Differential miRNA expression profiles of exosomes derived from young and older BMSCs. (A) Differential miRNA expression of young and older BMSC exosomes was determined by TaqMan miRNA array analysis. (B) Schematic of the modification of older BMSC exosomes. Young BMSC exosome-specific miRNA mimics were transfected directly into older BMSC exosomes by Exo-fect. (C) Quantification of tube-like structures to determine the antiangiogenic effect of modified exosomes. Older BMSC exosomes transfected with miR-340 mimics (miR-340 exosomes) and older BMSC exosomes transfected with miR-365 mimics (miR-365 exosomes) significantly inhibited HUVEC tube formation in comparison with the control (older BMSC exosomes transfected with negative control miR; control miR) (control vs miR-340 exosomes; *P < .01, Student t test; **P < .001, control vs miR-365 exosomes). Values represent the mean ± SD. Ct, comparative threshold cycle.