst reducing labeling variation, materials, and time. To date, the FCB assay has found utility for analyzing the phosphorylation status of intracellular targets but has not been intensively employed for cellular immunophenotypic analyses using cell surface markers. In this study we developed a modified FCB assay for multiplexed analysis of human mesenchymal stromal cells (hMSCs) to evaluate the quality of these cells during bioprocessing. A panel of fluorochrome-conjugated antibodies was used to target 15 ubiquitously expressed or stage-specific markers together with a fixable viability dye eFluor 506 acting as the cell barcoding agent. Critical technical considerations and validation steps were presented in the context of monitoring hMSC status, defined by generic, and specific surface markers for cell identity and quality. It was found that at discrete passages, inter-analyst expression patterns between hMSCs cultures were similar, but in contrast, diverse marker expression was evident between passages. A side-by-side analysis of barcoded and non-barcoded cells demonstrated the potential of this technique for the rapid phenotypic characterization of cells exposed to different bioprocessing conditions. Additionally, the method incorporates fewer subjective factors; including sample preparation and instrument day-to-day variations and is customizable across a diversity of cell types. © 2017 International Society for Advancement of Cytometry.