Sonic Hedgehog Signaling in Primary Culture of Human Corpora Cavernosal Tissue From Prostatectomy,Diabetic, and Peyronie's Patients

BackgroundCavernous nerve (CN) injury causes penile remodeling, including smooth muscle apoptosis and increased collagen, which results in erectile dysfunction (ED), and prevention of this remodeling is critical for novel ED therapy development.AimWe developed 2 peptide amphiphile (PA) hydrogel delivery vehicles for Sonic hedgehog (SHH) protein to the penis and CN, which effectively suppress penile distrophic remodeling (apoptosis and fibrosis), in vivo in a rat CN injury model, and the aim of this study is to determine if SHH PA can be used to regenerate human corpora cavernosal smooth muscle deriving from multiple ED origins.MethodsCorpora cavernosal tissue was obtained from prostatectomy, diabetic, hypertension, cardiovascular disease and Peyronie's (control) patients (n = 21). Primary cultures (n = 21) were established, and corpora cavernosal cells were treated with SHH protein, MSA (control), 5E1 SHH inhibitor, and PBS (control). Growth was quantified by counting the number of cells at 3–4 days. Statistics were performed by ANOVA with Scheffe's post hoc test. Concentration of SHH protein for maximal growth was optimized, and a more active SHH protein examined.OutcomesCultures were characterized by immunohistochemical analysis with ACTA2, CD31, nNOS and P4HB, and smooth muscle was quantified in comparison to DAPI.ResultsCultures established were >97% smooth muscle. SHH protein increased growth of smooth muscle cells from prostatectomy, diabetic, and Peyronie's patients in a similar manner (49%–51%), and SHH inhibition decreased growth (20%–33%). There was no difference in growth using 25 ug and 10 ug SHH protein, suggesting a threshold concentration of SHH protein above which smooth muscle growth is enhanced. A more active lipid modified SHH peptide further enhanced growth (15%), indicating a more robust growth response. SHH increased growth in smooth muscle cells from hypertension (37%) and cardiovascular disease (32%) patients. SHH protein increased growth under normal and high glucose conditions, suggesting that high glucose conditions that may be present in under controlled diabetic patients would not detract from SHH regenerative capacity.Clinical ImplicationsSHH PA would be beneficial to enhance smooth muscle regeneration in patients with ED of multiple etiologies.Strengths and LimitationsUnderstanding how human corpora cavernosal tissue responds to SHH treatment is critical for clinical translation of SHH PA to ED patients.ConclusionCorpora cavernosal smooth muscle from all ED patients responded to SHH treatment with increased growth.Stupp, SI. Sonic Hedgehog Signaling in Primary Culture of Human Corpora Cavernosal Tissue From Prostatectomy, Diabetic, and Peyronie's Patients. J Sex Med 2022;19:1228–1242.     

Inhibition of Cyclic GMP Export by Multidrug Resistance Protein 4: A New Strategy to Treat Erectile Dysfunction?

BackgroundIntracellular cyclic guanosine monophosphate (cGMP) concentrations are regulated by degradation enzymes (phosphodiesterases) and by active transport across the plasma membrane by multidrug resistance proteins (MRPs) 4 and 5.AimTo evaluate the functional effect of MRP-4 inhibition and the role of MRP-4–mediated cGMP export in mouse corpora cavernosa.MethodsIsometric tension of mouse corpora cavernosa was measured after cumulative addition of MK-571, an inhibitor of MRP-4, or sildenafil, a phosphodiesterase type 5 inhibitor. In addition, the effect of MRP-4 inhibition on cGMP-independent and cGMP-dependent relaxations was studied. In vivo intracavernosal pressure and mean arterial pressure measurements were performed after intracavernosal injection of MK-571. The effect of MRP-4 inhibition on cGMP content was determined using an enzyme immunoassay kit.OutcomesMeasurement of the effect of MK-571 on cGMP content, relaxant responses of mouse corpora cavernosa to cGMP-independent and cGMP-dependent vasodilating substances, and determination of the ratio of intracavernosal pressure to mean arterial pressure after intracavernosal injection of MK-571.ResultsMK-571 and sildenafil relaxed the corpora cavernosa concentration dependently, with sildenafil being the more potent relaxing compound. Furthermore, MK-571 enhanced relaxing responses to cGMP-dependent substances, such as sodium nitroprusside, sildenafil, acetylcholine, and electrical field stimulation, with the latter even under in vitro diabetic conditions. In contrast, cGMP-independent relaxations were not altered by MRP-4 inhibition. Intracavernosal administration of MK-571 significantly increased intracavernosal pressure, with minimal effect on mean arterial pressure. The cGMP analysis showed that MRP-4 inhibition was accompanied by increased cGMP levels.Clinical TranslationMRP-4, at least when targeted locally in the penis or when combined with a phosphodiesterase type 5 inhibitor, might be a valuable alternative strategy for the treatment of (diabetic) erectile dysfunction.Strengths and LimitationsThis study is the first to demonstrate an in vitro direct relaxant and an in vivo pro-erectile effect of the MRP-4 inhibitor, MK-571, on mouse corpora cavernosa. However, the functional effect of MRP-5–mediated export in mouse corpora cavernosa was not explored, which has been suggested to play the predominant role in cGMP export.ConclusionInhibition of MRP-4 increases basal and stimulated levels of cGMP, leading to corpora cavernosa relaxation and penile erection. Therefore, in addition to degradation of cGMP, export of cGMP by MRP-4 could contribute substantially to regulating cGMP levels in mouse corpora cavernosa.Boydens C, Pauwels B, Vanden Daele L, Van de Voorde J. Inhibition of Cyclic GMP Export by Multidrug Resistance Protein 4: A New Strategy to Treat Erectile Dysfunction? J Sex Med 2017;14:502–509.     

