Fig. 5

(A) Categorization of cell-free miRNAs and supposed origins of ci-miRNAs [254]. However, in different tissues involved in the ci-miRNA pool, most miRNAs may be obtained from blood. Ci-miRNAs can be released from necrotic or apoptotic cells, released vesicles, including microvesicles or EXOs in protein compounds and lipoprotein compounds (HDL and LDL compounds) [282, 283]. (B) EXO formation steps into donor cells and different uptake of EXOs in recipient cells [284]. EXOs fundamentally combine with the cell membrane either after Ca2+-related activation or behind the triggering of Rab-GTPases. Rab25 controls EXO connecting before and securing the cell membrane and Rab27b EXO discharge [285]