Optimization of sexual function outcome after radical prostatectomy using phosphodiesterase type 5 inhibitors

Cavernous Nerve Injury Resulted Erectile Dysfunction and Regeneration

Erectile dysfunction (ED) is an important cause of reduced quality of life for men and their partners. Recent studies have found that cavernous nerve injury (CNI) during prostate cancer surgery and other pelvic surgery results in medically induced CNIED in more than 80% of patients. The efficacy of first- and second-line treatment options for ED is poor. A great deal of research has been devoted to exploring new methods of neuroprotection and nerve regeneration to save erectile function in patients with CNIED, especially in patients with cavernous nerve injury after prostate cancer surgery. In addition, such as neuromodulatory proteins, proimmune ligands, gene therapy, stem cell therapy, and the current cutting-edge low-energy shock wave therapy have shown advantages in basic research and limited clinical studies. In the context of today's modern medicine, these new therapeutic techniques are expected to be new tools in the treatment of cavernous nerve injury erectile dysfunction. This article presents the main causes, mechanisms, and treatment of cavernous nerve injury erectile dysfunction and combines them with new treatment strategies.

Beneficial effect of PEDF-transfected ADSCs on erectile dysfunction in a streptozotocin-diabetic rat model

Diabetes mellitus (DM) is an important risk factor for erectile dysfunction. Adipose-derived stem cells (ADSCs) are essential for maintaining erectile function but their function is impaired during hyperglycemia. To evaluate the effects of pigment epithelium-derived factor (PEDF)-transfected ADSCs on the restoration of erectile function ADSCs and PEDF-transfected ADSCs were exposed to normal or high glucose levels for 72 h and the effects on cell survival and protein expression were determined. For in vivo studies, rats with streptozocin-induced DM were intravenously injected with ADSCs or PEDF-transfected ADSCs. Two weeks later, the intracavernosal pressure (ICP) and mean arterial pressure (MAP) were measured to assess erectile function, and penile tissues were harvested for further evaluation. PEDF overexpression in ADSCs protected cells against hyperglycemia-induced apoptosis (as determined by a TUNEL assay), increasing the expression of neurotrophic factors and decreasing the expression of inflammatory cytokines and oxidative stress-related proteins (as determined by western blotting and ELISA). In DM rats, transplantation with PEDF-transfected ADSCs effectively restored erectile function, as determined by the ICP/MAP ratio, compared with untreated ADSCs. PEDF overexpression also resulted in higher survival rates and decreased apoptosis of ADSCs. Promotion of neurotrophic factor expression and suppression of inflammatory cytokines and oxidative stress-related proteins were also observed after transplantation of PEDF-transfected ADSCs. Thus, our results demonstrate that transplantation of ADSCs restored erectile function in a rat model of DM, attenuating the negative effects of hyperglycemia. These findings indicate the therapeutic potential of ADSCs for treating erectile dysfunction and the additional benefits of PEDF overexpression.

Phosphodiesterase type 5 inhibitor administered immediately after radical prostatectomy temporarily increases the need for incontinence pads, but improves final continence status

Purpose

To evaluate the effects of phosphodiesterase type 5 inhibitor (PDE5i) on urinary continence recovery after bilateral nerve-sparing radical prostatectomy (BNSRP).

Materials and Methods

Between 2002 and 2012, 137 of 154 consecutive patients who underwent BNSRP in our institution retrospectively divided into 3 groups that included patients taking PDE5i immediately after surgery (immediate PDE5i group, n=41), patients starting PDE5i at an outpatient clinic after discharge (PDE5i group, n=56), and patients taking no medication (non-PDE5i group, n=40). Using self-administered questionnaires, the proportion of patients who did not require incontinence pads (pad-free patients) was calculated preoperatively and at 1, 3, 6, 12, 18, and 24 months after BNSRP. Severity of incontinence was determined based on the pad numbers and then compared among the 3 groups.

Results

Proportions of pad-free patients and severity of incontinence initially deteriorated in all of the groups to the lowest values soon after undergoing BNSRP, with gradual improvement noted thereafter. The deterioration was most prominent in the immediate PDE5i group. As compared to the non-PDE5i group, both the PDE5i and immediate PDE5i groups exhibited a better final continence status.

Conclusions

PDE5i improves final continence status. However, administration of PDE5i immediately after surgery causes a distinct temporary deterioration in urinary incontinence.

