VEGF gene therapy augments localized angiogenesis and promotes anastomotic wound healing: a pilot study in a clinically relevant animal model.

BACKGROUND

Anastomotic leak related to ischemia is a source of significant morbidity and mortality in gastrointestinal surgery. The aim of this study was to apply growth factor gene transfection for the purpose of up-regulating angiogenesis, increasing anastomotic strength, and ultimately preventing dehiscence.

METHODS

An opossum esophagogastrostomy model was employed. The human vascular endothelial growth factor (VEGF(165)) gene was incorporated into a recombinant plasmid. The VEGF plasmid vector was then complexed with a cationic synthetic carrier, polyethyleneimine. Control animals received plasmid devoid of VEGF(165) (n = 6). The experimental group received VEGF(165) plasmid (n = 5). After esophagogastrectomy and gastric tubularization, plasmid was injected into the submucosa of the neoesophagus at the anastomotic site. Conduit arteriography was performed before and 10 days after injection. Euthanasia occurred on post-injection day 10 and the anastomosis was removed en bloc. A second group of animals treated with VEGF(165) were euthanized 30 and 37 days post injection. Blood flow was measured with laser-Doppler prior to euthanasia. Ex vivo anastomotic bursting pressure was performed. Tissue samples were procured for RNA extraction and von Willebrand Factor staining. Microvessel counts were obtained by two blinded observers. Tissue VEGF transcript levels were measured with reverse transcriptase polymerase chain reaction (RT-PCR).

RESULTS

There was one anastomotic leak in the control group. Experimental animals demonstrated significantly increased bursting pressure (104.25 +/- 6.2 vs 86.73 +/- 9.4 mmHg, p = 0.021) and neovascularization (33.87 +/- 9.6 vs 20.33 +/- 8.1 vessels/hpf, p = 0.032) compared to controls. In addition, there was a strongly positive correlation between the number of microvessels and bursting pressure (r = 0.808, p = 0.015, Pearson's). On angiographic examination, treated animals demonstrated more neovascularization compared to controls. RT-PCR demonstrated up to a 5.6-fold increase in VEGF mRNA in treated compared to controls.

DISCUSSION: This description of gene therapy in gastrointestinal surgery using VEGF(165) transfection demonstrates increased angiogenesis with subsequently improved anastomotic healing in a clinically relevant model.