Stain vesicle membrane precisely

Fluorescent Dye-Dextran Conjugates or membrane staining reagents are used to visualize endocytosis. However, they have limitations in observing the dynamics of endosomes in live cells in terms of precision of staining or retentivity of reagent. ECGreen is the reagent that over comes these limitations.

ECGreen-Endocytosis Detection is a pH dependent fluorescence dye that localizes to vesicle membrane. The visualization of endocytosis using the ECGreen is a more direct method than fluorescent analogs and allows visualization endocytosis from the stage of early endosomes.

ECGreen-Endocytosis Detection is more sensitive to pH changes than exiting fluorescently labeled dextrans.
Therefore, ECGreen-Endocytosis Detection is appreciable for detection of early endosomes with high sensitivity.

Clear visualization of intracellular vesicular trafficking

It has been known that Wortmannin inhibits the recycling of endosomes or transition to lysosomes and causes enlargement of endosomes. To evaluate these changes caused by Wortmannin, early endosomes were co-stained by ECGreen and Rab5-RFP (marker protein of early endosomes), and lysosomes were co-stained by ECGreen and lysosome staining reagent. In adding Wortmannin, ECGreen was colocalized with enlarged endosomes (Rab5-RFP). On the other hand, ECGreen wasn’t colocalized with lysosomes.

Endosomes (ECGreen, green): Ex. 405 nm / Em. 500 – 560 nm
Early endosomes (Rab5-RFP, red): Ex. 561 nm / Em. 560 – 620 nm
Late endosomes (Rab7-RFP, red): Ex. 561 nm / Em. 560 – 620 nm
Lysosomes (Lamp1-RFP, red): Ex. 561 nm / Em. 560 – 620 nm

(1) Preapare HeLa cells in 8 wells of μ-Slide and incubate overnight.
(2) After washing with HBSS, 200 µl of Wortmannin (final concentration: 100 nmol/l) prepared in 10% FBS-containing MEM medium was added.
(3) Incubate at 37°C for 30 minutes
(4) 200 µl of ECGreen (diluted 1,000-fold) prepared in 10% FBS-containing MEM medium without removing the supernatant
(5) Incubate at 37°C for 30 minutes
(6) Wash the cells twice with HBSS and add MEM medium containing 10% FBS.
(7) Observation with a confocal laser microscope

Experimental example: Time-lapse imaging of Endosome localization

Endosomes (ECGreen, green): Ex. 405 nm / Em. 500 – 560 nm
Lysosome (Lysosome staining dye, red): Ex. 561 nm / Em. 600 – 700 nm

(1) HeLa cells and culture them overnight.
(2) Wash the cells once with HBSS.
(3) ECGreen (diluted 1,000-fold) prepared in 10% FBS-containing MEM medium and lysosomal staining dye (final concentration: 100 nmol/l) were added.
(4) Observe unwashed cells at each hour using a confocal laser microscope.

Visualization of EVs uptake via endocytic pathway

Mem Dye-labeled EVs are internalized via endocytosis:
HeLa cells were incubated with 10 μmol/L ECGreen for 30 min. Then, Mem Dye-Deep Red (Code: EX03) labeled EVs (quantified as 10 µg of protein) were added to HeLa cells. After 30 or 120 min incubation, the cells were washed and observed under a fluorescence microscope (Scale Bar: 10 µm).