Tumor-associated angiogenesis is the generation of new blood vessel networks that promote tumor growth and provide a pathway for tumor cells to spread to other organs. Even though recent research has revealed several key mechanisms in the association of angiogenesis to cancer, fundamental questions remain regarding the characteristics of tumor-associated angiogenesis and how it is different from the angiogenesis involved in normal physiological processes. It has been demonstrated that tumor blood vessels are phenotypically different from their normal counterparts, showing a defective endothelial monolayer and abnormal vessel hierarchy. However, it is still unknown how tumor-associated endothelial cells (TEnCs) compare functionally to normal endothelial cells (NEnCs) and how their differences subsequently impact cancer progression. Important functional differences may include differences in angiogenic activity that are inherent to these types of endothelial cells or that are dependent on their surrounding microenvironment. For our study the primary source of TEnCs is cell isolation from patient samples, which allows us to also isolated NEnCs and tumor and normal epithelial cells (TEpCs and NEpCs respectively) to have a direct comparison of tumor versus normal microenvironment. To further characterize differences of TEnCs and NEnCs, we used a biomimetic blood vessel microfluidic platform that allows the reconstruction of the blood vessel luminal structure in vitro. This platform provided a 3D microenvironment that allowed the discovery of previously unknown characteristics of TEnCs in monoculture. First, we found that TEnCs generate more angiogenic sprouts than cells from normal tissue. We also found that the architecture of the TEnC-generated blood vessels is significantly different from NEnC-generated blood vessels when stimulated with a VEGF gradient. In addition, TEnCs form an irregular and permeable endothelial wall, allowing diffusion of small particles out of the vessels, a previously described hallmark of tumor blood vessels. Finally, TEnC vessels have a different anti-angiogenic drug response compared to their normal counterpart and it varies between patient samples, where in some patients the anti-angiogenic drug stopped angiogenesis but in other patients the angiogenesis was enhanced or not affected. When TEpCs spheroids are added next to the biomimetic blood vessel to create a co-culture model, we found that angiogenesis is down-regulated in TEnCs vessels but up-regulated in NEnCs vessels. In addition, there is cell invasion from the TEpCs spheroids toward the vessel in the TEnCs/TEpCs co-culture model but not when co-cultured with NEnCs vessels. Here we show an in vitro organotypic model that can elucidate functional characteristics of TEnCs and NEnCs in co-culture with TEpCs and NEpCs, enabling a platform that can potentially be used for therapeutic drug screening and personalized medicine.
Citation Format: Jose A. Jimenez-Torres, Kyung E. Sung, Moon He-Lee, Jason Abel, David J. Beebe. Patient-derived in vitro cancer model to study tumor-associated angiogenesis. [abstract]. In: Proceedings of the AACR Special Conference: Patient-Derived Cancer Models: Present and Future Applications from Basic Science to the Clinic; Feb 11-14, 2016; New Orleans, LA. Philadelphia (PA): AACR; Clin Cancer Res 2016;22(16_Suppl):Abstract nr A19.