Stem Cells in Male Sexual Dysfunction: Are We Getting Somewhere?

Bibliometric and Visualization Analysis of Stem Cell Therapy for Erectile Dysfunction

Purpose

As a common male disease, erectile dysfunction (ED) seriously affects the physical and mental health of patients. In recent years, studies have continued to point out the great potential of stem cell therapy (SCT) in the treatment of ED. The purpose of this study is to comprehensively analyze the research of SCT for ED and understand the development trends and research frontiers in this field.

Methods

Publications regarding SCT and ED were retrieved and collected from the Web of Science Core Collection. CiteSpace and VOSviewer software were then utilized for bibliometric and visualization analysis.

Results

A total of 524 publications were eventually included in this study. The annual number of publications in this field was increasing year by year. China and the USA were the two most productive countries. Lin GT, Lue TF and Lin CS, and the University of California San Francisco where they worked were the most productive research group and institution, respectively. The journal with the largest number of publications was The Journal of Sexual Medicine, and the following were mostly professional journals of urology and andrology. Diabetes mellitus-induced ED and cavernous nerve injury-related ED were the two most commonly constructed models of ED in studies. Concerning the types of stem cells, mesenchymal stem cells derived from adipose and bone marrow were most frequently used. Moreover, future research would mainly focus on exosomes, tissue engineering technology, extracorporeal shockwave therapy, and clinical translation.

Conclusion

The research of SCT for ED will receive increasing global attention in the future. Our study provided bibliometric and visualization analysis of published literature, helping researchers understand the global landscape and frontiers in this field. More preclinical and clinical studies should be conducted to more deeply explore the underlying mechanisms of treatment and promote clinical translation.

Therapeutic efficacy and promise of stem cell-derived extracellular vesicles in Alzheimer's disease and other aging-related disorders

The term extracellular vesicles (EVs) refers to a variety of heterogeneous nanovesicles secreted by almost all cell types, primarily for intercellular communication and maintaining cellular homeostasis. The role of EVs has been widely reported in the genesis and progression of multiple pathological conditions, and these vesicles are suggested to serve as 'liquid biopsies'. In addition to their use as biomarkers, EVs secreted by specific cell types, especially with stem cell properties, have shown promise as cell-free nanotherapeutics. Stem cell-derived EVs (SC-EVs) have been increasingly used as an attractive alternative to stem cell therapies and have been reported to promote regeneration of aging-associated tissue loss and function. SC-EVs treatment ameliorates brain and peripheral aging, reproductive dysfunctions and inhibits cellular senescence, thereby reversing several aging-related disorders and dysfunctions. The anti-aging therapeutic potential of SC-EVs depends on multiple factors, including the type of stem cells, the age of the source stem cells, and their physiological state. In this review, we briefly describe studies related to the promising effects of SC-EVs against various aging-related pathologies, and then we focus in-depth on the therapeutic benefits of SC-EVs against Alzheimer's disease, one of the most devastating neurodegenerative diseases in elderly individuals. Numerous studies in transgenic mouse models have reported the usefulness of SC-EVs in targeting the pathological hallmarks of Alzheimer's disease, including amyloid plaques, neurofibrillary tangles, and neuroinflammation, leading to improved neuronal protection, synaptic plasticity, and cognitive measures. Cell culture studies have further identified the underlying molecular mechanisms through which SC-EVs reduce amyloid beta (Aβ) levels or shift microglia phenotype from pro-inflammatory to anti-inflammatory state. Interestingly, multiple routes of administration, including nasal delivery, have confirmed that SC-EVs could cross the blood-brain barrier. Due to this, SC-EVs have also been tested to deliver specific therapeutic cargo molecule/s (e.g., neprilysin) to the brain. Despite these promises, several challenges related to quality control, scalability, and biodistribution remain, hindering the realization of the vast clinical promise of SC-EVs.

