Exosomes derived from M2 macrophage promote HUVECs proliferation, migration and tube formation in vitro.

Angiogenesis is one of the hallmarks of solid tumors. Exosomes are extracellular vesicles, which are involved in multiple stages of tumor progression. The role of macrophage-derived exosomes in angiogenesis in oral squamous cell carcinoma (OSCC), where macrophages are crucial components of the tumor microenvironment (TME), remains to be explored. The M2 macrophages and microvessels in OSCC were stained by immunohistochemistry. M2 macrophages were induced in vitro and exosomes were extracted by gradient centrifugation using ultracentrifugation. Fluorescence confocal microscopy was used to observe the uptake of M2 macrophage-derived exosomes by human umbilical vein endothelial cells (HUVECs). CCK-8 proliferation assay, TRANSWELL migration assay and tube formation assay were used to detect the effects of M2 macrophage-derived exosomes on the proliferation, migration and tube formation of HUVECs. Immunohistochemical study showed that M2 macrophage infiltration was positively correlated with microvessel density in OSCC. We induced M2 macrophages in vitro and successfully extracted its exosomes. The cellular internalization of fluorescence-labeled exosomes by HUVECs was dynamically monitored via laser scanning confocal microscopy. The M2 macrophage-derived exosomes promoted the proliferation, migration, and tube-forming ability of HUVECs. The results showed that M2 macrophage-derived exosomes could promote the proliferation, migration and tubulation of HUVECs.