Poly(Adenosine diphosphate-ribose) polymerase inhibition preserves erectile function in rats after cavernous nerve injury

Effects of Cells Self-aggregation in the Treatment of Neurogenic Erectile Dysfunction With Traditional Single Cell Suspension of Adipose-derived Stem Cells

OBJECTIVE

To clarify the effects of cellular self-aggregation of adipose-derived stem cells (ADSCs) on erectile function (EF).

METHODS

A model of neurogenic erectile dysfunction was performed using bilateral cavernous nerve crush injury in rats. ADSCs suspensions (1 × 10⁶/0.2 ml), were administered via intracavernous injection (ICI) after being allowed to shelve for 0 minute (ICI 0) or 60 minutes (ICI 60) in vitro, as well as cell aggregates isolated from ICI 60 (ICI A). The caudal vein injection group (CVI 60) was used to evaluate whether cell self-aggregation was beneficial to EF when introduced into the peripheral circulation. One day after the transplantation, the distribution of cells was observed. EF and histopathological changes were evaluated after 4 weeks.

RESULTS

Approximately 85% of ADSCs self-aggregated into cell clusters at 60 minutes. The ICI 60 had more significant improvements in EF and more visualized ADSCs retained in the corpus cavernosum (CC) than ICI 0 and CVI 60 (P <.05), but no significant difference between ICI 60 and ICI A. In the CVI 60 group, the cell clusters formed by self-aggregation could hardly reach the CC and were mostly found in lung tissue. Immunofluorescence staining showed increased the content of expressing biomarkers of smooth muscle, nerve within the CC tissue in the ICI groups when compared to the CVI group.

CONCLUSION

ADSCs self-aggregation before ICI may be an influential factor in the treatment of neurogenic erectile dysfunction. Its potential mechanism may be through improving cell retention in the CC.

Comparative study of intracavernous pressure and cavernous pathology after bilateral cavernous nerve crushing and resection in rats

This study aimed to compare the effects of bilateral cavernous nerve crushing (BCNC) and bilateral cavernous nerve resection (BCNR) on intracavernous pressure (ICP) and cavernous pathology in rats and to explore the optimal treatment time for the BCNC and BCNR models. Seventy-two male rats aged 12 weeks were randomly divided into three equal groups: Sham (both cavernous nerves exposed only), BCNC (BCN crushed for 2 min), and BCNR (5 mm of BCN resected). Erectile function was then measured at 1 week, 3 weeks, and 5 weeks after nerve injury, and penile tissues were harvested for histological and molecular analyses by immunohistochemistry, immunofluorescence, Western blot, and cytokine array. We found that erectile function parameters including the maximum, area, and slope of ICP/mean arterial pressure (MAP) significantly decreased after BCNR and BCNC at 1 week and 3 weeks. At 5 weeks, no significant differences were observed in ICP/MAP between the BCNC and Sham groups, whereas the ICP/MAP of the BCNR group remained significantly lower than that of the Sham group. After BCNC and BCNR, the amount of neuronal-nitric oxide synthase-positive fibers, smooth muscle cells, and endothelial cells decreased, whereas the amount of collagen III content increased. These pathological changes recovered over time, especially in the BCNC group. Our findings demonstrate that BCNC leads to acute and reversible erectile dysfunction, thus treatment time should be restricted to the first 3 weeks post-BCNC. In contrast, the self-healing ability of the BCNR model is poor, making it more suitable for long-term treatment research.

