Spheroid/Tumor Organoid Invasion Assay
Materials Required
Principle
The spheroid/tumor organoid invasion assay measures outward movement of cancer cells from a compact 3D aggregate into an extracellular matrix, usually collagen I, basement membrane matrix, or mixed collagen-Matrigel hydrogels; the readout is generated by bright-field, fluorescence, confocal, or time-lapse imaging of cell egress, invasion area, invasion distance, dispersion, protrusion formation, basement-membrane perforation, or cell trajectories[1][2][3][4][5]. The assay reflects cell-cell cohesion, cell-matrix adhesion, matrix remodeling, protease-dependent invasion, contractility, and invasion behavior in a 3D microenvironment rather than migration on a flat 2D surface[6][7][8][9].
MCE has not independently verified the accuracy of these methods. They are for reference only.
Experimental Materials
• Use tumor spheroids, cancer cell-line spheroids, microcarrier-based spheroids, or freshly isolated murine/human tumor organoids as the invasive biological sample; use cell culture medium appropriate to the source cell or organoid system; use collagen I as a stromal ECM, basement membrane matrix/Matrigel as a basement-membrane-like ECM, or collagen-Matrigel mixtures when the experimental goal is to model matrix composition at an invasive tumor edge[1][2][3][4][5][8].
• Neutralized collagen I gels and mixed collagen-Matrigel hydrogels have been used for embedding spheroids or cells, and reported mixed-matrix examples include 2 mg/mL collagen I alone, 2 mg/mL collagen I plus 2 mg/mL Matrigel, and 2 mg/mL collagen I plus 4 mg/mL Matrigel[6][8].
• Use fluorescent nuclear labels or cell-tracker fluorescence when automated segmentation, single-cell tracking, or time-lapse quantification is required; use collagen IV immunostaining to visualize encapsulating basement membrane around spheroids and basement-membrane disruption during invasion; use phalloidin or F-actin staining when invasion-associated morphology or cytoskeletal organization is part of the endpoint[3][5][6][11].
• Use ultra-low-attachment round-bottom plates or hanging-drop culture formats to generate spheroids, standard tissue-culture incubators for spheroid/organoid culture, pipettes and chilled handling conditions for ECM preparation where required by matrix polymerization behavior, an inverted microscope for bright-field imaging, fluorescence or confocal microscopy for labeled cells and matrix structures, and time-lapse microscopy when dynamic invasion or cell tracking is the endpoint[1][2][3][4][5][10].
• Neutralized collagen I gels and mixed collagen-Matrigel hydrogels have been used for embedding spheroids or cells, and reported mixed-matrix examples include 2 mg/mL collagen I alone, 2 mg/mL collagen I plus 2 mg/mL Matrigel, and 2 mg/mL collagen I plus 4 mg/mL Matrigel[6][8].
• Use fluorescent nuclear labels or cell-tracker fluorescence when automated segmentation, single-cell tracking, or time-lapse quantification is required; use collagen IV immunostaining to visualize encapsulating basement membrane around spheroids and basement-membrane disruption during invasion; use phalloidin or F-actin staining when invasion-associated morphology or cytoskeletal organization is part of the endpoint[3][5][6][11].
• Use ultra-low-attachment round-bottom plates or hanging-drop culture formats to generate spheroids, standard tissue-culture incubators for spheroid/organoid culture, pipettes and chilled handling conditions for ECM preparation where required by matrix polymerization behavior, an inverted microscope for bright-field imaging, fluorescence or confocal microscopy for labeled cells and matrix structures, and time-lapse microscopy when dynamic invasion or cell tracking is the endpoint[1][2][3][4][5][10].
Experimental Procedure
• Generate uniform spheroids before embedding by self-assembly in low-attachment microplates, hanging drops, or microcarrier-based culture, or prepare tumor organoids from fresh murine or human primary/metastatic tumor tissue when the assay is intended to preserve tumor heterogeneity[1][2][4][5][10].
• Use spheroids with comparable initial size within each experiment because invasion-area measurements can be affected by starting spheroid geometry[1][5].
• Prepare the ECM immediately before embedding using collagen I, basement membrane matrix, or collagen-Matrigel mixtures matched to the biological question; collagen I is appropriate for stromal invasion, basement membrane matrix is appropriate for basement-membrane-like contexts, and mixed collagen-Matrigel matrices have been used to test how matrix composition, stiffness, adhesion, and protease activity affect invasion or migration[1][2][3][7][8].
