Evaluation of Collection and Processing Conditions for Gene Expression Analysis Using Human Myeloid Cells.

Background: The population of blast cells among peripheral blood mononuclear cells (PBMCs) obtained from patients is a desirable specimen for analyzing gene expression in diseases including acute myeloid leukemia. Although the enrichment of blast cells often needs to be performed at a central laboratory, acceptable conditions for sample transport from clinical sites remain to be established. Methods: We evaluated storage temperature, duration, and tube type before initiating sample processing for the analysis of cluster of differentiation (CD)33⁺ myeloid cells among PBMCs as an alternative to CD34⁺/CD33⁺ blast cells. Results: CD33⁺ myeloid cells were successfully purified by MACS. The cell viability and the RNA integrity were sustained during storage up to 48 hours before sample processing. Storage at 4°C had minimal effects on gene expression, whereas storage at room temperature induced the senescence pathway, characterized by the expression of stress-inducible genes. A CPT tube was also better than an ethylenediaminetetraacetic acid tube for minimizing gene expression change. Conclusions: Our study provided important clues for establishing a sample handling approach for gene expression analysis with purified cell fractions from human PBMCs. To keep the variation of gene expression to a minimum, samples should be delivered at 4°C within 48 hours before processing.