Assays and Tools to Monitor Biology in 3D Cell Cultures

Can I use standard CellTiter-Glo® Assay or CellTiter-Glo® 2.0 for 3D cell cultures?

Use the CellTiter-Glo® 3D Cell Viability Assay because it is specifically optimized for 3D models and ensures complete lysis. CellTiter-Glo® or CellTiter-Glo® 2.0 may not have sufficient lytic performance to ensure complete lysis of 3D models, which could lead to unintended bias and increased variability in the assay readout.

Which assay should I use for spheroids vs. organoids?

Both spheroids and organoids are compatible with most Promega 3D assays. Key differences: spheroids are simpler, typically cell-type homogeneous; organoids contain multiple cell types with distinct tissue architecture. For organoids, non-lytic assays often perform better (RealTime-Glo™ MT, metabolic activity assays) to preserve tissue structure. Consult assay-specific application notes for optimized protocols.

Can I multiplex assays in the same 3D culture well?

It depends on the assay—same-well multiplexing is a major advantage for several 3D assays. For example: measure viability with RealTime-Glo™ MT, then add CellTox™ Green to detect dead cells in the same well, continuing kinetic monitoring. Consider extracting DNA or RNA from the same well for genomic characterization or expression analysis (e.g., using ReliaPrep™ Miniprep systems, or Maxwell® RSC Kits). Always verify assay compatibility in technical manuals, or consider reaching out to Promega Technical Services to discuss options (techserv@promega.com).

Do I need to lyse my spheroid for cell viability measurement?

Not always. Choose based on your workflow: Lytic assays (CellTiter-Glo® 3D, NAD/NADH-Glo™) fully lyse spheroids and penetrate cores completely, but remove the ability to run further assays on the samples. Non-lytic assays (RealTime-Glo™ MT, metabolic assays) preserve cells and are best for kinetic or multi-measurement workflows. Additionally, non-lytic assays allow for potential multiplexing with other assays to interrogate other aspects of the spheroid biology (e.g., metabolic markers), and for downstream DNA/RNA extraction.

Which assays are validated for high-throughput screening (HTS) in 3D?

Promega offers a wide portfolio of bioluminescent assays specifically designed to be high-throughput compatible. These include CellTiter-Glo® 3D, Caspase-Glo® 3/7 3D Assay, These assays are HTS-compatible and scalable to 384-well plates. Multi-dose studies can run in parallel wells. Check application notes for recommended timepoints, plate types, and GloMax® plate reader settings for 3D-specific optimization.

Can I use the same 3D culture well for multiple assay measurements?

Yes, with non-lytic assays. Example workflow: (1) Day 0–3: kinetic viability monitoring with RealTime-Glo™ MT; (2) Day 3: media supernatant samples for metabolic activity screening (e.g., glucose and/or lactate measurements from 5 µl media, measured in a separate plate); (3) Day 5: extract RNA from intact spheroid; (4) Day 5: run RT-qPCR on extracted RNA. Lytic assays consume the sample and prevent downstream analysis.

What is the typical timeframe for 3D culture assays?

Spheroids/organoids are typically measured 48 hours to 7 days post-seeding. Kinetic assays (RealTime-Glo™ MT) provide continuous monitoring across this range. Lytic assays (CellTiter-Glo® 3D) work best at endpoint (3–7 days). Optimization may be required based on cell type and model. See assay application notes for specific recommendations.

Do Promega 3D assays work with different plate types?

Yes. Ultra-low attachment plates (ULA) are standard for spheroid culture and compatible with all assays. Hanging drop plates also work. For organoids, your choice depends on culture method. Hydrogel-based cultures are compatible; verify with assay-specific technical documentation. Plate geometry may affect penetration kinetics. Always make sure to test in your model system to ensure plate compatibility.

What platforms measure Promega 3D assays?

GloMax® readers are primary platforms for luminescent assays. GloMax® Discover Instrument supports combined luminescence + fluorescence for multiplexing. For kinetic reads over 72 hours, ensure your cells are cultured under the appropriate environmental conditions. Fluorescence assays (e.g., CellTox™ Green) work on any fluorescence plate reader.

How do I perform genomic analysis on 3D culture systems like spheroids and organoids?

Genomic analysis of 3D cultures follows three main steps: harvest, nucleic acid extraction, and downstream analysis.

• Step 1. Recover cells from their matrix (e.g., dissolve hydrogels, optionally dissociate spheroids enzymatically). The extracellular matrix and the compact architecture of spheroids and organoids can lower yields and trap inhibitors, so gentle, thorough lysis is critical.
• Step 2. Extract DNA or RNA. For low-input or precious samples, automated systems such as the Maxwell® System of instruments and kits improve reproducibility across replicates. Column-based options, such as ReliaPrep™ Miniprep systems, suit budget-friendly manual workflows or small sample numbers. Because 3D structures often yield less material than 2D monolayers, consider pooling multiple organoids or selecting kits validated for low-input samples.
• Step 3. Analysis. Extracted nucleic acids can feed into qPCR, RT-qPCR, whole-genome or RNA sequencing, methylation analysis, or genotyping to characterize gene expression, mutations, or clonal heterogeneity.

To maximize data from limited samples, you can also extract DNA/RNA from the same well used for upstream viability or cytotoxicity assays. Always verify compatibility first. For help matching an extraction method to your model and downstream application, contact Promega Technical Services (techserv@promega.com).

How do I measure live-cell protein dynamics in 3D cultures?

HaloTag® and NanoLuc® reporters let you track protein abundance, localization, and turnover in living spheroids and organoids without destroying the model. HaloTag, paired with cell-permeable Janelia Fluor® ligands, enables live-cell imaging of protein localization and turnover, including pulse-chase studies, in advanced 3D models. Combined with NanoLuc® reporters, the system delivers real-time, non-destructive monitoring of 3D systems where endpoint assays fall short. Promega scientists have used a HaloTag®-NanoLuc® fusion with Janelia Fluor® ligands to quantify protein expression and measure real-time neuritogenesis in cerebral spheroids over multi-day timecourses. Because real-time 3D imaging requires signals that persist for days while preserving spheroid viability, validate ligand and substrate longevity and penetration in your model (see Q1).

For 3D-specific guidance, see the white paper "Real-Time Monitoring of Cerebral Organoids Using NanoLuc® and HaloTag® Technologies".