Therapeutic applications of PARP inhibitors: anticancer therapy and beyond

The aim of this article is to describe the current and potential clinical translation of pharmacological inhibitors of poly(ADP-ribose) polymerase (PARP) for the therapy of various diseases. The first section of the present review summarizes the available preclinical and clinical data with PARP inhibitors in various forms of cancer. In this context, the role of PARP in single-strand DNA break repair is relevant, leading to replication-associated lesions that cannot be repaired if homologous recombination repair (HRR) is defective, and the synthetic lethality of PARP inhibitors in HRR-defective cancer. HRR defects are classically associated with BRCA1 and 2 mutations associated with familial breast and ovarian cancer, but there may be many other causes of HRR defects. Thus, PARP inhibitors may be the drugs of choice for BRCA mutant breast and ovarian cancers, and extend beyond these tumors if appropriate biomarkers can be developed to identify HRR defects. Multiple lines of preclinical data demonstrate that PARP inhibition increases cytotoxicity and tumor growth delay in combination with temozolomide, topoisomerase inhibitors and ionizing radiation. Both single agent and combination clinical trials are underway. The final part of the first section of the present review summarizes the current status of the various PARP inhibitors that are in various stages of clinical development. The second section of the present review summarizes the role of PARP in selected non-oncologic indications. In a number of severe, acute diseases (such as stroke, neurotrauma, circulatory shock and acute myocardial infarction) the clinical translatability of PARP inhibition is supported by multiple lines of preclinical data, as well as observational data demonstrating PARP activation in human tissue samples. In these disease indications, PARP overactivation due to oxidative and nitrative stress drives cell necrosis and pro-inflammatory gene expression, which contributes to disease pathology. Accordingly, multiple lines of preclinical data indicate the efficacy of PARP inhibitors to preserve viable tissue and to down-regulate inflammatory responses. As the clinical trials with PARP inhibitors in various forms of cancer progress, it is hoped that a second line of clinical investigations, aimed at testing of PARP inhibitors for various non-oncologic indications, will be initiated, as well.

Penile rehabilitation after radical prostatectomy: what the evidence really says

The pathophysiology of erectile dysfunction after radical prostatectomy (RP) is believed to include neuropraxia, which leads to temporarily reduced oxygenation and subsequent structural changes in penile tissue. This results in veno-occlusive dysfunction, therefore, penile rehabilitation programmes focus on tissue oxygenation. Animal studies support the use of phosphodiesterase type 5 inhibitors (PDE5Is) after cavernous nerve damage but results from human studies are contradictory. The largest study to date found no long-term effect of either daily or on-demand PDE5I administration after RP compared with placebo. The effects of prostaglandin and vacuum erection devices are questionable and high-quality studies are lacking. Better documentation for current penile rehabilitation and/or better rehabilitation protocols are needed. One must be careful not to repeat the statement that penile rehabilitation improves erectile function after RP so many times that it becomes a truth even without the proper scientific backing.

Poly(ADP-ribose) polymerase inhibition improves erectile function by activation of nitric oxide/cyclic guanosine monophosphate pathway in diabetic rats

INTRODUCTION

Endothelial dysfunction-induced abnormalities of the nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) signaling pathway in the corpus cavernosum are thought to be the main factors involved in the pathogenesis of diabetes-induced erectile dysfunction (ED). Recent studies have shown that the poly(adenosine diphosphate ribose) polymerase (PARP) pathway plays a critical role in diabetic endothelial dysfunction.

AIM

  The aim of this study is to determine whether activation of the PARP pathway is involved in diabetic cavernosal endothelial dysfunction and abnormalities of the NO/cGMP pathway.

METHODS

Male Sprague-Dawley rats were randomly divided into three groups: age-matched controls, diabetic controls (DM), and the 3-aminobenzamide (3-AB, a PARP inhibitor)-treated diabetic group (DM+3-AB). Diabetes was induced by intraperitoneal injection of streptozotocin. Eight weeks after inducing diabetes, the DM+3-AB group was treated with 3-AB for 4 weeks.

MAIN OUTCOME MEASURES

Erectile function was assessed at 12 weeks after inducing diabetes by stimulating the cavernous nerve. Expression of poly(ADP-ribose), protein kinase B (Akt), phospho-Akt, endothelial nitric oxide synthase (eNOS), phospho-eNOS, and neuronal nitric oxide synthase (nNOS) were evaluated by Western blot. Cavernous NO generation and cGMP levels were also determined.

