FITC-Dextran (MW 150000) is a fluorescein isothiocyanate (FITC) dextran fluorescent probe with excitation at 491 nm and emission at 518 nm. It is used as a marker to reveal cell damage caused by heat shock and to study both the early and late stages of apoptosis. Additionally, FITC-Dextran (MW 150000) is employed in perfusion studies and fluorescent microlymphography in animals to investigate processes affecting blood-brain barrier (BBB) permeability. This compound also serves as a fluorescent probe for studying cell permeability.

Cell Labeling: Suitable for labeling apoptotic HeLa cells and human peripheral blood mononuclear cells (PBMC), as live HeLa and PBMC are not stained by FITC-Dextran. First, cells undergo apoptosis induction by incubating at 43.5°C for 1 hour and then at 37°C for 8 hours. Next, suspend the cells in 100 μL of culture medium, mix in a Q-prep tube with 10 μL of propidium iodide (PI) and 10 μL of FITC-Dextran (MW 150000), achieving final concentrations of 7.5 μM for PI and 1.13 μM for FITC-Dextran. Incubate cells in the dark at room temperature for 25 minutes. Centrifuge the labeled cells with 3 mL culture medium at 500 g for 10 minutes. Following centrifugation, resuspend cells in 1 mL of culture medium and analyze using flow cytometry or fluorescence microscopy (PI: Ex=500 nm, Em=600 nm; FITC-Dextran (MW 150000): Ex=495 nm, Em=525 nm). Paracellular Permeability Testing [4]: Add FITC-Dextran (0.1 mg/mL) to the basal culture medium in the transwell chamber. After 15 minutes, collect medium from the transwell insert and measure fluorescence signal (Ex=485 nm, Em=538 nm). Determine the FITC-Dextran concentration based on fluorescence intensity and calculate permeability.

Assessment of intestinal barrier function involves the following steps: 1. Subject mice to a 4-hour fasting period. 2. Administer FITC-Dextran (MW 150000) orally at a dosage of 0.6 mg/g to the mice. 3. Measure the fluorescence intensity within four hours (Ex nm/Em 520 nm).