Suppression of Cavernosal Fibrosis in a Rat Model

Autophagy in erectile dysfunction: focusing on apoptosis and fibrosis

ABSTRACT

In most types of erectile dysfunction, particularly in advanced stages, typical pathological features observed are reduced parenchymal cells coupled with increased tissue fibrosis. However, the current treatment methods have shown limited success in reversing these pathologic changes. Recent research has revealed that changes in autophagy levels, along with alterations in apoptosis and fibrosis-related proteins, are linked to the progression of erectile dysfunction, suggesting a significant association. Autophagy, known to significantly affect cell fate and tissue fibrosis, is currently being explored as a potential treatment modality for erectile dysfunction. However, these present studies are still in their nascent stage, and there are limited experimental data available. This review analyzes erectile dysfunction from a pathological perspective. It provides an in-depth overview of how autophagy is involved in the apoptotic processes of smooth muscle and endothelial cells and its role in the fibrotic processes occurring in the cavernosum. This study aimed to develop a theoretical framework for the potential effectiveness of autophagy in preventing and treating erectile dysfunction, thus encouraging further investigation among researchers in this area.

Melatonin-pretreated mesenchymal stem cell-derived exosomes alleviate cavernous fibrosis in a rat model of nerve injury-induced erectile dysfunction via miR-145-5p/TGF-β/Smad axis

BACKGROUND

Cavernous nerve injury-induced erectile dysfunction (CNI-ED) is a common complication after radical prostatectomy. Conventional treatment approaches have had little success in treating the severe cavernous fibrosis which is a consequence of CNI-ED.

METHODS

Pre-treatment of adipose-derived stem cells with melatonin allows for the extraction of active exosomes (MT-hASC-EVs) from the conditioned medium. The therapeutic effects of MT-hASC-EVs were assessed in a rat model of CNI-ED, and the anti-fibrotic properties were evaluated. MicroRNA sequencing was used to identify specific microRNAs highly expressed in MT-hASC-EVs, and differential microRNAs were screened for regulatory pathways through target gene enrichment analysis. Finally, the conclusions from bioinformatics analysis were validated through in vitro experiments.

RESULTS

Intracavernous injection of MT-hASC-EVs significantly restored erectile function and reduced the extent of corpus cavernosum fibrosis in the CNI-ED rat model. MT-hASC-EVs promoted the proliferation and anti-apoptotic effects of corpus cavernosum smooth muscle cells (CCSMCs) in vitro. Mechanistically, MT-hASC-EVs inhibit fibrosis by delivering miR-145-5p, which targets TGF-β2/Smad3 axis.

CONCLUSIONS

MT-hASCs-EVs can inhibit cavernous fibrosis and improve erectile function in a rat model of CNI-ED by targeting the miR-145-5p/TGF-β/Smad axis.

The Role of Autophagy in Erectile Dysfunction

Autophagy is a conservative lysosome-dependent material catabolic pathway, and exists in all eukaryotic cells. Autophagy controls cell quality and survival by eliminating intracellular dysfunction substances, and plays an important role in various pathophysiology processes. Erectile dysfunction (ED) is a common male disease. It is resulted from a variety of causes and pathologies, such as diabetes, hypertension, hyperlipidemia, aging, spinal cord injury, or cavernous nerve injury caused by radical prostatectomy, and others. In the past decade, autophagy has begun to be investigated in ED. Subsequently, an increasing number of studies have revealed the regulation of autophagy contributes to the recovery of ED, and which is mainly involved in improving endothelial function, smooth muscle cell apoptosis, penile fibrosis, and corpus cavernosum nerve injury. Therefore, in this review, we aim to summarize the possible role of autophagy in ED from a cellular perspective, and we look forward to providing a new idea for the pathogenesis investigation and clinical treatment of ED in the future.

Collagen-based materials in male genitourinary diseases and tissue regeneration

Male genitourinary dysfunction causes serious physical or mental distress, such as infertility and psychological harm, which leads to impaired quality of life. Current conventional treatments involving drug therapy, surgical repair, and tissue grafting have a limited effect on recovering the function and fertility of the genitourinary organs. To address these limitations, various biomaterials have been explored, with collagen-based materials increasingly gaining attention for reconstructing the male genitourinary system due to their superior biocompatibility, biodegradability, low antigenicity, biomimetic 3D matrix characteristics, hemostatic efficacy, and tissue regeneration capabilities. This review covers the recent biomedical applications of collagen-based materials including treatment of erectile dysfunction, premature ejaculation, penile girth enlargement, prostate cancer, Peyronie's disease, chronic kidney disease, etc. Although there are relatively few clinical trials, the promising results of the existing studies on animal models reveal a bright future for collagen-based materials in the treatment of male genitourinary diseases.

