Intracavernous Delivery of Stromal Vascular Fraction Restores Erectile Function Through Production of Angiogenic Factors in a Mouse Model of Cavernous Nerve Injury

Introduction. Erectile dysfunction (ED) is a major complication of radical prostatectomy. Men with radical prostatectomy-induced ED respond less positively to oral phosphodiesterase-5 inhibitors. Aim. The study aims to examine whether and how stromal vascular fraction (SVF) restores erectile function in mice with cavernous nerve injury (CNI). Methods. Twelve-week-old male C57BL/6J mice were used and the animals were distributed into five groups: sham operation group and CNI group receiving a single intracavernous injection of phosphate-buffered saline (PBS) or SVF (1 x 10(4), 1 x 10(5), or 3 x 10(5) cells/20 mu L, respectively). SVF was isolated from epididymal adipose tissues of green fluorescence protein transgenic mice. Main Outcome Measures. Two weeks after injection, erectile function was measured by cavernous nerve stimulation. The penis was stained with antibodies to platelet/endothelial cell adhesion molecule-1, phosphohistone H3, and phosphorylated endothelial nitric oxide synthase (phospho-eNOS). We also performed Western blot for angiopoietin-1 (Ang-1), vascular endothelial growth factor-A, hepatocyte growth factor, phospho-eNOS, and eNOS in the corpus cavernosum tissue. Results. Local delivery of SVF restored erectile function in a dose-dependent manner in CNI mice. The highest erectile response was noted at a dose of 3 x 10(5) cells, for which the response was comparable with that in the sham operation group. Local delivery of SVF significantly increased the expression of angiogenic factor proteins and induced cavernous endothelial cell proliferation and eNOS phosphorylation compared with that in the PBS-treated CNI group. SVF-induced promotion of cavernous angiogenesis and erectile function was diminished in the presence of soluble antibody to Tie2, a receptor tyrosine kinase of Ang-1. Conclusion. Secretion of angiogenic factors from SVF is an important mechanism by which SVF induces cavernous endothelial regeneration and restores erectile function. These findings suggest that cavernous endothelial regeneration by using SVF may represent a promising treatment strategy for radical prostatectomy-induced ED.