Abstract: Objective To explore the method of isolation and identification of exosomes of bone marrow mesenchymal stem cells. Methods The mesenchymal stem cells were cultured by whole bone marrow adherence method. A new reagent - exosomes extraction kit was used to isolate and collecte exosomes. The exosomes were identified by electron microscopy, particle size detection, flow cytometry and Western blot. Results The expression of CD45 on the surface of the third generation bone marrow mesenchymal stem cells was negative, and CD73 and CD105 were positive;exosomes derived from bone marrow mesenchymal stem cells were round or oval, the size is non-uniform, the diameter is 30 ~ 100 nm, have a complete membrane structure, and containing low-density substances;Particle size detection particle diameter of the main peak is 61.25nm, in which the diameter of particles shows about 20-200nm accounted for 72.4%;exosome expressed CD63 and CD81 ;The expression of CD9 and CD63 in cell culture supernatants was positive. Conclusions The exosomes can be collected in the medium of mesenchymal stem cells. The exosomes derived from bone marrow mesenchymal stem cells can be identified by electron microscopy, particle size detection, flow cytometry and Western blot.

Key words: Key words: mesenchymal stem cells, exosome, cell separation, identification