Patient-derived tumor organoids are a sophisticated model system for basic and translational research. This methods article details the use of multiplexed fluorescent live-cell imaging for simultaneous kinetic assessment of different organoid phenotypes.
Patient-derived organoid (PDO) models of cancer are a multifunctional research system that better recapitulates human disease as compared to cancer cell lines. PDO models can be generated by culturing patient tumor cells in extracellular basement membrane extracts (BME) and plating them as three-dimensional domes. However, commercially available reagents that have been optimized for phenotypic assays in monolayer cultures often are not compatible with BME. Herein, we describe a method to plate PDO models and assess drug effects using an automated live-cell imaging system. In addition, we apply fluorescent dyes that are compatible with kinetic measurements to quantify cell health and apoptosis simultaneously. Image capture can be customized to occur at regular time intervals over several days. Users can analyze drug effects in individual Z-plane images or a Z Projection of serial images from multiple focal planes. Using masking, specific parameters of interest are calculated, such as PDO number, area, and fluorescence intensity. We provide proof-of-concept data demonstrating the effect of cytotoxic agents on cell health, apoptosis, and viability. This automated kinetic imaging platform can be expanded to other phenotypic readouts to understand diverse therapeutic effects in PDO models of cancer.
Patient-derived tumor organoids (PDOs) are rapidly emerging as a robust model system to study cancer development and therapeutic responses. PDOs are three-dimensional (3D) cell culture systems that recapitulate the complex genomic profile and architecture of the primary tumor1,2. Unlike traditional two-dimensional (2D) cultures of immortalized cancer cell lines, PDOs capture and maintain intratumoral heterogeneity3,4, making them a valuable tool for both mechanistic and translational research. Although PDOs are becoming an increasingly popular model system, commercially available reagents and analysis methods for cellular effects that are compatible with PDO cultures are limited.
The lack of robust methods to analyze subtle changes in treatment response hinders clinical translation. The gold standard cell health reagent in 3D cultures, CellTiter-Glo 3D, utilizes ATP levels as a determinant of cell viability5,6. While this reagent is useful for endpoint assays, there are several caveats, most notably the inability to use samples for other purposes after completion of the assay.
Live-cell imaging is a sophisticated form of kinetic microscopy that, when combined with fluorescent reagents, has the capacity to quantify a variety of cell health readouts within PDO models, including apoptosis7,8,9 and cytotoxicity10. Indeed, live-cell imaging has been integral to high throughput screening of compounds in 2D platforms11,12. Systems such as the Incucyte have made the technology affordable and thus accessible to research groups in a variety of settings. However, the application of these systems to analyze 3D cultures is still in its infancy.
Herein, we describe a method to assess drug response in PDO models of cancer using multiplexed live-cell imaging (Figure 1). Through analysis of bright field images, changes in PDO size and morphology can be kinetically monitored. Furthermore, cellular processes can be simultaneously quantified over time using fluorescent reagents, such as Annexin V Red Dye for apoptosis and Cytotox Green Dye for cytotoxicity. The methods presented are optimized for the Cytation 5 live-cell imaging system, but this protocol may be adapted across different live-cell imaging platforms.
PDO cultures are becoming an increasingly popular in vitro model system due to their ability to reflect cellular responses and behaviors2. Significant advances have been made in PDO generation, culture, and expansion techniques, yet methods to analyze therapeutic responses have lagged. Commercially available 3D viability kits are lytic endpoint assays, missing out on potentially valuable kinetic response data and limiting subsequent analyses by other methods8. Emerging stud…
The authors have nothing to disclose.
We are grateful to the Tissue Procurement Core and Dr. Kristen Coleman at the University of Iowa for providing patient tumor specimens and to Dr. Sofia Gabrilovich in the Department of Obstetrics and Gynecology for assisting with PDO model generation. We also thank Dr. Valerie Salvatico (Agilent, USA) for critical analysis of the manuscript. We acknowledge the following funding sources: NIH/NCI CA263783 and DOD CDMRP CA220729P1 to KWT; Cancer Research UK, Prostate Cancer UK, Prostate Cancer Foundation and Medical Research Council to JSdB. The funders had no role in the design or analysis of experiments or decision to publish.
