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12 April 1995 In-vivo and ex-vivo spectrofluorometric and imaging study of liposome uptake by the liver using a pH-sensitive probe
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Liposomes are known to be uptaken by the liver cells after intraveinous injection. Only few techniques are available to follow this process in vivo like nuclear magnetic resonance spectroscopy or scintigraphy. Intracellular pathway and liposomes localization in the different liver cells require sacrifice of the animals, cells separation and electronic microscopy, then little is known about liposomes kinetic uptake by the acidic intracellular compartments in vivo. We propose in this study a new method to follow liposomes uptake in the liver in vivo using a fluorescent pH sensitive probe 5,6-carboxyfluorescein and two different composition of liposomes: phospholipids DSPC/Chol and DMPC in order to evaluate the influence of the formulation on the release characteristics of liposomes in the lysosomes. We have already demonstrated the ability of the fluorescence spectroscopy and imaging using a pH dependent probe to monitor pH in living tissues. As pH of lysosomes is very low, the kinetic liposomes uptake in this intracellular acidic compartment is followed by monitoring the pH of the whole liver in vivo and ex vivo. Carboxyfluorescein is used at high concentration (100 mM) in order to quench its fluorescence. Liposomes are injected to Wistar rats into the penil vein. After laparotomy, fluorescence spectra and images are recorded during two hours. Results show a clear relationship between formulation of liposomes and stability in the acidic compartments of hepatic cells. After sacrifice and flush with cold saline solution, pH of the liver ex vivo is found to be 5.0-5.5. Data show a rapid clearance of release dye and an uptake of liposomes by the liver cells and, as liposomes penetrate in the acidic compartment, dye is released from liposomes and is delivered in lysosomes leading to the decrease of the pH.
© (1995) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Sylvie Soulie-Begu, Jean-Marie Devoisselle, and Serge R. Mordon "In-vivo and ex-vivo spectrofluorometric and imaging study of liposome uptake by the liver using a pH-sensitive probe", Proc. SPIE 2387, Advances in Laser and Light Spectroscopy to Diagnose Cancer and Other Diseases II, (12 April 1995);

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