Preoperative Erectile Function Is an Independent Predictor for Decision to Spare Cavernous Nerves During Radical Prostatectomy

IntroductionCavernous nerve sparing (NS) is critical for recovery of erectile function (EF) as well as erectile tissue preservation following radical prostatectomy (RP). Clinical experience suggests that surgeons may opt for non‐NS RP in patients with impaired baseline EF.AimThis study was performed to define if baseline EF is an independent predictor of NS status during RP.MethodsA total of 2,323 mean (mean age 59 ± 7 years) who underwent RP at a tertiary referral academic medical center were retrospectively evaluated. Patients who underwent preoperative radiation therapy or androgen deprivation treatment were excluded.Main Outcome MeasuresPreoperative parameters evaluated included biopsy pathological characteristics, prostate‐specific antigen (PSA) level, patient age, and EF. Baseline EF was graded on a validated five‐point patient reported scale. NSS was graded intraoperatively by the surgeon, using a four‐point NS score assigned to each nerve where 1 = fully preserved, 2 = partially preserved, 3 = minimally preserved, and 4 = resected. NS surgery was defined as NSS of 1 or 2 on both sides, and nerve resection surgery was defined as NSS of 3 or greater on both sides.ResultsOn univariate analysis, factors related to nerve resection surgery included (all P < 0.01): increasing age (r = 0.16), Gleason score (r = 0.19), EF score (r = 0.21), percentage biopsy cores positive (r = 0.11), higher preoperative PSA (relative risk [RR] 1.72, 95% confidence interval [CI] 1.23–2.40), and clinical stage ≥T2 (RR 2.17, 95% CI 1.68–2.78). On multivariable analysis, factors independently predicting for non‐NS surgery included (all P < 0.01): baseline EF (odds ratio [OR] 1.50, 95% CI 1.33–1.68), biopsy Gleason sum (OR 1.95, 95% CI 1.65–2.36), clinical T stage ≥T2 (OR 1.59, 95% CI 1.15–2.20), patient age (OR 1.07, 95% CI 1.04–1.09), and percentage of biopsy cores positive (OR 1.01, 95% CI 1.00–1.02).ConclusionsWhile unfavorable clinical and prostate biopsy characteristics predict less NS, we have shown that poorer baseline EF also independently predicts for nerve resection RP. For every point increase in EF score (that is, worsening EF) the odds of not receiving NS during surgery increase by a factor of 1.5. Although NS is not associated with worse cancer outcomes in appropriately selected patients, failure to spare nerves is associated with poor post‐operative EF, urinary continence, and increased severity of cavernous venous leak. Patient anxiety related to cancer diagnosis and impending treatment may lead to falsely‐worsened apparent EF when recent erections are assessed during a pre‐operative planning visit. For these reasons prostatectomists should consider NS based solely on factors other than patient's baseline EF, even when it is impaired. Stember DS, Nelson CJ, and Mulhall JP. Preoperative erectile function is an independent predictor for decision to spare cavernous nerves during radical prostatectomy. J Sex Med 2013;10:2101-2107.     

CXCL5 Cytokine Is a Major Factor in Platelet-Rich Plasma's Preservation of Erectile Function in Rats After Bilateral Cavernous Nerve Injury

BackgroundThe neuro-protective and tissue-protective properties of platelet-rich plasma (PRP) have been demonstrated through treating bilateral cavernous nerve (CN) injury in rats, although the underlying mechanisms have not been fully clarified.AimTo determine factors released from PRP and explore their role in mediating preservation of erectile function (EF) in a rat model of CN injury.MethodsMale Sprague-Dawley rats (aged 10 weeks) were used in this study. 6 rats were used to obtain blood for PRP and whole plasma preparation. We probed samples using a cytokine antibody array and performed enzyme-linked immunosorbent assay (ELISA). We determined the expression patterns of C-X-C motif chemokine ligand 5 (CXCL5) and receptors in the major pelvic ganglion (MPG) and corpus cavernosum via immunostaining. 32 rats were divided into 4 groups based on the type of injection received: (i) sham, (ii) vehicle, (iii) 400 μL of PRP, and (iv) 30 ng/kg of CXCL5. Groups 2–4 were subjected to bilateral CN crush (BCNC) injury. 4 weeks later, EF was assessed by CN electrostimulation, and CNs and penile tissue were collected for histological analysis.OutcomeCytokine antibody array, ELISA, erectile response, and immunofluorescence staining readings.ResultsThe PRP contained high levels of CXCL5. MPG neurons expressed CXCL5 and CXCR2. PRP intracavernous injection stabilized CXCR2 and increased CXCL5 expression in the MPG after BCNC, thus enhancing neuroprotection. CXCL5 injection improved BCNC-induced erectile dysfunction by preventing smooth muscle atrophy.Clinical ImplicationsThe therapeutic efficacy of PRP in CN injury–induced erectile dysfunction may arise from the synergy among multiple biomolecules. Our study serves as a basis for future studies on PRP formulation to provide safe and effective medications for the maintenance of EF after radical prostatectomy in patients with prostate cancer.Strengths & LimitationsA strength of our study is that our model was able to isolate the role of cytokines, specifically CXCL5, as part of the mechanism responsible for PRP's protective properties. However, the rat cytokine array provided limited experimental targets. The rats used were not at the age corresponding to prostate cancer patients in clinical settings. Our study did not explore CXCL5 blocking in the PRP group. Finally, the main protein quantification results by western blotting were hampered because of small tissue samples.ConclusionsThis study provides evidence for the role of CXCL5 and CXCR2 as mediators of PRP effects in the preservation of EF after CN injury.Wu YN, Liao CH, Chen KC, et al. CXCL5 Cytokine Is a Major Factor in Platelet-Rich Plasma's Preservation of Erectile Function in Rats After Bilateral Cavernous Nerve Injury. J Sex Med 2021;18:698–710.     