Trans-corporal incision of Peyronie's plaques

IntroductionPatients presenting with Peyronie's disease (PD) curvature and erectile dysfunction (ED) can achieve straightening and rigidity through penile prosthesis implantation and manual modeling and, if necessary, a relaxing tunical incision with or without grafting. Unfortunately, this maneuver will not correct PD‐induced shortening. In addition, incision and grafting after the prosthesis has already been implanted adds to operative time and risk, and may indicate mobilization of the neurovascular bundle and, possibly, a secondary skin incision.AimThis work describes trans‐corporal incision (TCI), a minimally invasive endoscopic approach for plaque incision from within the corpora cavernosa, restoring straightness and length to the penis, before calibration of the corpora cavernosa, allowing implantation of a longer prosthesis in a straight penis, with neither mobilizing the neurovascular bundle nor a secondary incision.MethodsSixteen patients with PD deformity and refractory ED were operated upon. Intra‐operative artificial erection demonstrated the deformity. Through a penoscrotal incision, the corpora were dilated. TCI was performed to incise Peyronie's plaques at the point of maximum deformity. Artificial erection was re‐induced and correction of curvature evaluated. Length was measured before and after TCI. Implantation proceeded as usual.Main Outcome MeasuresPenile straightness and length.ResultsFollowing implantation, the penis was straight in all cases. Pre‐TCI length of the corpora was unequal on either side. Post‐TCI, both corpora were of equal length with an average increase of 2.5 cm (11.9%) on the right side and 1.9 (9.1%) on the left.ConclusionTCI; corporoscopic incision of Peyronie's plaques upon implantation of penile prosthesis is a minimally invasive approach that restores both straightness and length to patients with PD and ED, with neither mobilization of the neurovascular bundle nor plaque incision and grafting. Shaeer O. Trans‐corporal incision of Peyronie's Plaques. J Sex Med 2011;8:589–593.     

Low-Intensity Electrostimulation Enhances Neuroregeneration and Improves Erectile Function in a Rat Model of Cavernous Nerve Injury

BackgroundNeurogenic erectile dysfunction (ED) following radical prostatectomy (RP) is a frequent complication often leading to erectile tissue remodeling and permanent ED. Low-intensity electrostimulation (LIES) has been shown to enhance peripheral nerve regeneration, however, its application on cavernous nerves (CN) has never been investigated.AimsTo investigate whether LIES enhances CN regeneration, improves erectile function (EF) recovery, and prevents corpora cavernosal remodeling after CN injury, which is a principal factor for ED following RP.MethodsAdult male Sprague-Dawley rats were divided into Sham, Bilateral Cavernous Nerve Injury (BCNI), and BCNI + LIES (1V, 0.1ms, 12Hz, 1h/day). After 7days, EF was assessed (ICP measurement). Penes and CN were collected for molecular analyses of TGF-$\beta$1, Il-6, CRP, eNOS, ERK and AKT protein levels in corpus cavernosum (CC), and immunohistological analysis of DHE, total collagen and α-SMA in CC and S-100, Tub-III, DAPI, TUNEL, and nNOS in CN.OutcomesEffects of LIES on EF, erectile tissue remodeling and CN structure.ResultsEF was decreased (P < .05) 7 days after BCNI and increased (P < .05) by LIES. Intracavernosal reactive oxygen species (DHE) was increased (P < .05) after BCNI and normalized by LIES. Protein expressions of TGF-β1, IL-6, and CRP were increased in the penis (P < .05) after BCNI and normalized by LIES. The α-SMA and/or total collagen ratio was decreased (P < .05) after BCNI in the penis and normalized by LIES. Protein expression ratio of p-ERK/ERK and p-AKT/AKT did not change after BCNI but increased (P < .05) in LIES group. Myelination and number of nNOS positive cells in the CN were decreased (P < .05) after BCNI and normalized by LIES. The number of apoptotic nerve cells within the dorsal penile nerve was increased (P < .05) after BCNI and decreased (P < .05) by LIES compared to the BCNI group. There were no differences in eNOS expression in the penis between study groups.Clinical TranslationLIES may offer a potential new tool for penile rehabilitation and ED management following RP, potentially enhancing EF recovery and minimizing the side effects of this surgery.Strengths & LimitationsThis study provides evidence of the protective effect of LIES on EF and tissue remodeling following CN injury; nevertheless, this study has been conducted on animals and the translation to humans remains to be demonstrated. Further research to identify the underlying mechanisms of action is required.ConclusionThis study demonstrates that LIES of the CN after CN injury protects CN structure, enhances EF recovery, and prevents corpora cavernosal remodeling.Sturny M, Karakus S, Fraga-Silva R, et al. Low-Intensity Electrostimulation Enhances Neuroregeneration and Improves Erectile Function in a Rat Model of Cavernous Nerve Injury. J Sex Med 2022;19:686–696.     