News and future perspectives of non-surgical treatments for erectile dysfunction

The significant discontinuation rate of available therapies and the paucity of curative options promoted the research on potential novel treatments suitable for erectile dysfunction patients. The aim of this study was to provide a summary of available evidence regarding the news and future perspectives related to the non-surgical treatment of erectile dysfunction. A narrative review of the literature was performed. A comprehensive search in the MEDLINE, Embase, and Scopus databases was done. Papers in English-language, published until April 2022, were included. No chronological restriction was applied. Retrospective and prospective clinical studies, as well as meta-analyses, were considered. Oro-dispersible formulations of phosphodiesterase type 5 inhibitors are particularly indicated in patients who have difficulty in swallowing solid dosage form; in addition, they constitute a discrete route of administration not requiring water. Low-intensity extracorporeal shock wave therapy is indicated in mild vasculogenic erectile dysfunction and in patients with vasculogenic erectile dysfunction poorly responsive to phosphodiesterase type 5 inhibitors. Stem cell therapy, platelet-rich plasma injections, and gene therapy seem promising regenerative treatments for selected patients with erectile dysfunction. Novel oral formulations of drugs commonly used in erectile dysfunction patients have recently become part of standard clinical practice. Regenerative treatments have been emerging in recent years and could become routine curative options in the near future. Further well-designed randomized controlled trials are needed to provide conclusive evidence on this topic and guide appropriate recommendations.

Stem Cell Therapy for Erectile Dysfunction: A Step towards a Future Treatment

Background: The improvement of absent or partial response in the medical treatment of erectile dysfunction (ED) has led to the development of minimally invasive new treatment modalities in the field of regenerative medicine. Methods: A literature review on stem cell therapy for the treatment of ED was performed. We searched for the terms "erectile dysfunction" and "stem cell therapy" in PubMed and Clinicaltrials.gov. Literature searching was conducted in English and included articles from 2010 to 2022. Results: New treatment modalities for ED involving stem cell therapy are not only conceived with a curative intent but also aim to avoid unnecessary adverse effects. Several sources of stem cells have been described, each with unique characteristics and potential applications, and different delivery methods have been explored. A limited number of interventional studies over the past recent years have provided evidence of a safety profile in their use and promising results for the treatment of ED, although there are not enough studies to generate an appropriate protocol, dose or cell lineage, or to determine a mechanism of action. Conclusions: Stem cell therapy is a novel treatment for ED with potential future applications. However, most urological societies agree that further research is required to conclusively prove its potential benefit.

[Biotherapies for erectile dysfunction and Peyronie's disease: Where are we now?]

INTRODUCTION

Clinical trials of cell therapy for erectile dysfunction (ED) and Peyronie's disease (PD) were recently conducted after preclinical studies.

AIMS

The aims of this study are to give an update on biotherapy for ED and PD and to describe the regulatory framework for these therapies.

MATERIALS AND METHODS

A literature review was performed through PubMed and Clinical.trials.gov addressing cell therapy for ED and PD and using following keywords "erectile dysfunction", "Peyronie's disease", "stem cell", and "platelet-rich plasma".

RESULTS

Preclinical studies in rodent models have shown the potential benefit of cell therapy for ED after radical prostatectomy or caused by metabolic diseases, and PD. The tissues used to obtain the therapeutic product were bone marrow, adipose tissue and blood (PRP, platelet-rich plasma). Mechanism of action was shown to be temporary and mainly paracrine. Four clinical trials were published concerning ED after radical prostatectomy and in diabetic patients and one for PD. Eleven clinical trials including three randomized trials are currently going on. Preclinical and preliminary clinical results suggested the possibility to improve spontaneous erectile function and response to pharmaceutical treatment in initially non-responder patients. This effect is mediated by an improvement of penile vascularization. A reduction of penile curvature without side effect was noted after injections into the plaque of PD patients. Most of these therapeutic strategies using autologous cells were considered as "Advanced Therapy Medicinal Products" with strict regulatory frameworks imposing heavy constraints, in particular in case of "substantial" modification of the cells. The regulatory framework remains unclear and more permissive for PRP and cell therapy processes with extemporaneous preparation/injection and no "substantial" modifications.

CONCLUSIONS

First results on cell therapy for ED and PD are promising. The regulatory framework can significantly change according to cell preparations and origins leading to various constraints. This regulatory framework is crucial to consider for the choice of the procedure.

Drug delivery options and therapeutic advances in the management of erectile dysfunction

INTRODUCTION

Erectile dysfunction (ED) is defined as the inability to achieve or maintain an erection sufficient for satisfactory sexual performance. It is estimated that 20-30% of adult men will have at least one episode of ED during their lifetime and the prevalence increases with age. ED is known to have significant negative psychological implications for men, resulting in impaired functional status and a greater prevalence of anxiety and depression.

