(549d) Co-Cultures of Mammary Organoids and Macrophages Provide Insight into Breast Cancer Recurrence
AIChE Annual Meeting
2020
2020 Virtual AIChE Annual Meeting
Food, Pharmaceutical & Bioengineering Division
Organotypic Models of Tissue Development and Dysregulaton
Thursday, November 19, 2020 - 8:45am to 9:00am
To evaluate immune cell recruitment, we irradiated inguinal murine mammary fat pads (MFPs) of 8-12 week old female Nu/Nu and BALB/c mice in vivo to a dose of 20 Gy. MFPs were resected 10 days post-irradiation. Tissues were either processed for immunohistochemical characterization or into a single cell suspension for flow cytometry. Cells were stained with F4/80 in addition to CD86+ or CD206+ to determine M1 and M2 macrophage polarization, respectively. To obtain mammary organoids, MFPs were resected, irradiated ex vivo to 20 Gy, and digested with collagenase to isolate epithelial cells before self-assembly in low adhesion plates. Control unirradiated and irradiated organoids were then cultured with biologically relevant ratios of M1/M2-polarized RAW 264.7 macrophages. Co-culture experiments were monitored up to 48 hours with live cell imaging. Conditioned media from the co-culture was used for in vitro invasion assays with murine TNBC 4T1 cells.
We identified an increase in F4/80+ macrophage infiltration following in vivo irradiation, recapitulating observations from previous studies. We also quantified enhanced recruitment of tumor associated M2 macrophages in irradiated sites (p < 0.05), potentially implicating the role of wound healing macrophages in tumor cell recruitment. These results were confirmed in vitro as tumor cell invasiveness was associated with irradiation and higher M2/M1 macrophage ratios in the co-culture model.
This work describes the interplay between an in vivo and in vitro model that may elucidate the role of radiation in immune-facilitated recurrence in a biologically relevant environment. This model will provide insight into the mechanisms behind radiation-induced tumor and immune cell recruitment, which will have significant implications for patients suffering from TNBC recurrence.