In vivo molecular imaging and histological analysis of changes induced by electric pulses used for plasmid DNA electrotransfer to the skin: a study in a dorsal window chamber in mice.
Electropermeabilization/electroporation (EP) is a physical method that by application of electric pulses to cells increases cell membrane permeability and enables the introduction of molecules into the cells. One of the uses of EP in vivo is plasmid DNA electrotransfer to the skin for DNA vaccination. EP of tissues induces reduction of blood flow and, in combination with plasmid DNA, induction of an immune response. One of the EP protocols for plasmid DNA electrotransfer to the skin is a combination of high-voltage (HV) and low-voltage (LV) pulses. However, the effects of this pulse combination on skin-vessel blood flow are not known. Therefore, using intravital microscopy in a dorsal window chamber in mice and fluorescently labeled dextrans, the effects of one HV and eight LV pulses on skin vasculature were investigated. In addition, a detailed histological analysis was performed. Image analysis of fluorescence intensity changes demonstrated that EP induces a transient constriction and increased permeability of blood vessels as well as a "vascular lock." Histological analysis revealed rounding up of endothelial cells and stacking up of erythrocytes at 1 h after EP. In addition, extravasation of erythrocytes and leukocyte infiltration accompanied by edema were determined up to 24 h after EP. In conclusion, our results show that blood flow modifying effects of EP in skin contribute to the infiltration of immune cells in the exposed area. When combined with plasmid DNA for vaccination, this could enable the initial and prolonged contact of immune cells with encoded therapeutic proteins.
Department of Experimental Oncology, Institute of Oncology Ljubljana, Zaloska 2, 1000 Ljubljana, Slovenia.
Bostjan
B
Markelc
Elisabeth
E
Bellard
Gregor
G
Sersa
Sandrine
S
Pelofy
Justin
J
Teissie
Andrej
A
Coer
Muriel
M
Golzio
Maja
M
Cemazar
D000818:Animals; D002199:Capillary Permeability; D048430:Cell Shape; D003911:Dextrans / Q000378:metabolism; D004487:Edema / Q000276:immunology / Q000473:pathology; D018274:Electroporation; D042783:Endothelial Cells / Q000473:pathology / Q000502:physiology; D005260:Female; D016650:Fluorescein-5-isothiocyanate / Q000378:metabolism; D005456:Fluorescent Dyes / Q000378:metabolism; D007700:Kinetics; D051379:Mice; D008810:Mice, Inbred C57BL; D010957:Plasmids / Q000235:genetics*; D012867:Skin / Q000098:blood supply / Q000276:immunology / Q000473:pathology*; D059008:Time-Lapse Imaging; D014162:Transfection; D014661:Vasoconstriction
D003911:Dextrans; D005456:Fluorescent Dyes; D016650:Fluorescein-5-isothiocyanate