Pharmacologic characterization of a kinetic in vitro human co-culture angiogenesis model using clinically relevant compounds.

Angiogenesis, the formation of new vessels from preexisting vessels, involves multiple cell types acting in concert to cause endothelial cell proliferation, migration, and differentiation into microvascular arrays. Under pathologic conditions, microenvironment changes result in altered blood vessel production. Historically, in vitro angiogenesis assays study individual aspects of the process and tend to be variable, difficult to quantify, and limited in clinical relevance. Here, we describe a kinetic, quantitative, co-culture angiogenesis model and demonstrate its relevance to in vivo pharmacology. Similar to in vivo angiogenesis, a co-culture of human umbilical vein endothelial cells with normal human dermal fibroblasts remains sensitive to multiple cytokines, resulting in a concentration-dependent stimulation of tube formation over time. Treatment with axitinib, a selective vascular endothelial growth factor (VEGF) antagonist, inhibited VEGF-mediated tube length and branch point formation and was selective for inhibiting VEGF over basic fibroblast growth factor (bFGF), similar to previous studies. Conversely, an FGFR-1 selective compound, PD-161570, was more potent at inhibiting bFGF-mediated angiogenesis. These results demonstrate the cytokine dynamics, selective pharmacology, and translational application of this model system. Finally, combining quantitative angiogenic biology with kinetic, live-content imaging highlights the importance of using validated in vitro models in drug discovery research.