RESULTS

The DM group showed impaired erectile function and significantly increased PARP activity. Expression of total eNOS and nNOS, phospho-Akt, and eNOS decreased significantly in the DM group compared with those in the control group. In addition, cavernous NO generation and cGMP levels decreased significantly in the DM group compared with those in the control group. Treatment with 3-AB restored erectile function and significantly reversed all molecular alterations except decreased nNOS expression.

CONCLUSION

Overactivation of the PARP pathway in the corpus cavernosum of diabetic rats was involved in cavernosal endothelial dysfunction and abnormalities of the NO/cGMP pathway resulting in ED. These findings may be applied to develop novel therapies for patients with diabetic ED.

Adipose tissue-derived stem cell-seeded small intestinal submucosa for tunica albuginea grafting and reconstruction

Porcine small intestinal submucosa (SIS) has been widely used in tunica albuginea (TA) reconstructive surgery. Adipose tissue-derived stem cells (ADSCs) can repair damaged tissue, augment cellular differentiation, and stimulate release of multiple growth factors. The aim of this rat study was to assess the feasibility of seeding ADSCs onto SIS grafts for TA reconstruction. Here, we demonstrate that seeding syngeneic ADSCs onto SIS grafts (SIS-ADSC) resulted in significant cavernosal tissue preservation and maintained erectile responses, similar to controls, in a rat model of bilateral incision of TA, compared with sham-operated animals and rats grafted with SIS graft (SIS) alone. In addition to increased TGF-β1 and FGF-2 expression levels, cross-sectional studies of the rat penis with SIS and SIS-ADSC revealed mild to moderate fibrosis and an increase of 30% and 40% in mean diameter in flaccid and erectile states, respectively. SIS grafting induced transcriptional up-regulation of iNOS and down-regulation of endothelial NOS, neuronal NOS, and VEGF, an effect that was restored by seeding ADCSs on the SIS graft. Taken together, these data show that rats undergoing TA incision with autologous SIS-ADSC grafts maintained better erectile function compared with animals grafted with SIS alone. This study suggests that SIS-ADSC grafting can be successfully used for TA reconstruction procedures and can restore erectile function.

Multipotent stromal cell therapy for cavernous nerve injury-induced erectile dysfunction

INTRODUCTION

Erectile dysfunction (ED) following radical prostatectomy (RP) is a result of inadvertent damage to the cavernous nerves that run close to the prostate capsula. The mechanisms behind the development of post-RP ED are increasingly recognized and include cavernosal fibrosis and cavernosal smooth muscle apoptosis, resulting from cavernous nerve degeneration due to neuropraxia. In recent years, cell-based therapies have received increasing attention regarding their potential for recovery of erectile function following cavernous nerve injury (CNI). Multipotent stromal cells (MSCs) are an attractive cell source for this application based on their regenerative potential and their clinical applicability.

AIM

To review available evidence on the efficacy and mechanisms of action of MSC application for the treatment of ED, with an emphasis on ED following CNI.

METHODS

A nonsystematic review was conducted on the available English literature between 1966 and 2011 on the search engines SciVerse-sciencedirect, SciVerse-scopus, Google Scholar, and PubMed.

RESULTS

MSCs from both bone marrow and adipose tissue have shown beneficial effects in a variety of animal models for ED. While MSC application in chronic disease models such as diabetes, aging, and hyperlipidemia may result in cell engraftment and possibly MSC differentiation, this observation has not been made in the acute CNI rat model. In the latter setting, MSC effects seem to be established by cell recruitment toward the major pelvic ganglion and local paracrine interaction with the host neural tissue.

CONCLUSIONS

While the type of model may influence the mechanisms of action of this MSC-based therapy, MSCs generally display efficacy in various animal models for ED. Before translation to the clinic is established, various hurdles need to be overcome.