• Embed one spheroid or organoid per matrix region or well when single-spheroid quantification is planned, center the spheroid within the gel when possible, and avoid analyzing spheroids located at matrix edges because microcarrier-spheroid studies reported that spheroid position within the matrix can alter cell movement paths and generate misleading invasion results[1][5].
• Allow the ECM to polymerize under the conditions reported for the selected matrix system, then add culture medium without disturbing the gel[1][2][3][5][6].
• Acquire an initial image immediately after embedding to define the baseline spheroid area, then image the same spheroid repeatedly over the invasion period; published spheroid invasion protocols commonly monitor invasion from time 0 through approximately 72-96 h, while organotypic tumor organoid assays support real-time imaging and endpoint molecular analysis depending on the model[1][4].
• For time-lapse assays, track cell dispersion or individual cell movement in 3D matrices when dynamic invasion behavior rather than only endpoint area is required[5].
• For basement-membrane invasion models, first generate spheroids with an encapsulating basement membrane, embed them in 3D collagen I gel, and assess invasion through basement-membrane disruption and outward migration into collagen; collagen IV staining can be used to confirm basement membrane continuity or perforation[3][11].
• Quantify invasion using image-based measures reported in the literature, including invasion area, change in total invaded area over time, maximum or mean invasion distance from the spheroid border, cell dispersion in matrix, and single-cell trajectories from time-lapse imaging[1][5][8].
• Normalize invasion measurements to the baseline spheroid size when comparing spheroids with different starting areas, and exclude poorly centered spheroids or edge-positioned spheroids when matrix geometry compromises interpretation[1][5].
• Use non-invasive or weakly invasive cells/spheroids as negative comparators when available, invasive cancer cells as positive comparators, and matrix-only/no-cell wells as imaging-background controls; when testing matrix-degradation mechanisms, compare untreated cultures with metalloproteinase-inhibited cultures because collagen I and mixed collagen-Matrigel studies show matrix- and MMP-dependent differences in invasion[5][7][8].
• Use biological replicates across independent cultures and technical replicate spheroids per condition when comparing treatments or matrices, and analyze matched time points with the same segmentation criteria across all groups[1][5][8].
• Use spheroids with comparable initial size within each experiment because invasion-area measurements can be affected by starting spheroid geometry[1][5].
• Prepare the ECM immediately before embedding using collagen I, basement membrane matrix, or collagen-Matrigel mixtures matched to the biological question; collagen I is appropriate for stromal invasion, basement membrane matrix is appropriate for basement-membrane-like contexts, and mixed collagen-Matrigel matrices have been used to test how matrix composition, stiffness, adhesion, and protease activity affect invasion or migration[1][2][3][7][8].
• Embed one spheroid or organoid per matrix region or well when single-spheroid quantification is planned, center the spheroid within the gel when possible, and avoid analyzing spheroids located at matrix edges because microcarrier-spheroid studies reported that spheroid position within the matrix can alter cell movement paths and generate misleading invasion results[1][5].
• Allow the ECM to polymerize under the conditions reported for the selected matrix system, then add culture medium without disturbing the gel[1][2][3][5][6].
• Acquire an initial image immediately after embedding to define the baseline spheroid area, then image the same spheroid repeatedly over the invasion period; published spheroid invasion protocols commonly monitor invasion from time 0 through approximately 72-96 h, while organotypic tumor organoid assays support real-time imaging and endpoint molecular analysis depending on the model[1][4].
• For time-lapse assays, track cell dispersion or individual cell movement in 3D matrices when dynamic invasion behavior rather than only endpoint area is required[5].
• For basement-membrane invasion models, first generate spheroids with an encapsulating basement membrane, embed them in 3D collagen I gel, and assess invasion through basement-membrane disruption and outward migration into collagen; collagen IV staining can be used to confirm basement membrane continuity or perforation[3][11].
• Quantify invasion using image-based measures reported in the literature, including invasion area, change in total invaded area over time, maximum or mean invasion distance from the spheroid border, cell dispersion in matrix, and single-cell trajectories from time-lapse imaging[1][5][8].
• Normalize invasion measurements to the baseline spheroid size when comparing spheroids with different starting areas, and exclude poorly centered spheroids or edge-positioned spheroids when matrix geometry compromises interpretation[1][5].