COX-2-10aa-PGIS Gene Therapy Improves Erectile Function in Rats after Cavernous Nerve Injury

IntroductionErectile dysfunction (ED) is a very common complication after radical prostatectomy. COX-2-10aa-PGIS is a newly engineered protein with COX-2 and prostacyclin synthase activities that converts arachidonic acid directly to prostacyclin (prostaglandin I2 [PGI2]). PGI2 is a potent smooth muscle relaxant.AimThe purpose of this study was to explore the effect and mechanism of COX-2-10aa-PGIS gene therapy in penile rehabilitation.MethodsBilateral cavernous nerve crush (BCNC) in adult Sprague-Dawley rats was used to mimic radical prostatectomy-induced ED. Sprague-Dawley rats were randomly assigned into four groups: 1. sham surgery; 2. BCNC; 3. BCNC + null control recombinant adenovirus intracavernous injection; and 4. BCNC + Ad-COX2-10aa-PGIS intracavernous injection. Twenty-eight days later, intracavernosal pressure (ICP) was recorded under cavernous nerve stimulation; in the meantime, the mean arterial pressure (MAP) was monitored. At the end of the measurement, the penis was harvested and processed for (i) immunohistochemistry analysis of endothelial nitric oxide synthase (eNOS), alpha-smooth muscle actin (α-SMA), and transforming growth factor beta-1 (TGF-β1); (ii) Masson's trichrome stain for smooth muscle/collagen ratios; (iii) Western blot of eNOS, α-SMA, TGF-β1, and COX2-10aa-PGIS; and (iv) terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay for apoptosis.Main Outcome MeasuresErectile function was evaluated by ICP/MAP. Smooth muscle and endothelium functions in corpora cavernosum were assessed by Masson's trichrome stain, immunohistochemistry, and Western blot. Apoptosis was identified by TUNEL assay.ResultsThe results were the following: 1. COX2-10aa-PGIS gene therapy improved erectile function (82%, compared with control) in the BCNC rat model; 2. COX2-10aa-PGIS gene therapy increased eNOS (121%) and α-SMA (118%) expression and decreased TGF-β1 (45%) expression; 3. COX2-10aa-PGIS gene therapy reduced cell apoptosis after cavernous nerve injury (64%); and 4. COX2-10aa-PGIS gene therapy improved smooth muscle/collagen ratios (81%).ConclusionOur data demonstrated that COX2-10aa-PGIS improved erectile function after cavernous nerve injury through antifibrotic and anti-apoptotic mechanisms.     

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.     

Intracavernosal Adeno-Associated Virus-Mediated S100A1 Gene Transfer Enhances Erectile Function in Diabetic Rats by Promoting Cavernous Angiogenesis via VEGF-A/VEGFR2 Signaling

