Circulating small extracellular vesicles promote proliferation and migration of vascular smooth muscle cells via AXL and MerTK activation

by Selleckchem | Apr 08 2023

The proliferation and migration of vascular smooth muscle cells (VSMCs) after vascular injury lead to neointimal hyperplasia, thus aggravating vascular diseases. However, the molecular mechanisms underlying neointima formation are not fully elucidated. Extracellular vesicles (EVs) are mediators of various intercellular communications. The potential of EVs as regulators in cardiovascular diseases has raised significant interest. In the current study we investigated the role of circulating small extracellular vesicles (csEVs), the most abundant EVs (1010 EVs/mL serum) in VSMC functions. csEVs were prepared from bovine, porcine or rat serum. We showed that incubation with csEVs (0.5 × 1010-2 × 1010) dose-dependently enhanced the proliferation and migration of VSMCs via the membrane phosphatidylserine (PS). In rats with ligation of right carotid artery, we demonstrated that application of csEVs in the ligated vessels aggravated neointima formation via interaction of membrane PS with injury. Furthermore, incubation with csEVs markedly enhanced the phosphorylation of AXL and MerTK in VSMCs. Pretreatment with BSM777607 (pan-TAM inhibitor), bemcentinib (AXL inhibitor) or UNC2250 (MerTK inhibitor) blocked csEV-induced proliferation and migration of VSMCs. We revealed that csEV-activated AXL and MerTK shared the downstream signaling pathways of Akt, extracellular signal-regulated kinase (ERK) and focal adhesion kinase (FAK) that mediated the effects of csEVs. We also found that csEVs increased the expression of AXL through activation of transcription factor YAP, which might constitute an AXL-positive feedback loop to amplify the signals. Finally, we demonstrated that dual inhibition of AXL/MerTK by ONO-7475 (0.1 µM) effectively hindered csEV-mediated proliferation and migration of VSMCs in ex vivo mouse aorta injury model. Based on these results, we propose an essential role for csEVs in proliferation and migration of VSMCs and highlight the feasibility of dual AXL/MerTK inhibitors in the treatment of vascular diseases.

Comments：

The study investigated the role of circulating small extracellular vesicles (csEVs) in vascular smooth muscle cell (VSMC) functions and neointima formation after vascular injury. The researchers prepared csEVs from bovine, porcine, and rat serum and demonstrated that incubation with csEVs dose-dependently enhanced the proliferation and migration of VSMCs via the membrane phosphatidylserine (PS). They also showed that application of csEVs in rats with ligation of right carotid artery aggravated neointima formation via interaction of membrane PS with injury.

The researchers further found that csEVs activated AXL and MerTK and shared downstream signaling pathways of Akt, extracellular signal-regulated kinase (ERK), and focal adhesion kinase (FAK) that mediated the effects of csEVs. They also found that csEVs increased the expression of AXL through activation of transcription factor YAP, which might constitute an AXL-positive feedback loop to amplify the signals.

The researchers demonstrated that pretreatment with BSM777607 (pan-TAM inhibitor), bemcentinib (AXL inhibitor), or UNC2250 (MerTK inhibitor) blocked csEV-induced proliferation and migration of VSMCs. They also found that dual inhibition of AXL/MerTK by ONO-7475 effectively hindered csEV-mediated proliferation and migration of VSMCs in an ex vivo mouse aorta injury model.

Overall, the study highlights the essential role of csEVs in proliferation and migration of VSMCs and proposes the feasibility of dual AXL/MerTK inhibitors in the treatment of vascular diseases.