Shock Wave Therapy Enhances Angiogenesis through VEGFR2 Activation and Recycling

Authors
Tien-Hung Huang, Cheuk-Kwan Sun, Yi-Ling Chen, Ching-Jen Wang, Tsung-Cheng Yin,Mel S Lee, and Hon-Kan Yip
Abstract
Although low-energy shock wave (SW) is adopted to treat ischemic diseases because of its pro-angiogenic properties, the underlying mechanism remains unclear. This study is aimed at testing whether SW-induced angiogenesis may be through endothelial vascular endothelial growth factor receptor 2 (VEGFR2) signaling and trafficking. Phosphorylation of VEGFR2-Akt-eNOS axis and production of nitric oxide (NO) were determined in human umbilical vein endothelial cells (HUVECs) treated with SW. Carotid artery in ob/ob mice was treated with SW before evaluation with sprouting assay. Critical limb ischemia was induced in ob/ob mice to evaluate blood flow recovery post-SW treatment. Tube formation and migration assays were also performed with/without SW treatment in the presence/absence of SU5416 (VEGFR2 kinase inhibitor) and siRNA-driven silencing of VEGFR2. Chloroquine was used for disrupting endosome, and Rab11a controlling slow endocytic recycling was silenced with siRNA in vitro. Following SW treatment, augmented ligand-independent phosphorylation in VEGFR2-Akt-eNOS axis and endogenous NO production, increased cellular migration and tube formation and elevated sprouting of carotid artery and blood flow in ischemic limb in ob/ob mice were noted. Moreover, SU5416 and VEGFR2 silencing both inhibited SW-induced angiogenesis. SW-induced angiogenesis, accompanied by increased VEGFR2 protein expression without transcriptional change, was suppressed by chloroquine and Rab11a silencing. We concluded that SW enhanced angiogenesis via ligand-independent activation of VEGFR2 and further prolonged angiogenesis through endosome-to-plasma membrane recycling in endothelial cells.
Volume
2016
Page Range
850-862
DOI
10.2119/molmed.2016.00108
Date Published
December 6, 2016
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Keywords
Huang, Sun, Chen, Wang, Yin, Lee, Yip, low-energy shock wave, SW, angiogenesis, vascular endothelial growth factor receptor 2, VEGFR2, VEGFR2 recycling, endothelial cell, endocytic recycling
Article Type
Research Article