Graphic Abstract

Carvacrol prevents D-( +)-galactose-induced aging-associated erectile dysfunction by improving endothelial dysfunction and oxidative stress in rats

Aging is one of the risk factors involved in the development of erectile dysfunction (ED). Growing evidence suggests that oxidative stress is the critical mediator of changes in endothelial function and penile vascular tone in the aging process. Thus, reducing reactive oxygen species (ROS) levels may preserve the bioactivity of the penile vasculature. Antioxidant compounds, such as carvacrol, limit the damage caused by ROS and, therefore, benefit the treatment of ED. Thus, this study aims to evaluate the effects of carvacrol on ED using the D-( +)-galactose aging model. The animals were divided into five groups: control, D-( +)-galactose 150 mg/kg, carvacrol 50 mg/kg or 100 mg/kg, and sildenafil 1.5 mg/kg treated daily for 8 weeks. The physiological, functional, and morphological characteristics of aging-associated ED were evaluated after treatment with carvacrol. Carvacrol prevented ED in a D-( +)-galactose-induced aging model by reducing hypercontractility, enhancing endothelial dysfunction in the rat corpus cavernosum, and improving endothelial health of rat cavernous endothelial cells. In addition, carvacrol prevented the destruction of erectile components essential for penile erection and promoted a reduction of penile tissue senescence, probably through mechanisms that involve the harmful modulation of oxidative stress. Carvacrol significantly improved the erectile function of rats in a D-( +)-galactose-induced aging model and has excellent potential as a new therapeutic alternative in treating erectile dysfunction.

Prenatal exposure to dibutyl phthalate contributes to erectile dysfunction in offspring male rats by activating the RhoA/ROCK signalling pathway

Prenatal exposure to dibutyl phthalate (DBP) has been reported to cause erectile dysfunction (ED) in adult offspring rats. However, its underlying mechanisms are not fully understood. Previously, we found that DBP activates the RhoA/ROCK pathway in the male reproductive system. This study investigated how prenatal exposure to DBP activates the RhoA/ROCK signalling pathway, leading to ED in male rat offspring. Pregnant rats were stratified into DBP-exposed and NC groups, with the exposed group receiving 750 milligrams per kilogram per day (mg/kg/day) of DBP through gavage from days 14-18 of gestation. DBP exposure activated the RhoA/ROCK pathway in the penile corpus cavernosum (CC) of descendants, causing smooth muscle cell contraction, fibrosis, and apoptosis, all of which contribute to ED. In vitro experiments confirmed that DBP induces apoptosis and RhoA/ROCK pathway activation in CC smooth muscle cells. Treatment of DBP-exposed offspring with the ROCK inhibitor Y-27632 for 8 weeks significantly improved smooth muscle cell condition, erectile function, and reduced fibrosis. Thus, prenatal DBP exposure induces ED in offspring through RhoA/ROCK pathway activation, and the ROCK inhibitor Y-27632 shows potential as an effective treatment for DBP-induced ED.

Mechanism of denervation muscle atrophy mediated by Ach/p38/MAPK pathway in rats with erectile dysfunction caused by nerve injury

BACKGROUND

Peripheral nerve injury can result in penile cavernosal denervation muscle atrophy, a primary factor in nerve injury erectile dysfunction (NED). While acetylcholine (Ach) is integral to erectile function, its role and mechanisms in NED need further exploration.

OBJECTIVE

To investigate the inhibition of CCMSCs Apoptosis and Protein Degradation Pathway by Ach in NED rat model.

METHODS

We investigated changes in Ach secretion and receptor expression in an NED rat model, followed by the evaluation of apoptosis and ubiquitin proteasome activation in hypoxic Cavernous smooth muscle cells (CCMSCs) and their co-cultures with Schwann cells (SWCs), under Ach influence. Further, key pathways in NED were identified via high-throughput sequencing, focusing on the p38/MAPK signaling pathway. We examined gene alterations related to this pathway using hypoxic cell models and employed p38 inhibitors to verify protein changes. Our findings in vitro were then confirmed in the NED rat model.

RESULTS

Nerve injury led to reduced Ach receptors and associated gene expression. Experimentally, Ach was shown to counteract CCMSC apoptosis and muscle protein degradation via the p38/MAPK pathway. Inhibition of the Ach degradation pathway demonstrated a capacity to slow NED progression in vivo.

DISCUSSION AND CONCLUSION

Activation of Ach receptors may decelerate denervation-induced cavernosal muscle atrophy, suggesting a potential therapeutic approach for NED. This study highlights the crucial role of the Ach/p38/MAPK axis in the pathophysiology of penis smooth muscle atrophy and its broader implications in managing NED and male erectile dysfunction.

Research progress on the therapeutic application of extracellular vesicles in erectile dysfunction

Erectile dysfunction (ED) is one of the most common male sexual dysfunctions and is related to many pathogenic factors. However, first-line treatment, represented by phosphodiesterase 5 inhibitors, is unable to maintain long-term efficacy. Extracellular vesicles (EVs) have recently attracted the attention of researchers in the fields of cardiovascular disease, neurologic disease, and regenerative medicine and may become a treatment for ED. This article reviews recent applications of EVs in the treatment of ED from the aspects of the source, the therapeutic mechanism, and the strategies to enhance therapeutic efficacy. These research advances lay the foundation for further research and provide references for in-depth understanding of the therapeutic mechanism and possible clinical application of EVs in ED.

IL-17A exacerbates corpus cavernosum fibrosis and neurogenic erectile dysfunction by inducing CSMC senescence via the mTORC2-ACACA pathway

BACKGROUND

Neurogenic erectile dysfunction, characterized by neurological repair disorders and progressive corpus cavernosum fibrosis (CCF), is an unbearable disease with limited treatment success. IL-17A exhibits a complex role in tissue remodelling. Nevertheless, the precise role and underlying mechanisms of IL-17A in CCF under denervation remain unclear.