Peptide Amphiphile Nanofiber Delivery of Sonic Hedgehog Protein to Reduce Smooth Muscle Apoptosis in the Penis after Cavernous Nerve Resection

IntroductionErectile dysfunction (ED) is a serious medical condition that affects 16–82% of prostate cancer patients treated by radical prostatectomy and current treatments are ineffective in 50–60% of prostatectomy patients. The reduced efficacy of treatments makes novel therapeutic approaches to treat ED essential. The secreted protein Sonic hedgehog (SHH) is a critical regulator of penile smooth muscle and apoptosis that is decreased in cavernous nerve (CN) injury and diabetic ED models. Past studies using Affi‐Gel beads have shown SHH protein to be effective in suppressing apoptosis caused by CN injury.AimWe hypothesize that SHH protein delivered via novel peptide amphiphile (PA) nanofibers will be effective in suppressing CN injury‐induced apoptosis.MethodsAdult Sprague Dawley rats (n = 50) were used to optimize PA injection in vivo. PA with SHH protein (n = 16) or bovine serum albumin (BSA) (control, n = 14) was injected into adult rats that underwent bilateral CN cut. Rats were sacrificed at 2, 4, and 7 days. Alexa Fluor‐labeled SHH protein was used to determine the target of SHH signaling (n = 3).Main Outcome MeasuresTerminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and semiquantitative immunohistochemical analysis for SHH protein and cluster differentiation protein three (CD3) were performed.ResultsSHH‐PA caused a 25% and 16% reduction in apoptosis at 4 and 7 days after CN injury and a 9.3% and 19% increase in SHH protein at 4 and 7 days after CN injury. CD3 protein was not observed in SHH‐PA‐treated penis. In vitro, 73% of SHH protein diffused from PA within 6 days. Labeled SHH was observed in smooth muscle.ConclusionsPA technology is effective in delivering SHH protein to the penis and SHH is effective in suppressing CN injury‐induced apoptosis. These results suggest substantial translational potential of this methodology and show that only a short duration of SHH treatment is required to impact the apoptotic index. Bond CW, Angeloni NL, Harrington DA, Stupp SI, McKenna KE, and Podlasek CA. Peptide amphiphile nanofiber delivery of Sonic hedgehog protein to reduce smooth muscle apoptosis in the penis after cavernous nerve resection. J Sex Med 2011;8:78–89.     

Losartan,an Angiotensin Type I Receptor,Restores Erectile Function by Downregulation of Cavernous Renin-Angiotensin System in Streptozocin-Induced Diabetic Rats

IntroductionThe high incidence of erectile dysfunction (ED) in diabetes highlights the need for good treatment strategies. Recent evidence indicates that blockade of the angiotensin type I receptor (AT1) may reverse ED from various diseases.AimTo explore the role of cavernous renin-angiotensin system (RAS) in the pathogenesis of diabetic ED and the role of losartan in the treatment of diabetic ED.MethodsThe AT1 blocker (ARB) losartan (30 mg/kg/d) was administered to rats with streptozocin (65 mg/kg)-induced diabetes. Erectile function, cavernous structure, and tissue gene and protein expression of RAS in the corpora cavernosa were studied.Main Outcome MeasureWe sought to determine the changes of cavernous RAS in the condition of diabetes and after treatment with losartan.ResultsRAS components (angiotensinogen, [pro]renin receptor, angiotensin-converting enzyme [ACE], and AT1) were expressed in cavernosal tissue. In diabetic rats, RAS components were upregulated, resulting in the increased concentration of angiotensin II (Ang II) in the corpora. A positive feedback loop for Ang II formation in cavernosum was also identified, which could contribute to overactivity of cavernous RAS in diabetic rats. Administration of losartan blocked the effect of Ang II, downregulated the expression of AT1 and Ang II generated locally, and partially restored erectile function (losartan-treated group revealed an improved intracavernous pressure/mean systemic arterial pressure ratio as compared with the diabetic group (0.480 ± 0.031 vs. 0.329 ± 0.020, P < 0.01). However, losartan could not elevate the reduced smooth muscle/collagen ratio in diabetic rats.ConclusionsThe cavernous RAS plays a role in modulating erectile function in corpora cavernosa and is involved in the pathogenesis of diabetic ED. ARB can restore diabetic ED through downregulating cavernous RAS. Yang R, Yang B, Wen Y, Fand F, Cui S, Lin G, Sun Z, Wang R, and Dai Y. Losartan, an angiotensin type I receptor blocker, restores erectile function by down-regulation of cavernous renin-angiotensin system in streptozocin-induced diabetic rats. J Sex Med 2009;6:696–707.     