Restoration of erectile function with intracavernous injections of endothelial progenitor cells after bilateral cavernous nerve injury in rats

Endothelial progenitor cells (EPCs) are bone marrow-derived endothelial cells capable of circulating, proliferating, and differentiating into mature endothelial cells. Circulating EPCs can be directly recruited to some extent at sites of injury, and their administration could accelerate repair or endothelialization of the damaged tissue. We investigated the effects of intracavernous injections of EPCs into the corpora cavernosa of rats with erectile dysfunction (ED) caused by bilateral cavernous nerve (CN) injury. Overall, 24 male Sprague-Dawley rats were randomized into three groups: sham surgery, vehicle-only, or EPC treatment. Rats in the EPC treatment and vehicle-only groups were subjected to bilateral CN injury before injection of EPCs or vehicle, respectively, into the corpora cavernosa. Four weeks after surgery, erectile function was assessed by measuring maximum intracavernosal pressure (ICP), change in ICP, area under the ICP curve, and ratio of change in ICP and mean arterial pressure (MAP; ΔICP/MAP). Penile tissue was histomorphometrically analyzed for the expression of neural nitric oxide synthase (nNOS), neurofilament-1 (NF-1), von Willebrand factor (vWF), endothelial NOS (eNOS), and smooth muscle cell content. Maximum ICP and all other functional parameters of erectile function were significantly reduced in the vehicle-only group vs. the sham and EPC treatment groups (all p < 0.001). Smooth muscle cell content was decreased in the vehicle-only vs. the sham and EPC treatment groups (both p < 0.01). Expressions of vWF and eNOS in the dorsal artery were significantly higher in the EPC treatment than the vehicle-only group (p < 0.05). In conclusion, EPC treatment restored erectile function in a rat model of bilateral CN injury through recruitment of EPCs toward the dorsal artery and preservation of smooth muscle cells in the corpus cavernosum. These findings elucidate the therapeutic potential of EPCs for treating ED in humans.

Prevention and management of post prostatectomy erectile dysfunction

Sexual dysfunction is common in patients with prostate cancer (PC) following radical prostatectomy (RP). Review the available literature concerning prevention and management strategies for post-RP erectile function (EF) impairment in terms of preoperative patient characteristics, intra and postoperative factors that may influence EF recovery, and postoperative treatments for erectile dysfunction (ED). A literature search was performed using Google and PubMed database for English-language original and review articles, either published or e-published up to July 2013. The literature still demonstrates a great inconsistency in the definition of what is considered normal EF both before and after RP. Thus, using validated psychometric instruments with recognized cut-offs for normalcy and severity during the pre- and post-operative evaluation should be routinely considered. Therefore, a comprehensive discussion with the patient about the true prevalence of postoperative ED, the concept of spontaneous or pharmacologically-assisted erections, and the difference between “back to baseline” EF and “erections adequate enough to have successful intercourse” clearly emerge as key issues in the eventual understanding of post-RP ED prevention and promotion of satisfactory EF recovery. Patient factors (including age, baseline EF, comorbid conditions status), cancer selection (non- vs. uni- vs. bilateral nerve-sparing), type of surgery (i.e., intra vs. inter vs. extrafascial surgeries), surgical techniques (i.e., open, laparoscopic and robotically-assisted RP), and surgeon factors (i.e., surgical volume and surgical skill) represent the key significant contributors to EF recovery. A number of preclinical and clinical data show that rehabilitation and treatment in due time are undoubtedly better than leaving the erectile tissue to its unassisted postoperative fate. The role of postoperative ED treatment for those patients who received a non-nerve-sparing RP was also extensively discussed. Optimal outcomes are achieved mainly by the careful choice of the correct patient for the correct type of surgery. Despite a plethora of potential rehabilitative approaches, they should be only considered as “strategies”, since incontrovertible evidence of their effectiveness for improving natural EF recovery is limited. Conversely, numerous effective therapeutic options are available for treating post-RP ED.

Impact of penile rehabilitation with low-dose vardenafil on recovery of erectile function in Japanese men following nerve-sparing radical prostatectomy