AREAS COVERED

Medications for the treatment of erectile dysfunction largely revolve around oral, injection, and topical therapies. Though all three modalities are widely used, each delivery option has its own advantages and specific indications. Likewise, there are several new developing treatments for ED that may change the landscape of treatment. The goal of this review is to summarize contemporary drug delivery options used in the treatment of ED and highlight future promising pharmacological developments.

EXPERT OPINION

There are a myriad of new developments on the horizon including new PDE5Is and drug targets, nanotechnology enhancements, stem cell and gene therapy, shockwave therapy, and platelet-rich plasma injections. These are all promising new methods to not only treat ED but also to address the pathology and prevent or eliminate further damage.

The good, bad, and the ugly of regenerative therapies for erectile dysfunction

Erectile dysfunction (ED) is a common condition which reduces quality of life of both patients and their partners, and is a significant health care expense every year. Although phosphodiesterase type-5 inhibitors are the current first-line treatment for men with ED, they are limited by their on-demand dosing, intolerance, and variable efficacy in complex patient populations such as men with multiple medical comorbidities or ED after pelvic surgery. Regenerative medicine has been introduced and investigated in andrology as an encouraging strategy to restore diseased erectile tissue structure and function. Novel regenerative therapies for ED are controversial but are perceived to offer a durable and safe tissue restorative approach to act as a long-term solution to this cumbersome disease process. Here, we review platelet-rich plasma, amniotic fluid membranes, low-intensity extracorporeal shockwave therapy, and stem cell therapy as regenerative strategies to treat ED. Most of these approaches have preclinical and occasionally clinical data to support their ongoing investigation; however, none of these treatments are currently supported for use in ED patients outside of clinical trials.

Evolving therapies for Peyronie's disease: how can we work towards new drugs?

Peyronie’s disease (PD) is an idiopathic chronic fibrotic disease that causes a penile curvature (PC), subsequent erectile dysfunction (ED) and impaired sexual intercourse in patients. As of yet, there are no reliable non-surgical treatment options available. Intralesional injection with collagenase Clostridum Histolyticum has been FDA approved since 2013, but post-approval studies have not been unanimously positive. Moreover, it renders a curvature improvement of only 30% on average, usually still requiring surgical intervention to remedy PC. Therefore, there is a need for drugs which could prevent surgery altogether. Development of new drugs can either be through a target-based or phenotypic assay-based approach. The current in vivo model for PD is dependent on treatment of primary PD-derived fibroblasts with transforming growth factor-β1. Moreover, despite the existence of a genetic in vivo PD model, it does not allow for drug screening or testing. While some advances have been made in the past few years, new in vivo and in vivo systems and well-designed studies are urgently needed for the non-surgical treatment of PD.

MicroRNA-145 engineered bone marrow-derived mesenchymal stem cells alleviated erectile dysfunction in aged rats

Background

Aging is one of the dominant factors contributing to erectile dysfunction (ED), and effective treatments for age-associated ED are urgently demanded. In this study, the therapeutic efficiency of bone marrow-derived mesenchymal stem cells (BMSCs) overexpressing microRNA-145 (miR-145) was evaluated in ED.

Methods

Sixty male Sprague-Dawley rats (24 months old) were randomly divided into 4 treatment groups (n = 15/group): PBS (control), BMSCs, BMSCs transfected with a blank vector (vector-BMSCs), and BMSCs transfected with a lentivirus overexpressing miR-145 (OE-miR-145-BMSCs). Fourteen days after transplantation of BMSCs, erectile function was evaluated by measuring intra-cavernous pressure (ICP) and mean arterial pressure (MAP). Subsequently, penile erectile tissues were harvested and subjected to Masson staining, qRT-PCR, immunofluorescence staining, dual luciferase assay, and Western blot analysis.

Results

Fourteen days after transplantation, the ICP/MAP was 0.79 ± 0.05 in the OE-miR-145-BMSC group, 0.61 ± 0.06 in the BMSC group, 0.57 ± 0.06 in the vector-BMSC group, and 0.3 ± 0.01 in the PBS group. Treatment with OE-miR-145-BMSCs significantly improved ED (P < 0.05), and the treatment increased the smooth muscle content in the penis tissues of ED rats (P < 0.05). In the OE-miR-145-BMSC group, the expression levels of α-SMA, desmin, and SM-MHC were higher than they were in the other ED groups (P < 0.05). In addition, the levels of collagen 1, MMP2, and p-Smad2 in the BMSC-treated group, especially in the OE-miR-145-BMSC group, were lower than those in the control group (P < 0.05).

