Key Takeaways
- Single-plane imaging can support standardized counting and projected-size measurements, while optical sectioning or volumetric imaging is needed to assess internal architecture and genuinely three-dimensional features.
- Light penetration, phototoxicity, and large data volumes are the main technical challenges.
- Confocal, spinning-disk, multiphoton, light-sheet, and widefield methods balance depth, speed, and light exposure differently.
- Standardized protocols and automated analysis reduce variability between users and laboratories.
- Imaging can be combined with laser capture microdissection (LCM) for downstream molecular analysis of selected regions.
What Are Organoids?
Organoids are three-dimensional cultures derived from stem cells or tissue that self-organize into structures resembling parts of native organs. They are simplified models and typically lack complete vascular, immune, and stromal components. Nature Methods named organoids its Method of the Year for 2017 (Nature Methods, 2018).
Single-plane brightfield imaging can be appropriate for monitoring organoid number, projected area, and overall growth when acquisition conditions are consistent and the measurements are validated.
However, a single plane or flattened projection cannot fully describe internal tissue architecture, depth-resolved cell distributions, or true organoid volume. Measurements of these features require suitable optical sectioning or volumetric imaging.
Likewise, projected size or morphology alone does not establish cell viability. Drug-response studies should use validated viability or functional measurements where those outcomes are required.
Selecting an imaging approach that matches the biological endpoint helps prevent misleading conclusions in organoid research.
Core Challenges
- Light penetration: organoid thickness and opacity limit imaging of inner structures. Refractive-index mismatch, debris, and neighboring organoids increase scattering.
- Phototoxicity: long time-lapse sessions increase light exposure. A 2024 study of intestinal organoids found that light exposure during live imaging altered gene expression and cell function (Yokoi et al., 2024).
- Data volume: three-dimensional, multiwell, time-lapse experiments generate large image datasets that require substantial storage and processing.
- Environmental control: temperature, CO₂, humidity, and media exchange must remain stable during long sessions.
- Labware: round-bottom and other specialized wells can complicate focusing and consistent imaging.
Imaging Techniques
Point-Scanning Confocal Microscopy
A pinhole blocks out-of-focus light, allowing high-resolution optical sections that can be assembled into Z-stacks. Limitations include higher light exposure, slower acquisition, and limited depth in thick samples.
Spinning-Disk Confocal Microscopy
Multiple pinholes scan simultaneously, which speeds acquisition and reduces light exposure compared with point scanning. This suits live, long-term imaging. Optical sectioning is generally weaker, and pinhole crosstalk can occur in thick samples.
Multiphoton Microscopy
Excitation is confined to the focal plane, which improves penetration in dense samples and reduces photodamage outside the focal plane. Multiphoton systems require specialized lasers and setup.
Light-Sheet Microscopy
A thin sheet of light illuminates one plane at a time, providing optical sectioning with low light exposure and fast acquisition. It suits larger live or cleared samples, although sample mounting can be more complex.
Widefield and High-Content Imaging
Automated widefield and high-content systems image many wells for screening. They provide throughput at the cost of optical sectioning. Deconvolution can improve contrast in widefield images.
Best Practices
- Optimize fixation, staining, and clearing. Test antibody concentrations and incubation times so labels penetrate the full organoid.
- Use tissue clearing when appropriate. Refractive-index matching reduces scattering. Ethyl cinnamate-based clearing has been applied to human organoids and other samples (Masselink et al., 2019).
- Stage magnification. Use low magnification for counting and screening, then higher magnification for structural detail.
- Match labels to the imaging system. Align excitation and emission spectra with available light sources and filters to reduce crosstalk.
- Include light-exposure controls. Image a subset of wells only at the start and end to assess phototoxicity separately from treatment effects.
After Imaging: Isolating Regions of Interest
Once imaging identifies a region of interest, laser capture microdissection can isolate that region from sectioned organoids for genomic or proteomic analysis. This links molecular data to structures seen in the images.
Quantitative Image Analysis
Drug screening and comparative studies require measurements such as organoid number, size, shape, and viability. Manual thresholding is slow and varies between analysts. Automated and deep-learning segmentation can apply the same analysis across many wells, but results should be validated against manual annotation for each organoid type and imaging setup.
Laxco Tools for Organoid Research
- CellLive: an imaging system designed for use inside the incubator, supporting time-lapse monitoring of cultures under stable conditions.
- SLi3Pro and SLi6Pro: inverted widefield fluorescence microscopes with SeBaLIT™ illumination. The SLi3Pro covers DAPI, FITC, and TRITC, and the SLi6Pro covers 390–662 nm with more than 110 compatible fluorochromes.
- LEAP AI: pairs Accuva LEAP optics with Media Cybernetics Image-Pro AI in an Image, Process, Measure, Report workflow, with pre-trained deep-learning segmentation and optional 3D visualization.
- Accuva Cellect: a laser capture microdissection system with an infrared laser for capture of single cells or small numbers of cells and a UV laser for cutting dense structures.
Laxco does not manufacture confocal, multiphoton, or light-sheet microscopes. It provides application training and technical support for its systems.
Frequently Asked Questions
Which imaging approach suits thick organoids?
Multiphoton and light-sheet microscopy are often preferred for thick organoids because they improve depth and limit out-of-focus exposure. For fixed samples, tissue clearing can extend imaging depth with other methods, including confocal microscopy.
How can phototoxicity be reduced during long-term imaging?
Reduce light intensity and exposure frequency, image only the channels you need, and include control wells imaged only at the start and end. Imaging inside the incubator also avoids repeated transfers that stress cultures.
Which Laxco system suits time-lapse monitoring of organoid cultures?
CellLive systems are designed for continuous imaging inside CO₂ incubators, with scheduled time-lapse imaging and remote monitoring. The CL22 adds phase contrast, multichannel fluorescence, and Z-stack scanning to brightfield imaging.
How do I make organoid measurements reproducible?
Apply the same segmentation settings to every well and validate them against manual annotation. LEAP AI uses pre-trained deep-learning segmentation in an Image, Process, Measure, Report workflow, which supports consistent batch analysis.
Can organoid regions be isolated after imaging?
Yes. Sectioned organoids can be processed by laser capture microdissection to isolate regions identified during imaging. Accuva Cellect supports fresh-frozen and FFPE sections, so structures seen in images can be linked to molecular data.
