EdU Cell Proliferation Assay Kit
EdU Cell Proliferation Assay Kit
Cell proliferation is one of the core evaluation indicators in tumor biology, stem cell research, regenerative medicine, and drug screening. Traditional methods such as ³H-thymidine incorporation or BrdU (5-bromo-2'-deoxyuridine) immunodetection often involve cumbersome procedures, require radioactivity or harsh DNA denaturation, and can substantially damage cellular structure and antigenicity. EdU (5-ethynyl-2'-deoxyuridine, 5-Ethynyl-2'- deoxyuridine), as a thymidine analog combined with copper-catalyzed click chemistry, provides researchers with a sensitive, rapid, and less disruptive DNA synthesis detection solution, and has gradually become an important tool for cell proliferation analysis and cell-cycle studies.
I、Why detect cell proliferation?
Cell proliferation essentially reflects DNA replication and cell-cycle progression. Cells in S phase synthesize new DNA, so the level of S-phase DNA synthesis is one of the most direct indicators for assessing cell proliferation. Typical applications include:
1.Oncology and drug screening: used to evaluate the inhibitory effects of anticancer drugs or candidate compounds on tumor-cell proliferation; together with cell-viability assays, it enables a multidimensional efficacy evaluation system.
2.Stem cells and regenerative medicine: tracking stem-cell proliferative capacity, colony-forming ability, and proliferation patterns during directed differentiation and tissue regeneration.
3.Developmental biology: analyzing the distribution of proliferating cells in different regions during embryonic development, organ formation, and tissue remodeling.
4.Toxicology and genotoxicity assessment: used to observe whether compounds induce abnormal proliferation or suppress physiological proliferation, and combined with DNA-damage assays to evaluate potential genotoxicity.
In these scenarios, researchers need a method with stable and quantifiable signals, easy compatibility with multicolor immunostaining, and minimal disruption to cellular and tissue structure. EdU technology was developed around these needs.
II、What is EdU?
EdU (5-Ethynyl-2'-deoxyuridine) is a structural analog of thymidine that can be incorporated into newly synthesized DNA strands by cellular DNA polymerases during DNA replication, thereby labeling cells undergoing proliferation. Its key features include:
1.Structural feature: highly similar to thymidine, except for a terminal alkyne group (–C≡CH) introduced on the pyrimidine ring; this alkyne provides a specific reaction site for subsequent click chemistry.
2.Basic information: the compound is 5-ethynyl-2'-deoxyuridine (EdU), CAS No. 61135-33-9, typically supplied as a lyophilized powder or DMSO stock solution. It can be directly added to culture medium to label S-phase proliferating cells.
III、Basic principle of EdU click-chemistry detection
1.EdU incorporation stage
Add EdU to the culture medium at an appropriate concentration (common starting range 5–20 μM; 10 μM is a typical optimization starting point). During S phase, cells incorporate EdU into newly synthesized DNA, partially replacing thymidine. The incubation time depends on cell type and experimental purpose and is usually optimized in pilot experiments within 0.5–2 h.
2.Click-reaction labeling stage
After fixation and permeabilization of cells or tissue samples, add a click-reaction working solution containing a fluorescent azide. The terminal alkyne on EdU reacts with the azide group under Cu(I) catalysis via azide–alkyne cycloaddition (CuAAC), forming a stable triazole ring and covalently linking the fluorophore to EdU-containing DNA. This reaction has:
1）High specificity and efficiency under mild conditions, usually completed at room temperature;
2）No need for strong acid/base, high-temperature, or enzymatic DNA denaturation, thereby better preserving nuclear structure and protein antigenicity.
3.Signal detection modes
Depending on the kit configuration and experimental needs, multiple readout formats can be used:
1）Fluorescence microscopy imaging: using a fluorescence or confocal microscope to observe EdU fluorescence signals in nuclei, directly showing the spatial distribution of proliferating cells; often combined with Hoechst 33342 nuclear staining or antibody fluorescence labeling.
2）Flow cytometry: quantifying the proportion of EdU-positive cells, and combining PI, 7-AAD, or other DNA dyes for cell-cycle analysis to obtain the proportions of G₀/G₁, S, and G₂/M phases.
3）Plate-based reading: in high-throughput screening, converting fluorescence into plate signals measured by a microplate reader or high-content imaging system, suitable for compound screening and dose–response experiments.
IV、Advantages of EdU over BrdU
Compared with BrdU immunodetection, EdU has multiple advantages:
1.No DNA denaturation required: click chemistry directly recognizes the alkyne on EdU, eliminating acid/heat/enzymatic denaturation steps; this preserves sample structure and protein antigenicity and is compatible with multicolor co-staining.
2.Simplified workflow: usually only four main steps—“EdU labeling–fixation–permeabilization–click reaction”—greatly shortening total assay time and enabling rapid multi-sample processing.
3.High signal-to-noise ratio and sensitivity: click reactions are highly specific with low background; covalent fluorophore–DNA linkage yields more stable signals, facilitating detection of low-proliferation cell populations.
