Goat colostrum-derived exosomes: Isolation and characterization.

Abstract

Exosomes are small (20-300 nm diameter) membranous vesicles observed in different biological fluids, as milk and colostrum. The most known function of exosomes is the cell-to-cell communication, but also exosomes are known nowadays because of their used in human cancer therapy. Additionally, the role of colostrum-derived exosomes in immunological processes has been reported. Colostrum intake during the first stages of life is crucial to ensure the newborn goat kids’ survival because the characteristics of goat’s placenta does not allow enough transfer of immune components during gestation. The objective of this study was to find the adequate isolation method and to characterize the size of goat colostrum-derived exosomes. To do that, six goat colostrum samples from Majorera breed were collected immediately after parturition. Each sample was divided in two aliquots, one stored at -20ºC and the other at -80ºC. Four exosomes isolation methods (M) were used, thus M1: ultracentrifugation; M2: ultracentrifugation with rennet precipitation; M3: ultracentrifugation with EDTA and M4: Total Exosome Isolation (from other body fluids) InvitrogenTM commercial kit. Polydispersity index (PDI) and exosomes size were determined using a Zetasizer Nano ZS (Malvern, UK). The data was analysed using the ANOVA and T-test procedures from Jamovi (V 2.2). A Tukey test was used to evaluate differences between groups. Significant differences were set as P ≤ 0.05. The isolation of exosomes was success only in samples stored at -80ºC and differences (P<0.001) in PDI were found depending on the isolation method, being the lowest (0.106±0.0076) polydispersity index observed in M1 following by M2 (PDI=0.167±0.0011). Similar (P>0.05) size was observed in the exosomes isolated using M1 (126±9.04 nm) and M2 (157±7.09 nm). In conclusion, the results suggest that the ultracentrifugation is the method of election to isolate goat colostrum-derived exosomes.