METHODS

PCR array was employed to identified differentially expressed genes between neurogenic ED and normal rats. IL-17A expression and its main target cells were analyzed using Western blotting, immunofluorescence and immunohistochemistry. The phenotypic regulation of IL-17A on corpus cavernosum smooth muscle cells (CSMCs) was evaluated by cell cycle experiments and SA-β-Gal staining. The mechanism of IL-17A was elucidated using non-target metabolomics and siRNA technique. Finally, IL-17A antagonist and ABT-263 (an inhibitor of B-cell lymphoma 2/w/xL) were utilized to enhance the therapeutic effect in a rat model of neurogenic ED.

RESULTS

IL-17A emerged as the most significantly upregulated gene in the corpus cavernosum of model rats. It augmented the senescence transformation and fibrotic response of CSMCs, and exhibited a strong correlation with CCF. Mechanistically, IL-17A facilitated CCF by activating the mTORC2-ACACA signalling pathway, upregulating of CSMCs lipid synthesis and senescence transition, and increasing the secretion of fibro-matrix proteins. In vivo, the blockade of IL-17A-senescence signalling improved erectile function and alleviated CCF in neurogenic ED.

CONCLUSIONS

IL-17A assumes a pivotal role in denervated CCF by activating the mTORC2-ACACA signalling pathway, presenting itself as a potential therapeutic target for effectively overcoming CCF and erection rehabilitation in neurogenic ED.

A low androgenic state inhibits erectile function by suppressing endothelial glycosides in the penile cavernous tissue of rats

Background

The endothelial glycocalyx is an important barrier that protects the structure and function of endothelial cells. Androgen deficiency is a common factor that causes structural and functional impairment of endothelial cells.

Aim

To investigate changes in the endothelial glycocalyx in the penile corpus cavernosum of the rat with low androgen status and its relationship with erection function.

Methods

Eighteen 10-week-old Sprague-Dawley male rats were randomly divided into 3 groups (n = 6 each): sham operation, castration, and castration + testosterone replacement. The maximum intracavernosal pressure/mean arterial pressure of the penis was measured after modeling for 4 weeks. The expression levels of endothelial nitric oxide synthase (eNOS), phospho-eNOS, syndecan 1, heparanase, and nitric oxide in penile cavernous tissue and the serum levels of heparan sulfate, hyaluronic acid, tumor necrosis factor α, and interleukin 6 were determined. Transmission electron microscopy was used to observe the ultrastructure of the endothelial glycocalyx in penile tissue.

Outcomes

The thickness of the endothelial glycocalyx in the penile corpus cavernosum of castrated rats was significantly lower than that of the control group.

Results

In the castrated rats, the endothelial glycocalyx thickness, syndecan 1 level, ratio of phospho-eNOS to eNOS, nitric oxide level, and maximum intracavernosal pressure/mean arterial pressure (3 V, 5 V) were significantly lower than those in the sham group (P < .05). The expression of heparanase and the serum levels of tumor necrosis factor α and interleukin 6 were significantly higher in the castrated group than in the sham group (P < .05).

Clinical Translation

Upregulating the expression of the endothelial glycocalyx in the penile corpus cavernosum may be a new method for treating erectile dysfunction caused by low androgen levels.

Strengths and Limitations

This study confirms that low androgen status promotes the breakdown of the endothelial glycocalyx. However, further research is needed to determine whether androgens are related to the synthesis of the endothelial glycocalyx.

Conclusion

Low androgen status may suppress the level of nitric oxide in the cavernous tissue of the penis via impairment of the endothelial glycocalyx, resulting in inhibited erection function in rats.

Cldn4 overexpression promotes penile cavernous smooth muscle cell fibrotic response via the JNK signaling pathway

BACKGROUND

Erectile dysfunction (ED), defined as the inability to achieve or maintain a penile erection sufficient to satisfy sexual behavior, is prevalent worldwide.

AIM

Using previous research, bioinformatics, and experimental confirmation, we aimed to discover genes that contribute to ED through regulating hypoxia in corpus cavernosum smooth muscle cells (CCSMCs).

METHODS

We used the Gene Expression Omnibus to acquire the sequencing data of the corpus cavernosum transcriptome for diabetic ED and nerve injury type ED rats. We intersected the common differentially expressed genes. Further verification was performed using single cell sequencing. Real-time quantitative polymerase chain reaction and immunofluorescence were used to investigate whether the differentially expressed genes are found in the corpus cavernosum. We used induced hypoxia to assess cell viability changes, and we developed a lentivirus overexpressing Cldn4 for in vitro and in vivo experiments to measure changes in JNK signaling, fibrosis, hypoxia, and erectile function.

OUTCOMES

Our results indicate that targeting the JNK pathway and decreasing local hypoxia may be better options for therapeutic intervention to improve erectile function.

RESULTS

We identified Cldn4 and found its expression increased in the corpora cavernosa of the 2 datasets. In addition, we found that hypoxia can increase the expression of Cldn4, activate the JNK signaling pathway, and exacerbate fibrosis in CCSMCs. Cldn4 overexpression in CCSMCs activated the JNK signaling pathway and increased fibrotic protein expression. Last, rat corpus cavernosum overexpressing Cldn4 activated the JNK signaling pathway, increased local fibrosis, and impaired erectile function.

CLINICAL IMPLICATIONS

Through bioinformatics and in vitro and in vivo experiments, we found that Cldn4 has a negative effect on ED, and targeting Cldn4 may provide new ideas for ED treatment.