Erectile dysfunction (ED) is a major complication after radical prostatectomy (RP); however, debate continues regarding the efficacy of penile rehabilitation in the recovery of the postoperative erectile function (EF). This study included a total of 103 consecutive sexually active Japanese men with localized prostate cancer undergoing nerve-sparing RP, and analyzed the postoperative EF, focusing on the significance of penile rehabilitation. In this series, 24 and 79 patients underwent bilateral and unilateral nerve-sparing RPs, respectively, and 10 or 20 mg of vardenafil was administered to 35 patients at least once weekly, who agreed to undergo penile rehabilitation. Twelve months after RP, 48 (46.6%) of the 103 patients were judged to have recovered EF sufficient for sexual intercourse without any assistance. The proportion of patients who recovered EF in those undergoing penile rehabilitation (60.0%) was significantly greater than that in those without penile rehabilitation (38.2%). Of several parameters examined, the preoperative International Index of Erectile Function-5 (IIEF-5) score and nerve-sparing procedure were significantly associated with the postoperative EF recovery rates in patients with and without management by penile rehabilitation, respectively. Furthermore, univariate analysis identified the preoperative IIEF-5 score, nerve-sparing procedure and penile rehabilitation as significant predictors of EF recovery, among which the preoperative IIEF-5 score and nerve-sparing procedure appeared to be independently associated with EF recovery. Considering these findings, despite the lack of independent significance, penile rehabilitation with low-dose vardenafil could exert a beneficial effect on EF recovery in Japanese men following nerve-sparing RP.

Penile rehabilitation after radical prostatectomy: does it work?

CONTEXT

Erectile dysfunction (ED) represents one of the most common long-term side effects in patients with clinically localized prostate cancer (PCa) undergoing nerve-sparing radical prostatectomy (RP).

OBJECTIVE

To analyze the role of penile rehabilitation in the recovery of erectile function (EF) after nerve-sparing RP.

EVIDENCE SYNTHESIS

Penile rehabilitation is defined as the use of any intervention or combination with the goal not only to achieve erections sufficient for satisfactory sexual intercourses, but also to return EF to preoperative levels. The concept of rehabilitation is based on the implementation of protocols aimed at improving oxygenation, preserving endothelial structure, and preventing smooth muscle structural alterations. Nowadays, the most commonly adopted approaches for penile rehabilitation after nerve-sparing RP are represented by the administration of phosphodiesterase type-5 inhibitors (PDE5-Is), intracorporeal injection therapy, vacuum erection devices (VED), and the combination of these therapies. Several basic science studies support the rational for the adoption of penile rehabilitation protocols. Particularly, rehabilitation, set as early as possible, seems to be better than leaving the erectile tissues unassisted. On the other hand, results from solid prospective randomized trials finally assessing the long-term beneficial effects of PDE5-Is, intracavernosal injections, or VED on EF recovery after surgery are still lacking.

CONCLUSIONS

Although preclinical evidences support the rationale for penile rehabilitation after nerve-sparing RP, clinical studies reported conflicting results regarding its efficacy on long-term EF recovery. Nowadays, which is the optimal rehabilitation program still represents a matter of debate.

Current status of penile rehabilitation after radical prostatectomy

Although disease-free survival remains the primary goal of prostate cancer treatment, erectile dysfunction (ED) remains a common complication that affects the quality of life. Even though several preventive and therapeutic strategies are available for ED after radical prostatectomy (RP), no specific recommendations have been made on the optimal rehabilitation or treatment strategy. Several treatment options are available, including phosphodiesterase-5 inhibitors, vacuum erection devices, intracavernosal or intraurethral prostaglandin injections, and penile prostheses. Urologists must consider more effective ways to establish optimal treatments for ED after RP. ED is an important issue among patients with prostate cancer, and many patients hope for early ED recovery after surgery. This review highlights the currently available treatment options for ED after RP and discusses the limitations of each.

Effects of phosphodiesterase type 5 inhibitor, tadalafil, on continence reflex in rats

INTRODUCTION AND HYPOTHESIS

Effects of tadalafil, a phosphodiesterase type 5 inhibitor, on the urethral continence reflex induced by sneezing were investigated.

METHODS

The amplitude of urethral pressure responses during sneezing (A-URS) and urethral baseline pressure (UBP) were measured in female rats using a microtransducer-tipped catheter. Sneeze leak-point pressure (S-LPP), defined as the lowest amount of pressure required to induce fluid leakage from the urethral orifice during sneezing, was measured in rats with stress urinary incontinence (SUI) induced by vaginal distension. Values were determined before and after tadalafil administration.

RESULTS

Tadalafil dose dependently and significantly decreased A-URS and S-LPP. At the highest dose tested (6.0 mg/kg), A-URS and S-LPP decreased from 49.7 to 32.3 and from 63.9 to 44.2 cmH2O, respectively, whereas UBP did not significantly change.

CONCLUSIONS

Tadalafil attenuated the sneeze-induced urethral continence reflex by relaxing the striated muscles of the external urethral sphincter.