Single cell gene expression profiling in normal HSCs and CML stem cells

CML stem cells (CMLSCs) and normal hematopoietic stem cells (HSCs) display the same set of surface markers (CD34+CD38-CD90+CD45RA-), making it infeasible to separate these two populations within the same sample. To overcome this challenge, and to minimize variations in gene expression due to individual variation, here we perform single-cell RNA-seq to compare expression profiles of CMLSCs and HSCs isolated from the same patient. We captured ~600 HSCs (CD34+CD38-CD90+CD45RA-) (~200 from each of three CML patient samples), separated them into CMLSCs (BCR-ABL+) or normal HSCs (BCR-ABL-) based on the presence of the BCR-ABL transcript, and performed paired-end deep sequencing. Typically, we obtained ~2.5 million mapped reads (>70% average mapping efficiency) and detected ~5,000 genes (transcript per million [TPM]>1) per cell. Despite the heterogeneity of the gene expression pattern, we were able to identify genes that were significantly more highly expressed in CMLSCs than in normal HSCs. Notably, among these genes are two cell surface markers, CD33 and CD47, that could potentially be used to distinguish CMLSCs from normal HSCs. We also found genes, such as PIM2, that could be targeted for CML therapy using available small molecule inhibitors. Overall design: Hematopoietic stem cell population from three chronic phase CML patients with no detectable BCR-ABL mutation.

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Ma L, Pak ML, Ou J, Yu J, St Louis P, Shan Y, Hutchinson L, Li S, Brehm MA, Zhu LJ, Green MR