STRENGTHS AND LIMITATIONS

Although we have identified Cldn4 as a potential target for ED treatment, we have only conducted preliminary validation on CCMSCs, and we still need to further validate in other cell lines.

CONCLUSION

CCSMC hypoxia leads to increased Cldn4, in both nerve injury and diabetic ED rat models, and promotes fibrosis by activating the JNK signaling pathway.

Caveolin-1 scaffolding domain peptide prevents corpus cavernosum fibrosis and erectile dysfunction in bilateral cavernous nerve injury-induced rats

BACKGROUND

Corpus cavernosum (CC) fibrosis significantly contributes to post-radical prostatectomy erectile dysfunction (pRP-ED). Caveolin-1 scaffolding domain (CSD)-derived peptide has gained significant concern as a potent antagonist of tissue fibrosis. However, applying CSD peptide on bilateral cavernous nerve injury (BCNI)-induced rats remains uninvestigated.

AIM

The aim was to explore the therapeutic outcome and underlying mechanism of CSD peptide for preventing ED in BCNI rats according to the hypothesis that CSD peptide may exert beneficial effects on erectile tissue and function following BCNI through limiting collagen synthesis in CC smooth muscle cells (CCSMCs) and CC fibrosis.

METHODS

After completing a random assignment of male Sprague Dawley rats (10 weeks of age), BCNI rats received either saline or CSD peptide treatment, as opposed to sham-operated rats. The evaluations of erectile function (EF) and succedent collection and histological and molecular biological examinations of penile tissue were accomplished 3 weeks postoperatively. In addition, the fibrotic model of CCSMCs was used to further explore the mechanism of CSD peptide action in vitro.

OUTCOMES

The assessments of EF, SMC/collagen ratio, α-smooth muscle actin, caveolin-1 (CAV1), and profibrotic indicators expressions were conducted.

RESULTS

BCNI rats exhibited significant decreases in EF, SMC/collagen ratio, α-SMA, and CAV1 levels, and increases in collagen content together with transforming growth factor (TGF)-β1/Smad2 activity. However, impaired EF, activated CC fibrosis, and Smad2 signaling were attenuated after 3 weeks of CSD peptide treatment in BCNI rats. In vitro, TGF-β1-induced CCSMCs underwent fibrogenetic transformation characterized by lower expression of CAV1, higher collagen composition, and phosphorylation of Smad2; then, the delivery of CSD peptide could significantly block CCSMC fibrosis by inactivating Smad2 signaling.

CLINICAL IMPLICATIONS

Based on available evidence of CSD peptide in the prevention of ED in BCNI rats, this study can aid in the development and clinical application of CSD peptide targeting pRP-ED.

STRENGTHS AND LIMITATIONS

This study provides data to suggest that CSD peptide protects against BCNI-induced deleterious alterations in EF and CC tissues. However, the available evidence still does not fully clarify the detailed mechanism of action of CSD peptide.

CONCLUSION

Administration of CSD peptide significantly retarded collagen synthesis in CCSMCs, limited CC fibrosis, and prevented ED via confrontation of TGF-β1/Smad signaling in BCNI rats.

Buyang Huanwu Decoction Ameliorates Damage of Erectile Tissue and Function Following Bilateral Cavernous Nerve Injury

OBJECTIVE

To verify the effect of Buyang Huanwu Decoction (BHD) in ameliorating erectile dysfunction (ED) after radical prostatectomy (RP).

METHODS

The composition of BHD was verified by ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS/MS) analysis. Bilateral cavernous nerve crush injury (BCNI) in rats was used to mimic the neurovascular injury occurring after RP. By the envelope method, forty rats were randomly divided into 4 groups as follows: sham (cavernous nerves exposed only), model (BCNI), low-dosage BHD [LBHD, 12.8 g/(kg·d)], and high-dosage BHD [HBHD, 51.2 g/(kg·d)] groups, 10 rats in each group, feeding for 3 weeks respectively. Erectile function was evaluated by measuring intracavernosal pressure (ICP). Changes in the histopathology of corpus cavernosum (CC) were examined by hematoxylin-eosin staining. Meanwhile, the fibrosis of CC was measured by Masson's trichrome staining and Western blot was used to detect the expressions of collagen I, transforming growth factor beta 1 (TGF- β 1) and α-smooth muscle actin (α-SMA). Apoptosis index was detected by terminal-deoxynucleoitidyl transferase mediated nick end labeling (TUNEL) and Western blot for determining the expressions of B-cell lymphoma 2 (Bcl-2) and Bcl-2-associated X (Bax). The oxidative stress in the CC were assessed by the superoxide dismutase (SOD), malondialdehyde (MDA) and reactive oxygen species (ROS) levels. The proteins expression of c-Jun N-terminal kinase (JNK) and c-Jun were detected by Western blot. In addition, the expression of α-SMA and p-c-Jun in the CC was observed by double immunofluorescence staining.

