GravityTRAP™ ULA Plate

An enhanced, ultra-low attachment spheroid plate optimized for scaffold-free 3D cell culture-based assays

  • Cost-effective formation of scaffold-free spheroids via self-assembly in 96-well ultra-low attachment (ULA)-treated plates
  • SureXchange™ tapered ledge and culture chamber for easy medium exchange and spheroid visualization during long-term growth and analysis
  • 3D-optimized protocols available for analysis in GravityTRAP™ ULA Plate


  • Spheroid formation in GravityTRAP™ ULA Plates

    The GravityTRAP™ Ultra-Low Attachment (ULA) Plate represents a simple, flexible, and automation-compatible platform for the generation, long-term cultivation, observation and testing of scaffold-free 3D microtissue spheroids in 96 well format. Each plate consists of a special non-adhesively coated 96-well sterile-packaged GravityTRAP™ (Tissue Re-aggregation and Assay Plate), and lid.

    InSphero recommends GravityTRAP™ ULA Plates for the generation of spheroids using immortalized cell lines that are known to readily form microtissues, or as a starting point for investigating whether or not a cell type can form self-aggregating, scaffold-free spheroids. InSphero recommends our patented GravityPLUS® Hanging Drop System (ISP-06-001,ISP-06-010) if generating spheroids in more complex 3D cell culture scenarios, such as when using primary cells, cell lines that are resistant to self-aggregation, or when generating co-culture microtissues (e.g., tumor/stroma). In such cases, the GravityPLUS® Hanging Drop System provides the greatest opportunity for success.

    GravityTRAP™ Ultra Low Attachment Plates Workflow

    Figure 1: Spheroid formation in the GravityTRAP™ ULA Plate begins with initial seeding of cells in suspension, followed by a brief spin to concentrate cells. Following microtissue maturation,the SureXchange™ ledge of the tapered well facilitates medium exchange and compound dosing without disturbing or losing the microtissue.

    Hey Tumor Spheroids at Day 3 After Seeding in Ultra Low Attachment Plates

    Figure 2: HCT-116 and Hey tumor spheroids at day 3 of culture following seeding in the GravityTRAP™ ULA Plate at various cell densitites, demonstrating consistent, spheroid shaped microtissue formation.

    Average Spheroid Size in Ultra Low Attachment Plates

    Figure 3:  Average size (day 3) of HCT-116 and Hey tumor spheroids as assessed by volume using the Cell3iMager. Standard deviation of 6 replicates per cell density shown for each cell line.

    Spheroid ATP Viability Comparison in Ultra Low Attachment Plates

    Figure 4:  Average ATP content of HCT-116 and Hey tumor spheroids as assessed by Promega CellTiter-Glo® assay. Standard deviation of 6 replicates per cell density shown for each cell line.

  • GravityTRAP™ ULA Plates are recommended for:

    • Cell lines known to readily form spheroids
    • Low-cost screening of cell lines for spheroid formation


    Analysis and assays in GravityTRAP™ ULA Plate

    The GravityTRAP™ ULA Plate format is compatible with a broad variety of biochemical methods and allows for spectrometrical meaurements with a multiwell plate reader or for visual inspection of microtissues by an inverted microscope (similar to analysis of standard 2D cultures):

    Biochemical Assays
    Several validated biochemical assay protocols for microtissues in the GravityTRAP™ ULA Plate are available. Please see Technical Protocols in the support section of InSphero’s website:

    Microtissues are amenable to analysis by histology. Please request our Technical Protocol TP006.

    Fluorescent/luminescent multiwell plate reader compatibility
    Growth changes and profiles in tumor microtissues expressing GFP/RFP can easily be analyzed using fluorescent plate readers, as the signal intensity is stronger than with monolayer cultured cells.

    Automated imaging
    The GravityTRAP™ ULA Plate is ideal for use in automated imaging equipment, such as the SCREEN Cell3iMager and PerkinElmer Operetta, as the 1 mm diameter optically clear base of each well will be positioned exactly in the center of the field of view.

Company video