[Release of Exosomes Derived from Leukocyte-Depleted Red Cell Suspension and Its Regulation on Hematological Tumor Cells].

Objective: To investigate the release of exosome (Exo) from leukocyte-depleted red cell suspension (LDRCS) at different storage time and its regulation on proliferation of hematological tumor cells and possible mechanism.

Methods: The Exo (RBC-Exo) in LDRCS at different storage time was obtained by ultracentrifugation, and the morphology and immunological marker of RBC-Exo were detected by transmission electron microscopy and Western blot, respectively. The particle size distribution of RBC-Exo in LDRCS at different storage time was detected by Dynamic Light Scattering. CCK-8 assay was used to explore the effect of RBC-Exo on hematological tumor cell proliferation. Western blot was used to detect the expression of proliferation-related proteins in hematological tumor cells after co-culture with RBC-Exo.

Results: RBC-Exo was isolated, which was characterized by cup-like shape, particle size distribution ranged from 20 to 200 nm, CD63/TSG101 enriched, Calnexin negative, CD235a positive and CD41 negative. The particle size distribution of RBC-Exo from LDRCS between middle was not significantly different and late stored stage. But the particle size distribution of RBC-Exo at middle-late stored stage(>14 d) was larger than that at early stored stage (≤14 days). Compared with the control group, RBC-Exo could significantly promote the proliferation of HBL1, U2932 and Jurkat cells. Compared with the control group, the cycle-related protein P21 was significantly down-regulated in HBL1, U2932 and Jurkat cells after co-culture with RBC-Exo for 3 days, while the anti-apoptotic protein BCL-2 was not changed significantly.

Conclusion: The morphology of RBC-Exo from LDRCS at middle-late stored stage was different from that at early stored stage. RBC-Exo could promote the proliferation of hematological tumor cells, possibly by regulating the expression of cycle-associated protein P21.