RESULTS

The UPLC-QTOF-MS/MS analysis showed that BHD contained calycosin-7-O- β -D-glucoside, ononin, calycosin and formononetin. Compared with the model group, LBHD and HBHD treatment improved the ICP and the circumference, area, and weight of CC (P<0.05 or P<0.01). Furthermore, LBHD and HBHD treatments increased CC smooth muscle content and decreased apoptosis index (P<0.05 or P<0.01). LBHD and HBHD also elevated SOD and expression level of α -SMA and Bcl-2, and reduced MDA and ROS levels, as well as expression of TGF- β 1, collagen I, Bax, p-c-JNK, p-JNK in the CC compared with the model group (P<0.05 or P<0.01). The double immunofluorescence staining showed that the fluorescence degree of p-c-Jun in both LBHD and HBHD treatment groups was significantly reduced, whereas the α -SMA expression increased (P<0.05 or P<0.01).

CONCLUSIONS

BHD can improve ED of rats with BCNI, which is related to inhibiting fibrosis, apoptosis, and oxidative stress of CC. The ROS/JNK/c-Jun signaling pathway may play an important role in the process.

Downregulation of the expression of galanin impairs erectile function in hypoandrogenic rats

Background

The relationship between galanin and erectile function under low androgen levels is still unclear.

Aim

To explore whether a low testosterone level damages the erection of a rat by regulating the expression of galanin and GalR in penile cavernous tissue.

Methods

Thirty-six male Sprague-Dawley rats, 8 weeks of age, were randomly grouped as follows (n = 6): control, castration, castration + testosterone replacement, control + transfection, castration + transfection, and castration + empty transfection. At 4 weeks after castration, rats in the transfection group were injected with lentivirus carrying the targeting galanin gene (2 × 10⁸ TU/mL, 10 μL) in the corpus cavernosum. After 1 week of injection, the intracavernosal pressure (ICP), mean arterial blood pressure (MAP), nitric oxide (NO), serum testosterone concentration, galanin, GalR1-3, ROCK1, ROCK2, and p-eNOS/eNOS in the rat penile tissues were evaluated.

Outcomes

ICPmax/MAP and the expression of galanin in the corpus cavernosum in castrated rats were obviously decreased as compared with those in the control rats.

Results

The castrated rats showed remarkably lower ICPmax/MAP, galanin, GalR1-3, p-eNOS/eNOS, and NO content and markedly higher ROCK1 and ROCK2 in penile tissues than the control group (P < .05). The transfected rats administrated with LV Gal had obviously higher ICPmax/MAP, p-eNOS/eNOS, and NO content and less ROCK1 and ROCK2 protein expression in the corpus cavernosum when compared with the castration group (P < .05).

Clinical Translation

Upregulating the expression of galanin in the penile corpus cavernosum might be a novel method of treating erectile dysfunction caused by a low androgen level.

Strengths and Limitations

The conclusions obtained in the animal experiments need to be confirmed in human data.

Conclusion

The erectile function of hypoandrogen rats might be inhibited by downregulating the level of galanin and GalR1-3, upregulating ROCK1 and ROCK2 levels, and inhibiting the eNOS/NO signaling pathway in penile corpus cavernosum.

Overexpression of PRDX2 in Adipose-Derived Mesenchymal Stem Cells Enhances the Therapeutic Effect in a Neurogenic Erectile Dysfunction Rat Model by Inhibiting Ferroptosis

Neurogenic erectile dysfunction (NED) is a common and serious complication after pelvic surgery. The clinical translation of adipose-derived mesenchymal stem cell (ADSC) therapies in NED remains a major challenge due to their low survival rate and limited therapeutic effect. Peroxiredoxin 2 (PRDX2) is a member of the peroxidase family that exerts its therapeutic effects by inhibiting oxidative stress (OS) and ferroptosis, and PRDX2 is expected to enhance the therapeutic effect of ADSCs in treating NED. The purpose of this study was to investigate whether PRDX2 could improve the survival of ADSCs and determine whether overexpression of PRDX2 in ADSCs (PRDX2-ADSCs) could enhance the therapeutic effect of NED. This study investigated the potential role of PRDX2-ADSCs through a NED model induced by bilateral cavernous nerve injury (BCNI) and three in vitro models established by H₂O₂-stimulated ADSCs, H₂O₂-stimulated corpus cavernosum smooth muscle cells (CCSMCs), and RSL3-stimulated CCSMCs. We found that PRDX2 could significantly improve the viability of ADSCs by suppressing apoptosis and OS in H₂O₂-stimulated ADSCs. We also found that BCNI triggered ferroptosis of the corpus cavernosum, which was manifested by increased reactive oxygen species (ROS), total iron content, and MDA as well as decreased SOD and GSH. Our results further demonstrated changes in the expression of key proteins (GPX4 and ACSL4) in the ferroptosis pathway, whereas PRDX2-ADSCs ameliorated BCNI-induced erectile dysfunction and ferroptosis of the corpus cavernosum in NED rats. Consistently, PRDX2-ADSCs attenuated OS in H₂O₂-stimulated CCSMCs and inhibited ferroptosis in RSL3-stimulated CCSMCs, as evidenced by the decrease in ROS, total iron content, and MDA and the increase in SOD and GSH together with changes in ferroptosis-related protein (GPX4 and ACSL4) expression. In conclusion, overexpression of PRDX2 in ADSCs enhanced the therapeutic effect in a rat model of neurogenic erectile dysfunction by inhibiting ferroptosis via regulation of the GPX4/ACSL4 axis.