1.5 mL microcentrfuge tube | Dot Scientific Inc | 1008113 | |
15 mL conical centrifuge tube | Sarstedt | 62.554.100 | |
554 NM LED Cube | Agilent | 1225012 | |
96-well plate | Corning Costar | 3596 | Prewarmed to 37 °C |
96-well plate | Agilent | 204626-100 | Prewarmed to 37 °C |
A83-01 | Tocris | 2939 | Final concentration is 500 nM (component of organoid culture media) |
Advanced DMEM/F-12 | Gibco | 12634-010 | component of organoid culture media |
B27 Supplement | Gibco | 17504044 | Final concentration is 1x (component of organoid culture media) |
BioTek BioSpa 8 Automated Incubator | Agilent | BIOSPAG-SN | Tabletop incubator; BioSpa OnDemand scheduling software comunicates with Gen5 to transfer plates between the BioSpa and the Cytation 5 for imaging (this protocol uses version 1.01.10) |
BioTek Cytation 5 Cell Imaging Multimode Reader | Agilent | CYT5PW-SN | Plate reader; Gen5 software is used for this device (this protocol uses version 3.12.08) |
Cultrex UltiMatrix Reduced Growth Factor Basement Membrane Extract | R&D Systems | BME001-10 | |
Daunorubicin HCl | Sigma-Aldrich | S3035 | Reconstituted in DMSO |
Dimethyl sulfoxide | Sigma-Aldrich | D2438 | |
EDTA (0.5 M) | Thermo Fisher | AM9260G | |
Forskolin | Tocris | 1099 | Final concentration is 10 µM (component of organoid culture media) |
Glutamax | Gibco | 35050-061 | Final concentration is 1x (component of organoid culture media) |
HEPES | Gibco | 15630-080 | Final concentration is 10 mM (component of organoid culture media) |
Human EGF, Animal-Free Recombinant Protein | Gibco | AF-100-15-1MG | Final concentration is 0.5 ng/mL (component of organoid culture media) |
Human FGF-10 Recombinant Protein | Gibco | 100-26-1MG | Final concentration is 10 ng/mL (component of organoid culture media) |
Human R-Spondin 1 Recombinant Protein | Gibco | 120-38-5UG | Final concentration is 250 ng/mL (component of organoid culture media) |
Hydrocortisone Stock Solution | StemCell Technologies | 7926 | Final concentration is 500 ng/mL (component of organoid culture media) |
Imaging Filter Cube- GFP | Agilent | 1225101 | |
Imaging Filter Cube- TRITC | Agilent | 1225125 | |
Imaging LED GFP/CFP | Agilent | 1225001 | |
Incucyte Annexin V Red Dye | Sartorius | 4641 | Reconstituted in organoid culture media |
Incucyte Cytotox Green Dye | Sartorius | 4633 | DMSO solution |
N-Acetyl-L-cysteine | Sigma-Aldrich | A7250 | Final concentration is 1.25 mM (component of organoid culture media) |
Nexcelom Bioscience ViaStain AOPI Staining Solution | Fisher-Scientific | 13366169 | Add 1:50 volume |
Nicotinamide | Sigma-Aldrich | N0636 | Final concentration is 10 mM (component of organoid culture media) |
Noggin | R&D Systems | 6057-NG | Final concentration is 100 ng/mL (component of organoid culture media) |
Penicillin-Streptomycin | Gibco | 15140122 | Final concentration is 10 units/mL (component of organoid culture media) |
Phosphate Buffered Saline (1x) | Gibco | 14190-144 | |
Primocin | InvivoGen | ant-pm-05 | Final concentration is 100 µg/mL (component of organoid culture media) |
Recombinant Human Heregulinβ-1 | Pepro Tech | 100-03 | Final concentration is 37.5 ng/mL (component of organoid culture media) |
Staurosporine solution from Streptomyces sp. | Sigma-Aldrich | S6942 | |
TrypLE Express | Life Technologies | 12604013 | |
Y-27632, CAS 331752-47-7 | Sigma-Aldrich | 688000 | Final concentration is 5 µM (component of organoid culture media) |
β-Estradiol | Sigma-Aldrich | E2758 | Final concentration is 100 nM (component of organoid culture media) |