IntroductionNovel therapeutic targets for diabetes-induced erectile dysfunction (DED) are urgently needed. Previous studies have proved that S100A1, a small Ca²⁺-binding protein, is a pluripotent regulator of cardiovascular pathophysiology. Its absence is associated with endothelial dysfunction, the central event linking cardiovascular changes in diabetes. However, the role of S100A1 in DED remains unknown.AimTo explore the effect and underlying mechanisms of S100A1 in restoring erectile function in type I diabetic rat model.MethodsDiabetes was induced by intraperitoneal injection of streptozotocin and then screened by apomorphine (APO) to confirm erectile dysfunction. Rats that met the criteria of penile erection were marked as APO-positive; otherwise, the result was APO-negative. In experiment 1, S100A1 gene expression alterations in the corpus cavernosum in moderate and established stages of DED were analyzed. In experiment 2, S100A1 and control GFP gene were delivered into the corpus cavernosum in APO-negative rats by adeno-associated virus (AAV) serotype 9. Erectile function was assessed at 4 weeks after gene therapy.Main Outcome MeasuresErectile response, histologic and molecular alterations.ResultsS100A1 protein was localized to the area surrounding the cavernosal sinusoids in the penis, and it was gradually downregulated synchronized with the progression of DED. Compared with an injection of AAV-GFP, a single injection of AAV-S100A1 significantly restored erectile function in diabetic rats. S100A1 overexpression significantly upregulated the expression of endogenous VEGF-A, promoted VEGFR2 internalization, and subsequently triggered the protein kinase B–endothelial nitric oxide synthase pathway in diabetic erectile tissues. Marked increases in nitric oxide and endothelial content were noted in AAV-S100A1-treated diabetic rats.Clinical ImplicationsLocal S100A1 overexpression may be an alternative therapy for DED and should be further investigated by future clinical studies.Strength & LimitationsThis is the first study demonstrating the angiogenic role of S100A1 in DED, but does not preclude the contribution of the effects of S100A1 in other tissues such as the neuronal tissue on the functional effects observed in erectile responses.ConclusionThe decreased expression of S100A1 during hyperglycemia might be important in the development of erectile dysfunction. S100A1 may play a potential role in restoring erectile function in rats with DED through modulating cavernous angiogenesis.Yu Z, Zhang Y, Tang Z, et al. Intracavernosal Adeno-Associated Virus-Mediated S100A1 Gene Transfer Enhances Erectile Function in Diabetic Rats by Promoting Cavernous Angiogenesis via VEGF-A/VEGFR2 Signaling. J Sex Med 2019;16:1344–1354.     

Scaffoldless Tissue Engineering of Stem Cell Derived Cavernous Tissue for Treatment of Erectile Function

IntroductionAs one-third of erectile dysfunction (ED) patients do not respond to phosphodiesterase-5 inhibitors, there is great demand for new therapeutic options. Adipose tissue-derived stem cells (ADSCs) represent an ideal source for new ED treatment.AimTo test if ADSCs can be differentiated into smooth muscle cells (SMCs) and endothelial cells (ECs), if these differentiated cells can be used to engineer cavernous tissue, and if this engineered tissue will remain for long time after implantation and integrate into corporal tissue.MethodRat ADSCs were isolated and differentiated into SMC and ECs. The differentiated cells were labeled with 5-ethynyl-2-deoxyuridine (EdU) and used to construct cavernous tissue. This engineered tissue was implanted in penises of normal rats. The rats were sacrificed after 1 and 2 months; penis and bone marrow were collected to assess cell survival and inclusion in the penile tissues.Main Outcome MeasuresThe phenotype conversion was checked using morphology, immunocytochemistry (immunohistochemistry [IHC]), and Western blot for SMC and EC markers. The cavernous tissue formation was assessed using rat EC antibody (RECA), calponin, and collagen. The implanted cell survival and incorporation into penis were evaluated with hematoxylin and eosin, Masson's trichrome, and IHC (RECA, calponin, and EdU).ResultsThe phenotype conversion was confirmed with positive staining for SMC and EC markers and Western blot. The formed tissue exhibited architecture comparable to penile cavernous tissue with SMC and ECs and extracellular matrix formation. The implanted cells survived in significant numbers in the penis after 1 and 2 months. They showed proof of SMC and EC differentiation and incorporation into penile tissue.ConclusionsThe results showed the ability of ADSCs to differentiate into SMC and ECs and form cavernous tissue. The implanted tissue can survive and integrate into the penile tissues. The cavernous tissue made of ADSCs forms new technology for improvement of in vivo stem cell survival and ED treatment. Orabi H, Lin G, Ferretti L, Lin C-S, and Lue TF. Scaffoldless tissue engineering of stem cell derived cavernous tissue for treatment of erectile function. J Sex Med 2012;9:1522–1534.     

Amelioration of Cavernosal Fibrosis and Erectile Function by Lysyl Oxidase Inhibition in a Rat Model of Cavernous Nerve Injury

Background

Cavernous nerve injury (CNI) causes fibrosis and loss of smooth muscle cells (SMCs) in the corpus cavernosum and leads to erectile dysfunction, and lysyl oxidase (LOX) activation has been found to play an important role in fibrotic diseases.

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.     

