1) development of a more efficacious cationic liposome which 
improves efficiency of gene delivery 
2) improvements in vector design which further enhance 
expression in vivo 
3) inclusion of catheter-based gene delivery 
4) application to different tumor cell types 
The preliminary data regarding each of these developments is 
shown in Section 13 (Preliminary Data) . Briefly, a new 
formulation of cationic lipids has been described recently by Dr. 
Phillip Feigner in which a different cationic lipid, 1,2- 
dimyristyloxypropyl-3-dimethyl-hydroxyethyl ammonium bromide 
(DMRIE) , is utilized with dioleoyl phosphatidylethanolamine 
(DOPE) . This has two properties which make it more suitable for 
these studies. First, it shows up to 10-fold improved 
transfection efficiency compared to our previous formulation, DC- 
chol, in vitro. More importantly, this formulation does not 
aggregate at high concentrations, in contrast to the DC-Chol 
liposome. This characteristic thus allows higher absolute 
concentrations of DNA and liposomes to be introduced into 
experimental animals without toxicity (Section 13, Preliminary 
Data) . Because of these properties, it now becomes possible to 
introduce 100-1000 times more DNA which could markedly improve 
gene expression in vivo (Section 13, Preliminary Data). 
The vector improvements are divided into two categories for 
this proposal. In the first case, expression of the HLA-B7 
vector has been improved by the addition of a consensus 
translation initiation sequence and removal of an intron. In 
Recombinant DNA Research, Volume 17 
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