Endotoxemia increases the clearance of mPEGylated 5000-MW quantum dots as revealed by multiphoton microvascular imaging.
Imaging the microcirculation is becoming increasingly important in assessing life-threatening disease states. To address this issue in a highly light absorbing and light scattering tissue, we use laser scanning multiphoton microscopy and fluorescent 655-nm 5000-MW methoxy-PEGylated quantum dots to image the functional microcirculation deep in mouse hind limb skeletal muscle. Using this approach, we are able to minimize in vivo background tissue autofluorescence and visualize complete 3-D microvascular units, including feeding arterioles, capillary networks, and collecting venules to depths of 150 to 200 microm. In CD1 mice treated with lipopolysaccharide to model an endotoxemic response to bacterial infection, we find that these quantum dots accumulate at microvascular bifurcations and extravasate from the microcirculation in addition to accumulating in organs (liver, spleen, lung, and kidney). The quantum dots are cleared from the circulation with a first-order elimination rate constant seven times greater than under normal conditions, 1.6+/-0.06 compared to 0.23+/-0.05 h(-1), P<0.05, thereby reducing the imaging time window. In vitro experiments using TNFalpha treated isolated leukocytes suggest that circulating monocytes (phagocytes) increased their nonspecific uptake of quantum dots when activated. In combination with multiphoton microscopy, quantum dots provide excellent in vivo imaging contrast of deep microvascular structures.
Bateman
Ryon M
RM
University of British Columbia, Critical Care Research Laboratories, James Hogg iCAPTURE Centre, St. Paul's Hospital, Vancouver, British Colombia, Canada, V6Z 1Y6. rbateman@mrl.ubc.ca
Hodgson
Kevin C
KC
Kohli
Kapil
K
Knight
Darryl
D
Walley
Keith R
KR
D000818:Animals; D019446:Endotoxemia / Q000097:blood* / Q000473:pathology; D008297:Male; D008657:Metabolic Clearance Rate; D051379:Mice; D008833:Microcirculation / Q000473:pathology / Q000503:physiopathology; D018613:Microscopy, Confocal / Q000379:methods; D036641:Microscopy, Fluorescence, Multiphoton / Q000379:methods*; D018482:Muscle, Skeletal / Q000098:blood supply*; D011092:Polyethylene Glycols / Q000737:chemistry / Q000493:pharmacokinetics*; D045663:Quantum Dots; D019265:Spectroscopy, Near-Infrared / Q000379:methods
D011092:Polyethylene Glycols; C028210:monomethoxypolyethylene glycol