A novel fluorescence microscopy-based imaging technique has been reported for performing imaging of the hepatobiliary excretory function in rats.
The in vivo imaging technique is based on intravital microscopy, which helps differentiate between pathophysiological and physiological conditions.
Cholestasis leads to accumulation of toxic substances in the systemic circulation and the liver. Liver has to perform bile excretion in order to remove xenobiotics and endogenous compounds. Any harm to the bile flow will lead to cholestasis.
The researchers initially utilized indocyanine green (ICG) to visualize the hepatocellular transport. They then utilized a benzopyrylium-based hemocyanine dye, DY635, for improving the analysis. Fluorophotometric determination of the DY635 dye was done in bile, blood and urine of rats to ascertain its hepatic clearance.
The scientists induced cholestasis in rats and then administered the dyes. They used an inverted epifluorescence microscope to study the left liver lobes through intravital microscopy. From the portal triad, the ICG was delivered and transported through the sinusoids, during which the hepatocytes took up the dye. This led to hepatocellular accumulation of ICG as the uptake was more than the excretion. This also occurred in healthy animals. The bile canaliculi were comparatively more clearly visible during transcellular transport of DY635 than ICG.
When compared to control animals, the hepatobiliary excretion of DY635 was significantly different in cholestatic animals. Intravital fluorescence microscopy showed more dye concentrations in cholestatic livers.
The novel method may help study various forms of cholestasis. Michael Bauer from the Jena University Hospital in Germany led the team which utilized the novel imaging technique for the study.