Extravasation From liver

The shape, surface characteristics, and size of a nanoparticle have a key role in biodistribution in vivo. The effects of size have been studied extensively with spherically shaped particles. Particles less than 5 nm are rapidly cleared from the circulation through renal clearance or extravasations of liver and spleen. Nanoparticle behavior in the size range of 10 nm to 15 pM varies widely in terms of biodistribution, and cellular uptake of nanoparticles in this range is heavily dependent on cell type (Fujita et al., 2006). 

There are differences in the ease of extravasation of macromolecules from the bloodstream into different tissues [14, 104, 105]. Capillaries in the liver, spleen, and bone marrow have incomplete basal membranes and are lined with endothelial cells which are not continuously arranged. Capillaries in the muscle have a somewhat tighter arrangement, and there is an almost impermeable barrier which isolates the central nervous system from circulating blood. The rate of glomerular filtration of macromolecules depends on their hydrodynamic radius, the threshold being approx. 45 A [106]. Structure of the macromolecule is of utmost importance, since shape, flexibility, and charge influence the penetration and possible readsorption in the tubular epithelia [100]. 

In trauma of the kidney, excretory-phase imaging after 3 to 10 min can provide valuable information about the extent of the injury into the renal collection system (Fig. 42.3) (Park et al. 2006). When injuries to the spleen and liver are present, late-phase images help to plan interventions because they allow differentiating pseudoaneurysms from lacerations and active contrast material extravasations (Marmery and Shanmuganathan 2006). 

Figure 14.5 (See color insert) IVM observation of GFP-CHO-Kl and GFP-avj83-CHO-Kl cells in liver after portal vein injection, (a) Invasion of GFP-CHO-Kl (left) and GFP-avy33-CHO-Kl (right) cells 1 x 10 cells were injected into Balb/c nu/nu mice via a portal vein. At 24 h after the injection, liver was examined under a fluorescence microscope [reprinted with permission from Ref. (22)]. Bars represent 100 p,m. (b) IVM analysis was performed as described in (a), at 1, 2, and 24 h after the injection of GFP-expressing CHO-Kl cells the number of fluorescent cells sequestered in blood vessels or extravasated into surrounding tissue were counted under a fluorescence microscope. The data indicate the percentage of cells that had invaded into tissue vs. total cells counted.

Bilomas result from rupture of the biliary system, which can be spontaneous, traumatic, or iatrogenic following surgery or interventional procedures (Mortele and Ros 2001 Murphy et al. 1989). Bilomas can be intrahepatic or perihepatic. Extravasation of bile into the liver parenchyma generates an intense inflammatory reaction, thereby inducing formation of a well-defined pseudocapsule. Clinical manifestations depend on the location and size of the biloma (Mortel and Ros 2001 Murphy et al. 1989). 

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