title: Development and characterization of a high-throughput in vitro cord formation model insensitive to VEGF inhibition.
abstract: BACKGROUND
  Anti-VEGF therapy reduces tumor blood vessels, however, some vessels always remain. These VEGF insensitive vessels may help support continued tumor growth and metastases. Many in vitro assays examining multiple steps of the angiogenic process have been described, but the majority of these assays are sensitive to VEGF inhibition. There has been little focus on the development of high-throughput, in vitro assays to model the vessels that are insensitive to VEGF inhibition.
  
  
  METHODS
  Here, we describe a fixed end-point and kinetic, high-throughput stem cell co-culture model of cord formation.
  
  
  RESULTS
  In this system, cords develop within 24 hours, at which point they begin to lose sensitivity to VEGF inhibitors, bevacizumab, and ramucirumab. Consistent with the hypothesis that other angiogenic factors maintain VEGF-independent vessels, pharmacologic intervention with a broad spectrum anti-angiogenic antagonist (suramin), a vascular disrupting agent (combretastatin), or a combination of VEGF and Notch pathway inhibitors reduced the established networks. In addition, we used our in vitro approach to develop an in vivo co-implant vasculogenesis model that connects with the endogenous vasculature to form functional blood vessels. Similar to the in vitro system, over time these vessels become insensitive to VEGF inhibition.
  
  
  CONCLUSIONS
  Together, these models may be used to identify novel drugs targeting tumor vessels that are not sensitive to VEGF inhibition.
authors.affiliation: Department of Cancer Angiogenesis, Lilly Corporate Center, Indianapolis, IN 46285, USA.
authors.forename: Beverly L
authors.initials: BL
authors.lastname: Falcon
authors.forename: Belinda
authors.initials: B
authors.lastname: O'Clair
authors.forename: Don
authors.initials: D
authors.lastname: McClure
authors.forename: Glenn F
authors.initials: GF
authors.lastname: Evans
authors.forename: Julie
authors.initials: J
authors.lastname: Stewart
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Swearingen
authors.forename: Yuefeng
authors.initials: Y
authors.lastname: Chen
authors.forename: Kevin
authors.initials: K
authors.lastname: Allard
authors.forename: Linda N
authors.initials: LN
authors.lastname: Lee
authors.forename: Kuldeep
authors.initials: K
authors.lastname: Neote
authors.forename: Dyke P
authors.initials: DP
authors.lastname: McEwen
authors.forename: Mark T
authors.initials: MT
authors.lastname: Uhlik
authors.forename: Sudhakar
authors.initials: S
authors.lastname: Chintharlapalli
mesh_terms: D017667:Adipocytes / Q000166:cytology / Q000187:drug effects; D020533:Angiogenesis Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D000818:Animals; D018920:Coculture Techniques; D005260:Female; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects; D057166:High-Throughput Screening Assays / Q000379:methods*; D061307:Human Umbilical Vein Endothelial Cells / Q000166:cytology / Q000187:drug effects; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D009369:Neoplasms / Q000098:blood supply / Q000188:drug therapy; D009389:Neovascularization, Pathologic / Q000188:drug therapy / Q000473:pathology; D018919:Neovascularization, Physiologic / Q000187:drug effects; D013234:Stem Cells / Q000166:cytology / Q000187:drug effects; D042461:Vascular Endothelial Growth Factor A / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D020533:Angiogenesis Inhibitors; D042461:Vascular Endothelial Growth Factor A