Conclusions

MicroRNA-145 engineered BMSCs effectively attenuate age-related ED. Transplantation of miR-145-overexpressing BMSCs may provide a promising novel avenue for age-associated ED therapy.

Mesenchymal Stem Cells Treatment for Erectile Dysfunction in Diabetic Rats

INTRODUCTION

Aging men with diabetes mellitus are more easily suffering from erectile dysfunction (ED), which was poor to respond to drugs. Mesenchymal stem cell treatment (MSCT) offers us an alternative approach that might reverse diabetes mellitus erectile dysfunction (DMED).

AIM

The aim of this study was to review the current studies investigating mesenchymal stem cell approach in diabetic rat models of ED for future research.

METHODS

A medical literature search was performed in PubMed by using the keywords including erectile dysfunction, mesenchymal stem cells, diabetes mellitus, and rat model.

MAIN OUTCOME MEASURE

Representative studies on DMED rats treated by MSCT were reviewed.

RESULTS

Streptozocin-induced type 1 diabetes mellitus rats were used in most studies because of cost and convenience. With the development of stem cell treatment for DMED research, many kinds of stem cells were used in animal experiment, such as bone marrow-derived mesenchymal stem cells, adipose-derived stem cells, human umbilical cord blood mononuclear cells, muscle-derived stem cells, urine-derived stem cells, neural crest stem cells, and endothelial progenitor cells. Although diverse stem cells were applied for DMED treatment, the mechanism behind these approaches was identical, including improving vascular injury, recovering smooth muscle, restoring neuronal cells, inhibiting the generation of inflammatory cytokines, homing mesenchymal stem cells, and decreasing apoptosis in corpus cavernosum. Meanwhile, combination therapies, including MSCT with drug, herb, and low-energy extracorporeal shockwave treatment showed satisfactory results for ED.

CONCLUSION

It has been proved that MSCT is an effective and safe treatment for the DMED rats. What's more, MSCT might be a potential and promising approach for patients with DMED as a minimally invasive treatment. Combination of MSCT with various methods was proved to be a more efficient treatment and dependable option to make up for deficiencies of MSCT. Kim SW, Zhu GQ, Bae WJ. Mesenchymal Stem Cells Treatment for Erectile Dysfunction in Diabetic Rats. Sex Med Rev 2020;8:114-121.

Stem-cell regenerative medicine as applied to the penis

PURPOSE OF REVIEW

Tissue engineering and regenerative medicine has emerged as a new scientific interdisciplinary field focusing on developing new strategies to repair or recreate tissues and organs. This review gathers findings on erectile dysfunction and, Peyronie's disease from recent preclinical and clinical studies under heading of stem-cell regenerative medicine.

RECENT FINDINGS

Over the last 2 years, preclinical studies on rat models demonstrated the tangible beneficial role of stem cells and stromal vascular fraction in the context of preventing fibrosis and restoring erectile function in different animal models of Erectile dysfunction and Peyronie's disease. There are not solid evidences in the clinical settings.

SUMMARY

Large randomized, double blind clinical trials are needed to prove the efficacy of stem-cell therapy on human patients. Owing to the lack of solid evidences, the stem-cell therapy should be only administrated in a clinical research setting.

Engineered Mesenchymal Stem Cells Expressing Stromal Cell-derived Factor-1 Improve Erectile Dysfunction in Streptozotocin-Induced Diabetic Rats

