A primer on the restorative therapies for erectile dysfunction: a narrative review

INTRODUCTION

Erectile dysfunction (ED) is a common condition that affects millions worldwide. Patients and urologists alike are seeking alternative therapies that can provide long-lasting results in the treatment of ED. This review provides a comprehensive overview of restorative treatments available for ED, such as platelet-rich plasma, stem cell therapy, and shockwave therapy.

OBJECTIVE

The aim of this narrative review is to provide a primer for urologists and general practitioners on the basics of implementing ED restorative therapies in their practice.

METHODS

The PubMed, MEDLINE, and Google Scholar databases were searched for articles in the English language through August 31, 2023, that included key terms such as "erectile dysfunction," "restorative therapy," "shockwave therapy," "platelet-rich plasma," "stem cell therapy," and "stromal vascular fraction." Reference lists of selected studies were manually reviewed to find articles not identified by the initial database search.

RESULTS

Shockwave therapy has demonstrated effectiveness in treating ED, with devices like the Medispec ED1000 and Storz Duolith showing statistically significant improvements in patient scores for International Index of Erectile Function (IIEF)-Erectile Function scores in clinical trials. In reported studies of platelet-rich plasma injections, a substantial percentage of patients reached a minimal clinically important difference in the IIEF-Erectile Function scale after treatment. Studies of ED treatment with stem cell therapy, while limited and with small sample sizes, have demonstrated encouraging improvements in patient scores for the abridged 5-item version of the IIEF after treatment.

CONCLUSION

Shockwave, platelet-rich plasma, and stem cell therapies are important, novel, noninvasive restorative treatments for ED that can provide relief for patients wishing to avoid a more invasive approach. While these therapies have shown promising results in clinical trials, more research is required to establish them as standardized and efficacious options in the management of ED.

Neurovascular dysfunction associated with erectile dysfunction persists after long-term recovery from simulations of weightlessness and deep space irradiation

There has been growing interest within the space industry for long-duration manned expeditions to the Moon and Mars. During deep space missions, astronauts are exposed to high levels of galactic cosmic radiation (GCR) and microgravity which are associated with increased risk of oxidative stress and endothelial dysfunction. Oxidative stress and endothelial dysfunction are causative factors in the pathogenesis of erectile dysfunction, although the effects of spaceflight on erectile function have been unexplored. Therefore, the purpose of this study was to investigate the effects of simulated spaceflight and long-term recovery on tissues critical for erectile function, the distal internal pudendal artery (dIPA), and the corpus cavernosum (CC). Eighty-six adult male Fisher-344 rats were randomized into six groups and exposed to 4-weeks of hindlimb unloading (HLU) or weight-bearing control, and sham (0Gy), 0.75 Gy, or 1.5 Gy of simulated GCR at the ground-based GCR simulator at the NASA Space Radiation Laboratory. Following a 12-13-month recovery, ex vivo physiological analysis of the dIPA and CC tissue segments revealed differential impacts of HLU and GCR on endothelium-dependent and -independent relaxation that was tissue type specific. GCR impaired non-adrenergic non-cholinergic (NANC) nerve-mediated relaxation in the dIPA and CC, while follow-up experiments of the CC showed restoration of NANC-mediated relaxation of GCR tissues following acute incubation with the antioxidants mito-TEMPO and TEMPOL, as well as inhibitors of xanthine oxidase and arginase. These findings indicate that simulated spaceflight exerts a long-term impairment of neurovascular erectile function, which exposes a new health risk to consider with deep space exploration.

Implantable Penile Prosthesis for Erectile Dysfunction: Insurance Coverage in the United States

INTRODUCTION

A manufacturer's benefit verification database was evaluated to ascertain United States health plan insurance coverage for implantable penile prostheses for erectile dysfunction.

METHODS

All-payer and employer-sponsored health plan benefit verification databases were queried to determine implantable penile prosthesis approval status. For the all-payer analysis, data by payer were available and presented for 2019-2021 to assess approval status varied by payer and over time. For the employer-sponsored health plan analysis, data by payer were available from 2018-2021.

RESULTS

Benefit verification records for the all-payer database were available for 3,167 patients in 2019, 3,016 in 2020, and 2,837 in 2021. Insurance type was preferred provider organization (27.5%), Medicare Advantage (26.9%), Medicare (15.9%), or point-of-service (10.5%). Most patients were approved or verified for implantable penile prosthesis coverage (79.4% in 2019, 79.6% in 2020, and 78.4% in 2021). Coverage was most extensive for government-based insurance (Medicare 98.7%, Medicare Advantage 97.1%, Tricare 100%, and Veterans Affairs 80.0%) but was also favorable for commercial insurance (75.0%). The most common reason for lack of coverage was employer exclusion; the proportion of patients with no coverage due to exclusion increased from 13.5% in 2019 to 17.5% in 2021. Analyses of the employer-sponsored health plan database (n=3,083 patients) showed that 63.1% of patients were approved or verified for coverage and 34.2% did not have coverage due to health plan exclusions.

