2D and 3D in vitro angiogenesis assays highlight different aspects of angiogenesis

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In angiogenesis research, scientists need to carefully select appropriate in vitro models to test their hypotheses to minimize the risk for false negative or false positive study results. In this study, we investigate molecular differences between simple two-dimensional and more complex three-dimensional angiogenesis assays and compare them to in vivo data from cancer-associated angiogenesis using an unbiased transcriptomic analysis. Human umbilical vein endothelial cells were treated with VEGF in 2D wound healing and proliferation assays and the 3D spheroid sprouting assay. VEGF-induced transcriptomic shifts were assessed in both settings by bulk RNA sequencing. Immunocytochemistry was used for protein detection. The data was linked to the transcriptomic profile of vascular endothelial cells from a single cell RNA sequencing dataset of various cancer tissue compared to adjacent healthy tissue control. VEGF induced a more diverse transcriptomic shift in vascular endothelial cells in a 3D experimental setting (767 differentially expressed genes) compared to the 2D settings (167 differentially expressed genes). Particularly, VEGF-induced changes in cell-matrix interaction, tip cell formation, and glycolysis were pronounced in the 3D spheroid sprouting experiments. Immunocytochemistry for VCAM1 and CD34 confirmed enhanced expression in response to VEGF-treatment in 3D settings. In vivo, vascular endothelial cells within various cancer tissue were characterized by strong transcriptomic changes in cell-matrix interaction and glycolysis similar to the 3D setting. Consequently, 3D assays may better address certain key aspects of angiogenesis in comparison to fast and scalable 2D assays. This should be taken into consideration within the context of each research question.