Spatial-temporal patterns of gene expression in mouse skeletal muscle after injection of lacZ plasmid DNA.
Gene therapy for muscular diseases requires the efficient transfection of a large proportion of myofiber cells within a given muscle. In the present experiments, patterns of beta-galactosidase expression were examined in mouse rectus femoris muscles at various time-points after a single injection of lacZ encoded plasmid DNA. beta-Galactosidase expression was detected 3 h after injection and rose to peak levels at 3-14 days, and then stabilized at lower levels. beta-Galactosidase staining was detected in an average of about 6% (up to 15%) of the total 4000 myofiber cells, and in about 70% of those myofibers located in the discrete area containing the greatest proportion of transfected cells. Soon after injection of DNA encoding cytoplasmic or nuclear-targeted beta-galactosidase, expression was noted predominantly in the myotendinous junction areas, after which beta-galactosidase activity progressed toward the central parts of the myofibers. This preferential transgene expression at the myotendinous junction may result from some unique, local property of the myofiber cells and/or from a restricted diffusion or binding of the injected plasmid DNA at tendinous surfaces. A better understanding of the reasons for this pattern of reporter gene expression in muscle may suggest procedures for increasing the number of myofiber cells transfected by direct DNA injections.
Doh
S G
SG
Department of Cell, Vical Incorporated, San Diego, CA 92121, USA.
Vahlsing
H L
HL
Hartikka
J
J
Liang
X
X
Manthorpe
M
M
D000818:Animals; D004251:DNA Transposable Elements; D015870:Gene Expression; D007273:Injections, Intramuscular; D007763:Lac Operon; D008156:Luciferases / Q000235:genetics; D051379:Mice; D018482:Muscle, Skeletal / Q000201:enzymology / Q000502:physiology*; D013194:Staining and Labeling; D013997:Time Factors; D014162:Transfection; D001616:beta-Galactosidase / Q000235:genetics*
D004251:DNA Transposable Elements; D008156:Luciferases; D001616:beta-Galactosidase