Growth and Characterization of Irradiated Organoids from Mammary Glands

Summary

Organoids developed from mouse mammary glands were irradiated and characterized to assess epithelial traits and interactions with immune cells. Irradiated organoids can be used to better evaluate cell-cell interactions that may lead to tumor cell recruitment in irradiated normal tissue.

Abstract

Organoids derived from the digested tissue are multicellular three-dimensional (3D) constructs that better recapitulate in vivo conditions than cell monolayers. Although they cannot completely model in vivo complexity, they retain some functionality of the original organ. In cancer models, organoids are commonly used to study tumor cell invasion. This protocol aims to develop and characterize organoids from the normal and irradiated mouse mammary gland tissue to evaluate the radiation response in normal tissues. These organoids can be applied to future in vitro cancer studies to evaluate tumor cell interactions with irradiated organoids. Mammary glands were resected, irradiated to 20 Gy and digested in a collagenase VIII solution. Epithelial organoids were separated via centrifugal differentiation, and 3D organoids were developed in 96-well low-adhesion microplates. Organoids expressed the characteristic epithelial marker cytokeratin 14. Macrophage interaction with the organoids was observed in co-culture experiments. This model may be useful for studying tumor-stromal interactions, infiltration of immune cells, and macrophage polarization within an irradiated microenvironment.

Introduction

Approximately 60% of the triple negative breast cancer (TNBC) patients choose breast-conserving therapy (BCT) as a form of treatment¹. In this treatment modality, the tumor containing part of the breast tissue is removed, and the surrounding normal tissue is exposed to ionizing radiation to kill any residual tumor cells. Treatment reduces recurrence in much of the breast cancer population; however, approximately 13.5% of treated patients with TNBC experience locoregional recurrences². Therefore, studying how radiation may recruit circulating tumor cells (CTCs) will lead to important insights into local recurrence

Protocol

Animal studies were performed in accordance with institutional guidelines and protocols approved by the Vanderbilt University Institutional Animal Care and Use Committee.

1. Preparation of mice and cell acquisition (adapted from Nguyen-Ngoc et al.¹¹)

1. Sacrifice athymic Nu/Nu mice (8-10 weeks old) using CO­₂ asphyxiation followed by cervical dislocation. Clean the skin using 70% ethanol.
2. Resect abdominal and inguinal mammary glands from mice using pre-sterilized scissors and forceps. Remove lymph nodes before resection. Rinse in sterile 1x phosphate buffered saline (PBS) (

Results

Irradiated epithelial mammary organoids were successfully obtained from mouse mammary glands, processed, and cultured on low-adhesion plates (Figure 1). Organoid yield was tested by seeding in different growth environments (Figure 2A-G). Seeding cells directly onto tissue culture treated 10 cm cell plates yielded an overgrowth of fibroblast cells. Fibroblasts were identified under phase contrast microscopy in or near the same plane of focus as organoids, and they quickly gre.......

Discussion

In this protocol, we have developed a method for reproducible growth and characterization of irradiated mammary organoids (Figure 1). An irradiation dose of 20 Gy was applied to mirror previous in vivo models of tumor cell recruitment⁵. Irradiation of mammary glands ex vivo prior to organoid formation allowed for isolation of radiation damage effects without a corresponding infiltration of immune cells. The development of an in vitro irradiated normal tissue model ena.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
10% Neutral Buffered Formalin	VWR	16004-128
Anti-cytokeratin 14	abcam	ab181595	Lot: GR3200524-3
Bovine Serum Albumin	Sigma	A1933-25G
Collagen Type I	Corning	354236
Collagenase from Clostridium Histolyticum, Type VIII	Sigma	C2139
Collagenase I	Gibco	17018029
DMEM/F12	Thermofisher	11320-033
DNAse	Roche	10104159001
DPBS	Fisher	14190250
E-Cadherin	Cell Signaling	24E10	Lot: 13
FBS	Sigma	F0926
Gentamicin	Gibco	15750
Goat anti-rabbit secondary	abcam	ab150077	green Lot: GR3203000-1
Goat anti-rabbit secondary	abcam	ab150080	red Lot: GR3192711-1
Hoechst 33342	Fisher	62249	Lot: TG2611041
Insulin (10 mg/mL)	Sigma	I9278
Insulin-Transferrin-Selenium, 100x	Gibco	51500-056
Matrigel Basement Membrane (basement membrane extracted from Engelbreth-Holm-Swarm mouse sarcoma)	Corning	356237
Normal Goat Serum	Vector Laboratories	S-1000
Nuclon Sphera 96 well plates	Thermo	174927
PBS	VWR	10128-856
Pen/strep	Fisher	15140122
Phalloidin	abcam	ab176757	Lot: GR3214582-16
Tight Junction Protein 1	Novus	NBP1-85047	Lot: C115428
Triton X-100 (4-(1,1,3,3-Tetramethylbutyl)phenyl-polyethylene glycol)	Sigma	X100-100ML
Trypsin	Gibco	27250-018
Tween-20 (Polyethylene glycol sorbitan monolaurate)	Sigma	P1379-100ML