Erectile dysfunction in hypospadiac male adult rats induced by maternal exposure to di-n-butyl phthalate

For the treatment of hypospadias, a significant number of studies focus on penile reconstruction. However, scant attention is given to sexual behavior of hypospadiac patients and underlying mechanisms. A rat model of hypospadias was constructed by maternal di-n-butyl phthalate (DBP) exposure (800 mg/kg/day by gavage during gestational days 14-18). Ten-week-old male rats with hypospadias undertook significantly decreased penis/body weight ratio, reduced testis/body weight ratio, lower serum testosterone level and thinner myelin sheath thickness of cavernosum nerves. Meanwhile, erectile dysfunction (ED) was found in hypospadiac rats, which showed significant increases in transforming growth factor-β1 (TGF-β1) protein expression and decreases in the expression of alpha smooth muscle actin (α-SMA) protein, neuronal and endothelial nitric oxide synthase protein (nNOS and eNOS). In addition, phosphorylated protein kinase B/protein kinase B (pAkt/Akt) ratios were remarkably lower, but the Bcl-2-associated X protein (Bax)/Bcl-2 ratios, caspase-3 protein expression, nuclear factor erythroid 2-related factor 2/ Kelch-like ECH-associated protein 1 (Nrf2/Keap-1) ratios, NAD(P)H dehydrogenase quinone 1(NQO1) protein expression and heme oxygenase-1 (HO-1) protein expression were higher in the hypospadias groups than the control group. Notably, ED is comorbid with hypospadias in cases. Penile fibrosis, testosterone deficiency, and endothelial dysfunction lead to ED in hypospadias induced by DBP eventually, which might be explained by activating Akt/Bad/Bax/caspase-3 pathway, Nrf2/Keap-1 pathway and suppressing NOS/cGMP pathway in penis.

Acetyl-L-carnitine improves erectile function in bilateral cavernous nerve injury rats via promoting cavernous nerve regeneration

BACKGROUND

Neurogenic erectile dysfunction (NED) caused by cavernous nerve (CN) injury is a typical complication after pelvic surgery, which lacks efficient treatments. Acetyl-L-carnitine (ALCAR) has been proven to promote nerve repair.

OBJECTIVES

To investigate the effect and potential mechanism of ALCAR in the treatment of NED.

MATERIALS AND METHODS

Thirty-two rats were randomly divided into bilateral cavernous nerve injury (BCNI) group, BCNI + lower-dose ALCAR (50 mg/kg/day) group, BCNI + higher-dose (100 mg/kg/day) group and sham-operated group. Erectile function was assessed 14 days after daily intraperitoneal injection of ALCAR or placebo. The penile tissues were gathered for subsequent histological and molecular biological analysis. Rat Schwann cell (SC) line S16 was used to verify the mechanism of ALCAR in vitro.

RESULTS

We found that the erectile function of the rats in BCNI group was severely impaired, which was improved considerably in both BCNI+ALCAR-LD and BCNI+ALCAR-HD groups. Also, we observed decreased smooth muscle and increased collagen content in corpus cavernosum in BCNI group. The expressions of fibrosis markers TGF-β, CTGF, and Smad 2/3 were significantly up-regulated in the BCNI group. The above changes were alleviated after the administration of lower and higher-dose ALCAR. Meanwhile, the NO/cGMP pathway was promoted and the RhoA/ROCK pathway was inhibited in the corpus cavernosum of BCNI rats after ALCAR treatment, accompanied by increased nNOS and down-regulated Tyrosine Hydroxylase. In vitro, ALCAR promoted the migration and proliferation of SC, and increased the expression of Pmp22 and NGF. Further, rats treated with ALCAR had high expression of ATF3 and S100 in the distal nerve tissues of the CN extrusion site.

DISCUSSION AND CONCLUSION

ALCAR could promote nerve repair and regeneration, inhibit penile fibrosis and improve penile erection by promoting the proliferation and migration of SC and the secretion of NGF. Our study confirms that ALCAR may be a potential treatment strategy for NED. This article is protected by copyright. All rights reserved.

Integrated bioinformatics analysis identifies established and novel TGFβ1-regulated genes modulated by anti-fibrotic drugs

Fibrosis is a leading cause of morbidity and mortality worldwide. Although fibrosis may involve different organ systems, transforming growth factor-β (TGFβ) has been established as a master regulator of fibrosis across organs. Pirfenidone and Nintedanib are the only currently-approved drugs to treat fibrosis, specifically idiopathic pulmonary fibrosis, but their mechanisms of action remain poorly understood. To identify novel drug targets and uncover potential mechanisms by which these drugs attenuate fibrosis, we performed an integrative 'omics analysis of transcriptomic and proteomic responses to TGFβ1-stimulated lung fibroblasts. Significant findings were annotated as associated with pirfenidone and nintedanib treatment in silico via Coremine. Integrative 'omics identified a co-expressed transcriptomic and proteomic module significantly correlated with TGFβ1 treatment that was enriched (FDR-p = 0.04) with genes associated with pirfenidone and nintedanib treatment. While a subset of genes in this module have been implicated in fibrogenesis, several novel TGFβ1 signaling targets were identified. Specifically, four genes (BASP1, HSD17B6, CDH11, and TNS1) have been associated with pirfenidone, while five genes (CLINT1, CADM1, MTDH, SYDE1, and MCTS1) have been associated with nintedanib, and MYDGF has been implicated with treatment using both drugs. Using the Clue Drug Repurposing Hub, succinic acid was highlighted as a metabolite regulated by the protein encoded by HSD17B6. This study provides new insights into the anti-fibrotic actions of pirfenidone and nintedanib and identifies novel targets for future mechanistic studies.

