Abstract
PURPOSE: Breast cancer (BC) research has suffered from a lack of model systems that can recapitulate the complex 3D microenvironment that exists within the tumor. This has limited the translation of many promising pre-clinical therapies into clinical application. The tumor microenvironment significantly influences BC cell phenotype and similarly the microenvironment is modulated by the tumor cells themselves. In the breast, adipose stromal cells (ASCs) and mature adipocytes are thought to affect BC cells via paracrine signaling as well as through direct metabolic effects; immune cells and fibroblasts may promote desmoplasia; stiffer extracellular matrices are thought to enhance cancer aggression. Herein, we present an organotypic model of BC, with the full complement of breast adipose, vascular, and epithelial cells, functional epithelial ducts, and vascular channels within a biocompatible and tunable collagen construct. We tune the mechanical and cellular properties of this system to study their influence on tumor progression and vascular remodeling. METHODS: Discarded tissue was acquired from patients undergoing breast reductions and abdominoplasties and digested to retrieve adipocytes and stromal cells. Adipocytes and stromal cells were encapsulated into type I collagen and injected into a polydimethylsiloxane base which was fabricated using positive molds constructed by additive manufacturing (3D printing). Three 1mm diameter lumens were formed and seeded with fluorescently labeled vascular cells, MDAMB 231 (BC cell line), and epithelial cells, to mimic the vasculature, ductal carcinoma, and healthy breast ducts, respectively. The adipocytes were also fluorescently labeled with the lipid dye boron-dipyrromethene (BODIPY 493/503 and BC cell invasion into the collagen-stromal bulk was analyzed with confocal microscopy. RESULTS: Over 40 adipose tissue specimens were collected and included in a tissue biobank. The collagen hydrogel bulk demonstrated a dense culture of mature adipocytes containing fluorescent lipid droplets neighbored by stromal cells, mimicking the native architecture of breast adipose tissue. The fluorescent tags allowed for observation of each of the 3 luminal structures. Metastatic potential was evaluated by assessing BC cell invasion from the lumen into stromal cell-containing hydrogels. Within the ductal carcinoma lumen, BC cells formed a mass of cells and fluorescently tagged cells were observed leaving the original lumen into the breast stromal bulk collagen. In the vascular lumen, green fluorescent endothelial cells formed a single layer along the lumen. Vascular remodeling was analyzed by endothelial cell lining disruption. CONCLUSION: We have established a novel 3D biomimetic tissue engineered platform to study the BC microenvironment, utilizing primary cells derived from specific patients’ tissues. Our high fidelity biomimetic platform provides the means for more accurate interrogation of the complex interplay within the BC tumor microenvironment and will allow for high-throughput diagnostic and therapeutic analyses in a patient-specific manner. Y. Toyoda: None. K. Celie: None. J. Buro: None. A. Lin: None. J. Xu: None. A. Abadeer: None. J. Jin: None. J. Morgan: None. K.A. Brown: None. J.A. Spector: None.
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