Direct Fusion between Poly(ethylene oxide)-lipid Modified Liposomes and Murine Mitotic B16 Melanoma Cells

摘要

The interactions between the poly(ethylene oxide)-bearing lipid (PEO-lipid) were investigated with the average number of ethylene oxide units of 5,15 and 32-reconstituted egg PC liposomes and murine mitotic B16 melanoma cells.Water-soluble FITC-dextran (20kDa) and lipophilic octadecyl rhodamine B (OD-RhoB) were encapsulated in liposomes to study the inter- action modes with these cells by fluorescence microscopic techniques.Both fluo- rescent probes loaded in the PEO-lipid (n=32,20mol%)-reconstituted liposome were specifically transferred to the mitotic cells.This process was not inhibited at 4°C or after the treatment of endocytosis inhibitor cytochalasin B or D.Confo- cal fluorescence microscopic observation of the cells treated with the liposome at 4 deg C revealed that FITC-dextran and OD-RhoB were transferred to the cytosol and the plasma membrane,respectively.In addition,when the mitotic cells were treated with the PEO-lipid (n=32,20mol%)-reeonstituted liposome encapsu- lated diphtheria toxin fragment A (DTA),approximately 30% of the cells were killed by the DTA-dependent cytotoxicity.These data indicate that the PEO- lipid (n=32,20mol%)-reconstituted liposome directly fused with the plasma membrane of the murine mitotic B16 melanoma cells.