GM-CSF ameliorates microvascular barrier integrity via
pericyte-derived Ang-1 in wound healing
Min Yan, PhD, MD
; Yange Hu, MD
; Min Yao, PhD, MD
; Shisan Bao, PhD, MD
; Yong Fang, PhD, MD
1. Department of Plastic Surgery, The Ninth People’s Hospital, Shanghai Jiaotong University of Medicine, Shanghai, China, and
2. Discipline of Pathology, Bosch Institute and School of Medical Sciences, The University of Sydney, Sydney, Australia
Yong Fang, Department of Plastic Surgery,
The Ninth People’s Hospital,
Shanghai Jiaotong University of
Medicine, Shanghai 200011, China.
Manuscript received: June 13, 2017
Accepted in final form: December 4, 2017
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,
postinjury. Eventually, vessel integrity has to be reestablished 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 microvascular
barrier integrity and the underlying mechanism remain still unclear. Aim of
this study was to investigate the effects of GM-CSF on modulation of
microvascular permeability in wound healing and underlying mechanisms.
Wound closure and microvascular 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 microvascular
stabilization, Ang-1 siRNA was applied to inhibit Ang-1 production in vivo
and in vitro. Wound closure was significantly accelerated and microvascular
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 microvascular barrier integrity both in vivo and in vitro. Our data
indicate that GM-CSF ameliorates microvascular barrier integrity via pericyte-
derived Ang-1 during wound healing.
Skin wound healing involves highly complex coordinated
interactions of different cell types, tissues, and biochemical
It is usually accompanied by a transient
increase in blood vessel permeability, due to the enlarge-
ment of cell junction gaps
modulated by inflammatory
mediators after injury. Vascular barrier integrity will be re-
established through restoration of tight junctions by
recruiting supporting cells and producing extracellular
for stabilization of the vessels in and around the
wounded area. Granulocyte macrophage colony stimulating
factor (GM-CSF) with pleiotropic functions
wound healing via recruiting inflammatory cells, stimulat-
ing reepithelization and angiogenesis.
Our previous report
demonstrated that wound healing is compromised in GM-
CSF KO mice, accompanied with reduced infiltration of
neutrophils and macrophages.
vascularization is observed in the wound beds of GM-CSF
As expected, wound healing is enhanced with
exogenous GM-CSF, particularly in patients with diabetes
or hydroxyurea-related leg ulcers.
Therefore, it is believed
that GM-CSF plays a key role during wound healing via
promotion of angiogenesis in wound beds. Besides, it is
reported GM-CSF regulates maturation of microvessels by
manipulating the spatial-temporal Ang-1/Ang-2 balance
and the phosphorylation of Tie-2.
The results of studies
provide a strong rationale for the exploration of GM-CSF
in vessel stabilization during wound healing. Thus, GM-
CSF not only initiates the sprouting phase of angiogenesis
but can also promote the maturation and stabilization of
new microvessels. However, whether GM-CSF is involving
Wound Rep Reg (2017) 25 933–943
2018 by the Wound Healing Society