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Live-Cell ImagingLearn the simple steps to stain your live cells for dynamic imaging experiments. |
Fluorescence imaging of live cells is used to observe dynamic cellular processes and track cellular biomolecules and structures over time. Live-cell fluorescence imaging allows researchers to examine cells in their native state so that cellular function is preserved, enabling the study of cellular processes including cytoskeletal rearrangement, apoptosis, cell migration, endocytosis, phagocytosis, and organelle dynamics to obtain more relevant findings in drug discovery, cancer, developmental biology, environmental science, and other medical research fields.
Use this guide to build live-cell imaging experiments, pick reagents, and generate publication quality data.
Live-cell imaging reagents include both targeted fluorescent proteins and small membrane permeant fluorescent dyes. To enable live-cell imaging experiments, many reagents are designed for time-lapse over several hours or days, while others are optimal for end-point assays in which cells are imaged and analyzed immediately after staining. Staining concentration, incubation time, and the appropriate time window and imaging interval/frequency should be determined empirically to minimize cytotoxicity and preserve cellular function.
The reagents found within the live-cell imaging guide below are compatible with automated high-content and incubator-based fluorescence imaging systems such as: Thermo Fisher Scientific’s EVOS M7000 and M5000 Cell Imaging Systems with EVOS Onstage Incubator, CellInsight HCS Platforms, PerkinElmer’s MuviCyte™ live-cell imaging system*, Leica’s Thunder and Mica*, and Sartorius’ Incucyte® Live-Cell Analysis System™*.
Fluorescence imaging platforms combined with incubators provides a controlled and stable environment that allows long-term imaging of cells in their natural state. The EVOS Onstage Incubator for the EVOS M7000 and M5000 Cell Imaging Systems and the Invitrogen HCA Onstage Incubator for automated high-content screening and analysis on the CellInsight HCS/HCA platforms enable time-lapse and kinetic imaging and analysis of live cells within an environmental chamber. When performing long-term live-cell imaging within an incubated environment, reagents should be used in traditional cell culture medium or FluoroBrite DMEM (Cat. No. A1896701) buffered with bicarbonate to maintain physiological pH in a 5% CO2 environment.
Cellular apoptosis is a tightly controlled programmed cell death process used to remove excess, damaged, and unneeded cells or tissues. Apoptosis can be detected through caspase activation, DNA fragmentation, disruption in active mitochondria, and plasma membrane changes. The CellEvent Caspase 3/7 reagents are fluorogenic caspase substrates that detect caspase activation to assay for apoptosis in live cells. These reagents do not require wash steps and can be used for real-time and time-lapse live-cell imaging of apoptosis for 48 hours or longer.
Figure 1. Apoptosis live-cell endpoint assay workflow using the CellEvent Caspase-3/7 Green Detection Reagent (Cat. No. C10432). Seed cells and follow with treatment. Add diluted CellEvent Caspase-3/7 Green Detection Reagent to cells. CellEvent Caspase 3/7 dyes may be imaged directly on cells in complete media without wash. Measure fluorescence starting as early as 30 minutes to as long as 72 hours.
Figure 2. Example of Live Cell Imaging of apoptotic cells stained with CellEvent Caspase 3/7 Green. HuVEC cells treated with a cocktail stained with CellEvent Caspase 3/7 Green Assay (Cat. No. C10432) and imaged with Incucyte® ZOOM Live-Cell Analysis System at 0, 24, 48, and 72 hours after treatment. (Image from: Sambi M, Samuel V, Qorri B, Haq S, Burov SV, Markvicheva E, Harless W, Szewczuk MR. A Triple Combination of Metformin, Acetylsalicylic Acid, and Oseltamivir Phosphate Impacts Tumour Spheroid Viability and Upends Chemoresistance in Triple-Negative Breast Cancer. Drug Des Devel Ther. 2020;14:1995-2019 PMID: 32546966)
Live-cell imaging reagents include both cell structure reagents used to identify cellular components and cell function reagents to analyze cellular functions and processes. For instance, MitoTracker dyes accumulate in active mitochondria in live cells and covalently attach to mitochondria to allow evaluation of mitochondrial localization and abundance. In contrast, TMRM and TMRE are dynamic mitochondria membrane potential indicator dyes that fluctuate in and out of the mitochondria based on membrane potential.
