Organ-specific endothelial cell uptake of cationic liposome-DNA complexes in mice

Abstract

This study identified the organ and cellular distribution of cationic liposome-DNA complexes injected intravenously into CD-1 mice for gene delivery. DOTIM-cholesterol liposomes were labeled with the fluorescent dye CM-Dil and complexed with plasmid DNA encoding the chloramphenicol acetyltransferase reporter gene. The distribution of the complexes was examined in 29 organs and tissues by fluorescence, confocal, and electron microscopy from 5 min to 24 h after injection. The complexes formed clusters in blood, which were cleared within 20 min. Complexes visible by fluorescence microscopy were taken up by endothelial cells, leukocytes, and macrophages and did not leave the vasculature except in the spleen. At 5 min, the complexes formed a patchy coating on the endothelial surface, but by 4 h, they were internalized into endosomes and lysosomes in organ- and vessel-specific patterns. Uptake by capillary endothelial cells was greatest in the lung, ovary, and anterior pituitary, less in muscle and the heart, and nearly absent in the brain and pancreatic islets. In lymph nodes and intestinal Peyer's patches, the uptake was sparse in capillaries but abundant in high endothelial venules. In the liver and spleen, most of the uptake was in Kupffer cells and macrophages. Measurements of chloramphenicol acetyltransferase reporter gene expression were generally consistent with the pattern of uptake by endothelial cells. The uptake and gene expression were accompanied by a decrease in circulating leukocytes and platelets. Overall, our results showed that the complexes were internalized by endothelial cells in organ- and vessel-specific patterns that did not match any previously identified properties of the microvasculature. The unusual distribution of endothelial cell uptake may be explained by a heterogeneously distributed membrane receptor for which the complexes are ligands.

The role of tissue macrophages in the induction of proinflammatory cytokine production following intravenous injection of lipoplexes

“…We and other groups have also reported that lipoplexes accumulate in the liver and spleen, as well as the lung after intravenous administration and liver Kupffer cells and spleen macrophages are directly involved in the uptake of lipoplexes. [14][15][16][17] These data suggest that these cells may play an important role in the production of proinflammatory cytokines. These cells are also involved in the uptake of adenovirus and cytokine production after intravenous administration of recombinant adenovirus vectors.…”

“…Several reports have suggested that intravenously administered DNA-cationic molecule complexes are mainly taken up by liver Kupffer cells. [14][15][16][17] Kupffer cell depletion by GdCl 3 would lead to a reduction in lipoplex accumulation in the liver. We could not find any differences in the accumulation of lipoplex in the spleen (Figure 1c).…”

Novel cationic cardiolipin analogue-based liposome for efficient DNA and small interfering RNA delivery in vitro and in vivo

“…The uptake capability of cationic liposome by the capillary endothelial cells is shown to be highest in the lung, less in the muscle and heart. 27 In addition, the size of the liposomes has also been shown to play important role in the tissue distribution. Reduced distribution to the lung can be achieved by decreasing the size of the liposomes.…”

True

“…Kumagai et al (1987) observed a rapid binding and endocytosis of cationized albumin to isolated brain capillaries, suggesting that the anionic barrier facilitates the endothelial absorption and endocytosis of cationic molecules. Cationic liposomes have been demonstrated to be taken up by endothelial cells in an organ-specific pattern with highest accumulation in the lung (McLean et al, 1997). However, angiogenic endothelial cells in tumours and in chronic inflammation revealed a preferential uptake of cationic liposomes, with a high proportion being associated with endothelial fenestrae (Thurston et al, 1998).…”

“…Consequently, the excretion of proteins larger than the renally filterable size may initially require catabolism in the liver; and smaller metabolites can then be filtered and excreted through the kidney (Behr et al, 1995). In addition to liver and kidney, organs such as the lung (McLean et al, 1997) and the immune system may be involved in the clearance of charge modified molecules. Bass et al (1990) have shown that cationization of albumin alters its molecular conformation.…”