Tumor Necrosis Factor‐Related Apoptosis‐Inducing Ligand (TRAIL) and Its Death Receptor (DR5) in Peyronie's Disease. A Biomolecular Study of Apoptosis Activation

IntroductionPeyronie's disease (PD) is a connective tissue disorder of tunica albuginea (TA), a thick fibrous sheath surrounding the corpora cavernosa of the penis. Relatively, little is known about the disease itself.AimTo investigate whether the apoptosis cascade in degenerated and macroscopically deformed TA from men with PD is activated through the extrinsic pathway, by assessing the immunoexpression of tumor necrosis factor‐related apoptosis‐inducing ligand (TRAIL) and its death receptor, DR5.MethodsTA plaques from 15 men with PD and from four unaffected men were processed for TRAIL and DR5 immunohistochemistry and Western blot analysis.Main Outcome MeasuresA greater understanding of the pathophysiology of PD through a molecular approach, to gain insights that may lead to novel forms of treatment.ResultsActivation of the apoptosis mechanisms through the extrinsic pathway was demonstrated by TRAIL and DR5 overexpression in fibroblasts and myofibroblasts from affected TA.ConclusionThe finding that apoptosis activation in TA plaques occurs, at least in part, via the extrinsic pathway may help devise novel therapeutic options for these patients. Loreto C, Barbagli G, Djinovic R, Vespasiani G, Carnazza ML, Miano R, Musumeci G, Sansalone S. Tumor necrosis factor‐related apoptosis‐inducing ligand (TRAIL) and its death receptor (DR5) in Peyronie's disease. A biomolecular study of apoptosis activation. J Sex Med 2011;8:109–115.     

Effects of icariin on improving erectile function in streptozotocin-induced diabetic rats

IntroductionIcariin has been shown to improve penile hemodynamics in animal models of erectile dysfunction from cavernous nerve injury and castration. The effects of icariin on penile hemodynamics in diabetic animals remain to be determined. Transforming growth factor β1 (TGFβ1) has been implicated in the pathogenesis of diabetes‐related erectile dysfunction.AimThe aim of this study was to investigate the effects of icariin in the penis of streptozotocin (STZ)‐induced diabetic rat.MethodsTwo‐month‐old Sprague–Dawley male rats received one‐time intraperitoneal (IP) STZ (60 mg/kg) or vehicle injection after a 16‐hour fast. Three days later, the STZ‐induced diabetic rats were randomly divided into four groups and were treated with daily gavage feedings of a 50:50 mix of normal saline and dimethyl sulfoxide (DMSO) or icariin dissolved in DMSO at doses of 1, 5, and 10 mg/kg for 3 months. A positive control group underwent IP injection of saline followed by daily gavage of saline/DMSO solution. Treatment was stopped 1 week prior to functional assay and euthanasia.Main Outcome MeasurePenile hemodynamics was assessed by electrical stimulation of the cavernous nerves with real‐time intracavernous pressure (ICP) measurement. After euthanasia, penile tissue was studied using immunohistochemistry, Western blot, and enzyme‐linked immunosorbent assay (ELISA) to assess the nitric oxide‐cyclic guanosine monophosphate (NO‐cGMP) and TGFβ1/Smad2 signaling pathway.ResultsDiabetes attenuated ICP response in control animals. Untreated diabetic animals had decreased smooth muscle/collagen ratio and endothelial cell content in the corpora cavernosa; treatment with icariin partially attenuating these effects. Icariin‐treated animals also had a significantly greater expression of nicotinamide adenine dinucleotide phosphate‐positive nerves and the endothelial cell markers, von Willebrand factor (vWF), and platelet endothelial cell adhesion molecule‐1 (PECAM). TGFβ1/Smad2 signaling pathway was down‐regulated in the penis from icariin‐treated models relative to what was observed in negative control animals.ConclusionIcariin treatment preserved penile hemodynamics, smooth muscle and endothelial integrity, and neuronal nitric oxide synthase expression in the penis of diabetic rats. Down‐regulation of TGFβ1/Smad2 signaling pathway might mediate this effect. Liu T, Xin H, Li W‐R, Zhou F, Li G‐Y, Gong Y‐Q, Gao Z‐Z, Qin X‐C, Cui W‐S, Shindel AW, and Xin Z‐C. Effects of icariin on improving erectile function in streptozotocin‐induced diabetic rats. J Sex Med 2011;8:2761–2772.     

