GM-CSF Ameliorates Micro-vascular Barrier Integrity via Pericytes Derived Ang-1 in Wound Healing

Abstract

Background: Skin wound healing involves complex coordinated interactions of cells, tissues and mediators. Maintaining microvascular barrier integrity is one of the key events for endothelial homeostasis during wound healing. Vasodilation is observed after vasoconstriction, which causes blood vessels to become porous, facilitates leukocyte infiltration and aids angiogenesis at the wound-area, post-injury. Eventually, vessel integrity has to be re-established for vascular maturation. Numerous studies have found that granulocyte macrophage colony-stimulating factor (GM-CSF) accelerates wound healing by inducing recruitment of repair cells into the injury area and releases of cytokines. However, whether GM-CSF is involving in the maintaining of micro-vascular barrier integrity and the underlying mechanism remain still unclear.

Objectives: Aim of this study was to investigate the effects of GM-CSF on modulation of micro-vascular permeability in wound healing and underlying mechanisms.

Methods: Wound closure and micro-vascular leakage was investigated using a full-thickness skin wound mouse model after GM-CSF intervention. The endothelial permeability was measured by Evans-blue assay in vivo and in vitro endothelium/pericyte co-culture system using a FITC-Dextran permeability assay. To identify the source of angiopoietin-1 (Ang-1), double staining is used in vivo and ELISA and qPCR are used in vitro. To determine the specific effect of Ang-1 on GM-CSF maintaining micro-vascular stabilization, Ang-1 siRNA was applied to inhibit Ang-1 production in vivo and in vitro.

Results: Wound closure was significantly accelerated and micro-vascular leakage was ameliorated after GM-CSF treatment in mouse wound sites. GM-CSF decreased endothelial permeability through tightening endothelial junctions and increased Ang-1 protein level that was derived by perictye. Furthermore, applications of siRNAAng-1 inhibited GM-CSF mediated protection of micro-vascular barrier integrity both in vivo and in vitro.

Conclusions: Our data indicate that GM-CSF ameliorates micro-vascular barrier integrity via pericyte derived Ang-1 during wound healing. This article is protected by copyright. All rights reserved.