Extracellular vesicles derived from macrophage promote angiogenesis In vitro and accelerate new vasculature formation In vivo.

BACKGROUND

Ischemia is the partial or complete blockage of blood supply to tissues. Extracellular vesicles (EVs) are emerging as a therapeutic tool for ischemic diseases. Most EV-based ischemia therapies are based on various stem cells. Here, we propose an alternative cell source for the isolation of pro-angiogenic EVs.

METHODS

EVs were isolated from a mouse macrophage cell line (Raw 264.7). The characteristic features of the macrophage-derived EVs (MAC-EVs) were assessed using transmission electron microscopy, nanoparticle tracking analysis, and Western blotting (WB) analysis. WB and qRT-PCR were performed to identify the pro-angiogenic VEGF and Wnt3a proteins and microRNAs (miR-210, miR-126, and miR-130a) in the MAC-EVs. In vitro and in vivo Matrigel plug assays were performed to investigate the capacity of the MAC-EVs for tube (blood vessel-like) formation and new blood vessel formation and assessed by histology.

RESULTS

The MAC-EVs was positive for ALIX and negative for calnexin, with a round shape and an average size of 189 ± 65.1 nm. WB and qRT-PCR results revealed that VEGF, Wnt3a and miR-130a were more abundant in the MAC-EVs than cells. MAC-EVs treatment resulted in increased endothelial cellular proliferation, migration, and tube formation in vitro. In vivo assay results revealed that MAC-EVs increased the formation of new and larger blood vessels in the Matrigel plug of mice compared to the formation in the control group.

CONCLUSION

Our results suggest that MAC-EVs have the potential to induce angiogenesis in vitro and in vivo, could serve as a pro-angiogenic alternative for ischemic diseases.