New-Product-Cell-ViabilityICT’s FLIVO Kits

FLIVO is a reagent you can use to assess apoptotic cell death via caspase activity in whole animals in vivo.

Flivo Products Table

  • FLIVO probes are non-cytotoxic fluorescent inhibitors of caspases, and contain the preferred binding sequence for many caspases, Val-Ala-Asp (VAD).
  • FLIVO is a cell-permeant reagent that readily diffuses in and out of all cells that it encounters as it circulates through the body. If there are active caspase enzymes inside a cell, FLIVO will form an irreversible covalent bond with a reactive cysteine on the large subunit of the caspase heterodimer, thereby inhibiting further enzymatic activity. The bound FLIVO probe will remain inside the cell as long as the cell membrane is intact. Any unbound FLIVO is removed from the circulation of the animal.
  • Apoptotic cells will retain a higher concentration of FLIVO and fluoresce brighter than non-apoptotic cells.
  • FAM-FLIVO and SR-FLIVO are injectable inhibitors for labeling active caspases in tissues.
  • NIR-FLIVO are injectable tracers for labeling caspase activity in whole animals. NIR-FLIVO Tracers utilize near-infrared fluorescent labels for non-invasive detection of active caspases using whole animal imagers.

What are FLIVO® Poly Caspase Inhibitors?

Figure 1FLIVO Poly Caspase Inhibitors are in vivo research tools for detecting caspase activation and apoptosis in excised animal tissues. ICT’s FLIVO inhibitors are available in green (carboxyfluorescein or FAM) or red (sulforhodamine B or SR) fluorescence. FAM-FLIVO and SR-FLIVO are injectable caspase inhibitors that can be used to quantify cell death in living animal tissues. FAM-FLIVO and SR-FLIVO are direct stains that can be used to quantitate poly caspase activity in the tissues of live animals. Once labeled, tissues are ready for analysis and no further processing is neccesary. FAM-FLIVO Poly Caspase Inhibitor optimally excites at 488- 492 nm and has a peak emission at 515-535 nm. SR-FLIVO Poly Caspase Inhibitor optimally excites at 550-580 nm and has a peak emission at 590-600 nm.

What are FLIVO® Poly Caspase Tracers?

NIR-FLIVO Poly Caspase Tracers are in vivo research tools for detecting caspase activation and apoptosis in whole live animals. ICT’s NIR-FLIVO Tracers utilize the near- infrared fluorescent labels Dylight® 690 and Dylight® 747 to enable researchers to illuminate caspase-positive, apoptotic cells and tissues in living animal models using whole animal imagers. NIR-FLIVO 690 Poly Caspase Tracer optimally excites at 690 nm and has a peak emission at 709 nm. NIR-FLIVO 747 Poly Caspase Tracer optimally excites at 747 nm and has a peak emission at 776 nm.

Figure 2How is FLIVO used?

After control and experimental animal subjects are prepared for the investigation, FLIVO is intravenously injected and al- lowed to circulate for 6-18 hours. FLIVO is a direct stain; once labeled, apoptotic cells will fluoresce upon excitation and no further processing is necessary. If using FAM-FLIVO or SR- FLIVO, caspase activity in cells and tissues can be detected using a window chamber system, or tissues can be excised and cells can then be analyzed by flow cytometry, fluorescence microscopy, or fluorescence plate reader. If using NIR- FLIVO, the tracers can be non-invasively imaged with whole animal imagers, or tissues can be excised and cells can then be analyzed by flow cytometry, fluorescence microscopy, or fluorescence plate reader.

How does FLIVO work?

Our FLIVO products are cell permeant, non-toxic caspase inhibitors, allowing for the in vivo detection of caspase- mediated apoptosis in living animals. FLIVO inhibitors and tracers consist of the amino acid peptide sequence valine- alanine-aspartic acid (VAD), which is targeted by active caspase enzymes, a fluoromethyl ketone group that aids in the formation of a covalent bond with active caspases, and the fluorescence label for detection.

Figure 3After intravenous injection, FLIVO diffuses in and out of all cells that it encounters as it circulates through the body. Active caspase enzymes will covalently bond with FLIVO and retain the fluorescent signal within the cell as long as the cell remains intact. Unbound FLIVO is rapidly cleared from the circulation of the animal, although it may be held in the liver for 4-6 hours, and it may accumulate in the bladder and the feces until excreted. FLIVO is very sensitive and will also detect naturally occurring, low-level apoptosis.