Scratch Assay · Wound Healing Assay · Migration Assay

The complete wound healing assay —
from scratch to publication-ready data.

Reproducible gap creation. Continuous automated imaging. Automatic analysis. 24 conditions in parallel. Everything from one system, inside your incubator.

Book a free demo See the protocol →
The complete end-to-end workflow
步骤一
Cell seeding
Confluent monolayer
步骤 2
Gap creation
ScratchMaker · <5% variability
第三步
Imaging
zenCELL owl · 24 wells · 5 min
Step 4
Analysis
Auto gap closure · CSV export
Result
出版
Reproducible · peer-reviewed
Understanding the assay

What is a wound healing assay — and what is the difference to a scratch assay or migration assay?

The three terms describe the same fundamental technique. Knowing the distinctions helps you use the right terminology in publications and grants.

TermWhat it meansWhen to use it
划痕实验The method: a gap is physically created in a cell monolayer using a pipette tip, stencil or deviceLab use, describing experimental setup
Wound Healing AssayThe biological model: cells migrate to close the gap, mimicking in vivo tissue repairRegenerative medicine, dermatology, tissue biology context
Cell Migration AssayThe broader category: includes scratch, Transwell, Boyden chamber and microfluidics methodsPublications, grant applications, method sections
2D Migration AssaySpecifically the scratch / wound healing assay — as opposed to 3D or insert-based assaysWhen explicitly distinguishing from 3D invasion assays
The principle — in one sentence

A confluent monolayer of adherent cells is scratched to create a cell-free gap. Cells at the wound edge sense the loss of contact inhibition and migrate collectively to close the gap. The rate and completeness of closure reflects the cells' migratory capacity — and is directly influenced by treatment, genetics, substrate and growth factors.

Scratch Assay vs. Transwell vs. Boyden Chamber — which to choose?

方法MeasuresKinetics?费用最佳
划痕/伤口愈合测定Collective 2D migration✓ Full timelapse非常低Drug screening, wound healing, cancer invasion models, HTS
Transwell MigrationIndividual cell chemotaxis仅终点MediumChemotaxis, gradient-driven migration
Boyden Chamber (Invasion)Invasion through Matrigel仅终点HigherInvasive potential of cancer cells
µ-Slide Insert (ibidi)Collective migration, defined gap✓ If imaged liveMedium (insert cost)When ECM damage must be avoided
The zenCELL end-to-end system

Three products. One complete workflow.

No other system combines reproducible gap creation, automated continuous imaging and built-in analysis in one integrated solution.

Consumables

刮痕制造板

Pre-coated plates optimised for scratch assay cell adhesion and clean gap edges. Available in collagen, fibronectin and standard coating. Sterile, ready to use.

格式6-well, 24-well, 96-well
CoatingsCollagen / Fibronectin / Std.
Pack size5× / 10× pack, sterile
兼容性ScratchMaker + any microscope

The manual pipette tip scratch introduces ±30–60% gap width variability between wells and operators — making inter-assay comparisons unreliable and affecting migration rate calculations. The ScratchMaker reduces this to <5%. Combined with zenCELL 貓頭鷹 continuous imaging, you get complete kinetic data across 24 identical gaps simultaneously.

<5%
Gap width variability
24
Conditions parallel
Auto
Gap closure analysis
Complete protocol

Wound Healing Assay Protocol — Step by Step

Full protocol from cell seeding to data export. Works with manual pipette tip scratch or ScratchMaker system.

1

Seed cells — 16–24h before scratching

Seed adherent cells at a density to reach >95% confluence overnight.

  • 24-well plate: 100,000–200,000 cells/well in 500 µL–1 mL complete medium
  • Common cell lines: L929 fibroblasts, HaCaT keratinocytes, A549, MDA-MB-231, HeLa, HUVEC
  • Incubate at 37°C, 5% CO₂ overnight
Standard cell seeding protocol
2

Optional: Mitomycin C pre-treatment (to separate migration from proliferation)

Add Mitomycin C (10 µg/mL) 2h before scratching to block cell division. Ensures gap closure reflects migration only.

  • Required for: assays >12h, fast-cycling cell lines, drug studies affecting proliferation
  • Skip for: short assays (<12h), slowly proliferating primary cells
⏱ 2h pre-treatment
3

Create the scratch / wound

Option A — Manual pipette tip: Use a P200 pipette tip held perpendicular (90°) to the plate. Draw one continuous line in a single motion. Do not back-and-forth. Mark the plate bottom for reference.

Option B — ScratchMaker (recommended): Place stencil, draw along the precision channel, or use UV-LED device for 96 simultaneous scratches in <60 seconds. <5% width variability guaranteed.

