The inhibitory effect of serum is one of the main obstacles to the in
vivo use of cationic liposomes as a DNA delivery system. We have found
that a novel liposome formulation, DODAC:DOPE (1:1) is totally resist
ant to the inhibitory effects of serum for transfection of cultured my
oblasts and myotubes. Transfection with a lacZ reporter gene in the pr
esence of 95% fetal bovine serum gave up to 25% beta-gal-positive cell
s in C2C12 myoblasts and about six-fold less in primary human myoblast
s. The lower transgene expression in primary cells does not appear to
be a result of less DNA uptake but might result from differences in in
tracellular trafficking of the complexes. DODAC-based liposomes are un
ique in their resistance to serum inhibition and may therefore be valu
able for the systemic delivery of genetic information to muscle and ot
her tissues.