Detection of myeloma cell-derived microvesicles: a tool to monitor multiple myeloma load

The persistence of tumor load in multiple myeloma (MM) lead to relapse in patients achieving complete remission (CR). Appropriate and effective methods of myeloma tumor load monitoring are important for guiding clinical management. This study aimed to clarify the value of microvesicles in monitoring MM tumor load. Microvesicles in bone marrow and peripheral blood were isolated by differential ultracentrifugation and detected by flow cytometry. Western blotting was applied to assess myosin light chain phosphorylation levels. Flow cytometry to detect Ps⁺CD41a^-, Ps⁺CD41a^-CD138⁺, Ps⁺CD41a^-BCMA⁺ microvesicles from bone marrow can be used to predict myeloma burden, furthermore, Ps⁺CD41a^- microvesicles may as a potential index to MRD test. Mechanistically, the releasing of microvesicles from MM cell was regulated by Pim-2 Kinase via Phosphorylation of MLC-2 protein.