Human peripheral blood‑derived exosomes for microRNA delivery.

Exosomes serve important functions in cell‑to‑cell communication and biological functions by serving as a delivery cargo shuttle for various molecules. The application of an improved delivery method for microRNAs (miRNAs/miRs) may enhance their potential as a therapeutic tool in cardiac diseases. Thus, the present study investigated whether human peripheral blood‑derived exosomes may be used as a delivery cargo system for miRNAs, and whether the delivery of miR‑21 using a human peripheral blood derived‑exosome may influence the degree of remodeling following myocardial infarction (MI). In H9C2 and HL‑1 cells, miR‑21 expression was successfully regulated by treatment with human peripheral blood derived‑exosomes loaded with an miR‑21 mimic or inhibitor compared with untreated cells. In addition, the mRNA and protein expression levels of SMAD family member 7 (Smad7), phosphatase and tensin homolog (PTEN) and matrix metalloproteinase 2 (MMP2), which are involved in cardiac fibrosis, were associated with the uptake of miR‑21 mimic‑ or inhibitor‑loaded exosomes. Similarly, the in vivo mRNA and protein expression of Smad7, PTEN and MMP2 were altered following treatment with miR‑21 mimic‑ or inhibitor‑loaded exosomes. Furthermore, miR‑21 mimic‑loaded exosomes enhanced fibrosis, whereas miR‑21 inhibitor‑loaded exosomes reduced fibrosis in a mouse MI model. These results suggested that miRNA‑loaded human peripheral blood derived‑exosomes may be used as a therapeutic tool for cardiac diseases.