An in vitro cord formation assay identifies unique vascular phenotypes associated with angiogenic growth factors

PLoS One. 2014 Sep 11;9(9):e106901. doi: 10.1371/journal.pone.0106901. eCollection 2014.

Abstract

Vascular endothelial growth factor (VEGF) plays a dominant role in angiogenesis. While inhibitors of the VEGF pathway are approved for the treatment of a number of tumor types, the effectiveness is limited and evasive resistance is common. One mechanism of evasive resistance to inhibition of the VEGF pathway is upregulation of other pro-angiogenic factors such as fibroblast growth factor (FGF) and epidermal growth factor (EGF). Numerous in vitro assays examine angiogenesis, but many of these assays are performed in media or matrix with multiple growth factors or are driven by VEGF. In order to study angiogenesis driven by other growth factors, we developed a basal medium to use on a co-culture cord formation system of adipose derived stem cells (ADSCs) and endothelial colony forming cells (ECFCs). We found that cord formation driven by different angiogenic factors led to unique phenotypes that could be differentiated and combination studies indicate dominant phenotypes elicited by some growth factors. VEGF-driven cords were highly covered by smooth muscle actin, and bFGF-driven cords had thicker nodes, while EGF-driven cords were highly branched. Multiparametric analysis indicated that when combined EGF has a dominant phenotype. In addition, because this assay system is run in minimal medium, potential proangiogenic molecules can be screened. Using this assay we identified an inhibitor that promoted cord formation, which was translated into in vivo tumor models. Together this study illustrates the unique roles of multiple anti-angiogenic agents, which may lead to improvements in therapeutic angiogenesis efforts and better rational for anti-angiogenic therapy.

MeSH terms

  • Adipose Tissue / drug effects
  • Adipose Tissue / growth & development
  • Cell Line
  • Culture Media
  • Endothelial Cells / cytology
  • Endothelial Cells / drug effects
  • Epidermal Growth Factor / administration & dosage
  • Fetal Blood
  • Fibroblast Growth Factors / administration & dosage
  • Humans
  • Muscle, Smooth / cytology
  • Muscle, Smooth / drug effects
  • Neovascularization, Pathologic / drug therapy
  • Neovascularization, Pathologic / metabolism*
  • Pericytes / cytology
  • Pericytes / drug effects
  • Stem Cells / cytology*
  • Stem Cells / drug effects
  • Vascular Endothelial Growth Factor A / antagonists & inhibitors
  • Vascular Endothelial Growth Factor A / metabolism*

Substances

  • Culture Media
  • Vascular Endothelial Growth Factor A
  • Fibroblast Growth Factors
  • Epidermal Growth Factor

Grants and funding

All of the authors are employed with Eli Lilly and Company. The funder provided support in the form of salaries for all the authors, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the “author contributions” section.