Features and Benefits
• Sensitive: The maximum intensity of labeling (cell staining) of apoptotic cells is higher than the nick translation method
• Fast: The use of fluorescein-dUTP allows analysis of the samples directly after the TUNEL reaction, but before the addition of the secondary detection system
• Convenient: The direct labeling procedure using fluorescein-dUTP allows verification of the efficiency of the TUNEL reaction during the assay procedure
• Accurate: Identification of apoptosis at a molecular level (DNA-strand breaks) and identification of cells at the very early stages of apoptosis
• Flexible: No substrate included; provides the opportunity to select the staining procedure of choice
General description
Kit for the detection and quantification of apoptotic cell death on a single-cell level by light microscopy in immunohistocytochemistry.
Contents:
• Enzyme Solution (TdT)
• Label Solution (fluorescein-dUTP)
• Converter AP (anti-fluorescein antibody-AP), ready-to-use
Other Notes
For life science research only. Not for use in diagnostic procedures.
Packaging
1 kit containing 3 components.
Principle
The In Situ Cell Death Detection Kit, AP is based on the detection of single- and double-stranded DNA breaks that occur at the early stages of apoptosis.
Apoptotic cells are fixed and permeabilized. Subsequently, the cells are incubated with the TUNEL reaction mixture that contains TdT and fluorescein-dUTP. During this incubation period, TdT catalyzes the addition of fluorescein-dUTP at free 3′-OH groups in single- and double-stranded DNA. After washing, the label incorporated at the damaged sites of the DNA is marked by an anti-fluorescein antibody conjugated with the reporter enzyme alkaline phosphatase. After washing to remove unbound enzyme conjugate, the AP retained in the immune complex is visualized by a substrate reaction.
Preparation Note
Working solution: Add total volume (50 μl) of Enzyme Solution to the remaining 450 μl Label Solution to obtain 500 μl TUNEL reaction mixture.
Mix well to equilibrate components.
Storage conditions (working solution): TUNEL reaction mixture
The TUNEL reaction mixture should be prepared immediately before use and should not be stored. Keep TUNEL reaction mixture on ice until use.
Converter-AP
Once thawed the Converter-AP solution should be stored at 2 to 8 °C (maximum stability
6 months).
Note: Do not freeze.
Specificity
The TUNEL reaction preferentially labels DNA strand breaks generated during apoptosis. This allows discrimination of apoptosis from necrosis and from primary DNA strand breaks induced by cytostatic drugs or irradiation.
Application
The In Situ Cell Death Detection Kit, AP, is a precise, fast, and simple nonradioactive technique to detect and quantify apoptotic cell death at the single-cell level in cells and tissues by light microscopy; it is not intended for diagnostic procedures. Thus, the In SituCell Death Detection Kit can be used in many different assay systems. Examples are:
• Detection of individual apoptotic cells in frozen and formalin-fixed tissue sections in basic research†[3][2]
• Determination of sensitivity of malignant cells to drug-induced apoptosis in cancer research[4]
• Typing of cells undergoing cell death in heterogeneous populations by double staining procedures
Specifications
Widely used methods to determine apoptosis include the analysis of the genomic DNA by agarose-gel electrophoresis and DNA fragmentation assays based on 3H-thymidine and, alternatively, 5-Bromo-2′-deoxy-uridine. The methods involve the separation of fragmented, low molecular-weight DNA from unfragmented, high molecular-weight DNA in a given cell population. Thus, these methods do not provide information about the fate of an individual cell in a given cell population or, particularly, in tissue sections. Alternatively, individual apoptotic cells may be microscopically recognized because of the characteristic appearance of nuclear chromatin condensation and fragmentation, but this method is subjective and limited to a relatively narrow time window when the morphological changes are at a maximum.
The hallmark of apoptosis is DNA degradation, which in early stages is selective to the internucleosomal DNA linker regions. The DNA cleavage may yield double-stranded and single-stranded DNA breaks (nicks). Both types of breaks can be detected by labeling the free 3′-OH termini with modified nucleotides (e.g., biotin-dUTP, DIG-dUTP, fluorescein-dUTP) in an enzymatic reaction. The enzyme terminal deoxynucleotidyl transferase (TdT) catalyzes the template-independent polymerization of deoxyribonucleotides to the 3′-end of single- and double-stranded DNA. This method has also been termed TUNEL (TdT-mediated dUTP-X nick end labeling). Alternatively, free 3′-OH groups may be labeled using DNA polymerases by the template-dependent mechanism called nick translation. However, the TUNEL method is considered to be more sensitive and faster.
Sample material: Cytospin and cell smear preparations, adherent cells grown on slides, and frozen and paraffin-embedded tissue sections.