Transplantation of nonhematopoietic adult bone marrow stem/progenitor cells isolated by p75 nerve growth factor receptor into the penis rescues erectile function in a rat model of cavernous nerve injury

PURPOSE

Radical prostatectomy for prostate cancer frequently results in erectile dysfunction and decreased quality of life. We investigated the effects of transplanting nonhematopoietic adult bone marrow stem/progenitor cells (multipotent stromal cells) into the corpus cavernosum in a rat model of bilateral cavernous nerve crush injury.

MATERIALS AND METHODS

Multipotent stromal cells were isolated from the bone marrow of transgenic green fluorescent protein rats by plastic adherence (rat multipotent stromal cells) or magnetic activated cell sorting using antibodies against p75 low affinity nerve growth factor receptor (p75 derived multipotent stromal cells). Bilateral cavernous nerve crush injury was induced in adult male Sprague-Dawley rats. Immediately after injury 8 rats each were injected intracavernously with phosphate buffered saline (vehicle control), fibroblasts (cell control), rat multipotent stromal cells (cell treatment) or p75 derived multipotent stromal cells (cell treatment). Another 8 rats underwent sham operation (phosphate buffered saline injection). Four weeks after the procedures we assessed erectile function by measuring the intracavernous-to-mean arterial pressure ratio and total intracavernous pressure during cavernous nerve stimulation.

RESULTS

Intracavernous injection of p75 derived multipotent stromal cells after bilateral cavernous nerve crush injury resulted in a significantly higher mean intracavernous-to-mean arterial pressure ratio and total intracavernous pressure compared with all other groups except the sham operated group (p <0.05). Rats injected with typical multipotent stromal cells had partial erectile function rescue compared with animals that received p75 derived multipotent stromal cells. Fibroblast (cell control) and phosphate buffered saline (vehicle control) injection did not improve erectile function. Enzyme-linked immunosorbent assay suggested that basic fibroblast growth factor secreted by p75 derived multipotent stromal cells protected the cavernous nerve after bilateral cavernous nerve crush injury.

CONCLUSIONS

Transplantation of adult stem/progenitor cells may provide an effective treatment for erectile dysfunction after radical prostatectomy.

PARP inhibitors: new tools to protect from inflammation

Poly(ADP-ribosylation) consists in the conversion of β-NAD(+) into ADP-ribose, which is then bound to acceptor proteins and further used to form polymers of variable length and structure. The correct turnover of poly(ADP-ribose) is ensured by the concerted action of poly(ADP-ribose) polymerase (PARP) and poly(ADP-ribose) glycohydrolase (PARG) enzymes, which are responsible for polymer synthesis and degradation, respectively. Despite the positive role of poly(ADP-ribosylation) in sensing and repairing DNA damage, generated also by ROS, PARP over-activation could allow NAD depletion and consequent necrosis, thus leading to an inflammatory condition in many diseases. In this respect, inhibition of PARP enzymes could exert a protective role towards a number of pathological conditions; i.e. the combined treatment of tumors with PARP inhibitors/anticancer agents proved to have a beneficial effect in cancer therapy. Thus, pharmacological inactivation of poly(ADP-ribosylation) could represent a novel therapeutic strategy to limit cellular injury and to attenuate the inflammatory processes that characterize many disorders.

Herpes simplex virus vector-mediated delivery of neurturin rescues erectile dysfunction of cavernous nerve injury

Neurturin (NTN), a member of glial cell line-derived neurotrophic factor (GDNF) family, is known as an important neurotrophic factor for penis-projecting neurons. We recently demonstrated significant protection from erectile dysfunction (ED) following a replication-defective herpes simplex virus (HSV) vector-mediated GDNF delivery to the injured cavernous nerve. Herein, we applied HSV vector-mediated delivery of NTN to this ED model. Rat cavernous nerve was injured bilaterally using a clamp and dry ice. For HSV-treated groups, 20 microl of vector stock was administered directly to the damaged nerve. Delivery of an HSV vector expressing both green fluorescent protein and lacZ (HSV-LacZ) was used as a control. Intracavernous pressure along with systemic arterial pressure (ICP/AP) was measured 2 and 4 weeks after the nerve injury. Fluorogold (FG) was injected into the penile crus 7 days before being killed to assess neuronal survival. Four weeks after nerve injury, rats treated with HSV-NTN exhibited significantly higher ICP/AP compared with untreated or control vector-treated groups. The HSV-NTN group had more FG-positive major pelvic ganglion neurons than the control group following injury. HSV vector-mediated delivery of NTN could be a viable approach for the improvement of ED following cavernous nerve injury.

