Fig. 4

Platelet–derived miR-21/let-7b induced NETs formation by EVs transmission. A Hierarchical clustering of plasma–derived EV-carried microRNA (miRNA) profiles in COVID-19 patients and the healthy control (HC) group using next generation sequencing analysis. The red color represents a relative expression greater than the median expression level across all samples and the green color represents an expression level lower than the median. B and C Comparison of (B) exo-miR-21 and (C) exo-let-7b levels in COVID-19 patients and HC. D Human platelets were stimulated with the SARS-CoV-2 spike protein (2 μg/ml) for 1 h; the levels of intracellular miR21/let-7b (left panel) and platelet–derived EVs (pEVs)-carried miR21/let-7b (right panel) were analyzed using QRT-PCR, respectively. E The miR-21/let-7b mimic or mimic control (10 μM) were loaded into human pEVs using electroporation. The levels of miR-21/let-7b loaded were measured by QRT-PCR. F and G Human neutrophils were treated with pEVs that carried-different miRNAs for 24 h. F The intracellular miRNAs were analyzed using QRT-PCR. G NETs formation was observed using confocal microscopy (left panel) and quantified by the MPO-DNA PicoGreen assay (right panel). The scale bar in the IFA image represents 5 μm. All experiments were performed in triplicate and data were presented as mean ± SD. *P < 0.05, **P < 0.01, ***P < 0.005