Exosomal MiR-29a in Cardiomyocytes Induced by Angiotensin II Regulates Cardiac Microvascular Endothelial Cell Proliferation, Migration and Angiogenesis by Targeting VEGFA.

BACKGROUND

Exosomes released from cardiomyocytes (CMs) potentially play an important role in angiogenesis through microRNA (miR) delivery. Studies have reported an important role for miR-29a in regulating angiogenesis and pathological myocardial hypertrophy. However, whether CMderived exosomal miR-29a is involved in regulating cardiac microvascular endothelial cell (CMEC) homeostasis during myocardial hypertrophy has not been determined.

METHODS

Angiotensin II (Ang II) was used to induce CM hypertrophy, and ultracentrifugation was then used to extract exosomes from a CM-conditioned medium. CMECs were cocultured with a conditioned medium in the presence or absence of exosomes derived from CMs (Nor-exos) or exosomes derived from angiotensin II-induced CMs (Ang II-exos). Moreover, a rescue experiment was performed using CMs or CMECs infected with miR-29a mimics or inhibitors. Tube formation assays, Transwell assays, and 5-ethynyl-20-deoxyuridine (EdU) assays were then performed to determine the changes in CMECs treated with exosomes. The miR-29a expression was measured by qRT-PCR, and Western blotting and flow cytometry assays were performed to evaluate the proliferation of CMECs.

RESULTS

The results showed that Ang II-induced exosomal miR-29a inhibited the angiogenic ability, migratory function, and proliferation of CMECs. Subsequently, the downstream target gene of miR- 29a, namely, vascular endothelial growth factor (VEGFA), was detected by qRT-PCR and Western blotting, and the results verified that miR-29a targeted the inhibition of the VEGFA expression to subsequently inhibit the angiogenic ability of CMECs.

CONCLUSION

Our results suggest that exosomes derived from Ang II-induced CMs are involved in regulating CMCE proliferation, migration, and angiogenesis by targeting VEGFA through the transfer of miR-29a to CMECs.