INTERACTION OF A FUSOGENIC LIPOSOME WITH HELA-CELL

A plasmid, pActDTA, whose expression is fatal to mammalian cells, caus ed a decrease in HeLa cell survival only if the plasmid was encapsulat ed in egg PC liposome whose surface was modified with a poly(ethylene glycol) derivative bearing two alkyl chains (abbreviated as PEG-lipid) . This result suggests that the reconstitution of PEG-lipid into the l iposome made direct transport of the plasmid into the cytosol of the c ell by a mechanism other than endocytosis possible. Furthermore, a tra nsmission electron micrographic observation showed that the interactio n between HeLa cell and the PEG-lipid reconstituted liposome was consi stent with fusion. This interaction was unique to the PEG-lipid recons tituted liposome. These results strongly suggest that this be the firs t example of PEG-lipid induced fusion of liposome to a mammalian cell and support the validity of the PEG-lipid reconstituted liposome as a fusogenic liposome to a mammalian cell.