FIGURE 4.

Tetraspanin-normalized surface antigen expression by sEVs. Surface antigen expression of sEVs isolated by methods I (blue), II (green), III (red) and IV (orange) was analyzed using MACSPlex technology. sEVs were bound by capture beads with epitopes against each analyzed surface antigen and detected indirectly by an APC-coupled detection reagent directed against the tetraspanins CD9, CD63, and CD81. Due to the indirect detection, fluorescence intensity of each surface antigen was normalized on mean fluorescence intensity of CD9, CD63, and CD81, resulting in tetraspanin-normalized expression. Data are presented as mean ± SD, and N ≥ 3 independent experiments were performed. Statistically significant differences are depicted as follows: *: p < 0.05, **: p < 0.01, ***: p < 0.001, ****: p < 0.0001.