Single cell RNA sequencing revealed a chemokine self-feeding of myeloma cells for extramedullary metastasis

To determine the mechanisms of the initial extramedullary translocation of myeloma cells from bone marrow into peripheral blood. We found that the clonal cPCs were more frequently detected by flowcytometry in extramedullary plasmacytoma patients and worsened their prognosis. It is technically much easier to collect single cPCs using FACS than it is to perform EMP biopsy. Combining imaging extramedullary plasmacytoma diagnosis and cPCs detection may be a promising strategy for prognostic stratification. Using single-cell transcriptome analysis, we found that CXCL12, a key molecule for the CXCR4-dependent cell retention mechanism in bone marrow, was abnormally up-regulated in cPCs and might initially enable cPCs evasion and translocation into blood. Overall design: We perform single cell RNA-seq using Smart-Seq2 for single myeloma cells derived from bone marrow of a patient with multiple myeloma.