Figure 3. Monitoring active mitochondria in live cells. Fibroblast lines from patients were cultured and stained with MitoTracker Red (Cat. No. M22426), Image-iT DEAD Green dyes (Cat. No. I10291), Hoechst (Cat. No. R37165) and imaged on an Incucyte® ZOOM Live-Cell Analysis System. (Image from Smith GA, Jansson J, Rocha EM, Osborn T, Hllett PJ, Isacson O. Fibroblast Biomarkers of Sporadic Parkinson's Disease and LRRK2 Kinase Inhibition. Mol Neurobiol. 2016 Oct;53(8):5161-77. PMCID: PMC5012155. )
Cell impermeant nucleic acid stains can be used as dead cell indicators in live-cell imaging experiments. Nucleic acid stains such as YOYO-1 and YOYO-3 are nontoxic dyes that have bright signals and large fluorescence enhancement upon binding to DNA. These dyes are impermeant to viable cells and selectively stain dead cells with compromised membranes to enable live-cell imaging over time.
Keeping cells alive and healthy during various experimental manipulations, detection, and imaging is no small task. The choice of medium is particularly important for time-lapse imaging and experiments where cells are exposed to ambient conditions for longer periods. For reliable results with live cells, it is essential that the cells be healthy and kept in an environment as close as possible to physiological temperature, pH, oxygen level, and other conditions.
These media and wash buffers are created specifically for live-cell imaging and detection. Employing them in your experiments can help you improve image clarity, reduce background fluorescence, and optimize cell viability.
TipsYou can improve image clarity, reduce background fluorescence, and optimize cell viability by using media and wash buffers created specifically for live-cell imaging and detection. See product selection guide |
The appropriate fluorophore (targeted fluorescent protein or small membrane-permeant reagent) should be used to monitor your target cellular structure or process. Additional fluorophores can be used to monitor multiple cellular structures and processes, but the excitation and emission spectra should be checked using the Fluorescence SpectraViewer or Stain-iT Cell Staining Simulator to ensure minimal spectra overlap. It is critical to avoid using too much fluorescent label because excessive fluorescent labeling can result in:
Tips
|
Signal-to-background ratio can be optimized by using reagents that reduce extracellular fluorescence and increase fluorophore photostability. It is important to image in media that have been specifically designed for maintaining cell health while reducing or eliminating background fluorescence in live-cell imaging experiments (see Table 1). The addition of a background suppressor compatible with live cells can also help reduce extracellular background fluorescence and eliminate the need for a wash step. ProLong Live Antifade Reagent can be applied to samples to reduce photobleaching of fluorophores, preventing signal loss with multiple or long exposures.
Table 1. Imaging media comparison.
Reagent | Cell washing | Short-term imaging | Imaging up to 4 hours | Long-term imaging |
---|---|---|---|---|
Gibco PBS, pH 7.4 | ||||
Gibco FluoroBrite DMEM | ||||
Invitrogen Live Cell Imaging Solution |
Tips
|
To minimize phototoxicity, choose imaging systems that give you the greatest control of light sources. Try to minimize light intensity, exposure time, wavelength range, and amount of excitation energy for illuminating your cells while still generating a good signal with low background. Use the illumination that gives you the highest signal with the lowest level of fluorophore excitation. In some cases (particularly when you wish to image over a long period of time), it is advisable to sacrifice resolution by using shorter exposure times or lower magnification in exchange for healthier cells.
Live-cell imaging over longer periods of time can be challenging because the target may move out of focus during the course of the experiment. Many microscopes have autofocusing features that can help keep your target in focus longer and reduce focal drift. Additionally, maintaining cells at a constant temperature and keeping the volume of solution in the vessel constant will help with focal drift.