Intravenous Preload of Mesenchymal Stem Cells Rescues Erectile Function in a Rat Model of Cavernous Nerve Injury

IntroductionWe evaluated the potential preventive effects and mechanisms of intravenously preloaded mesenchymal stem cells (MSCs) for erectile dysfunction (ED) in a cavernous nerve (CN) injury model.MethodsMale Sprague–Dawley (SD) rats were used for this study. Rats were randomized into two groups. One group was intravenously preloaded with MSCs (1.0 × 10⁶ cells in 1 mL total fluid volume) and the other was infused with medium alone (1 mL Dulbecco's modified Eagle's medium [DMEM]) for sham control, respectively. Crushed CN injury was induced immediately after infusion. The surgeon was blind to the experimental conditions (MSC or medium).Main Outcome MeasuresTo assess erectile function, we measured the intracavernous pressure (ICP) and arterial pressure (AP) at 1 hour and 2 weeks after CN injury. After measuring the initial ICP/AP of pre‐injury (normal) male SD rats, they were randomized into the two groups and infused with MSCs or medium. PKH26‐labelled MSCs were used for tracking. To investigate the mRNA expression levels of neurotrophins in the major pelvic ganglia (MPG), we performed real‐time quantitative real‐time polymerase chain reaction.ResultsThe reduction of ICP/AP and area under the curve of ICP (ICP‐AUC) in the MSC group was significantly lower than in the DMEM group (P < 0.05; P < 0.05) at 1 hour. The ICP/AP and ICP‐AUC at 2 weeks post‐injury in the MSC group was significantly higher than in the DMEM group (P < 0.01; P < 0.05). The preloaded PKH26‐labelled MSCs were detected in the MPG and CN using confocal microscopy indicating homing of the cells to the injured nerve and ganglia. Glia cell‐derived neurotrophic factor (GDNF) and neurturin, which are important neurotrophic factors for erection, had expression levels in MPG significantly higher in the MSC group than in the DMEM group (P < 0.01, 0.05).ConclusionIntravenous preload of MSCs before a CN injury may prevent or reduce experimental ED. Takayanagi A, Sasaki M, Kataoka‐Sasaki Y, Kobayashi K, Matsuda Y, Oka S, Masumori N, Kocsis JD and Honmou O. Intravenous preload of mesenchymal stem cells rescues erectile function in a rat model of cavernous nerve injury. J Sex Med 2015;12:1713–1721.     

Udenafil Enhances the Recovery of Erectile Function and Ameliorates the Pathophysiological Consequences of Cavernous Nerve Resection

IntroductionRadical prostatectomy is the treatment of choice for prostate cancer patients. Despite the introduction of nerve-sparing surgical techniques, its success is not entirely guaranteed and the majority of patients report compromised erectile function following surgical procedures.AimThis study was performed to investigate the effect of repeated dosing of udenafil, a novel phosphodiesterase type 5 inhibitor, on penile hypoxia and fibrosis induced by bilateral cavernous nerve resection (BCNR) in rats.MethodsThirty male Sprague-Dawley rats (300–320 g) were used in this study. The animals were divided into three groups; group I consisted of sham-operated animals (N = 10), animals in group II underwent BCNR alone (N = 10), and animals in group III were orally treated with 10 mg/kg udenafil b.i.d. for 8 weeks following BCNR (N = 10).Main Outcome MeasuresThe expression of transforming growth factor-β1, hypoxia-inducible factor-1α, endothelial nitric oxide synthase, neuronal nitric oxide synthase, and endothelin B receptor in penile tissue was examined at gene level. Additionally, erectile function, measured by intracavernous pressure (ICP), and pathological changes in the corpus cavernosum were examined.ResultsWhile fibrosis, apoptosis, and the expression of TGF-β1, HIF-1α, and ET_B were significantly increased, and the expression of eNOS and nNOS were significantly decreased in group II, compared with the sham-operated animals, repeated dosing of udenafil significantly ameliorated these changes. Erectile function was profoundly impaired in animals that underwent BCNR alone, and udenafil treatment significantly attenuated this impairment as measured by ICP.ConclusionsThese results demonstrate that long-term administration of udenafil ameliorates penile hypoxia and fibrosis induced by cavernous nerve resection. This study also suggests the potential beneficial role of repeated dosing of udenafil in the recovery of erectile function in patients with neuronal erectile dysfunction. Lee C-H, Shin J-H, Ahn G-J, Kang K-K, Ahn B-O, and Yoo M. Udenafil enhances the recovery of erectile function and ameliorates the pathophysiological consequences of cavernous nerve resection.     

Ginsenoside Rg3 Improves Erectile Function in Streptozotocin‐Induced Diabetic Rats

