Abstract 331: A novel perfusion bioreactor system maintains long-term viability of a three dimensional in vitro breast carcinoma surrogate

Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA Background: Breast carcinomas are complex, three-dimensional (3D) tissues composed of breast cancer epithelial cells and stromal components, including fibroblasts and extracellular matrix (ECM). Most in vitro models of carcinoma consist only of cancer epithelial cells, omitting the stroma and, therefore, the 3D architecture of a tumor in vivo. While more accurate 3D modeling allows for enhanced recapitulation of tumor biology and behavior, 3D culture is acknowledged to be challenging with cell viability decreasing dramatically overtime due to lack of available nutrients. Here-in, a novel perfusion bioreactor system supplies medium through 400 uM-diameter channels to maintain survival of a 3D breast cancer surrogate consisting of MDA-MB-231 (231) breast cancer epithelial cells, breast cancer fibroblasts (CAF) and ECM. For optimization of ECM in the breast cancer surrogates, collagen I concentration and species were varied and the effect on 3D morphology and cell viability was assessed. Methods: To assess the effect of collagen concentration on 3D morphology and cell viability, 231 cells and CAF (2:1 ratio) were incorporated into 1.9, 4, 6, or 8 mg/ml (bovine or rat tail) collagen I mixed with 10% basement membrane (BM, i.e. GFR Matrigel) and cultured for 7 days in 8-well chamber slides (non-perfused, solid 3D cultures). H&E stained histologic sections were prepared after fixation and paraffin embedding of the cultures. Cell aggregation, as a measure of 3D morphology, and viability were assessed on histologic sections by image analysis (ImageJ) and autofluorescence, respectively. To compare cell viability in solid 3D culture to surrogates in the perfusion bioreactor system, 231 cells and CAF (2:1 ratio) were incorporated into an ECM composed of 6 mg/ml bovine collagen I mixed with 10% BM and grown in solid 3D culture or in the bioreactor system. The conditions were compared at 7, 14, and 21 days. Results: Collagen I concentration and species had no significant effect on the extent of cell aggregation. However, cell viability was significantly greater in 6 and 8 mg/ml (69.6% and 67.0% alive, respectively) than 1.9 mg/ml (31.9% alive) bovine collagen (ANOVA, p≤0.05). A similar increase in viability with increasing concentration was not seen with rat-tail collagen. Therefore, 6 mg/ml bovine collagen I was used in cancer surrogates in the perfusion bioreactor system. Cell viability was increased in the perfused surrogate (87.9% alive) in comparison to solid cultures (69.6% alive, t-Test, p = 0.03) at 7 days. There was no significant decrease in viability at 14 and 21 days in perfused surrogates (93.8% and 76.7% alive, respectively). Conclusions: Bovine collagen I concentration affects viability of breast cancer cells in 3D. The perfusion bioreactor system promotes cell viability allowing for multi-week culture of breast carcinoma surrogates. Citation Format: Kayla F. Goliwas, Lauren E. Marshall, Kun Yuan, Joel L. Berry, Andra R. Frost. A novel perfusion bioreactor system maintains long-term viability of a three dimensional in vitro breast carcinoma surrogate. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 331. doi:10.1158/1538-7445.AM2015-331