Chimerasome-mediated gene transfer in vitro and in vivo

Proteoliposome delivery vesicles can be prepared by the protein-cochleate method [Gould-Fogerite and Mannino, Anal. Biochem. 148 (1985) 15-25; Mannino and Gould-Fogerite, Biotechniques 6 (1988) 682-690]. Proteins which mediate the entry of enveloped viruses into cells are integrated in the lipid bilayer, and materials are encapsulated at high efficiency within the aqueous interior of these vesicles. We describe proteoliposomemediated delivery of proteins and drugs into entire populations of cells in culture. Material can be delivered gradually by Sendai-virus-glycoprotein-containing proteoliposomes. Alternatively, synchronous delivery to a population can be achieved by exposing cell-bound influenza glycoprotein vesicles briefly to low pH buffer. When DNA is encapsulated, chimeric proteoliposome gene-transfer vesicles (chimerasomes), which mediate high-efficiency gene transfer in vitro and in vivo, are produced. Stable expression of a bovine papilloma virus-based plasmid in tissue-cultured cells, at 100000 times greater efficiency than Ca · phosphate precipitation of DNA, with respect to the quantity of DNA used, has been achieved. Stable gene transfer and expression in mice has been obtained by subcutaneous injection of chimerasomes containing a plasmid expressing the early region of polyoma virus. In one experimental group, 50% of the mice developed tumors which were shown to express polyoma virus early proteins and contain the transferred DNA. This is the first report of stable gene transfer in animals mediated by a liposome- or proteoliposome-based system.