IntroductionGinsenoside Rg3 is one of the active ingredients isolated from Panax ginseng C.A. Meyer. Previous studies demonstrated that Rg3 has antioxidant and neuroprotective abilities.AimThe purpose of this study was to evaluate the protective effect of Rg3 on erectile function in streptozotocin (STZ)‐induced diabetic rats.MethodsTwo‐month‐old Sprague‐Dawley male rats received a one‐time intraperitoneal (IP) STZ (60 mg/kg) or vehicle injection after a 16‐hour fast. Three days later, rats were randomly divided into four groups and were treated with daily gavage feedings of a mix of distilled saline water and 0.5% carboxymethylcellulose or Rg3 dissolved in the mix at doses of 10 mg/kg and 100 mg/kg for 3 months. A sham group underwent IP injection of saline followed by daily gavage of the above mix for 3 months.Main Outcome MeasureErectile function was assessed by cavernosal nerve electrostimulation at 3 months. The penis was then harvested and deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) was performed. Western blot was performed to examine cleaved caspase‐3, platelet endothelial cell adhesion molecule (PECAM)‐1, and smooth muscle actin (SMA). Neural regeneration was measured by nicotinamide adenine dinucleotide phosphate (NADPH)‐diaphorase staining. Superoxide dismutase (SOD) and malondialdehyde (MDA) levels were detected by colorimetry.ResultsIn the negative control group, the functional evaluation showed a lower mean intracavernosal pressure (ICP) with cavernosal nerve stimulation than in the sham group; there was a significant change in the expression of cleaved caspase‐3, bcl‐2, bcl‐xl, PECAM‐1, and SMA, as well as in the SOD and MDA production in the corpus cavernosum. Histological analysis of specimens stained for NADPH showed a significant change in the staining quality of the neurons in the dorsal nerves; TUNEL showed a greater apoptotic index in corpus cavernosum cells. With daily oral gavage with 100 mg/kg Rg3, the ICP/mean arterial pressure value was significantly higher than in the controls. The level of cleaved caspase‐3, bcl‐2, bcl‐xl, PECAM‐1, and SMA and the number of positively stained nerve fibers tended to revert to normal after Rg3 treatment. The apoptotic index in corpus cavernosum cells was lowered.ConclusionOral gavage with Rg3 appears to both prevent degeneration of neurons in the dorsal nerves and exert an antioxidant effect in the corpus cavernosum of rats. Liu T, Peng Y‐F, Jia C, Yang B‐H, Tao X, Li J, and Fang X. Ginsenoside Rg3 improves erectile function in streptozotocin‐induced diabetic rats. J Sex Med 2015;12:611–620.     

Intracavernous Delivery of Clonal Mesenchymal Stem Cells Restores Erectile Function in a Mouse Model of Cavernous Nerve Injury

IntroductionRecently, much attention has focused on stem cell therapy; bone marrow‐derived stem cells (BMSCs) are one of the most studied mesenchymal stem cells used in the field of erectile dysfunction (ED). However, a major limitation for the clinical application of stem cell therapy is the heterogeneous nature of the isolated cells, which may cause different treatment outcomes.AimWe investigated the effectiveness of mouse clonal BMSCs obtained from a single colony by using subfractionation culturing method (SCM) for erectile function in a mouse model of cavernous nerve injury (CNI).MethodsTwelve‐week‐old C57BL/6J mice were divided into four groups: sham operation group, bilateral CNI group receiving a single intracavernous (IC) injection of phosphate‐buffered saline (20 μL) or clonal BMSCs (3 × 10⁵ cells/20 μL), and receiving a single intraperitoneal (IP) injection of clonal BMSCs (3 × 10⁵ cells/20 μL).Main Outcome MeasuresThe clonal BMSC line was analyzed for cell‐surface epitopes by using fluorescence‐activated cell sorting and for differentiation potential. Two weeks after CNI and treatment, erectile function was measured by electrically stimulating the cavernous nerve. The penis was harvested for histologic examinations and Western blot analysis.ResultsClonal BMSCs expressed cell surface markers for mesenchymal stem cells and were capable of differentiating into several lineages, including adipogenic, osteogenic, and chondrogenic cells. Both IC and IP injections of clonal BMSCs significantly restored cavernous endothelial and smooth muscle content, and penile nNOS and neurofilament content in CNI mice. IC injection of clonal BMSCs induced significant recovery of erectile function, which reached 90–100% of the sham control values, whereas IP injection of clonal BMSCs partially restored erectile function.ConclusionWe established a homogeneous population of mouse clonal BMSCs using SCM; clonal BMSCs successfully restored erectile function in CNI mice. The homogeneous nature of clonal mesenchymal stem cells may allow their clinical applications. Ryu J‐K, Kim D‐H, Song KM, Yi TG, Suh J‐K, and Song SU. Intracavernous delivery of clonal mesenchymal stem cells restores erectile function in a mouse model of cavernous nerve injury. J Sex Med 2014;11:411–423.     

