Folate-modified liposomes

Targeting tumors with folate-modified liposomes represents a very popular approach, since folate receptor (FR) expression is frequently overexpressed in many tumor cells. After early studies demonstrated the possibility of delivery of macromolecules (112) and then liposomes (113) into living cells utilizing FR... 

Tumor cells have an increased vascular permeability and a decrease in their lymphatic drainage system, which leads to the passive accumulation of macromo-lecular drugs in these neoplastie cells. The macromolecules may also contain groups that are preferentially taken up by cancer cells. For example, the presence of folate ions on the surface of boron eontaining hposomes greatly enhances the boron uptake in human KB squamous epithelial cancer cells, which have overexpressed foliate acceptors. " Other examples are the reconstituted LDLs, whieh stiU retain their ability to bond to LDL speeifie sites on the tumor cells. These liposomes and modified LDLs have the ability to deliver massive amounts of to cancer eells and have been... 

When polymer micelles were modified with folate-PEG lipid, polymer micelles with longer folate-linker PEG length showed high cellular uptake in KB cells, similar to nanoemulsion (Hayama et al. 2008). In these cases, nanoemulsions and polymer micelles are essentially composed of PEG lipid and PEG block copolymers, respectively. The effect of folate-PEG on FR-mediated endocytosis was not clear because of the covering with PEG moieties. Because conventional liposomes can be formed without PEG lipid (Figure 14.1), optimal folate modification could be examined. 

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