Surgical treatment of Peyronie's disease: choosing the best approach to improve patient satisfaction

AIM

To discuss important points on medical history, preoperative evaluation, real expectations, and selection of the appropriate surgical procedure to improve patient satisfaction after surgical procedures for Peyronie's disease.

METHODS

Recent advances in approaches to Peyronie's disease are discussed based on the literature and personal experiences. Issues concerning surgical indication, patient selection, surgical techniques, and grafting are discussed. Lengthening procedures on the convex side of the penile curvature by means of grafting offer the best possible gain from a reconstruction standpoint. Penile rectification and rigidity are required to achieve a completely functional penis. Most patients experience associated erectile dysfunction (ED), and penile straightening alone may not be enough to restore complete function. Twenty-five patients were submitted to total penile reconstruction on length and girth with concomitant penile prosthesis implant. The maximum length restoration was possible and limited by the length of the dissected neurovascular bundle. The mean age was 55.4 years (32-69 years) and the mean angle of curvature 74.2+/-22.4 degree (0-100 degree). Pericardial grafting was used to cover the defect. The mean follow-up time was 11.2 +/- 5.9 months (3-22 months).

RESULTS

Mean functional penile length gain was 3.40+/-0.73 cm (2-5 cm). Penile prosthesis maintained the penis straight. No infections occurred. Sexual intercourse was restored in all patients and all reported recovered self-esteem.

CONCLUSION

Improving patient satisfaction with the surgical treatment includes proper preoperative evaluation on stable disease, penile shortening, vascular and erectile status, patient decision and selection as well as extensive discussion on surgical technique for restoring functional penis (length and rigidity). Length and girth restoration is very important for self-esteem and patient satisfaction.

Erythropoietin receptor expression in the human urogenital tract: immunolocalization in the prostate, neurovascular bundle and penis

OBJECTIVE

To investigate whether the erythropoietin (EPO) receptor is expressed in human periprostatic (including the neurovascular bundles) and penile tissues, and define its distribution in these tissues, as the administration of exogenous EPO in cavernous nerve injury promoted the recovery of erectile function in a rat model.

MATERIALS AND METHODS

Human prostate (six samples) and penile (two) tissue were collected and paraffin-embedded. Tissue was sectioned and processed for immunohistochemical studies using an antibody for the EPO receptor; immunolocalization was assessed using light microscopy.

RESULTS

There was prominent staining for the EPO receptor in neuronal cell bodies of the periprostatic neurovascular bundles, and in the axons emanating from these ganglia. The glandular epithelium of the prostate also had weak staining. There was EPO receptor immunoreactivity in the penile specimens in the penile dorsal nerves, sinusoidal endothelium of the corpus cavernosum, and endothelial cells lining the dorsal veins and arteries. All slides processed with no primary antibody or blocking peptide showed no staining.

CONCLUSIONS

EPO receptor expression was identified and localized in human penile tissues and in the periprostatic neurovascular bundles responsible for erectile function. This suggests a likely role for endogenous EPO within these tissues, and provides the rationale for its clinical use as a protective agent locally.