Apocynin Improves Erectile Function in Diabetic Rats through Regulation of NADPH Oxidase Expression

IntroductionDiabetes is a risk factor for erectile dysfunction (ED). The proposed mechanisms responsible for diabetic ED are associated with an increase in reactive oxygen species (ROS) production, overactivity of RhoA/ROCK signaling pathway and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, as seen in experimental models of diabetic rats.AimThe aim of this study was to investigate whether NADPH oxidase inhibitor apocynin can ameliorate Streptozotocin (STZ)‐induced diabetes‐related ED by reducing the ROS production and inhibiting the activity of RhoA/ROCK signaling pathway.MethodsThe diabetic rats were treated with and without the NADPH oxidase inhibitor apocynin.Main Outcome MeasuresErectile responses were evaluated by determining mean arterial blood pressure (MAP) and intracavernosal pressure (ICP) with electrical stimulation of the cavernous nerve. Levels of mRNA expression were measured by real‐time polymerase chain reaction (RT‐PCR). Levels of protein expression were examined by Western Blot. ROS production was measured by dihydroethidium (DHE) staining and thiobarbituric acid reactive substances assay.ResultsThe ratio of Maximum ICP‐to‐MAP (MaxICP/MAP) was significantly decreased in diabetic ED rats, compared to that of age‐matched control rats (P < 0.05). Apocynin improved erectile function of diabetic rats (P < 0.05). Expression levels of RhoA (cytosol), nNOS and eNOS were reduced, compared to those of control rats (P < 0.05). Apocynin significantly elevated their expression levels in diabetic rats (P < 0.05). Expression levels of ROCK1, RhoA (membrane fraction), p‐MYPT1 and NADPH oxidase subunits p47^phox and p67^phox were increased in diabetic rats when compared to those of control rats (P < 0.05), and it was observed that apocynin significantly reduced their expression levels in diabetic rats (P < 0.05). ROS production was increased in diabetic rats when compared to that of control rats (P < 0.05), the effect of apocynin was a reduction in the ROS production in diabetic rats (P < 0.05).ConclusionNADPH oxidase inhibitor apocynin can ameliorate diabetes‐related ED by reducing the ROS production and inhibiting the activity of RhoA/ROCK signaling pathway. Li M, Zhuan L, Wang T, Rao K, Yang J, Yang J, Quan W, Liu J, and Ye Z. Apocynin improves erectile function in diabetic rats through regulation of NADPH oxidase expression. J Sex Med 2012;9:3041–3050.     

Icariin Combined with Breviscapine Improves the Erectile Function of Spontaneously Hypertensive Rats

IntroductionThe impaired erectile response in spontaneously hypertensive rats (SHR) is caused by increased signaling of RhoA/Rho‐kinase and decreased signaling of nitric oxide (NO). Icariin improves erectile function via upregulating multitargets in NO/cyclic guanosine monophosphate (NO/cGMP) pathway, which breviscapine accomplishes by downregulating RhoA/Rho‐kinase pathway.AimTo investigate the effect and mechanism of icariin combined with breviscapine on the erectile function of SHR.MethodsFive 12‐week‐old male Wistar‐Kyoto (WKY) rats and 20 age‐matched male SHR were evenly randomized into WKY rats control group, SHR control group, icariin‐treated group, breviscapine‐treated group, and combined treatment group treated by vehicle, icariin, breviscapine, and icariin plus breviscapine, respectively, by gavage for four successive weeks. Maximum intracavernosal pressure/mean arterial pressure (ICPmax/MAP) and the expression of endothelial nitric oxide synthase (eNOS), neuronal nitric oxide synthase (nNOS), phosphodiesterase type 5 inhibitors (PDE5), and Rho‐associated, coiled‐coil containing protein kinase 1 and 2 (ROCK1 and ROCK2) in the cavernous tissues were determined.ResultsThe ICPmax/MAP in the combined treatment group was significantly increased compared with SHR control group, icariin‐treated group, and breviscapine‐treated group. The expression of eNOS and nNOS was significantly higher in the combined treatment group than in SHR control group, icariin‐treated group, and breviscapine‐treated group (P < 0.05). The expression of PDE5 was significantly lower in the icariin‐treated group than in SHR control group (P < 0.05). The expression of ROCK1 was significantly lower in the combined treatment group than in other groups (P < 0.05). The expression of ROCK2 was significantly higher in SHR control group than in WKY rats control group, icariin‐treated group, and combined treatment group (P < 0.05). Among these groups, the expression of eNOS and nNOS was the strongest, and ROCK1 was the lowest in WKY rats control group.ConclusionIcariin combined with breviscapine has synergistic effects on erectile function of SHR through different signal pathways. Li Y, Jiang J, He Y, Jiang R, Liu J, Fan Z, and Cheng Y. Icariin combined with Breviscapine improves the erectile function of spontaneously hypertensive rats. J Sex Med 2014;11:2143‐2152.     

