Patient-Derived Organoid Invasion Assay
Materials Required
Principle
Patient-derived organoid (PDO) invasion assays are based on the ability of epithelial tumor organoids to self-organize in three-dimensional extracellular matrix (ECM) hydrogels (commonly Matrigel) and to recapitulate key aspects of in vivo tissue architecture, including polarity, proliferation, and invasive outgrowth when exposed to permissive microenvironmental cues[1][2]. In this system, invasion is operationally defined as the emergence of multicellular protrusions, collective budding, or single-cell dissemination from the organoid core into the surrounding ECM, reflecting epithelial-mesenchymal plasticity and matrix remodeling capacity[2][3]. Organoid morphology and invasive behavior are typically monitored using brightfield or confocal microscopy over time, enabling quantitative assessment of invasion area, protrusion number, and structural disruption of the organoid spheroid architecture[2][3].
MCE has not independently verified the accuracy of these methods. They are for reference only.
Experimental Materials
• Collagen I (optional ECM system): Used in some organoid invasion platforms to better model stromal collagen-rich tumor environments[3].
• Organoid basal medium with niche growth factors (e.g., EGF, R-spondin, Noggin depending on tissue origin): Supports survival and expansion of PDOs prior to invasion induction[1][2].
• Recombinant TGF-β or other pro-invasive stimuli (context-dependent): Used in cancer PDO systems to induce epithelial-mesenchymal transition-associated invasion programs[3].
• Live-cell viability dyes (e.g., Calcein AM or equivalent): Used for imaging viable invading organoid cells in real time (as applied in 3D organoid imaging systems)[3].
• Fluorescent nuclear stains (e.g., Hoechst-type dyes): Used to visualize cell distribution and dissemination within invading organoids[3].
• Biological safety cabinet and CO2 incubator (37°C): Maintains sterile culture conditions and physiological growth environment for PDOs[1][2].
• Inverted fluorescence/confocal microscope: Used to capture 3D invasion dynamics and quantify protrusive growth into ECM[2][3].
• Low-attachment plates or culture plates suitable for dome embedding: Used to maintain 3D ECM droplets containing organoids[1][2].
Experimental Procedure
• Prior to invasion assays, organoids are mechanically or enzymatically fragmented into uniform-sized clusters to reduce variability in baseline size-dependent invasion behavior[2][3].
• ECM (Matrigel or collagen I) is thawed on ice and prepared for embedding organoids in dome or sandwich configurations depending on assay design[1][3].
• Culture medium is pre-equilibrated with appropriate growth factors required for tissue-specific organoid maintenance[1][2]. PDO fragments are resuspended in cold ECM and plated as domes or embedded within collagen/Matrigel matrices, followed by polymerization at physiological temperature to establish a 3D scaffold[1][2].
• After gelation, organoids are overlaid with organoid maintenance medium, and invasion is initiated either under baseline conditions or following stimulation with pro-invasive cues such as TGF-β depending on the experimental design[2][3]. Over a defined culture period, organoids are monitored by phase-contrast or confocal microscopy to observe morphological transitions, including loss of spherical architecture, formation of invasive protrusions, and dissemination of single cells into the surrounding matrix[2][3].
• Imaging is performed longitudinally to capture dynamic invasion behavior, which is a hallmark of tumor progression in PDO systems[3]. Invasion is quantified by measuring changes in organoid morphology, including protrusion number, invasive area, and degree of structural disruption relative to baseline spheroid shape[2][3].
• Comparative analysis is typically performed between untreated controls and stimulated conditions to determine invasion-inducing effects of microenvironmental factors[3].
• Biological replicates are derived from independent patient organoid lines to capture inter-patient heterogeneity, while technical replicates ensure reproducibility within ECM embedding conditions[2][3].
Troubleshooting
Q1: Organoids fail to exhibit invasive protrusions in ECM
Problem: Lack of observable invasion despite stimulation.
Possible Cause
Insufficient ECM remodeling signaling or inappropriate ECM composition.Literature-supported Solution
Adjust ECM composition (e.g., switching between Matrigel and collagen I) or apply pro-invasive cues such as TGF-β, which has been shown to promote invasive phenotypes in cancer PDO systems[3].Q2: Organoids collapse or lose structural integrity during assay
Problem: Organoids disintegrate or lose 3D architecture.
Possible Cause
Mechanical instability or suboptimal ECM support.Literature-supported Solution
Maintain organoids in Matrigel-based 3D culture systems that preserve epithelial architecture prior to invasion induction[1][2].Q3: Excessive heterogeneity in invasion measurements
Problem: High variability in invasion metrics between samples.
Possible Cause
Variation in organoid size or inconsistent fragmentation prior to embedding.Literature-supported Solution
Standardize organoid fragmentation into uniform clusters before embedding to reduce baseline morphological variability[2][3].References:
- [1]. Sato, T., et al. Single Lgr5 stem cells build crypt-villus structures in vitro without a mesenchymal niche. Nature. 2009;459(7244):262-265. [Content Brief]
- [2]. Boj, S.F., et al. Organoid models of human and mouse ductal pancreatic cancer. Nature Medicine. 2015;21(7):604-612. [Content Brief]
- [3]. Kopper, O., et al. An organoid platform for ovarian cancer captures intra- and interpatient heterogeneity. Cell. 2019;177(2):362-377.e27. [Content Brief]
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