Figure 5. Formation and brain delivery of ExoBDNF complex.

(a) ExoBDNF were isolated using protein G magnetic beads modified with BDNF-specific antibodies. The presence of LAMP 2 in the magnetic bead-separated fractions indicated that the exosomes were captured on the beads. A control group of exosomes without BDNF treatment was used to account for nonspecific binding. (b) Native PAGE of the mixtures of Mϕ exosomes and BDNF at different protein ratios. Exosomes prevented the neurotrophic factor migration in the gel toward the cathode up to a BDNF: exosomal protein weight ratio of 1:5. (c) Healthy mice were co-injected with ¹³¹I-BSA and ¹²⁵I-BDNF with or without Mϕ exosomes via jugular vein. The brain/serum ratios at time points of 1, 2, 3, 4, 5, 6, 7.5, 10, 15, 20, 30 min were averaged. ### p < 0.001 by unpaired two-tailed t-test. (d) Multiple-time regression analysis of co-injected BSA in healthy mice. Both slopes are comparable to 0 (p=0.064 for BSA and p=0.09 for BSA + Exosomes). (e) Brain accumulation of naked BDNF or BDNF in ExoBDNF in healthy or brain-inflamed mice at 10 min. Data are means ± SEM, n = 4, ** p < 0.01 indicated group by one-way ANOVA and post Newman-Keuls multiple comparison test. (f) Distribution of BDNF or BDNF in ExoBDNF in brain parenchyma at 10 min in healthy mice determined by capillary depletion assay. Data are means ± SEM, n = 5, && p < 0.01 and &&& p < 0.001 by paired two-tailed t-test, ### p < 0.001 by unpaired two-tailed t-test.