Rate of brain weight to body weight in different experimental groups. AlCl3 treatment caused a significant decrease in brain-to-body weight with respect to the control group (P < 0.01). 2 or 5 injections of BM-MSC extracted exosomes significantly protected against the deficit effect of Alcl3 on brain-to-body weight rate. Each value represents mean ± SEM, n = 6, **p < 0.01 vs. saline group and ⁺⁺p < 0.01 vs. Alcl3 group. Abbreviations: Sal, Saline; Exo [2], Two injections of exosomes; Exo [5], five injections of exosomes.