Many cells cannot tolerate deviations from their optimal temperature, osmolarity, pH, and humidity. Requirements vary depending on what experimental question you are asking. For example, experiments investigating cell growth and division may have a different set of requirements than experiments involving receptor activation and calcium accumulation. Some robust immortalized cell lines will tolerate being imaged or monitored for short periods of time without any environmental control. Conversely, for long-term imaging and detection studies, good results with both immortalized cells and primary cells typically require tightly controlled environmental parameters.
A scratch wound in a culture of HDFn cells loaded with Invitrogen CellTracker Deep Red Dye. (A) The illuminated area was subjected to repeated illumination for 10 hours. Cells in this area show signs of phototoxicity (a loss of viability as cells were not able to grow into the wound). (B) Cells in the non-illuminated area show viable cell growth into the wound.
The top cell shows catastrophic blebbing of the cell membrane caused by excessive light exposure. Blebbing is a term used to describe membrane perturbation caused by toxicity. By contrast, the bottom cell remains relatively healthy and is not displaying aberrant morphology.
To avoid the pitfall of proceeding to the next step in your experiment with unhealthy cells, a quick check for cell health can be done on the Countess 3 FL Automated Cell Counter when used in conjunction with a variety of fluorescent reagents to detect cell viability, apoptosis, cytotoxicity, and transfection efficiency. The reusable slide option reduces consumption cost.
Designed specifically for Invitrogen EVOS imaging systems, the Invitrogen EVOS Onstage Incubator is an environmental chamber that enables precise control of temperature, humidity, and three gases for time-lapse imaging of live cells under both physiological and nonphysiological conditions.
The Invitrogen HCA Onstage Incubator for Thermo Scientific CellInsight HCA platforms allows precise control of temperature, humidity, and CO2 levels so that you may observe and measure biological activity and changes over time. Data gathered from longer-term imaging studies are the basis of quantitative analysis studies, especially when combined with Thermo Scientific HCS Studio Software for increased statistical power.
Tips
|
Keeping cells alive and healthy during various experimental manipulations, detection, and imaging is no small task. The choice of medium is particularly important for time-lapse imaging and experiments where cells are exposed to ambient conditions for longer periods. For reliable results with live cells, it is essential that the cells be healthy and kept in an environment as close as possible to physiological temperature, pH, oxygen level, and other conditions.
These media and wash buffers are created specifically for live-cell imaging and detection. Employing them in your experiments can help you improve image clarity, reduce background fluorescence, and optimize cell viability.
TipsYou can improve image clarity, reduce background fluorescence, and optimize cell viability by using media and wash buffers created specifically for live-cell imaging and detection. See product selection guide |
The appropriate fluorophore (targeted fluorescent protein or small membrane-permeant reagent) should be used to monitor your target cellular structure or process. Additional fluorophores can be used to monitor multiple cellular structures and processes, but the excitation and emission spectra should be checked using the Fluorescence SpectraViewer or Stain-iT Cell Staining Simulator to ensure minimal spectra overlap. It is critical to avoid using too much fluorescent label because excessive fluorescent labeling can result in:
Tips
|
Signal-to-background ratio can be optimized by using reagents that reduce extracellular fluorescence and increase fluorophore photostability. It is important to image in media that have been specifically designed for maintaining cell health while reducing or eliminating background fluorescence in live-cell imaging experiments (see Table 1). The addition of a background suppressor compatible with live cells can also help reduce extracellular background fluorescence and eliminate the need for a wash step. ProLong Live Antifade Reagent can be applied to samples to reduce photobleaching of fluorophores, preventing signal loss with multiple or long exposures.
Table 1. Imaging media comparison.
Reagent | Cell washing | Short-term imaging | Imaging up to 4 hours | Long-term imaging |
---|---|---|---|---|
Gibco PBS, pH 7.4 | ||||
Gibco FluoroBrite DMEM | ||||
Invitrogen Live Cell Imaging Solution |
Tips
|
To minimize phototoxicity, choose imaging systems that give you the greatest control of light sources. Try to minimize light intensity, exposure time, wavelength range, and amount of excitation energy for illuminating your cells while still generating a good signal with low background. Use the illumination that gives you the highest signal with the lowest level of fluorophore excitation. In some cases (particularly when you wish to image over a long period of time), it is advisable to sacrifice resolution by using shorter exposure times or lower magnification in exchange for healthier cells.