CONCLUSIONS

Approximately 80% of patients had implantable penile prosthesis coverage. Employer exclusion was the most common reason for lagging coverage; rates of employer exclusion increased 29.3% from 2019-2021.

Complete study for erectile dysfunction (CompED) improving diagnosis and treatment decision-making

Erectile dysfunction is a condition associated with increasing age. Patient evaluation and management should follow a comprehensive, stepwise approach. The aim of this article was to report our experience with the complete study for erectile dysfunction, including intracavernous injection rigidity test, biothesiometry and colour duplex Doppler ultrasound. Data were collected and analysed prospectively. The primary end point was to determine whether treatment decision-making was eased by the CompED test. Secondary end points were to establish which clinical variables prior to the study could impact the results of the CompED test, to finally improve patient selection for the study. 187 patients were recruited, 31.2% of the patients had an axial rigidity below 50%, 28.5% had a peak systolic velocity <25 cm/s, 13.2% had an end-diastolic velocity >5cm/s and 27.5% had an abnormal biothesiometry. The factors that best predicted an abnormal result in any of the tests were age >70 years, IIEF domain A < 14 points, and previous radical prostatectomy or radiotherapy. The CompED test stands as a new alternative for the evaluation of patients with erectile dysfunction, being less time consuming, aiding in a more accurate determination of the aetiology and guiding treatment decision-making.

British Association of Urological Surgeons (BAUS) consensus document for the management of male genital emergencies - penile fracture

Male genital emergencies relating to the penis and scrotum are rare and require prompt investigation and surgical intervention. Clinicians are often unfamiliar with the management of these conditions and may not work in a specialist centre with on-site expertise in genitourethral surgery. The aim of these consensus statements is to provide best practice guidance for urological surgeons based in the UK which are developed by an expert consensus. Penile fracture is a rare emergency and in most cases requires prompt exploration and repair to prevent erectile dysfunction and penile curvature.

Molecular Profile of Priapism Associated with Low Nitric Oxide Bioavailability

Priapism is a disorder in which prolonged penile erection persists uncontrollably, potentially leading to tissue damage. Priapism commonly afflicts patient populations with severely low nitric oxide (NO) bioavailability. Because NO is a primary mediator of erection, the molecular mechanisms involved in priapism pathophysiology associated with low NO bioavailability are not well-understood. The objective of this study was to identify dysregulated molecular targets and signaling pathways in penile tissue of a mouse model of low NO bioavailability that have potential relevance to priapism. Neuronal plus endothelial NO synthase double knockout mice (NOS1/3^-/-) were used as a model of low NO bioavailability. Priapic-like activity was demonstrated in the NOS1/3^-/- mice relative to wild-type (WT) mice by the measurement of prolonged erections following cessation of electrical stimulation of the cavernous nerve. Penile tissue was processed and analyzed by reverse-phase liquid chromatography tandem mass spectrometry. As a result, 1279 total proteins were identified and quantified by spectral counting, 46 of which were down-regulated and 110 of which were up-regulated in NOS1/3^-/- versus WT (P < 0.05). Ingenuity Pathway Analysis of differentially expressed proteins revealed increased protein kinase A and G-protein coupled receptor signaling in NOS1/3^-/- penises, which represent potential mechanisms contributing to priapism for secondary to low NO bioavailability.

The mechanism of opiorphin-induced experimental priapism in rats involves activation of the polyamine synthetic pathway

Intracorporal injection of plasmids encoding opiorphins into retired breeder rats can result in animals developing a priapic-like condition. Microarray analysis demonstrated that following intracorporal gene transfer of plasmids expressing opiorphins the most significantly upregulated gene in corporal tissue was the ornithine decarboxylase gene (ODC). Quantitative RT-PCR confirmed the upregulation of ODC, as well as other genes involved in polyamine synthesis, such as arginase-I and -II, polyamine oxidase, spermidine synthase, spermidine acetyltransferase (SAT), and S-adenosylmethionine decarboxylase. Western blot analysis demonstrated upregulation of arginase-I and -II, ODC, and SAT at the protein level. Levels of the polyamine putrescine were upregulated in animals treated with opiorphin-expressing plasmids compared with controls. A direct role for the upregulation of polyamine synthesis in the development of the priapic-like condition was supported by the observation that the ODC inhibitor 1,3-diaminopropane, when added to the drinking water of animals treated with plasmids expressing opiorphins, prevented experimental priapism. We also demonstrate that in sickle cell mice, another model of priapism, there is increased expression of the mouse opiorphin homologue in corporal tissue compared with the background strain at a life stage prior to evidence of priapism. At a life stage when there is onset of priapism, there is increased expression of the enzymes involved in polyamine synthesis (ODC and arginase-I and -II). Our results suggest that the upregulation of enzymes involved in the polyamine synthetic pathway may play a role in the development of experimental priapism and represent a target for the prevention of priapism.