In vivo behaviour of long-circulating liposomes in blood vessels in hamster inflammation and septic shock models-use of intravital fluorescence microscopy.
This study aimed to observe liposome uptake by leukocytes in vivo. The study was performed on skin by using a dorsal skin-fold chamber implanted in golden hamsters using intravital microscopy. 5 and 6-CF-encapsulated polyethylene glycolated liposomes were injected intravenously. The skin microcirculation was observed with an intravital Eclipse E800 Nikon microscope (using x40, x80 magnification) fitted with a Xenon light source and an epifluorescence assembly (excitation, 470 nm, FWHM 40 nm; emission, 540 nm, FWHM 40 nm). An ultra-high sensitivity videocamera mounted on the microscope projected the image onto a monitor, and the images (720 x 576 pixels) were recorded for playback analysis with a digital video cassette recorder. An acute inflammatory response was obtained by removing one complete layer of skin and the underlying fascia and avascular tissue on the opposing side of the flap corresponding to an area equivalent to the window aperture. Using this model and set-up, leukocyte rolling and adhesion were easily observed and the entry of PEGylated liposomes into hamster blood leukocytes was studied for a period of 6 h. PEGylated liposomes were clearly identified alone inside the blood flow and inside the leukocytes as soon as the inflammatory reaction appeared. This study shows for the first time that blood leukocytes in their natural milieu of whole blood are capable of interacting with, and taking up, liposomes. This observation is in accordance with previous in vitro studies.
Devoisselle
J M
JM
UMR CNRS/ENSCM 5618 and Faculté de Pharmacie, 34060 Montpellier, France. devoisse@pharma.univ-montp1.fr
Begu
S
S
Tourné-Péteilh
C
C
Desmettre
T
T
Mordon
S
S
D000818:Animals; D001808:Blood Vessels / Q000378:metabolism*; D006224:Cricetinae; D007249:Inflammation / Q000097:blood*; D008081:Liposomes; D008647:Mesocricetus; D008856:Microscopy, Fluorescence / Q000379:methods*; D012772:Shock, Septic / Q000097:blood*
D008081:Liposomes