Effective therapies for erectile dysfunction (ED) associated with diabetes mellitus (DM) are needed. In this study, the effects of stromal cell-derived factor-1 (SDF-1)-expressing engineered mesenchymal stem cells (SDF-1 eMSCs) and the relevant mechanisms in the corpus cavernosum of a streptozotocin (STZ)-induced DM ED rat model were evaluated. In a randomized controlled trial, Sprague–Dawley (SD) rats (n = 48) were divided into four groups (n = 12/group): Normal (control), DM ED (diabetes induced by STZ), DM ED + BM-MSC (treated with bone marrow [BM]-derived MSCs), and DM ED + SDF-1 eMSC (treated with SDF-1-expressing BM-MSCs). After four weeks, intracavernosal pressure (ICP), an indicator of erectile function, was 0.75 ± 0.07 in the normal group, 0.27 ± 0.08 in the DM ED group, 0.42 ± 0.11 in the DM ED + BM-MSC group, and 0.58 ± 0.11 in the DM ED + SDF-1 eMSC group. BM-MSCs, especially SDF-1 eMSCs, improved ED (p < 0.05). SDF-1 eMSC treatment improved the smooth muscle content in the corpus cavernosum (p < 0.05). As SDF-1 expression increased, ED recovery improved. In the SDF-1 eMSC group, levels of neuronal nitric oxide synthase (nNOS) and phosphorylated endothelial NOS (p-eNOS) were higher than those in other groups (p < 0.05). In addition, high stromal cell-derived factor-1 (SDF-1) expression was associated with increased vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) in DM ED rats (p < 0.05). Higher levels of phosphorylated protein kinase B (p-AKT)/protein kinase B (AKT) (p < 0.05) and B-cell lymphoma-2 (Bcl-2) and lower levels of the apoptosis factors Bcl2-associated x (Bax) and caspase-3 were observed in the MSC-treated group than in the DM ED group (p < 0.05). SDF-1 eMSCs showed beneficial effects on recovery from erectile function.

Advances in stem cell therapy for erectile dysfunction

INTRODUCTION

Stem cell (SC) application is a promising area of research in regenerative medicine, with the potential to treat, prevent, and cure disease. In recent years, the number of studies focusing on SCs for the treatment of erectile dysfunction (ED) and other sexual dysfunctions has increased significantly.

AREAS COVERED

This review includes critical ED targets and preclinical studies, including the use of SCs and animal models in diabetes, aging, cavernous nerve injury, and Peyronie's disease. A literature search was performed on PubMed for English articles.

EXPERT OPINION

Combination treatment offers better results than monotherapy to improve pathological changes in diabetic ED. Regenerative medicine is a promising approach for the maintenance of sexual health and erectile function later in life. Cavernous nerve regeneration and vascular recovery employing SC treatment may be focused on radical prostatectomy-induced ED. Notwithstanding, there are a number of hurdles to overcome before SC-based therapies for ED are considered in clinical settings. Paracrine action, not cellular differentiation, appears to be the principal mechanism of action underlying SC treatment of ED. Intracavernosal injection of a single SC type should be the choice protocol for future clinical trials.

Stem cell therapy in erectile dysfunction: science fiction or realistic treatment option?

Stem cell therapy has become a subject of great interest to researchers worldwide. One of the medical conditions being studied for possible treatment with the use of stem cells is erectile dysfunction, and particularly organic and post-radical prostatectomy erectile dysfunction. However, is stem cell therapy a viable treatment option for erectile dysfunction? The current body of literature provides a wide array of clinical trials performed on animal models simulating different types of human erectile dysfunction. Unfortunately, only a handful of studies have been performed on human patients and almost all of them were phase 1 studies limited by the small sample size. This review aims to summarize the available evidence on the use of stem cell therapy for the treatment of erectile dysfunction and also to provide an overview of upcoming and ongoing clinical trials in this field.

Phase I and phase II clinical trials for the treatment of male sexual dysfunction-a systematic review of the literature

INTRODUCTION

The prevalence of sexual dysfunctions has increased over the last decades; despite a number of available treatments for erectile dysfunction (ED), premature ejaculation (PE), and Peyronie's disease (PD), still several unmet therapeutic needs deserve to be fulfilled. The aim of this review is to detail on phase I and II clinical trials investigating novel medical treatments for ED, PE, and PD.

AREAS COVERED

We conducted a systematic review of the literature including both published and ongoing phase I and II registered trials focused on medical treatment of ED, PE, and PD during the last 5 years. A total of 35 trials have been identified. Most studies (63%) investigated ED treatments and 26% were still ongoing. Stem cells (SCs) therapy was assessed in 28% of trials.

EXPERT OPINION

SCs therapy represent a promising treatment for ED although only few patients have been treated to date. Likewise, the oral selective oxytocin receptor antagonists for treating PE showed excellent safety profile and deserve further investigations in phase III trials. Preliminary results of novel topical treatments for PD with fibrinolytic and antiinflammatory drugs are encouraging, but urgently need to be confirmed in large placebo-controlled trials.