• Use non-invasive or weakly invasive cells/spheroids as negative comparators when available, invasive cancer cells as positive comparators, and matrix-only/no-cell wells as imaging-background controls; when testing matrix-degradation mechanisms, compare untreated cultures with metalloproteinase-inhibited cultures because collagen I and mixed collagen-Matrigel studies show matrix- and MMP-dependent differences in invasion[5][7][8].
• Use biological replicates across independent cultures and technical replicate spheroids per condition when comparing treatments or matrices, and analyze matched time points with the same segmentation criteria across all groups[1][5][8].
Troubleshooting
Problem: Spheroids show inconsistent invasion between wells.
• Possible Cause: Initial spheroid size, spheroid formation method, or spheroid position within the matrix differs between wells.• Literature-supported Solution: Use uniform spheroid-generation methods, record baseline images, normalize invasion to starting spheroid size, and exclude spheroids located at matrix edges or positions that bias movement paths[1][5][10].
Problem: Cells invade poorly in collagen-rich gels.
• Possible Cause: Collagen I can impose a stromal barrier that requires matrix remodeling and MMP activity in some cancer models.• Literature-supported Solution: Confirm whether the tested cell type invades collagen I, compare collagen I with basement membrane or mixed matrices, and include MMP-inhibition controls only when the experimental question concerns protease-dependent invasion[6][7][8].
Problem: Basement-membrane invasion cannot be interpreted.
• Possible Cause: The spheroid may lack a continuous encapsulating basement membrane before collagen embedding.• Literature-supported Solution: Confirm basement membrane formation with collagen IV staining before assessing perforation or invasion into collagen gel[3][11].
Problem: Endpoint invasion area does not capture the observed invasion pattern.
• Possible Cause: Invasion can occur through dynamic single-cell dispersion, collective strands, protrusions, or matrix remodeling rather than uniform radial expansion.• Literature-supported Solution: Add time-lapse imaging, fluorescence tracking, or confocal endpoint imaging to quantify cell paths, dispersion, protrusions, and matrix-associated morphology[5][6][9][11].
References:
- [1]. Vinci M, et al. Three-dimensional (3D) tumor spheroid invasion assay. J Vis Exp. 2015;(99):e52686. [Content Brief]
- [2]. Berens EB, et al. A cancer cell spheroid assay to assess invasion in a 3D setting. J Vis Exp. 2015;(105):e53409. [Content Brief]
- [3]. Nazari SS. Generation of 3D tumor spheroids with encapsulating basement membranes for invasion studies. Curr Protoc Cell Biol. 2020;87(1):e105. [Content Brief]
- [4]. Padmanaban V, Grasset EM, Neumann NM, Fraser AK, Henriet E, Matsui W, et al. Organotypic culture assays for murine and human primary and metastatic-site tumors. Nat Protoc. 2020;15(8):2413-2442. [Content Brief]
- [5]. Liu H, et al. A microcarrier-based spheroid 3D invasion assay to monitor dynamic cell movement in extracellular matrix. Biol Proced Online. 2020;22:3. [Content Brief]
- [6]. De Wever O, Hendrix A, De Boeck A, Eertmans F, Westbroek W, Braems G, et al. Single cell and spheroid collagen type I invasion assay. Methods Mol Biol. 2014;1070:13-35. [Content Brief]
- [7]. Sodek KL, et al. Collagen I but not Matrigel matrices provide an MMP-dependent barrier to ovarian cancer cell penetration. BMC Cancer. 2008;8:223. [Content Brief]
- [8]. Anguiano M, Morales X, Castilla C, Pena AR, Ederra C, Martínez M, et al. The use of mixed collagen-Matrigel matrices of increasing complexity recapitulates the biphasic role of cell adhesion in cancer cell migration: ECM sensing, remodeling and forces at the leading edge of cancer invasion. PLoS One. 2020;15(1):e0220019. [Content Brief]
- [9]. Jimenez Valencia AM, Wu PH, Yogurtcu ON, Rao P, DiGiacomo J, DiGiacomo J, et al. Collective cancer cell invasion induced by coordinated contractile stresses. Oncotarget. 2015;6(41):43438-43451. [Content Brief]
- [10]. Foty R. A simple hanging drop cell culture protocol for generation of 3D spheroids. J Vis Exp. 2011;(51):2720. [Content Brief]
- [11]. Nazari SS, et al. Mechanisms of basement membrane micro-perforation during cancer cell invasion into a 3D collagen gel. Gels. 2022;8(9):567. [Content Brief]
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