Platelet‐Derived Growth Factor Regulation of Type‐5 Phosphodiesterase in Human and Rat Penile Smooth Muscle Cells

IntroductionRelaxation of cavernous smooth muscle cells (SMCs) is a key component in the control of the erectile mechanism. SMCs can switch their phenotype from a contractile differentiated state to a proliferative and dedifferentiated state in response to a change of local environmental stimuli. Proliferation and contraction are both regulated by the intracellular second messengers cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP), which are degraded by phosphodiesterases (PDEs). The most abundant PDE present in corpora cavernosa is the electrolytic cGMP‐specific phosphodiesterase type 5 (PDE5).AimWe investigated the cellular localization of PDE5 in in vitro cultured corpora cavernosa cells and the effect of mitogenic stimulation on PDE5 expression.MethodsBiochemical ad molecular techniques on cultured SMCs from human and rat penis.Main Outcome MeasuresWe studied the ability of the quiescent SMC phenotype vs. the proliferating phenotype in modulation of PDE5 expression.ResultsWe demonstrated that PDE5 is localized in the cytoplasm, in the perinuclear area, and in discrete cytoplasmic foci. As previously demonstrated in human myometrial cells, the cytoplasmic foci may correspond to centrosomes. In corpora cavernosa, PDE5 protein levels are strongly regulated by the mitotic activity of the SMCs, as they were increased in quiescent cultures. In contrast, treatment with platelet‐derived grow factor (PDGF), one of the most powerful mitogenic factors for SMCs, reduces the expression of PDE5 after 24 hours of treatment.ConclusionWe found that PDGF treatment downregulates PDE5 expression in proliferating SMCs, suggesting that PDE5 may represent one of the markers of the contractile phenotype of the SMCs of corpora cavernosa. Carosa E, Castri A, Forcella C, Sebastiani G, Di Sante S, Gravina GL, Ronchi P, Cesarini V, Dolci S, Di Stasi S, Lenzi A, and Jannini EA. Platelet‐derived growth factor regulation of type‐5 phosphodiesterase in human and rat penile smooth muscle cells. J Sex Med 2014;11:1675–1684.     

Radiation-induced erectile dysfunction using prostate-confined modern radiotherapy in a rat model

IntroductionThe mechanisms of radiation‐induced erectile dysfunction (ED) are unclear, as clinical studies are limited, and previous animal models were based on wide‐field irradiation, which does not model current radiotherapy (RT) techniques.AimsTo perform functional and morphological analyses of erectile function (EF) utilizing image‐guided stereotactic prostate‐confined RT in a rat model.MethodsSixty young adult male rats aged 10–12 weeks old were divided into age‐matched sham and RT groups. A single 20‐Gy fraction to the prostate was delivered to RT animals. Penile bulb, shaft, and testes were excluded from treatment fields.Main Outcome MeasuresBioassay and intracavernous pressure (ICP) measurements were conducted at 2, 4, and 9 weeks following RT. Perfusion analysis of the corpora cavernosa (CC) was conducted using Hoechst injected prior to sacrifice. Penile shaft and cavernous nerve (CN) were evaluated by immunohistochemistry. Plasma testosterone level was analyzed using a testosterone enzyme‐linked immunosorbent assay (ELISA) assay kit.ResultsIrradiated animals demonstrated statistically significant time‐dependent functional impairment of EF by bioassay and ICP measurement from 4 weeks. Neuronal nitric oxide synthase (NOS) expression was decreased in CN by 4 weeks. In CC, expression levels of anti‐alpha smooth muscle actin and endothelial NOS were significantly decreased at 9 weeks. In penile dorsal vessels, smooth muscle/collagen ratio was significantly decreased at 4 and 9 weeks. Additionally, Hoechst perfusion showed time‐dependent decrease in CC of RT animals, whereas CD31 expression was not affected. No toxicities were noted; testosterone levels were similar in both groups.ConclusionWe demonstrated time‐dependent ED following image‐guided stereotactic RT. Our results imply that reduction of neuronal NOS expression in cavernous nerve could trigger consecutive reduction of smooth muscle content as well as blood perfusion in CC that resulted in corporal veno‐occlusive dysfunction. Present study could be a cornerstone to future research that may bring comprehensive scientific understanding of radiation‐induced ED. Kimura M, Yan H, Rabbani Z, Satoh T, Baba S, Yin F‐F, Polascik TJ, Donatucci CF, Vujaskovic Z, and Koontz BF. Radiation‐induced erectile dysfunction using prostate‐confined modern radiotherapy in a rat model. J Sex Med 2011;8:2215–2226.     

