An In Vitro Vascularized Tumor Platform for Modeling Breast Tumor Stromal Interactions and Characterizing the Subsequent Response

Tumor stromal interactions have been shown to be the driving force behind the poor prognosis associated with aggressive breast tumors. These interactions, specifically between tumor and the surrounding ECM, and tumor and vascular endothelium, promote tumor formation, angiogenesis, and metastasis. In this study, we develop an in vitro vascularized tumor platform that allows for investigation of tumor-stromal interactions in three breast tumor derived cell lines of varying aggressiveness: MDA-IBC3, SUM149, and MDA-MB-231. The platform recreates key features of breast tumors, including increased vascular permeability, vessel sprouting, and ECM remodeling. Morphological and quantitative analysis reveals differential effects from each tumor cell type on endothelial coverage, permeability, expression of VEGF, and collagen remodeling. Triple negative tumors, SUM149 and MDA-MB-321, resulted in a significantly (p<0.05) higher endothelial permeability and decreased endothelial coverage compared to the control TIME only platform. SUM149/TIME platforms were 1.3 fold lower (p<0.05), and MDA-MB-231/TIME platforms were 1.5 fold lower (p<0.01) in endothelial coverage compared to the control TIME only platform. HER2+ MDA-IBC3 tumor cells expressed high levels of VEGF (p<0.01) and induced vessel sprouting. Vessels sprouting was tracked for 3 weeks and with increasing time exhibited formation of multiple vessel sprouts that invaded into the ECM and surrounded clusters of MDA-IBC3 cells. Both IBC cell lines, SUM149 and MDA-IBC3, resulted in a collagen ECM with significantly greater porosity with 1.6 and 1.1 fold higher compared to control, p<0.01. The breast cancer in vitro vascularized platforms introduced in this paper are an adaptable, high throughout tool for unearthing tumor-stromal mechanisms and dynamics behind tumor progression and may prove essential in developing effective targeted therapeutics.