Indications and characteristics of penile traction and vacuum erection devices

A variety of devices are available for the management of patients with erectile dysfunction, Peyronie's disease, penile dysmorphophobia, for support before and after penile prosthesis insertion, and after radical prostatectomy. Traction devices include, but are not limited to, Penimaster PRO (MSP Concept, Berlin, Germany), Andropenis and Andropeyronie (Andromedical, Madrid, Spain), and the Restorex (PathRight Medical, Plymouth, USA). The other type of devices are vacuum devices such the Osbon ErecAid (Timm Medical, MN, USA). Different devices are optimal for different clinical applications, and robust and contemporary clinical data show a variety of strengths and weaknesses for each device. Research currently favours the use of traction devices for improvement of penile curvature and erectile function in patients with Peyronie's disease compared with vacuum devices; Penimaster Pro and Restorex have been shown to be associated with the best outcomes in this indication. Vacuum devices are favoured for treatment of erectile dysfunction and penile length loss after radical prostatectomy; the Osbon ErecAid is the most well-studied device for this indication. Research into other uses of vacuum and traction devices, such as for penile dysmorphophobia or before and after penile prosthesis, is very limited. Compliance, cost and availability remain substantial challenges, and further high-quality evidence is required to clarify the role of traction devices in urology and sexual medicine.

Single-Cell RNA Sequencing of Human Corpus Cavernosum Reveals Cellular Heterogeneity Landscapes in Erectile Dysfunction

PURPOSE

To assess the diverse cell populations of human corpus cavernosum in patients with severe erectile dysfunction (ED) at the single-cell level.

METHODS

Penile tissues collected from three patients were subjected to single-cell RNA sequencing using the BD Rhapsody™ platform. Common bioinformatics tools were used to analyze cellular heterogeneity and gene expression profiles from generated raw data, including the packages Seurat, Monocle, and CellPhoneDB.

RESULTS

Disease-related heterogeneity of cell types was determined in the cavernous tissue such as endothelial cells (ECs), smooth muscle cells, fibroblasts, and immune cells. Reclustering analysis of ECs identified an arteriole ECs subcluster and another one with gene signatures of fibroblasts. The proportion of fibroblasts was higher than the other cell populations and had the most significant cellular heterogeneity, in which a distinct subcluster co-expressed endothelial markers. The transition trajectory of differentiation from smooth muscle cells into fibroblasts was depicted using the pseudotime analysis, suggesting that the expansion of corpus cavernosum is possibly compromised as a result of fibrosis. Cell-cell communications among ECs, smooth muscle cells, fibroblasts, and macrophages were robust, which indicated that inflammation may also have a crucial role in the development of ED.

CONCLUSIONS

Our study has demonstrated a comprehensive single-cell atlas of cellular components in human corpus cavernosum of ED, providing in-depth insights into the pathogenesis. Future research is warranted to explore disease-specific alterations for individualized treatment of ED.

X-ray micro-computed tomography in the assessment of penile cavernous fibrosis in a rabbit castration model

BACKGROUND

Current assessment methods of penile cavernous fibrosis in animal models have limitations due to the inability to provide complex and volume analysis of fibrotic alterations.

OBJECTIVE

The aim was to evaluate micro-computed tomography (micro-CT) for assessment of cavernous fibrosis and compare it with histological, histochemical, immunohistochemical, and RT-PCR analysis.

MATERIALS AND METHODS

A controlled trial was performed involving 25 New Zealand male rabbits with induced testosterone deficiency by orchidectomy. Penile samples were obtained before and after 7, 14, 21, 84 days from orchidectomy. We consistently performed: a) gray value analysis of corpora cavernosa 3D models reconstructed after micro-CT; b) morphometry of smooth muscles/connective tissue ratio, collagen type I/III ratio, and area of TGF-beta-1 expression in corpora cavernosa; c) RT-PCR of TGF-beta-1 expression.

RESULTS

Micro-CT allowed visualization of penile structures at the resolution comparable to light microscopy. Gray values of corpora cavernosa decreased from 1673 (1512-1773) on the initial day to 1184 (1089-1232) on 21 day (p < 0,005); however, on 84 day, it increased to 1610 (1551-1768). At 21 and 84 days, there were observed a significant decrease in smooth muscle/connective tissue ratio and a significant increase in collagen type I/III ratio (p < 0,05). TGF-beta1 expression increased on 84 day according to immunohistochemistry (p < 0,005). RT-PCR was impossible to conduct due to the absence of RNA in obtained samples after micro-CT.

DISCUSSION AND CONCLUSIONS

Micro-CT provided 3D visualization of entire corpora cavernosa and assessment of radiodensity alterations by gray value analysis in fibrosis progression. We speculate that gray value changes at early and late fibrosis stages could be related to tissue reorganization. RT-PCR is impossible to conduct on tissue samples studied by micro-CT due to RNA destruction. We also suggest that micro-CT could negatively affect the immunohistochemical outcome, as a significant increase of TGF-beta-1 expression occurs later than histological fibrotic signs. This article is protected by copyright. All rights reserved.

