Role of platelet-derived microparticles in transfer of the chemokine receptor CXCR4 to CXCR4-negative cells.

Membrane-derived microparticles (PMPs) are produced from platelets during activation, storage, and apoptosis. PMP can transfer some adhesion molecules such as CXCR4 to CXCR4-negative cells. In this study, the ability of PMPs to deliver CXCR4 molecule to CXCR4-null targets (Daudi, K562 and U937 cell line) was evaluated and the different concentrations of PMPs were examined to transfer CXCR4. In this experimental study, PMPs were prepared using serial centrifugations. After confirmation of PMP with flow cytometry, PMP concentration was evaluated using the Bradford method. CXCR4-negative cell lines (1×105 cells/ml) were cultured in RPMI1640 with 10% FBS and 1% antibiotic. PMPs in 7 different concentrations were added to cell culture plates and incubated for 1 hour at 37ºc and 5% CO2. The presence of CXCR4 on cells was analyzed by flowcytometry. In this study, characterization of PMPs and cell lines were done by flow cytometry. Then, the PMPs' ability to transfer CXCR4 to null cells (Daudi, K562 and U937 cell lines) was evaluated in 7 concentrations (10, 20, 50,125, 250, 500, 1000 μg/mL); incubation lasted for 1 hour. The best result of transferring CXCR4 by PMP was done in the concentration of 250µg/mL. PMPs in different concentrations can transfer CXCR4 to target cells. Also, the increase of PMPs concentration up to 250µg/mL can increase the CXCR4 presence on null cells.