Changes in the Penile Arteries of the Rat after Fractionated Irradiation of the Prostate: A Pilot Study

IntroductionExternal beam radiotherapy for prostate cancer leads to erectile dysfunction in 36%–43% of patients. The underlying mechanism is largely unknown, although some clinical studies suggest that the arterial supply to the corpora cavernosa is responsible. Two animal experimental studies reported on the effects of a single fraction of prostate irradiation on the penile structures. However, irradiation in multiple fractions is more representative of the actual clinical treatment.AimThe present prospective, controlled study was initiated to investigate the effect of fractionated prostate irradiation on the arteries of the corpora cavernosa.Main Outcome MeasuresHistological evaluation of the penile tissue in comparison with control rats at 2, 4, and 9 weeks after irradiation.MethodsThe prostate of twelve rats was treated with external beam radiation in 5 daily fractions of 7.4 gray. Three control rats were treated with sham irradiation. Prostatic and penile tissue was evaluated for general histology (hematoxylin–eosin). The penile tissue was further evaluated after combined staining for collagen (resorcin fuchsin) and α-smooth muscle actin (SMA) (Biogenex).ResultsThe prostate showed adequate irradiation with fibrosis occurring at 9 weeks after irradiation. The corpora cavernosa showed arteries that had developed loss of smooth muscle cells expressing SMA, thickening of the intima, and occlusions. All the control rats maintained normal anatomy.ConclusionThis is the first animal experimental study that demonstrates changes in the arteries of the corpora cavernosa after fractionated irradiation to the prostatic area. The preliminary data suggests that erectile dysfunction after radiotherapy might be caused by radiation damage to the arterial supply of the corpora cavernosa. van der Wielen GJ, Vermeij M, de Jong BWD, Schuit M, Marijnissen J, Kok DJ, van Weerden WM, and Incrocci L. Changes in the penile arteries of the rat after fractionated irradiation of the prostate: A pilot study. J Sex Med 2009;6:1908–1913.     

Sonic Hedgehog Is Neuroprotective in the Cavernous Nerve with Crush Injury

IntroductionThe cavernous nerve (CN) is commonly injured during prostatectomy, resulting in erectile dysfunction (ED). Although peripheral nerves have a limited ability to regenerate, a return of function typically does not occur due to irreversible down stream morphological changes in the penis that result from CN injury. We have shown in previous studies that sonic hedgehog (SHH) is critical for CN regeneration and improves erectile function after crush injury.AimsExamine a new direction, to determine if SHH is neuroprotective to the pelvic ganglia (PG)/CN after crush injury. A secondary focus is to examine if SHH signaling decreases with age in the PG/CN.MethodsSprague–Dawley rats underwent bilateral CN crush and SHH and glial fibrillary acidic protein were quantified by western analysis of the PG/CN (N = 6 rats at each time point) at 1, 2, 4, 7, and 14 days, and the apoptotic index was measured in the penis. SHH was quantified by western in the PG/CN with blockade of anterograde transport (N = 4 rats) in comparison to mouse IgG (N = 4 rats). If SHH is neuroprotective was examined at 4 (N = 14 rats) and 7 days (N = 16 rats) of treatment after CN crush. SHH protein was quantified in aging (P200‐300, N = 5 rats) PG/CN in comparison to normal adult (P115‐120, N = 3 rats) PG/CN.Main Outcome MeasuresSHH pathway was examined in PG via immunohistochemistry, in situ, western, and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL).ResultsSHH is neuroprotective in the PG/CN with injury. SHH localization in the PG/CN suggests SHH interaction in neuronal/glial signaling. SHH protein is significantly decreased in the PG/CN after crush injury and in the aged PG/CN. Signals from the PG are required to maintain SHH in the CN.ConclusionsThere is a window of opportunity immediately after nerve insult in which manipulation of SHH signaling in the nerve microenvironment can affect long‐term regeneration outcome.     

Role of Nanotechnology in Erectile Dysfunction Treatment

IntroductionThe biological importance of nanotechnology-based delivery vehicles for in vivo tissue regeneration is gaining acceptance by the medical community; however, its relevance and incorporation into the treatment of sexual dysfunction are evolving and have not been well evaluated.AimTo provide scientific evidence examining the use of state-of-the-art nanotechnology-based delivery methodology in the treatment of erectile dysfunction (ED) in animal models and in patients.MethodsThis review assessed the current basic science literature examining the role of nanotechnology-based delivery vehicles in the development of potential ED therapies.ResultsThere are four primary areas where nanotechnology has been applied for ED treatment: (i) topical delivery of drugs for on-demand erectile function, (ii) injectable gels into the penis to prevent morphologic changes after prostatectomy, (iii) hydrogels to promote cavernous nerve regeneration or neuroprotection, and (iv) encapsulation of drugs to increase erectile function (primarily of phosphodiesterase type 5 inhibitors).ConclusionBasic science studies provide evidence for a significant and evolving role for nanotechnology in the development of therapies for ED and suggest that properly administered nano-based therapies might be advantageous for treating male sexual dysfunction.     