⚠️ Manual tip: ±30–60% variability between wells ScratchMaker: <5% variability
4

Wash and replace medium — T=0 starts now

Aspirate medium, wash once gently with PBS to remove detached cells and debris. Replace with fresh medium ± test compound.

  • Low serum (0.5–2%) reduces proliferation contribution
  • Add compound treatment at this point
  • Volume: 500 µL/well (24-well) — avoids turbulence at the wound edge
T = 0 reference point
5

Image T=0 — within 15 minutes of scratching

Capture reference images of all wells immediately. This is the baseline wound area for all % closure calculations.

With zenCELL owl: place the plate, set imaging interval (5–30 min recommended for scratch assays), press Start. T=0 is captured automatically — the system runs unattended from here.

zenCELL owl: fully automated from this point
6

Monitor gap closure continuously

Run the assay until control wells reach 80–100% closure.

  • Fast migrating cells (HeLa, A549, MDA-MB-231): 12–18h to closure
  • Slow migrating cells (primary fibroblasts, HUVEC): 24–72h
  • Manual imaging: typical intervals 4h, 8h, 12h, 24h — kinetics missing between points
  • zenCELL owl: every 5–30 min, 24/7, zero incubator disruption, complete kinetic trace
7

Analyse and export results

zenCELL owl (automatic): Software calculates confluence per well at every timepoint → gap area → % wound closure → t½ closure time. Export as CSV for GraphPad Prism or Excel. Export timelapse as AVI video for figures.

ImageJ (manual, free): Use Wound Healing Size Tool plugin (Suarez-Arnedo et al., PLoS ONE 2020, cited 979×). See full ImageJ guide below.

Export: CSV · PNG · AVI
Data analysis

Scratch Assay Analysis — ImageJ Guide + automated alternative

Two options: manual analysis with the free ImageJ Wound Healing Size Tool, or fully automatic analysis built into zenCELL owl software.

% Wound closure

Most common readout. Normalised to T=0 area. Comparable across experiments and conditions.

% closure = (A₀ − Aₜ) / A₀ × 100

Migration rate (µm/h)

Average velocity of the cell front. Calculated from wound width reduction over time.

Rate = (Wᵢ − Wf) / (2 × t)

t½ gap closure

Time to 50% wound closure. Useful for comparing treatments with different plateau kinetics.

Auto-calculated by zenCELL owl

How to analyse scratch assay images in ImageJ — step by step

The most cited free tool is the Wound Healing Size Tool plugin (Suarez-Arnedo et al., PLoS ONE 2020 — 979 citations). It automatically detects wound boundaries and calculates area, width and coverage without manual tracing.

1

Download and install Fiji (ImageJ)

Get Fiji from fiji.sc — free, open-source, includes most plugins pre-installed. Works on Windows, Mac and Linux.

2

Install the Wound Healing Size Tool plugin

Download Wound_healing_size_tool_updated.zip. Unzip and place the .ijm file into Fiji.app/plugins/. Restart Fiji.

Plugins → Wound_healing_size_tool
3

Open image in 8-bit greyscale

File → Open your image. Convert: Image → Type → 8-bit. For timelapse: File → Import → Image Sequence → select folder.

Image → Type → 8-bit
4

Set scale (pixels → µm)

Analyze → Set Scale → enter your microscope's pixel/µm calibration. Required for migration rate calculation in µm/h.

Analyze → Set Scale
5

Run the plugin — results appear automatically

Plugins → Wound_healing_size_tool. Results window shows: wound area (µm²), wound width (µm), wound coverage (%), width SD. Tick "Save results" to auto-export CSV.

% closure = (1 − Aₜ/A₀) × 100
6

Export and plot in GraphPad Prism or Excel

Plot % wound closure vs. time per condition. Compare treatment vs. control. Use paired t-test or two-way ANOVA for statistical analysis across timepoints.

Other free ImageJ plugins for scratch assay analysis

MRI Wound Healing Tool (Montpellier Resources Imagerie) — coherency-based, analyses cell orientation within the migrating front.  |  CSMA (2025, IEEE Access) — improved detection of cells migrating into the wound centre.  |  TScratch — MATLAB-based, good for batch processing.  |  zenCELL owl software — no plugin installation, fully automatic per well at every timepoint.

Skip the ImageJ pipeline entirely: zenCELL owl software automatically calculates confluence and gap closure at every imaging timepoint — no plugin installation, no manual thresholding, no batch processing. Export CSV directly to GraphPad or Excel. Full timelapse available as AVI. 24 wells analysed simultaneously with zero post-processing time.

0
Post-processing steps
Auto
Per well, per timepoint
Troubleshooting

Common wound healing assay problems — and how to fix them

⚠️ Variable scratch width between wells

Cause: Manual pipette tip — operator-dependent angle, pressure, speed.
Fix: Use the ScratchMaker stencil for <5% width variation, or UV-LED device for 96 identical scratches in <60 seconds.