Predictors of Worsening Erectile Function in Men with Functional Erections Early After Radical Prostatectomy

BackgroundPrior studies suggest that men with good erectile function shortly after radical prostatectomy (RP) can subsequently have worsened erectile function.AimTo determine the prevalence and predictors of early erectile function recovery post-RP and of worsening erectile function after initial erectile function recovery.MethodsWe retrospectively queried our institutional database. Men who underwent RP during 2008–2017 and who completed the International Index of Erectile Function erectile function domain both pre-RP and serially post-RP, constituted the population. Functional erections were defined as International Index of Erectile Function (IIEF)-6 erectile function domain scores ≥24. We analyzed factors predicting functional erections at 3 months post-RP as well as factors predicting a decrease in functional erections between 3 and 6 months, defined as ≥2-point drop in the erectile function domain. Multivariable logistic regression models were used to identify predictors of early erectile function recovery and also of subsequent decline.OutcomesErectile function recovery rates at 3 months post-RP and predictive factors; rates of erectile function decline between 3-6 months and associated predictors.ResultsEligible patients comprised 1,655 men with median age of 62 (IQR 57, 67) years. Bilateral nerve-sparing (NS) surgery was performed in 71% of men, unilateral NS in 19%, and no NS in 10%. Of this population, 224 men (14%; 95% CI 12%, 15%) had functional erections at 3 months post-RP. On multivariable analysis, significant predictors of early erectile function recovery included: younger age (OR 0.93, P < .001), higher baseline erectile function domain score (OR 1.14, P < .001) and bilateral NS (OR 3.81, P = .002). The presence of diabetes (OR 0.43, P = .028) and a former smoking history (OR 0.63, P = .008; reference group: never smoker) was associated with the erectile dysfunction at 3 months post-RP. Of the men with early functional erections, 41% (95% CI 33%, 48%) had a ≥ 2-point decline in erectile function between 3 and 6 months. No factors were identified as predictors for this decline.Clinical ImplicationsOnly a small proportion of men have functional erections at 3 months post-RP and a notable number of them will experience a decline in erectile function between 3 and 6 months.Strengths and LimitationsStrengths: large patient population and the use of validated questionnaire. Limitations: single-center retrospective study.ConclusionA minority of men had functional erections 3 months post-RP, about half of whom had a decline in erectile function by month 6. We recommend appropriately counseling post-RP patients on the risk of such a decline in erectile function.Salter CA, Tin AL, Bernie HL, et al. Predictors of Worsening Erectile Function in Men with Functional Erections Early After Radical Prostatectomy. J Sex Med 2022;19:1790–1796.     

Chronic Administration of Sildenafil Modified the Impaired VEGF System and Improved the Erectile Function in Rats with Diabetic Erectile Dysfunction

IntroductionMen frequently develop diabetic erectile dysfunction (DMED), as a result of endothelial dysfunction. DMED patients often have reduced efficacy with phosphodiesterase type 5 inhibitors therapy.AimTo determine whether chronic sildenafil administration can modify the impaired vascular endothelial growth factor (VEGF) system and improve the erectile function in rats with diabetic erectile dysfunction.MethodsA group of Sprague Dawley rats (n = 30) with DMED were induced by intraperitoneal injection of streptozotocin (40 mg/kg) and screened by subcutaneous injection of Apomorphine (100 mg/kg). They were then exposed to either vehicle or sildenafil (prescribed in our hospital, 5 mg/kg and 10 mg/kg, respectively) for 10 weeks. An additional nondiabetic and age-matched control group (n = 10) was also allocated and given the routine diet for the same period. Assessments were performed to both groups at 36 hours after the last dose of sildenafil. Penile intracavernous pressure (ICP), mean arterial pressure (MAP), penile tissue morphology, immunohistologic analysis, and Western blot analysis of VEGF, VEGFR1, and eNOS were determined.Main Outcome MeasureFunctional, morphological, and proteomical changes on penile structures by the chronic Sildenafil (5 mg/kg and 10 mg/kg, respectively) administration were determined.ResultsA significant increase of ICP, ICP/MAP ratio, and area under the curve were observed in the both groups treated by sildenafil (5 mg/kg and 10 mg/kg, respectively), compared with the DMED rats without receiving Sildenafil. Immunohistochemical staining of their penile tissue showed a decrease in VEGF, VEGFR1, and eNOS staining in the controlled group compared with an improvement in the chronic sildenafil administration group. Western blot analysis demonstrated exactly the same results.ConclusionWe demonstrated that daily sildenafil administration can restore the impaired VEGF system in the penis of DMED rats and progressively improve both erectile function and endothelial function, suggesting a potential general mechanism of improved signaling through the VEGF/eNOS signaling cascade. Liu G, Sun X, Dai Y, Zheng F, Wang D, Huang Y, Bian J, and Deng C. Chronic administration of sildenafil modified the impaired VEGF system and improved the erectile function in rats with diabetic erectile dysfunction.     