The Use of Stromal Vascular Fraction in the Treatment of Male Sexual Dysfunction: A Review of Preclinical and Clinical Studies

INTRODUCTION

Stem cell therapy using stromal vascular fraction (SVF) is a promising treatment modality. SVF is comprised of a mixture of adipose-derived stem cells, endothelial precursor cells, and immune modulatory cells that act synergistically to facilitate angiogenesis and epithelial cell differentiation. This makes SVF an attractive option for men's sexual disorders that require reconstitution of vasculature and endothelial lining, namely erectile dysfunction (ED) and Peyronie's disease (PD).

AIM

The objective of this study was to compare and contrast the available literature regarding the use of SVF in the treatment of male sexual dysfunction.

METHODS

A literature review was performed in PubMed with the keywords "stromal vascular fraction" and/or "erectile dysfunction" and/or "Peyronie's disease" and/or "sexual dysfunction."

MAIN OUTCOME MEASURES

The main outcome measure for preclinical studies was erectile function, as measured by changes in intracavernous pressures, and results of histopathologic analysis of corporal tissue. Clinical endpoint analysis in humans included various patient questionnaires.

RESULTS

For ED, there were 5 preclinical studies included in the analysis, with 1 Phase 1 clinical trial in humans. Major limitations of both the preclinical and clinical studies included the absence of SVF component analysis, and short duration of follow-up. Despite a paucity of preclinical studies, there was a single clinical study assessing the efficacy of combination SVF and shock wave therapy in the treatment of PD. Limitations of this study included an absence of a control group and the use of subjective data.

CONCLUSION

Preclinical and clinical data in the use of SVF for the treatment of male sexual dysfunction is deficient. Even though multiple medicinal disciplines are studying the use of SVF on a myriad of pathologies, further investigative work elucidating the mechanism and potential adverse effects of SVF need to be performed before clinical trials are undertaken. Haney NM, Gabrielson A, Kohn TP, Hellstrom WJG. The Use of Stromal Vascular Fraction in the Treatment of Male Sexual Dysfunction: A Review of Preclinical and Clinical Studies. Sex Med Rev 2019;7:313-320.

2018 Canadian Urological Association guideline for Peyronie's disease and congenital penile curvature

Peyronie’s disease (PD) is a highly prevalent condition that affects the physical and psychosocial well-being and quality of life (QoL) for thousands of Canadian men. The specific etiology of PD remains poorly understood and there remains a paucity of randomized placebo-controlled trials evaluating treatment interventions.1-3 PD can be found in up to 8.9% of men, a remarkable increase in cited prevalence that is attributable to growing awareness (as historical data suggested a rate of less than 1%); the burden of disease is significant, and PD is often present in otherwise healthy men. The following guidelines were crafted by the committee with a full awareness of the limitations of the literature, and sought to provide actionable recommendations to guide PD care in the Canadian health system.

Surgical Techniques for Managing Post-prostatectomy Erectile Dysfunction

Purpose of Review

Due to the increasing numbers of radical prostatectomies (RP) performed for prostate cancer, a substantial number of patients are now suffering from post-operative erectile dysfunction (ED). The aim of this study is to summarize the current literature on surgical techniques for managing post-prostatectomy erectile dysfunction.

Recent Findings

The PubMed database was searched for English-language articles published up to Jan 2017 using the following search terms: “prostatectomy AND erectile dysfunction”, “prostatectomy AND penile prostheses”, and “prostatectomy AND penile implants”. All of the studies that evaluated medical treatment were excluded. In the last few decades, the understanding of the anatomy of the male pelvis and prostate has improved. This has led to significant changes in the nerve-sparing radical prostatectomy techniques, with the aim of preserving post-surgical erectile function (EF). In this scenario, the prostate vascular supply and the anatomy of the neurovascular bundles have a central role. Penile prosthesis implantation is considered the third-line treatment option for RP ED patients, and they have been reported to be a very successful treatment with the highest patient satisfaction rate.

Summary

Considering the failure of penile rehabilitation, and the lack of evidence for accessory pudendal artery (APA) preservation and nerve graft, nerve-sparing surgery and penile prostheses represent, today, the only methods to permanently and definitively preserve or erectile function after RP.