NOX1/4 Inhibitor GKT-137831 Improves Erectile Function in Diabetic Rats by ROS Reduction and Endothelial Nitric Oxide Synthase Reconstitution

BackgroundPrevious studies have shown that oxidative stress contributes to hyperglycemia-induced erectile dysfunction. A preferential direct inhibitor of NOX1 and NOX4, GKT-137831, exhibited a strong anti‑oxidative role via blockade of reactive oxygen species (ROS) generation in endothelial cells, but whether GKT-137831 could improve erectile function was not clear.AimOur study was designed to investigate the effect of NOX1/4 inhibition on improving diabetic erectile dysfunction (ED) in rats.MethodsWe used streptozotocin to induce type 1 diabetes mellitus (DM) in 32 male Sprague Dawley (SD) rats (8 weeks old). Eight weeks later, type 1 diabetes mellitus-induced erectile dysfunction (DMED) in rats was confirmed using an apomorphine test. Our study consisted of 3 groups: (i) nondiabetic control group (n = 8), (ii) DMED + vehicle group (DMED group; n = 8), and (iii) DMED + GKT-137831 group (n = 9); GKT-137831 was given as a once-daily intraperitoneal injection for 4 weeks. Cavernous nerve electrostimulation was used to evaluate erectile function. Western blot, ELISA, immunohistochemistry, and immunofluorescence were used to measure expression of specific proteins, and DHE fluorescent probe was performed to detect ROS level.OutcomesIntracavernous pressure (ICP), nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) signaling pathway, oxidative stress level, inflammatory response, corporal autophagy, and apoptosis were measured.ResultsErectile function in the DMED group was significantly impaired compared to the nondiabetic control group, whereas this impairment was improved with GKT-137831 treatment by 70%. Similarly, endothelial function and overactivated oxidative stress in the corpus cavernosum (CC) of the DMED + GKT-137831 group were improved. The DMED group showed serious inflammatory responses and excessive autophagy, which were inhibited by GKT-137831 treatment in the DMED + GKT-137831 group.Clinical TranslationOur study showed improvement in erectile function with GKT-137831 in a diabetic rat ED model.Strength and LimitationsThis study suggested for the first time that GKT-137831, an NOX1/4 inhibitor undergoing clinical trials, is effective in improving erectile function in rats with type 1 DMED. However, we only investigated GKT-137831 treatment of streptozotocin-induced type 1 diabetic rats, and therapeutic evidence in other types of diabetes is lacking.ConclusionGKT-137831 improves erectile function by 70% in type 1 DMED rats and constitutes a promising compound for the treatment of type 1 DMED, likely by inhibition of overactivated oxidative stress, down-regulation of proinflammatory factors, and amelioration of excessive autophagy and endothelial function.B Zhou, Y Chen, H Yuan, et al. NOX1/4 Inhibitor GKT-137831 Improves Erectile Function in Diabetic Rats by ROS Reduction and Endothelial Nitric Oxide Synthase Reconstitution. J Sex Med 2021;18:1970–1983.     

Exosome Released From Schwann Cells May Be Involved in Microenergy Acoustic Pulse–Associated Cavernous Nerve Regeneration

