A VEGF Trap Inhibits the Beneficial Effect of BFGF on Vasoreactivity in Corporal Tissues of Hypercholesterolemic Rabbits

Introduction: Hypercholesterolemia causes a decrease in normal corporal tissue vasoreactivity in a preclinical model of erectile dysfunction. Previous studies have shown that intracorporal injection (ICI) of basic fibroblast growth factor (bFGF) reverses some of the detrimental vasoreactivity effects of hypercholesterolemia and increases vascular endothelial growth factor (VEGF) expression.

Aim: We sought to determine whether the beneficial effects of bFGF are VEGF-mediated.

Methods: A total of 32 New Zealand white rabbits were fed a 1% cholesterol diet for 6 weeks and randomly divided into four groups (N = 8/group). Group 1 received a 2.5 microg bFGF ICI and 2.5 x 10(11) viral particle unit (vpu) of adenovirus encoding beta-galactosidase (Ad beta-gal) ICI, 10 days later. Group 2 received a 2.5 microg bFGF ICI and 2.5 x 10(11) vpu of adenovirus encoding soluble VEGF receptor (VEGFR) (AdsVEGFR, a VEGF trap) ICI, 10 days later. Group 3 received phosphate buffered saline solution (PBS) ICI and 2.5 x 10(11) vpu Ad beta-gal ICI, 10 days later. Group 4 received PBS ICI and 2.5 x 10(11) vpu AdsVEGFR ICI, 10 days later.

Main Outcome Measures: The corpus cavernosum was harvested for vasoreactivity studies 10 days post viral injection. The effective dose of 50% maximum relaxation was determined. VEGF levels were assessed by enzyme-linked immunosorbent assay. Total and phosphorylated Akt and endothelial nitric oxide were analyzed by Western blot.

Results: Endothelium-dependent vasoreactivity was significantly greater in Group 1 vs. all other groups. The VEGF trap eliminated the beneficial effects of bFGF on endothelium-dependent vasoreactivity and decreased Akt and nitric oxide phosphorylation.

Conclusions: These data demonstrate that VEGF activity contributes much of the therapeutic modulation of bFGF-mediated vasoreactivity in corporal tissue.