Article

Endothelial cell-by-cell profiling reveals the temporal dynamics of VEGFR1 and VEGFR2 membrane localization after murine hindlimb ischemia

1University of Illinois.
AJP Heart and Circulatory Physiology (Impact Factor: 3.84). 02/2013; 304(8). DOI: 10.1152/ajpheart.00514.2012
Source: PubMed

ABSTRACT

Vascular endothelial factor receptor (VEGFR) cell surface localization plays a critical role in transducing VEGF signaling towards angiogenic outcomes and quantitative characterization of these parameters is critical to advancing computational models for predictive medicine. However data to this point has largely examined intact muscle, thus essential data on the cellular localization of the receptors within the tissue are currently unknown. Therefore, our aims are to quantitatively analyze VEGFR localization on endothelial cells from mouse hindlimb skeletal muscles following the induction of hindlimb ischemia, an established model for human peripheral artery disease. Flow cytometry is used to measure and compare the ex vivo surface localization of VEGFR1 and VEGFR2 on CD31(+)/CD34(+) endothelial cells, 3 and 10 days after unilateral ligation of the femoral artery. We determine that 3 days after hindlimb ischemia VEGFR2 surface-levels are decreased by 80% compared to endothelial cells from the non-ischemic limb, and 10 days after ischemia, we observe a 2-fold increase in the surface-levels of the modulatory receptor, VEGFR1, along with increased PCNA, uPA, and uPAR mRNA expression, compared to the non-ischemic limb. The significant upregulation of VEGFR1 surface-levels indicates that VEGFR1 indeed plays a critical role in the ischemia-induced perfusion-recovery process, a process that includes both angiogenesis and arteriogenesis. The quantification of these dissimilarities for the first time, ex vivo, provides insight into the balance of modulatory (VEGFR1) and pro-angiogenic (VEGFR2) receptors in ischemia and lays a foundation for systems biology approaches towards therapeutic angiogenesis.

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Available from: Aleksander S Popel
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    • "In some circumstances, excessive influx of VEGF-A (either exogenous for cells in vitro, or endogenous for ischemia models in vivo) may dysregulate intrinsic VEGFR balance of target cells and switch them to VEGFR1 expression or may upregulate soluble VEGFR1 expression that can operate as a negative feedback system, thereby undermining the entire positive effect of the treatment [22][23][24]. Moreover, the qualitative and quantitative balance of VEGFR1 and VEGFR2 proteins may vary in human populations, further complicating the proper choice of treatment for some cases [23]. Considering this, any VEGF-A-based pro-angiogenic therapy may prove to be more reliable and lead to more predictable results when supported by some additional VEGF-A-independent line of intervention (e.g., using UC-MSCs). "
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    • "Several researchers believe that endothelial progenitor cells included in BMCs differentiated into endothelial cells and, after transplantation in the injury region, contributes to cell survival and angiogenesis[17,18]. Autologous BMCs and PRP are a rich source of growth factors that stimulates angiogenesis in ischemic muscle[19]. Moreover, angiogenic factors, including VEGF and epithelial growth factor (EGF), are also released from injured tissue recruiting BMCs to replace injured tissue[20,21].Previous studies similarly demonstrated that there is an additional contribution derived from BMCs or PRP progenitors which are mobilized in the setting of limb or myocardial ischemia, migrate to ischemic tissue, and are actively incorporate into new vessels[22]. "
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    • "Previous studies have been effective at measuring the numbers of VEGFRs in vitro29 and in vivo.30,31 Although the changes in VEGFRs have been investigated under ischemia,32 to our knowledge, the changes in surface receptors after antiangiogenic treatment have not been studied. Therefore, we investigate the changes in the number of VEGFR2 molecules on the endothelial cell surface after antiangiogenic treatment to better understand the cellular response to treatment. "
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