Abstract
Background and Objective
Laserโtissue interaction studies have focused on laserโinduced 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.
Study Design/Materials and Methods
We used a transgenic mouse model containing a VEGF promoter driving a GFP reporter gene to image VEGF expression in vivo. Twentyโtwo mice received two full thickness incisions in the dorsal skin: one with the Free Electron Laser (ฮปโ=โ6.45 ฮผm, 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 2โ3 weeks and was localized in fibroblasts. FEL lesions showed more total GFP expression than scalpel lesions but this was only statistically significant (Pโ<โ0.05) at 2 and 4 weeks. The fullโwidth halfโmax (FWHM) of the GFP expression was always larger for the FEL lesion compared to the scalpel lesion but was only statistically significant (Pโ<โ0.05) at 2 and 3 weeks. At 2 weeks the extent of the GFP expression in the laser lesion was on average 55 ฮผm 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 laserโinflicted 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. Lasers Surg. Med. 29:343โ350, 2001. ยฉ 2001 WileyโLiss, Inc.