image of a CellTrace™ Violet Cell Proliferation Kit

Flow cytometric visualization of cell generations

The CellTrace™ Violet kit is used to monitor distinct generations of proliferating cells by dye dilution. Live cells are covalently labeled with a very bright, stable dye. Every generation of cells appears as a different peak on a flow cytometry histogram.

This protocol can be used for:

  • Detecting cell proliferation using flow cytometry

This protocol should not be used for:

  • Fluorescence microscopy or microplate readers


Culture medium preparation

  1. To 1 L OpTmizer™  T Cell Expansion SFM, add the following:
    • 26 mL of T Cell Expansion Supplement (supplied in Cat. No. A10485-01)
    • 10 mL of Penicillin-Streptomycin-Glutamine
  2. Complete medium is stable for 4 weeks when stored at 2–8°C in the dark

Mononuclear cell isolation from whole blood

  1. Dilute 10 mL whole blood in 10 mL PBS and mix well
  2. Add 15 mL Ficoll-Paque™ Plus to a 50 mL centrifuge tube and gently layer 20 mL diluted whole blood on top
  3. Centrifuge for 30 minutes at 400 x g
  4. Carefully remove lymphocyte layer and transfer to a new tube
  5. Resuspend cells in 25 mL DPBS buffer in a 50 mL conical tube
  6. Centrifuge for 5 minutes at 300 x g, pour off supernatant, and resuspend in 25 mL DPBS
  7. Repeat wash step and resuspend in 10 mL DPBS
  8. Count cells on the Countess® Automated Counter or by another method; adjust concentration to 106 cells/mL

Cell staining

  1. Add 20 µL DMSO to a vial of CellTrace™ Violet staining solution
  2. Dilute this stock solution into 20 mL of PBS (warmed to 37°C) for a 5 µM staining solution
  3. Add 10 mL of cells to a 50 mL centrifuge tube
  4. Centrifuge cells for 5 minutes at 300 x g and carefully pour off supernatant
  5. Resuspend cells in 10 mL of CellTrace™ Violet staining solution
  6. Incubate cells for 20 minutes in a 37°C water bath
  7. Add 40 mL OpTmizer™ T Cell Expansion SFM to the cells to absorb any unbound dye
  8. Incubate cells for for 5 minutes
  9. Centrifuge cells for 5 minutes at 300 x g and resuspend the cell pellet in pre-warmed OpTmizer™ T Cell Expansion SFM

Stimulation and analysis

  1. Distribute aliquots of stained cells into culture plates or flasks
  2. Stimulate with 50 µL Dynabeads® Human T-Activator CD3/CD28 per 1 mL of cells, or other stimulus
  3. Incubate for desired length of time under growth conditions
  4. Harvest cells and stain for other markers if appropriate
  5. Analyze using a flow cytometer with 405 nm excitation and a 450/40 bandpass emission filter
Spectral information and storage
  CellTrace™ Violet
Excitation/Emission (in nm) 405/450
Standard filter set Pacific Blue™
Storage conditions ≤–20°C


Protocol tips

  • Reserve 1 mL of cells for unstained control and 1 mL of cells for a stained, but unstimulated control
  • Dynabeads® stimulation typically results in T-cell division every 18–20 hr
  • Analyze as many cells as possible from each sample
  • Use a viability dye and gate on live cells

Graph of histograms showing cell proliferation detection using CellTrace™ Violet Cell Proliferation Kit
Human PBMCs stained with  CellTrace™ Violet reagent and stimulated in culture for 7 days. The discrete peaks in this histogram represent successive generations of live cells. Analysis was completed using the Attune® Acoustic Focusing Cytometer with 405 nm excitation and a 450/40 nm bandpass emission filter. The unstimulated parent generation is indicated in red.