4.Compatible with multiple platforms: can be flexibly combined with microscopy, flow cytometry, high-content imaging, or plate-based quantification, enabling integration of proliferation, cell-cycle, and phenotypic markers within a single assay system.
5.Nonradioactive and safer: compared with ³H-thymidine, EdU kits are safer and easier for routine laboratory use.
V、Typical application scenarios
1.Antitumor drug screening and high-throughput compound profiling
Plate-based EdU kits can be used in 96- or 384-well plates to screen large numbers of candidate compounds. By measuring changes in EdU-positive fractions under different treatments, researchers can rapidly evaluate proliferation inhibition in tumor cells.
2.Stem-cell proliferation and differentiation research
EdU can assess stem-cell proliferation under different induction or microenvironmental conditions. Combined with lineage markers or differentiation-related immunostaining, it enables simultaneous observation of “proliferation status + fate decisions.”
3.Developmental biology and tissue regeneration
In vivo, animals can be injected with EdU to label proliferating cells, followed by tissue sectioning and click staining to map proliferation distributions during embryogenesis, organ formation, or injury repair.
4.Immune-cell function and vaccine-response research
Combining EdU with flow cytometry allows quantitative analysis of clonal expansion of T and B cells under antigen stimulation or vaccination. With surface marker staining, proliferation levels of different subsets can be distinguished to evaluate immune response quality.
VI、Aladdin-related products
Product Name | Catalog No. | Package Size | Kit Components |
EdU Cell Proliferation Detection Kit (AF594) | 50T/100T/200T | EdU(10 mM)；AF594 azide；Click Reaction Buffer；CuSO4；Click Additive；DAPI Staining Solution（1000×） | |
EdU Cell Proliferation Detection Kit (6-FAM) | 50T/100T/200T | EdU(10 mM)；6-FAM；Click Reaction Buffer；CuSO4；Click Additive；DAPI Staining Solution（1000×） | |
EdU Cell Proliferation Detection Kit (AF647) | 50T/100T/200T | EdU(10 mM)；AF647 azide；Click Reaction Buffer；CuSO4；Click Additive；DAPI Staining Solution（1000×） | |
EdU Cell Proliferation Detection Kit (AF488) | 50T/100T/200T | EdU(10 mM)；AF488 azide；Click Reaction Buffer；CuSO4；Click Additive；DAPI Staining Solution（1000×） |
Jurkat (human T-cell leukemia) cells were treated with 10 µM EdU (E131265) for 2 hours and detected according to the recommended staining protocol. The incorporated EdU was then conjugated to Alexa Fluor 488 azide via a click reaction and analyzed by flow cytometry using 488 nm (for Alexa Fluor 488) and 405 nm (for DAPI) excitation.
(A) Histogram of EdU-Alexa Fluor 488 signal, distinguishing EdU-positive S-phase cells from cells in other cell cycle phases.
(B) DNA content histogram (DAPI) resolving the G0/G1, S, and G2/M populations.
(C) Dot plot of EdU incorporation versus DNA content, allowing for direct quantification of S-phase cells.
Flow Cytometry: EdU Cell Proliferation Detection Kit (AF488)(E1373491)
Jurkat (human T-cell leukemia) cells were treated with 10 µM EdU (E131265) for 2 hours and detected according to the recommended staining protocol. The incorporated EdU was then conjugated to Alexa Fluor 647 azide via a click reaction and analyzed by flow cytometry using 640 nm (for Alexa Fluor 647) and 405 nm (for DAPI) excitation.
(A) Histogram of EdU-Alexa Fluor 647 signal, distinguishing EdU-positive S-phase cells from cells in other cell cycle phases.
(B) DNA content histogram (DAPI) resolving the G0/G1, S, and G2/M populations.
(C) Dot plot of EdU incorporation versus DNA content, allowing for direct quantification of S-phase cells.
Flow Cytometry: EdU Cell Proliferation Detection Kit (AF647)(E1373493)
The EdU Cell Proliferation Assay Kit is based on the core principles of thymidine-analog incorporation and copper-catalyzed click chemistry. Without requiring harsh DNA denaturation, it enables highly sensitive and stable labeling of newly synthesized DNA, thereby markedly overcoming the operational complexity and sample-disruptive limitations of traditional BrdU- or radioisotope-based methods. With kit formulations optimized for diverse applications—including cell culture, tissue sections, flow-cytometric analysis, and high-throughput screening (such as pre-made EdU labeling solution, click-reaction working solution, fluorescent azide dyes, and DNA stains)—researchers can rapidly and accurately obtain cell-proliferation and cell-cycle information across multiple fields, including anti-tumor drug screening, stem cell and regenerative medicine, developmental biology, immunology, and toxicology. As multicolor flow cytometry, high-content imaging, and integrated multi-omics approaches continue to expand, EdU will further serve as a foundational readout used in concert with antibodies, fluorescent probes, and functional reagents, providing richer and more reliable experimental tools for dissecting cell fate and proliferation-regulatory mechanisms.
Aladdin: https://www.aladdinsci.com/