Biological features of exosomes from the plasma and serum preserved for different periods of time / 医学研究生学报

ABSTRACT

Objective Exosomes play an extremely important role in the diagnosis and treatment of diseases, but very few studies have been reported on the method, time and results of their preservation. We observed the changes in the size, density, morphology and protein expression of exosomes in the plasma and serum preserved for different lengths of time. Methods Using the Exoquick kit, we isolated exosomes in the plasma and serum from healthy humans which were fresh or preserved at a temperature of －80℃ for 1, 3 or 5 years. We analyzed the numbers and diameters of the isolated exosomes with the nanoparticle-tracking analyzer NanoSight NS 300, observed their morphology under the transmission electron microscope, and detected the expressions of the exosome biomarkers TSG101 and CD63 by Western blot. Results The exosomes preserved for different periods of time ranged in diameter from 30 to 200 nm, more observed in the serum than in the plasma, and with no statistically significant difference in the morphological changes among different groups of preservation time. The expressions of the TSG101 and CD63 proteins in the exosomes were decreased with the prolonging of the preservation time, the latter even more significantly than the former. Conclusion There are no statistically significant differences in the diameter or morphology of the exosomes in the human plasma and serum preserved for different periods of time, but the protein biomarkers of the exosomes are decreased significantly with the prolonged time of preservation. Therefore, freshly isolated exosomes are recommended for experiments in the studies of exosome-related proteins.