Hypoxia Differentially Regulates Arterial and Venous Smooth Muscle Cell Migration

Abstract

ObjectiveIntimal hyperplasia (IH) is a clinical concern leading to failure of up to 50% of vein grafts and 10% of arterial grafts after 10 years with no known current treatment. Recent studies have shown that hypoxia differentially regulates proliferation of vein derived smooth muscle cells (V-SMC) compared to artery derived smooth muscle cells (A-SMC). The objective of this study is to evaluate the effect of hypoxia on cellular migration and the mechanisms underlying the differential effects of hypoxia on A-SMC and V-SMC migration.Methods and ResultsHypoxic treatment (3–5% O2) of Smooth Muscle Cells (SMC) resulted in differential migration in scratch wound and electric cell substrate impedance sensing (ECIS) assays. Hypoxia led to greater migration compared to normoxia with venous derived wound closure (V-SMC 30.8% Normoxia to 67% Hypoxia) greater than arterial wound closure (A-SMC 6.2% Normoxia to 24.7% Hypoxia). Paracrine factors secreted by hypoxic endothelial cells induced more migration in SMC compared to factors secreted by normoxic endothelial cells. Migration of V-SMC was greater than A-SMC in the presence of paracrine factors. Neutralizing antibody to Vascular Endothelial Growth Factor Receptor -1 (VEGFR-1) completely inhibited V-SMC migration while there was only partial inhibition of A-SMC migration. A-SMC migration was completely inhibited by Platelet Derived Growth Factor BB (PDGF-BB) neutralizing antibody. p38 Mitogen Activated Protein kinase (p38 MAPK) inhibitor pre-incubation completely inhibited migration induced by paracrine factors in both A-SMC and V-SMC.ConclusionOur study determines that SMC migration under hypoxia occurs via both an autocrine and paracrine mechanism and is dependent on Vascular Endothelial Growth Factor-A (VEGF-A) in V-SMC and PDGF-BB in A-SMC. Migration of both A-SMC and V-SMC is inhibited by p38 MAPK inhibitor. These studies suggest that pharmacotherapeutic strategies directed at modulating p38 MAPK activity can be exploited to prevent IH in vascular grafts.

Aryl Hydrocarbon Receptor Nuclear Translocator in Vascular Smooth Muscle Cells Is Required for Optimal Peripheral Perfusion Recovery

“…45,46 Evaluation of transcripts revealed divergent changes in drivers of hypoxia-induced phenotype modulation well described in pulmonary artery and aortic VSMCs (Figure 7). 20,[47][48][49][50][51][52] Expression of HIF targets, vascular endothelial growth factor A (Vegfa) and glucose transporter 1 (Glut1), whose levels increase in hypoxia and are attenuated by ARNT deletion in ECs, responded as expected. 33,[53][54][55] Hypoxia induced expression of Vegfa and Glut1 in Arnt lox/lox VSMCs, and loss of ARNT prevented induction of expression in hypoxia ( Figure 7A and 7B).…”

“…To assess ARNT's role in VSMC phenotype and responses to hypoxic stress in ischemic limbs, cultured aortic VSMCs from Arnt SMKO and Arnt lox/lox mice were challenged with 24‐hour hypoxic exposure at 2% O 2 . Evaluation of transcripts revealed divergent changes in drivers of hypoxia‐induced phenotype modulation well described in pulmonary artery and aortic VSMCs (Figure ) . Expression of HIF targets, vascular endothelial growth factor A ( Vegfa ) and glucose transporter 1 ( Glut1 ), whose levels increase in hypoxia and are attenuated by ARNT deletion in ECs, responded as expected .…”

“…65 However, recent reports of pulmonary artery SMCs consistently show HIF-mediated hypoxic responses increase proliferation, survival, and migration, and stimulate growth factor production, including vascular endothelial growth factor A. [47][48][49][50] HIF targets, including PDGFs and fibroblast growth factors, are key promoters of VSMC proliferation and migration; their inhibition impairs proliferation of pulmonary artery SMCs in vitro and prevents vascular remodeling in models of pulmonary hypertension. 66,67 Expression of multiple HIF targets in Arnt SMKO VSMCs diverges from levels seen in control cells.…”

Electric Cell-Substrate Impedance Sensing of Cellular Effects under Hypoxic Conditions and Carbonic Anhydrase Inhibition

“…Impedance studies with cells in hypoxic conditions are seldom reported [29,48], with a focus on barrier function assays. In contrast to the endpoint analyses, the use of this label-free bioanalytical platform allows dynamic evaluation of discrete, nonlethal effects of external stimuli at cellular level and enables a quantitative, multiparametric assessment of potential bioeffects.…”

“…It is amenable for multiplexing, and it can be combined with optical analyses and microfluidics and controlled environmental conditions. Nevertheless, EIS cell analysis under hypoxic conditions is seldom reported [28][29][30].…”