AB35. Future potential of the neuroprotective agent (local application) for the nerve injury in radical prostatectomy

Abstract: Neurogenic erectile dysfunction (ED) resulting from cavernous nerve injury is a major complication caused by radical prostatectomy (RP). Restoration of erectile function with intracavernous injections of platelet-rich plasma (PRP) or endothelial progenitor cells (EPC) after bilateral cavernous nerve injury in rats are studied in our laboratory. In each study, 24 male Sprague-Dawley rats are randomized into three groups: sham surgery, injured control, and PRP or EPC treatment. Injured-control and PRP or EPC treatment groups are subjected to bilateral CN injury before treatment with vehicle or PRP or EPCs injected into the corpora cavernous, respectively. Four weeks after surgery, erectile function (EF) is assessed by measuring maximal intracavernosal pressure (ICP), change in ICP, area under ICP curve, and ratio of change in ICP and mean arterial pressure. Both of the PRP and EPC treatment group result in significant recovery of EF, as compare with the vehicle-only group (P<0.05). Histomorphometrically we analyze myelinated axons number of cavernous nerve (CN) and dorsal nerve, collagen type change, number of apoptotic cells, and mRNA expression of caspase-3 and transforming growth factor-β 1 (TGF-β 1) in the corpus cavernosum. The PRP treatment group has a significant preservation of myelinated axons of CNs, reduced the apoptotic index and decreased the mRNA expression of TGF-β 1 in the corpus cavernosum compares with the vehicle-only group (P<0.05). The EPC treatment group shows a higher expression of von Willebrand factor (vWF), endothelial nitric oxide synthesis (eNOS)in dorsal artery than vehicle-only group (P<0.05). The EPCs can be detected in Corpus cavernosum for longer than seven days after injection. In conclusion, PRP injection into the corpus cavernosum increases the number of myelinated axons, EPC injection can recruit the EPCs toward dorsal artery and preserve the smooth muscle cells in the corpus cavernosum. Both of these treatments can facilitate recovery of EF through different mechanism in the bilateral CN injury rat model. They are also potentially to be good medications in the future for the treatment of neurogenic ED after RP.

Keywords: Erectile dysfunction (ED); radical prostatectomy (RP); nitric oxide synthesis (eNOS); Willebrand factor (vWF)