Electrotransfer at MR imaging: tool for optimization of gene transfer protocols--feasibility study in mice.
OBJECTIVE
To test, by using an electrotransfer protocol for the transfection of skeletal muscle with naked plasmid complementary DNA, whether in vivo magnetic resonance (MR) imaging can help delineate either the spatial extent of the electric field when contrast agent is injected intraperitoneally or the transfection area when contrast agent is injected locally.


METHODS
Three groups of five mice each were examined at 4 T. Gadopentetate dimeglumine was injected intraperitoneally before electroporation in group 1 and after electroporation in group 2. In group 3, gadopentetate dimeglumine was coinjected in situ with plasmid pCMV-beta Gal in the gastrocnemius muscle before electroporation. MR imaging and muscle preparation for histologic examination were performed 3 days later. On T1-weighted images, increase of muscle signal intensity was determined in regions of interest (ROIs) of treated legs and compared with contralateral ROIs. Comparison of signal intensity increase between groups 1 and 2 was performed with Kruskal-Wallis test.


RESULTS
In groups 1 and 3, T1-weighted images of treated muscle showed zones of strongly increased signal intensity. In corresponding ROIs of groups 1, 2, and 3, the mean T1-weighted signal intensity increase at day 3 was 1.64 +/- 0.20 (SD), 1.16 +/- 0.06, and 1.58 +/- 0.17, respectively. The difference between groups 1 and 2 (ie, gadopentetate dimeglumine injected before and after electrotransfer) was significant (P <.001) both without and with correction for T2 variation (1.47 +/- 0.19 and 1.04 +/- 0.09, respectively). In group 3, after in situ coinjection of gadopentetate dimeglumine and plasmid, the area of increased signal intensity revealed at ex vivo MR imaging of the muscle showed a reasonable concordance with the transfected area revealed with beta-galactosidase on histologic sections.


CONCLUSIONS
In vivo and ex vivo results indicate that atraumatic visualization of the permeabilized and transfected area is possible.
Paturneau-Jouas
Marion
M
INSERM U 582, Institut de Myologie, Hôpital de la Pitié-Salpêtrière, 47 Boulevard de l'Hôpital, 75651 Paris, France.
Parzy
Elodie
E
Vidal
Giovanni
G
Carlier
Pierre G
PG
Wary
Claire
C
Vilquin
Jean-Thomas
JT
de Kerviler
Eric
E
Schwartz
Ketty
K
Leroy-Willig
Anne
A
D000818:Animals; D003287:Contrast Media; D018274:Electroporation; D005240:Feasibility Studies; D019786:Gadolinium DTPA; D018014:Gene Transfer Techniques; D008279:Magnetic Resonance Imaging; D051379:Mice; D008810:Mice, Inbred C57BL; D018482:Muscle, Skeletal / Q000166:cytology; D010957:Plasmids; D014162:Transfection / Q000379:methods
D003287:Contrast Media; D019786:Gadolinium DTPA