Caloric Restriction Prevents Visceral Adipose Tissue Accumulation and Maintains Erectile Function in Aging Rats

IntroductionIncreased adiposity is an important risk factor for erectile dysfunction (ED) and cardiovascular disease (CVD). Although accumulation of visceral adipose tissue (VAT) is recognized as a key mediator in the pathogenesis of CVD, its role in ED has not been elucidated.AimTo determine whether caloric restriction (CR) could prevent VAT accumulation and thereby prevent the onset of ED in normotensive rats.MethodsMale Sprague Dawley rats (10 weeks) were randomized into three dietary groups: ad libitum control (CON), mild CR (CR_MI), and moderate CR (CR_MOD). Body weight (BW), body length abdominal girth (AG), and VAT (g‐magnetic resonance imaging based) were assessed longitudinally. Erections were assessed using the apomorphine bioassay (80 µg/kg, SQ) after 20 weeks of CR. Excised VAT (mesenteric, epididymal, omental, and retroperitoneal), the internal pudendal artery (IPA) and serum were collected postmortem. Structure and function of the IPA was assessed at study end.Main Outcome MeasuresErectile responses, adiposity (VAT), abdominal girth, serum analysis.ResultsBW (CON = 653 ± 58.6 g; CR_MI = 535 ± 47.4 g; CR_MOD = 409 ± 17.4 g) and VAT (CON = 39 ± 9.0 g; CR_MI = 30 ± 9.9 g; CR_MOD = 14 ± 3.5 g) were markedly different between the three groups. AG significantly correlated with longitudinal changes in VAT (R² = 0.61) and excised VAT (R² = 0.87). CR preserved erectile responses (CON = 0.6 ± 0.45, CR_MI = 1.2 ± 0.77 g, CR_MOD = 2.5 ± 0.43 g). A strong inverse correlation between VAT (%) and erectile function was found (R² = 0.74) whereas BW was less predictive of ED (R² = 0.48). There were no changes in traditional biomarkers (glucose, lipids) which could account for the ED. IPA structure was not different between groups, while CR_MOD preserved endothelial function.ConclusionsCR effectively prevented VAT accumulation in normotensive rats. Independently of changes in other metabolic markers, this intervention ameliorated the negative impact on erectile responses that occurs with age. Functional changes of the IPA may be a key mechanism by which erections are preserved with CR. AG was shown to be a strong index of VAT in rats. Maio MT, Hannan JL, Komolova M, and Adams MA. Caloric restriction prevents visceral adipose tissue accumulation and maintains erectile function in aging rats. J Sex Med 2012;9:2273–2283.     

Effectiveness of Intracavernous Delivery of Adenovirus Encoding Smad7 Gene on Erectile Function in a Mouse Model of Cavernous Nerve Injury

IntroductionMen with erectile dysfunction (ED) respond poorly to oral phosphodiesterase-5 inhibitors following radical prostatectomy. Recent studies have reported that up-regulation of transforming growth factor-β1 (TGF-β1) and activation of the Smad signaling pathway play important roles in cavernous fibrosis and in the deterioration of erectile function in a mouse model of cavernous nerve injury (CNI) and in patients with spinal cord injury. The mothers against decapentaplegic homolog 7 (Smad7) is known to inhibit the phosphorylation of Smad2 and Smad3.AimTo investigate the effectiveness of adenoviruses encoding Smad7 gene (Ad-Smad7) on erectile function in a mouse model of CNI.MethodsTwelve-week-old C57BL/6J mice were used and distributed into 7 groups: sham operation group, untreated CNI group, and CNI groups receiving a single intracavernous injection of adenovirus encoding LacZ (1 × 10⁸ virus particles [vp]/20 μL) or adenovirus encoding Smad7 (Ad-Smad7; 1 × 10⁷, 1 × 10⁸, 2 × 10⁸, or 1 × 10⁹ vp/20 μL).Main Outcome MeasuresTwo weeks after bilateral cavernous nerve crushing and treatment, erectile function was measured by electrical stimulation of the cavernous nerve. The penis was harvested for histologic examinations and Western blot analysis.ResultsThe highest erectile response was noted in CNI mice treated with Ad-Smad7 at a dose of 1 × 10⁸ vp, which reached up to 82–85% of sham control values. Local delivery of Ad-Smad7 significantly decreased endothelial cell apoptosis and the production of extracellular matrix proteins, including plasminogen activator inhibitor-1, fibronectin, collagen I, and collagen IV, and induced endothelial nitric oxide synthase phosphorylation in the corpus cavernosum tissue of CNI mice.ConclusionThe adenovirus-mediated gene transfer of Smad7 successfully restored erectile function by enhancing endothelial cell function and through antifibrotic effects. These findings suggest that inhibition of the TGF-β signaling pathway by use of Smad7 may represent a promising therapeutic strategy for ED induced by radical prostatectomy. Song KM, Chung J-S, Choi MJ, Jin H-R, Yin GN, Kwon M-H, Park J-M, Kim WJ, Lee S-J, Kim S-J, Ryu J-K, and Suh J-K. Effectiveness of intracavernous delivery of adenovirus encoding Smad7 gene on erectile function in a mouse model of cavernous nerve injury. J Sex Med 2014;11:51–63.