A novel approach to treat ischemic tissues by using gene therapy has recently been introduced on the basis of the angiogenic potential of certain growth factors. The authors investigated the effect of adenovirus-mediated gene therapy with vascular endothelial growth factor (VEGF) delivered into the subdermal space to treat compromised skin flaps. For this purpose, the epigastric skin flap model in rats, based solely on the right inferior epigastric vessels, was used. Thirty male Sprague-Dawley rats were divided into five groups of six rats each. Viral transfection with 108 plaque-forming units was performed 2 days before the epigastric flap elevation. Rats received subdermal injections of adenovirus encoding VEGF (Ad-VEGF) or green fluorescent protein (Ad-GFP) as treatment control. Another set of animals (n = 6) received no injections and were designated as control. To determine whether site of injection had an impact on flap viability, injections were given into the predicted local ischemic area (Ad-VEGF local, n = 6; Ad-GFP local, n = 6) and into the midline of the flap (Ad-VEGF midline, n = 6; Ad-GFP midline, n = 6). A flap measuring 8 x 8 cm was outlined on the abdominal skin extending from the xiphoid process proximally and the pubic region distally, to the anterior axillary lines bilaterally. Then, the epigastric flap was elevated as an island on the right inferior epigastric vessels and sutured back to its bed. Flap viability was evaluated at 7 and 14 days after the first operation. The epigastric flaps were scanned to the computer and areas of hypoxic and/or necrotic zones relative to total flap surface area were measured and expressed as percentages by using Image Pro Plus software. Specimens were taken for histologic evaluation at day 14 before the animals were killed. Combined area of necrotic and hypoxic zones as well as necrotic zone were decreased to 9.7 +/- 1.4 percent and 1.4 +/- 0.9 percent in Ad-VEGF local, and 11.8 +/- 1.9 percent and 3.5 +/- 1.64 percent in Ad-VEGF midline compared with the control and Ad-GFP treatment groups (control, 23 +/- 3.6 percent and 20.1 +/- 3.3 percent; Ad-GFP local, 24.8 +/- 4.8 percent and 16.2 +/- 5.9 percent; and Ad-GFP midline, 23.4 +/- 6.9 percent and 19.5 +/- 7.7 percent; p < 0.05). Histologic evaluation by light microscopy failed to demonstrate any quantitative difference in vascularity of skin flaps between the treatment groups. In this study, the authors demonstrated that adenovirus-mediated gene therapy using VEGF enhanced epigastric skin flap survival, as confirmed by the significant reduction in combined area of necrotic and hypoxic zones of the flap. Compared with the control, both local and midline subdermal injections of Ad-VEGF showed improvement in overall flap survival by 57.9 and 48.7 percent, respectively. The results of this study raise the possibility of using adenovirus-mediated therapeutic angiogenesis for safer flap surgery in high-risk patients.

An experimental study was conducted to investigate the effect of time of adenovirus-mediated vascular endothelial growth factor (VEGF) gene therapy on the viability of epigastric skin flaps. Eighty-four male Sprague-Dawley rats were used. Skin flaps measuring 8 x 8 cm were marked on the ventral abdominal wall. The upper border of the flap was 1 cm above the costal margin, and the lower border was at the pubis and the inguinal fold. The lateral borders of the flap corresponded to the location of the distinct conversion of the thin ventral skin to the thick dorsal skin. Seven sites in the predicted area of necrosis on the outlined skin flaps were chosen for subdermal injections. All injections were administered by an individual who was blinded to the different treatment groups. The rats received either saline (control group I, N = 28) or adenovirus encoding green fluorescent protein (Ad-GFP; group II, N = 28) or Ad-VEGF (group III, N = 28). The epigastric island skin flaps based solely on the right inferior epigastric vessels were elevated either on the same day of injection (day 0 = 12 hours after transfection, N = 7) or on day 3 (N = 7), day 7 (N = 7), or day 14 (N = 7) after subdermal gene therapy. Flaps were sutured back to their native configuration. Flap viability was evaluated on day 7 after surgery. Sections of the flaps were examined histologically after undergoing hematoxylin-eosin staining. There was a significant reduction in mean percentage of necrotic flap area by 56%, 67%, 70%, and 54% in flaps transfected with Ad-VEGF, 12 hours, 3 days, 7 days, and 14 days before flap elevation, respectively ( < 0.05). There was no evidence that the mean percentage of skin necrosis in the Ad-GFP group was different than in the control group ( = 0.26). There was evidence of mild inflammation in flaps pretreated with Ad-GFP and Ad-VEGF compared with the control group. The authors demonstrated that adenovirus-mediated gene therapy of the abdominal skin after subdermal injections was technically feasible. This was demonstrated by the visualization of GFP expression in control experiments using a fluorescence microscope. In this study, adenovirus-mediated VEGF gene therapy promoted epigastric flap survival, which was not related to the time of transfection. These findings raise the possibility that pretreatment with VEGF gene therapy using an adenovirus vector may be applicable in patients at risk for plastic surgery.

Cross-Sectional study with control group, Level II.