Live-cell imaging over longer periods of time can be challenging because the target may move out of focus during the course of the experiment. Many microscopes have autofocusing features that can help keep your target in focus longer and reduce focal drift. Additionally, maintaining cells at a constant temperature and keeping the volume of solution in the vessel constant will help with focal drift.
Many cells cannot tolerate deviations from their optimal temperature, osmolarity, pH, and humidity. Requirements vary depending on what experimental question you are asking. For example, experiments investigating cell growth and division may have a different set of requirements than experiments involving receptor activation and calcium accumulation. Some robust immortalized cell lines will tolerate being imaged or monitored for short periods of time without any environmental control. Conversely, for long-term imaging and detection studies, good results with both immortalized cells and primary cells typically require tightly controlled environmental parameters.
A scratch wound in a culture of HDFn cells loaded with Invitrogen CellTracker Deep Red Dye. (A) The illuminated area was subjected to repeated illumination for 10 hours. Cells in this area show signs of phototoxicity (a loss of viability as cells were not able to grow into the wound). (B) Cells in the non-illuminated area show viable cell growth into the wound.
The top cell shows catastrophic blebbing of the cell membrane caused by excessive light exposure. Blebbing is a term used to describe membrane perturbation caused by toxicity. By contrast, the bottom cell remains relatively healthy and is not displaying aberrant morphology.
To avoid the pitfall of proceeding to the next step in your experiment with unhealthy cells, a quick check for cell health can be done on the Countess 3 FL Automated Cell Counter when used in conjunction with a variety of fluorescent reagents to detect cell viability, apoptosis, cytotoxicity, and transfection efficiency. The reusable slide option reduces consumption cost.
Designed specifically for Invitrogen EVOS imaging systems, the Invitrogen EVOS Onstage Incubator is an environmental chamber that enables precise control of temperature, humidity, and three gases for time-lapse imaging of live cells under both physiological and nonphysiological conditions.
The Invitrogen HCA Onstage Incubator for Thermo Scientific CellInsight HCA platforms allows precise control of temperature, humidity, and CO2 levels so that you may observe and measure biological activity and changes over time. Data gathered from longer-term imaging studies are the basis of quantitative analysis studies, especially when combined with Thermo Scientific HCS Studio Software for increased statistical power.
Tips
|
U2OS cells treated with 50 mM menadione. Tetramethylrhodamine, Methyl Ester, Perchlorate (TMRM) (Cat. No. T668) mitochondrial potential indicator and fades with oxidative stress as indicated with CellROX Green reagent (Cat. No. C10444).
Hippocampal neurons labeled with Tubulin Tracker Deep Red (Cat. No. T34076).
U2OS cells transfected with CellLight Tubulin-GFP (Cat. No. C10613); CellLight Actin-RFP (Cat. No. C10583).
Poster: New generation sensors for caspase activation and mitochondrial superoxide in live cell microscopy
Poster: New and improved cellular health evaluation of 2D and 3D cellular models using microplate reader assays
Poster: Hypoxia measurements in live and fixed cells using fluorescence microscopy and high-content imaging
Poster: Evaluation of Cellular Senescence through Fluorescence Characterization
*Incucyte® Live-Cell Analysis System is trademarked or registered trademarks of Essen BioScience. Incucyte, Essen BioScience, and all names of Essen BioScience products are registered trademarks and the property of Essen BioScience unless otherwise specified. Essen BioScience is a Sartorius Company. MuviCyte™ live-cell imaging system is trademarked or registered trademarked of PerkinElmer. THUNDER Imager Live Cell & 3D Assay and MICA Microhub Microscope are sold by Leica Microsystems CMS GmbH.
For Research Use Only. Not for use in diagnostic procedures.