Herpes simplex virus vector-mediated delivery of glial cell line-derived neurotrophic factor rescues erectile dysfunction following cavernous nerve injury

Erectile dysfunction (ED) is frequently associated with injury to the cavernous nerve sustained during pelvic surgery. Functional recovery from cavernous nerve injury is generally incomplete and occurs over an extended time frame. We employed a therapeutic gene transfer approach with herpes simplex virus (HSV) vector expressing glial cell line-derived neurotrophic factor (GDNF). Rat cavernous nerve was injured bilaterally using a clamp and dry ice. For HSV-treated groups, 20 microl of purified vector stock was administered directly to and around the damaged nerve. Delivery of an HSV vector expressing both green fluorescent protein (GFP) and lacZ (HSV-LacZ) was used as a control. Intracavernous pressure along with systemic arterial pressure (ICP/AP) was measured 2 and 4 weeks after the nerve injury. Fluorogold (FG) was injected into the penile crus 7 days before killing to assess nerve survival. Approximately 60% of major pelvic ganglion (MPG) cells were GFP positive after viral administration. At 4 weeks after nerve injury, rats treated with HSV-GDNF exhibited significant recovery of ICP/AP compared with control vector or untreated groups. The HSV-GDNF group also yielded more FG-positive MPG cells than the control vector group. HSV vector-mediated delivery of GDNF presents a viable approach for the treatment of ED following cavernous nerve injury.

Diabetes mellitus is associated with severe Peyronie's disease

OBJECTIVES

To evaluate the severity of penile deformity and penile blood flow variables in men with Peyronie's disease (PD) and diabetes mellitus (DM), and those with no risk factors.

PATIENTS AND METHODS

Men with PD and DM (59 men, group 1) and those with no risk factors (109, group 2) were compared for penile blood flow variables, severity of penile deformity, patient's age, duration of PD, the presence of pain on erection, and the degree of erectile dysfunction (ED). The men were evaluated with penile duplex Doppler ultrasonography and were categorized into specific vascular groups, using established criteria. Penile curvature was objectively measured and stratified according to the Kelâmi classification. Results were compared using Student's t-test.

RESULTS

Men with PD and DM (group 1) were significantly older than those in group 2. The duration of disease was significantly longer in group 1 than in group 2 (median 24 vs 12 months). The mean degree of penile deformity in group 1 was significantly higher than in group 2 (45.2 degrees vs 30.2 degrees). The rate of severe penile curvature (>60 degrees ) was more frequent in group 1 (27.1% vs 5.5%). Pain on erection was significantly higher in group 2 (39.7% vs 25.5%), whereas the rate of ED was more common in group 1 (81% vs 47%). Group 1 had poorer peak-systolic velocity values and significantly higher rates of arterial insufficiency and mixed vascular disease. Nonvascular causes were twice as common in group 2 than in group 1.

CONCLUSIONS

This comparative clinical study suggests that the presence of DM as the only risk factor significantly increases the severity of PD. Furthermore, DM as a risk factor is associated with significantly worse vascular status, as shown by penile duplex Doppler ultrasonography, in men with PD.

Neuroimmunophilin ligands protect cavernous nerves after crush injury in the rat: new experimental paradigms

OBJECTIVES

We investigated the effects of the orally bioavailable non-immunosuppressive immunophilin ligand GPI 1046 (GPI) on erectile function and cavernous nerve (CN) histology following unilateral or bilateral crush injury (UCI, BCI, respectively) of the CNs.

METHODS

Adult male Sprague-Dawley rats were administered GPI 15 mg/kg intraperitoneally (ip) or 30 mg/kg orally (po), FK506 1 mg/kg, ip, or vehicle controls for each route of administration just prior to UCI or BCI and daily up to 7 d following injury. At day 1 or 7 of treatment, erectile function induced by CN electrical stimulation was measured, and electron microscopic analysis of the injured CN was performed.

RESULTS

Intraperitoneal administration of GPI to rats with injured CN protected erectile function, in a fashion similar to the prototypic immunophilin ligand FK506, compared with vehicle-treated animals (93%+/-9% vs. 70%+/-5% vs. 45%+/-1%, p<0.01, respectively). Oral administration of GPI elicited the same level of significant protection from CN injury. GPI administered po at 30 mg/kg/d, dosing either once daily or four times daily with 7.5 mg/kg, provided nearly complete protection of erectile function. In a more severe BCI model, po administration of GPI maintained erectile function at 24 h after CN injury. Ultrastructural analysis of injured CNs indicated that GPI administered at the time of CN injury prevents degeneration of about 83% of the unmyelinated axons at 7 d after CN injury.

