Generating and Imaging Mouse and Human Epithelial Organoids from Normal and Tumor Mammary Tissue Without Passaging

Summary

This protocol discusses an approach for generating epithelial organoids from primary normal and tumor mammary tissue through differential centrifugation. Furthermore, instructions are included for three-dimensional culturing as well as immunofluorescent imaging of embedded organoids.

Abstract

Organoids are a reliable method for modeling organ tissue due to their self-organizing properties and retention of function and architecture after propagation from primary tissue or stem cells. This method of organoid generation forgoes single-cell differentiation through multiple passages and instead uses differential centrifugation to isolate mammary epithelial organoids from mechanically and enzymatically dissociated tissues. This protocol provides a streamlined technique for rapidly producing small and large epithelial organoids from both mouse and human mammary tissue in addition to techniques for organoid embedding in collagen and basement extracellular matrix. Furthermore, instructions for in-gel fixation and immunofluorescent staining are provided for the purpose of visualizing organoid morphology and density. These methodologies are suitable for myriad downstream analyses, such as co-culturing with immune cells and ex vivo metastasis modeling via collagen invasion assay. These analyses serve to better elucidate cell-cell behavior and create a more complete understanding of interactions within the tumor microenvironment.

Introduction

The ability to model epithelial cells in vitro has been the foundation of modern biomedical research because it captures cellular features that are not accessible in vivo. For instance, growing epithelial cell lines in a two-dimensional plane can provide an assessment of the molecular changes that occur in an epithelial cell during proliferation¹. Furthermore, measuring the dynamic regulation between signaling and gene expression is limited in in vivo systems². In cancer research, cancer epithelial cell line modeling has enabled the identification of molecular drivers of disease progression and....

Protocol

All mouse tissue utilized in this manuscript has been ethically collected in accordance with the Institutional Animal Care and Use Committee (IACUC) regulations and guidelines of the University of Texas Southwestern Medical Center. Likewise, all the patients consented prior to tissue donation under the oversight of an Institutional Review Board (IRB), and the samples were deidentified.

NOTE: This protocol describes the generation of organoids from primary tissue.

1. Overnight preparation of materials

1. For embedding in basement extracellular matrix (BECM), thaw the BECM aliquot by leavi....

Results

The images featured in Figure 1 provide an example of wild-type and tumorous mammary epithelial organoids from human and mouse tissues. An at-a-glance illustration of the method for isolating epithelial organoids through differential centrifugation is provided in the cartoon workflow in Figure 1A, showing that primary tissues from different species can be processed in near-identical ways while yielding epithelial tissue as shown in the brightfield images (

Discussion

Different methods have been described in the literature to generate tumor organoids. This protocol highlights a method for generating tumor organoids directly from the tumor without passaging. Using this method, tumor organoids are producible within hours of initiating the procedure and generate close to 100% viable organoids compared to 70% reported in the literature³¹. In comparison, other methods require serial passaging of cells into organoids over several weeks. Thus, the downstream applicati.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
10 mM HEPES Buffer	Gibco	15630080
100x Antibiotic-Antimycotic	Gibco	15240-096
100x Glutamax	Life Technologies	35050-061	Glutamine supplement
100x Insulin-Transferrin-Selenium (ITS)	Life Technologies	51500-056
100x Penicillin/Streptomycin (Pen/Strep)	Sigma	P4333
10x DMEM	Sigma	D2429
50 mL/0.2 µm filter flask	Fisher	#564-0020
Amphotericin B	Life Technologies	15290-018
bFGF	Sigma	F0291
BSA Solution (32%)	Sigma	#A9576
Cholera Toxin	Sigma	C8052
CO2-Independent Medium	Gibco	18045-088
Collagenase A	Sigma	C2139
Deoxyribonuclease I from bovine pancreas (DNase)	Sigma	D4263
DMEM with 4500 mg/L glucose, sodium pyruvate, and sodium bicarbonate, without L-glutamine, liquid, sterile-filtered, suitable for cell culture	Sigma	D6546	Common basal medium
D-MEM/F12	Life Technologies	#10565-018	Basal cell medium
Dulbecco's Phosphate Buffered Saline (D-PBS)	Sigma	#D8662	PBS
Fetal bovine serum (FBS)	Sigma	#F0926
Gentamicin	Life Technologies	#15750-060
Human epidermal growth factor (EGF)	Sigma	E9644
Hydrocortisone	Sigma	H0396
Insulin	Sigma	#I9278
Matrigel	Corning	#354230	Basement Extracellular Matrix (BECM)
NaOH (1 N)	Sigma	S2770
Rat Tail Collagen I	Corning	354236
RPMI-1640 media	Fisher	SH3002701
Trypsin	Life Technologies	27250-018