Folate-conjugated liposomes preferentially target macrophages associated with ovarian carcinoma

The folate receptor (FR) is overexpressed on many epithelial cancers and has been exploited for targeted delivery of folate-linked liposomes to cancer cells in vitro. The present studies investigate the distribution of folate-targeted liposomes in a FR(+) mouse model of ovarian cancer. According to flow cytometric analysis, folate-conjugation of liposomes significantly enhanced their uptake into ovarian cancer cells and tumor-associated macrophages within tumor ascites fluid. Compared to ovarian cancer cells, macrophages acquired tenfold more liposomes, and approximately 50% of this uptake was FR-dependent. These results demonstrate that, in addition to their cancer cell-targeting properties, folate-liposomes may be useful for targeting drugs to tumor-associated macrophages in vivo.