CONCLUSIONS

The orally administered immunophilin ligand GPI neuroprotects CNs and maintains erectile function in rats under various conditions of CN crush injury.

Neuromodulatory Therapy to Improve Erectile Function Recovery Outcomes After Pelvic Surgery

PURPOSE

Erectile dysfunction is a recognized, common adverse consequence of radical prostatectomy as well as various other pelvic surgeries. While a host of management options have been considered to decrease this complication, neuromodulatory therapy has recently been advanced as an intervention that may be applied for this purpose. We evaluated concepts regarding the neuropathic basis for erectile dysfunction following pelvic surgery, principles for establishing neuromodulatory therapy in this clinical context, evidence from preclinical studies supporting neuromodulatory approaches as a therapeutic strategy and the progress of early clinical developments in this field.

MATERIALS AND METHODS

The exercise principally consisted of a current literature search using the National Library of Medicine PubMed Services, a survey of recent abstract proceedings from national meetings relevant to the topic and an Internet online search for current information on federally and privately supported clinical trials specific to this topic. References were made to such key words as neuroprotection, nerve regeneration, nerve growth factors, neurotrophic factors, cavernous nerves, nerve guides and penile erection.

RESULTS

Basic science research and clinical studies support the concept that erectile loss after pelvic surgery is frequently related to neuropathic effects, resulting in penile vascular impairment. An assortment of neurobiological studies using rodent models of cavernous nerve injury have shown nerve reconstitutive actions for a host of neurotrophic substances, including classic neurotrophins, growth hormone, cytokines and atypical neurotrophic mediators. Clinical trials of several proposed neuroprotective and neurotrophic applications have been done or are in progress.

CONCLUSIONS

Erectile dysfunction is a well recognized and yet ineffectively averted complication of pelvic surgery. Neuromodulatory therapy offers a therapeutic approach for addressing the neuropathic changes of the penis that occurs in this context with the goal of maximally preserving erectile function postoperatively. While several specific neuromodulatory applications have gained interest for their potential benefit with pelvic surgery, determining their actual roles awaits the completion of controlled clinical trials.

Update on erectile dysfunction in prostate cancer patients

PURPOSE OF REVIEW

Evolution in the management of prostate cancer includes increased attention being paid to patient quality of life after treatment, specifically with issues related to sexual function. Erectile dysfunction is one of the major concerns of patients undergoing treatment for prostate cancer. There are several recognized factors that determine the postoperative incidence of erectile difficulties, including patient age, degree of cavernosal nerve sparing during surgery, cancer stage, and associated vascular comorbidities. Early initiation of rehabilitation protocols after radical prostatectomy has been advocated to promote the speed and degree of recovery of erectile function. The aim of this communication is to review recent initiatives in erectile dysfunction restoration after prostate cancer therapy.

RECENT FINDINGS

In recognition of the neurogenic basis of erectile dysfunction after radical prostatectomy, new strategies have been devised to initiate the rehabilitation process. Type 5 phosphodiesterase inhibitors, vacuum erection devices, and intracavernosal and intraurethral application of vasoactive agents have all been reported in a positive light in recent studies. Developments in cavernous nerve graft interposition procedures, perioperative neuroprotection measures, and postoperative neurotrophic treatments aim to preserve prostate cancer patients' qualities of life.

SUMMARY

Data generated from a number of clinical investigations document that pharmacologic rehabilitation programs provide a higher rate of recovery of erectile function following radical prostatectomy. Both intracavernosal and intraurethral applications of vasoactive agents and vacuum devices can speed the recovery period for return of erectile function. Various neuroprotective and neurotrophic approaches are thought to provide integral roles for the maintenance of sexual function in men undergoing prostate cancer therapy.