⚠️ Gap closes too quickly

Cause: High serum concentration driving proliferation, not migration.
Fix: Reduce serum to 0.5–2%, add Mitomycin C (10 µg/mL, 2h pre-treatment), or use a wider gap.

⚠️ Cells detach at the scratch edge

Cause: Excessive pipette tip pressure, subconfluent monolayer, inadequate plate coating.
Fix: Ensure >95% confluence, reduce pressure, coat wells with fibronectin (1 µg/cm²) or use ScratchMaker plates.

⚠️ Cannot separate migration from proliferation

Fix: Add Mitomycin C 2h pre-scratch. Or image non-scratched reference wells in parallel with zenCELL owl — confluence increase in reference wells = proliferation contribution, can be subtracted.

⚠️ ImageJ fails to detect wound edges

Fix: Convert to 8-bit greyscale, enhance contrast (Image → Adjust → Brightness/Contrast), increase threshold parameter in Wound Healing Size Tool. Check cell/background contrast under brightfield — phase contrast is easier to threshold.

⚠️ Results not reproducible between experiments

Cause: Variable scratch width + inconsistent imaging timepoints + operator changes.
Fix: ScratchMaker for consistent gaps + zenCELL owl for automated continuous imaging = full reproducibility, no operator dependency.

常见问题解答

常见问题

划痕实验和伤口愈合实验的区别是什么?

The terms are interchangeable in most contexts. "Scratch assay" refers to the physical method — creating a gap by scratching. "Wound healing assay" refers to the biological model — cells migrating to close a wound as in tissue repair in vivo. Both describe the same experimental setup when a monolayer is scratched and gap closure is tracked over time.

What is the principle of the wound healing assay?

A confluent monolayer of adherent cells is scratched to create a cell-free gap. Cells at the wound edge lose contact inhibition and begin migrating collectively to close the gap. The rate of closure reflects the collective migratory capacity — influenced by treatment, growth factors, substrate, genetic modification or cell type.

How do I analyse scratch assay images in ImageJ?

Use the free Wound Healing Size Tool plugin (Suarez-Arnedo et al., PLoS ONE 2020, cited 979×). Install via Fiji → Plugins, open your image in 8-bit greyscale, run the plugin. It automatically calculates wound area, width and coverage. Export results as CSV for GraphPad Prism. See the full guide in the analysis section above, or use zenCELL owl software for fully automatic gap closure analysis without any ImageJ post-processing.

What is the difference between the scratch assay and the Transwell migration assay?

The scratch assay measures collective 2D migration — cells move as a sheet to close a gap. Transwell migration assays measure individual cell chemotaxis — single cells migrate through membrane pores toward a gradient. Scratch assays provide kinetic data, are cheaper and simpler. Transwell assays are better for studying directional single-cell migration and invasion through Matrigel (Boyden chamber).

Do I need Mitomycin C in my scratch assay?

For short assays (<12h) with slowly proliferating cells, Mitomycin C is optional. For assays >12h, fast-cycling cell lines (HeLa, A549), or experiments where you need to distinguish migration from proliferation, add Mitomycin C (10 µg/mL, 2h pre-treatment). zenCELL owl can also help here — monitor reference wells without a scratch in parallel, and use their confluence increase as a proliferation control.

Why is my scratch width not reproducible between wells?

Manual pipette tip scratches introduce ±30–60% width variability depending on operator, angle and pressure. This directly affects migration rate calculations and makes inter-assay comparisons unreliable. The ScratchMaker reduces this to <5% using precision stencils or a UV-LED device — without mechanical contact with the cells.

What imaging interval should I use for a wound healing assay?

With zenCELL owl: every 5–30 minutes is standard for scratch assays. Fast migrating cells (HeLa, MDA-MB-231) need 5–10 minute intervals to capture the full kinetic curve. Slowly migrating cells (primary fibroblasts, HUVEC) can be imaged every 30 minutes. The zenCELL owl runs continuously inside the incubator — all images are stored and available for retrospective analysis at any interval.

Can zenCELL owl run 24 scratch assay conditions simultaneously?

Yes. zenCELL owl monitors up to 24 wells simultaneously inside any standard CO₂ incubator. This means 24 different treatment conditions, concentrations, cell lines or time points can be run in a single experiment — with identical incubator conditions for all wells. Gap closure rate, t½ and migration rate are calculated automatically for each well. Book a free 30-minute demo to see it live →

See the complete wound healing assay system in action.

30-minute live demo — real cells, real data, ScratchMaker and zenCELL owl running together inside an incubator.

Book your free demo ScratchMaker details →
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