In vivo optical imaging of expression of vascular endothelial growth factor following laser incision in skin.
OBJECTIVE
Laser-tissue interaction studies have focused on laser-induced secondary effects on tissue and the postmortem histological analysis of laser wounds. In this study we addressed wound healing and possible impairment of wound healing due to collateral tissue damage by in vivo imaging of gene expression.


METHODS
We used a transgenic mouse model containing a VEGF promoter driving a GFP reporter gene to image VEGF expression in vivo. Twenty-two mice received two full thickness incisions in the dorsal skin: one with the Free Electron Laser (lambda = 6.45 microm, 52.9 mJ/mm(2)) and one with a scalpel. Mice were imaged for GFP expression at 3 days, 1, 2, 3, and 4 weeks. Confocal microscopic imaging was performed at 2 weeks.


RESULTS
Peak GFP expression was seen at 2-3 weeks and was localized in fibroblasts. FEL lesions showed more total GFP expression than scalpel lesions but this was only statistically significant (P < 0.05) at 2 and 4 weeks. The full-width half-max (FWHM) of the GFP expression was always larger for the FEL lesion compared to the scalpel lesion but was only statistically significant (P < 0.05) at 2 and 3 weeks. At 2 weeks the extent of the GFP expression in the laser lesion was on average 55 microm beyond that seen in the scalpel lesion but correlated with the number of laser passes.


CONCLUSIONS
Feasibility of using transgenic mice carrying photoactive reporter genes for studying cellular process of laser-inflicted wound repair in a noninvasive, in vivo manner was shown. GFP expression mediated by the VEGF promoter in fibroblast showed minimal impairment of wound healing due to the laser.
Izzo
A D
AD
Department of Biomedical Engineering, Box 79, Station B, Vanderbilt University, Nashville, Tennessee, USA.
Mackanos
M A
MA
Beckham
J T
JT
Jansen
E D
ED
D000818:Animals; D062109:Dermatologic Surgical Procedures; D004195:Disease Models, Animal; D016228:Endothelial Growth Factors / Q000235:genetics / Q000502:physiology* / Q000528:radiation effects*; D005240:Feasibility Studies; D015870:Gene Expression / Q000235:genetics / Q000502:physiology* / Q000528:radiation effects*; D049452:Green Fluorescent Proteins; D007202:Indicators and Reagents; D053685:Laser Therapy / Q000009:adverse effects*; D008164:Luminescent Proteins; D008222:Lymphokines / Q000235:genetics / Q000502:physiology* / Q000528:radiation effects*; D051379:Mice; D008822:Mice, Transgenic; D018613:Microscopy, Confocal / Q000379:methods; D008856:Microscopy, Fluorescence / Q000379:methods; D011832:Radiation Injuries / Q000209:etiology* / Q000235:genetics / Q000503:physiopathology; D011897:Random Allocation; D012867:Skin / Q000503:physiopathology / Q000528:radiation effects*; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D014945:Wound Healing / Q000235:genetics / Q000502:physiology* / Q000528:radiation effects*
D016228:Endothelial Growth Factors; D007202:Indicators and Reagents; D008164:Luminescent Proteins; D008222:Lymphokines; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D049452:Green Fluorescent Proteins