BackgroundNeurogenic erectile dysfunction (ED) is often refractory to treatment because of insufficient functional nerve recovery after injury or insult. Noninvasive mechano-biological intervention, such as microenergy acoustic pulse (MAP), low-intensity pulsed ultrasound, and low-intensity extracorporeal shockwave treatment, is an optimal approach to stimulate nerve regeneration.AimTo establish a new model in vitro to simulate nerve injury in neurogenic ED and to explore the mechanisms of MAP in vitro.MethodsSprague-Dawley rats were used to isolate Schwann cells (SCs), major pelvic ganglion (MPG), and cavernous nerve with MPG (CN/MPG). SCs were then treated with MAP (0.033 mJ/mm², 1 Hz, 100 pulses), and SC exosomes were isolated. The MPG and CN/MPG were treated with MAP (0.033 mJ/mm², 1 Hz) at different dosages (25, 50, 100, 200, or 300 pulses) or exosomes derived from MAP-treated SCs in vitro.OutcomesNeurite growth from the MPG fragments and CN was photographed and measured. Expression of neurotropic factors (brain-derived neurotrophic factor, nerve growth factor, and neurotrophin-3) was checked.ResultsNeurite outgrowth from MPG and CN/MPG was enhanced by MAP in a dosage response manner, peaking at 100 pulses. MAP promoted SC proliferation, neurotropic factor (brain-derived neurotrophic factor, nerve growth factor, and neurotrophin-3) expression, and exosome secretion. SC-derived exosomes significantly enhanced neurite outgrowth from MPG in vitro.Clinical ImplicationsMAP may have utility in the treatment of neurogenic ED by SC-derived exosomes.Strength & LimitationsWe confirmed that MAP enhances penile nerve regeneration through exsomes. Limitations of this study include that our study did not explore the exact mechanisms of how MAP increases SC exosome secretion nor whether MAP modulates the content of exosomes.ConclusionThis study revealed that neurite outgrowth from MPG was enhanced by MAP and by SC-derived exosomes which were isolated after MAP treatment. Our findings indicate that one mechanism by which MAP induces nerve regeneration is by stimulation of SCs to secrete exosomes.Peng D, Reed-Maldonado AB, Zhou F, et al. Exosome Released From Schwann Cells May Be Involved in Microenergy Acoustic Pulse–Associated Cavernous Nerve Regeneration. J Sex Med 2020;17:1618–1628.     

Removal of a Detached Head of the Brooks Dilator from the Corpora Cavernosa During Penile Prosthesis Implantation

IntroductionSeveral complications during and after penile implantation have been reported. The most difficult part of the procedure seems to be the dilatation of the corpora, especially in fibrotic cases.AimTo report a rare intraoperative complication during dilatation of the corpora and its management.MethodsDuring dilation of the corpora cavernosa with Brooks dilators for the implantation of penile prosthesis, its head was detached and stuck at the tip of the corpus cavernosum. Several trials to remove the head of the dilator using different kinds of clamps were unsuccessful. Finally, an incision was performed to the distal lateral part of the corpora cavernosa and the head of the dilator was removed. Implantation was completed uneventfully.ResultsThe patient instructed to inflate the prosthesis and use it for sexual intercourse after 6 weeks. Follow-up was 14 months and the patient is using properly the prosthesis.ConclusionsAlthough this is a very rare complication not previously described, we recommend examination of the dilators before use. Hatzimouratidis K, Koliakos N, Koutsogiannis I, Moisidis K, Giakoumelos A, and Hatzichristou D. Removal of a detached head of the Brooks dilator from the corpora cavernosa during penile prosthesis implantation.     

Intracavernous transplantation of bone marrow-derived mesenchymal stem cells restores erectile function of streptozocin-induced diabetic rats

IntroductionErectile dysfunction (ED) is a frequent complication of diabetes mellitus. The efficacy of common ED therapies is low for diabetes‐associated ED.AimTo explore the effects of transplantation of bone marrow‐derived mesenchymal stem cells (BM‐MSCs) on improving erectile function of streptozocin (STZ)‐induced diabetic rats.MethodsMale Sprague Dawley rats were injected either with STZ to induce diabetes or with citrate buffer as controls. Rat BM‐MSCs were harvested and labeled with CM‐DiI (Chloromethylbenzamido derivatives of 1,1′‐dioctadecyl‐3,3,3′,3′‐tetramethylindocarbocyanine perchlorate), and then transplanted into corporal cavernosum of STZ‐induced diabetic rats. Four weeks after transplantation, all rats were analyzed for erectile function and penile histology.Main Outcome MeasuresErectile function was evaluated by the ratio between intracavernous pressure (ICP) and mean arterial pressure (MAP) during electrostimulation of cavernous nerve. Fate of transplanted BM‐MSCs was identified using immunofluorescence staining. Smooth muscle and endothelium in corpora cavernosum were assessed using immunohistochemistry.ResultsAfter BM‐MSCs transplantation, the ICP/MAP ratio was increased significantly compared with diabetic controls. Content of smooth muscle and endothelium in corporal cavernosa of BM‐MSCs transplanted rats was significantly increased compared to diabetic controls. Immunofluorescence analysis demonstrated that CM‐DiI‐labeled BM‐MSCs could stay in corporal cavernosa for at least 4 weeks and some of them expressed von Willebrand Factor, CD31, calponin, or α‐smooth muscle actin, cells markers for endothelial cells or smooth muscle cells, respectively.ConclusionIntracavernous transplantation of BM‐MSCs had beneficial effects on erectile function of diabetic rats and increased the content of endothelium and smooth muscle in corporal cavernosum. Qiu X, Lin H, Wang Y, Yu W, Chen Y, Wang R, and Dai Y. Intracavernous transplantation of bone marrow‐derived mesenchymal stem cells restores erectile function of streptozocin‐induced diabetic rats.