D-(+)-Galactose-induced aging: A novel experimental model of erectile dysfunction

Erectile dysfunction (ED) is defined as the inability to achieve and/or maintain penile erection sufficient for satisfactory sexual relations, and aging is one of the main risk factors involved. The D-(+)-Galactose aging model is a consolidated methodology for studies of cardiovascular aging; however, its potential for use with ED remain unexplored. The present study proposed to characterize a new experimental model for ED, using the D-(+)-Galactose aging model. For the experiments, the animals were randomly divided into three groups receiving: vehicle (CTL), D-galactose 150 mg/kg (DGAL), and D-(+)-galactose 150 mg/Kg + sildenafil 1.5 mg/Kg (DGAL+SD1.5) being administered daily for a period of eight weeks. All of the experimental protocols were previously approved by the Ethics Committee on the Use of Animals at the Federal University of Paraíba n° 9706070319. During the treatment, we analyzed physical, molecular, and physiological aspects related to the aging process and implicated in the development of ED. Our findings demonstrate for the first time that D-(+)-Galactose-induced aging represents a suitable experimental model for ED assessment. This was evidenced by an observed hyper-contractility in corpora cavernosa, significant endothelial dysfunction, increased ROS levels, an increase in cavernous tissue senescence, and the loss of essential penile erectile components.

3D reconstruction and histopathological analyses on murine corporal body

PURPOSE

Erectile dysfunction (ED) is one of the increasing diseases with aging society. The basis of ED derived from local penile abnormality is poorly understood because of the complex three-dimensional (3D) distribution of sinusoids in corpus cavernosum (CC). Understanding the 3D histological structure of penis is thus necessary. Analyses on the status of regulatory signals for such abnormality are also performed.

METHODS

To analyze the 3D structure of sinusoid, 3D reconstruction from serial sections of murine CC were performed. Histological analyses between young (2 months old) and aged (14 months old) CC were performed. As for chondrogenic signaling status of aged CC, SOX9 and RBPJK staining was examined.

RESULTS

Sinusoids prominently developed in the outer regions of CC adjacent to tunica albuginea. Aged CC samples contained ectopic chondrocytes in such regions. Associating with the appearance of chondrocytes, the expression of SOX9, chondrogenic regulator, was upregulated. The expression of RBPJK, one of the Notch signal regulators, was downregulated in the aged CC.

CONCLUSIONS

Prominent sinusoids distribute in the outer region of CC which may possess important roles for erection. A possibility of ectopic chondrogenesis induced by alteration of SOX9/Notch signaling with aging is indicated.

Enhanced effects of salidroside on erectile function and corpora cavernosa autophagy in a cavernous nerve injury rat model

We explored the efficacy and mechanisms of salidroside treatment for erectile dysfunction induced by bilateral cavernous nerve injury (BCNI). Forty male rats were divided into four groups as follows: sham (cavernous nerves exposed only) (S); BCNI (M); BCNI + rapamycin (M + rapamycin); and BCNI + salidroside (M + salidroside). Erectile function in the rats was measured by intracavernosal pressure. Penile tissue was harvested for transmission electron microscopy, immunohistochemistry, immunofluorescence, Masson's trichrome staining, haematoxylin-eosin staining, TdT-mediated dUTP Nick End Labeling and western blotting. The M group exhibited a decrease in erectile responses and increased apoptosis and fibrosis compared to these in the S group. Meanwhile, nerve content and the penile atrophy index were also decreased in the M group. Treatment with salidroside and rapamycin for 3 weeks partially restored erectile function and significantly attenuated corporal apoptosis, fibrosis, nerve content and penile atrophy in the M group. Moreover, the autophagy level was further enhanced in the M + salidroside group, which was the same as that in the positive observation group (M + rapamycin). Salidroside treatment not only improved erectile function in rats with BCNI, but also inhibited apoptosis and fibrosis and ameliorated the loss of nerve content and endothelial and corpus cavernosum smooth muscle cells by promoting protective autophagy.

Low androgen status inhibits erectile function by increasing pyroptosis in rat corpus cavernosum

BACKGROUND

The mechanism of erectile dysfunction (ED) caused by low androgen status is not fully understood.

OBJECTIVES

To investigate whether low androgen status inhibits erectile function of rats by inducing pyroptosis in the corpus cavernosum (CC).

MATERIALS AND METHODS

Thirty-six eight-weeks-old healthy male Sprague-Dawley rats were equally divided into six groups: sham-operated group (4w sham, 8w sham), castration group (4w cast, 8w cast), and castration + testosterone (T) group (4w cast + T, 8w cast + T). The rats in castration + T groups were injected with testosterone propionate subcutaneously every other day. After 4 and 8 weeks, the ratio of maximum intracavernous pressure (ICPmax)/mean arterial pressure (MAP), the level of serum T, the concentration of nitric oxide (NO) and interleukin-1β (IL-1β), the expression of NOD-like receptor pyrin domain containing 3 (NLRP3), apoptosis-associated speck-like protein containing a caspase activation and recruitment domain (ASC), Caspase-1 p20, gasdermin D-N (GSDMD-N), transforming growth factor β1 (TGF-β1), collagen-I, and collagen-III, the ratio of smooth muscle/collagen (SM/C), and the proportion of pyroptotic cells in the CC were analyzed.

RESULTS

The ratio of ICPmax/MAP (3/5 V) and SM/C, the level of NO and serum T was significantly decreased in castration groups when compared to other groups (p < 0.01). NLRP3, ASC, Caspase-1, and GSDMD were mainly expressed in the cytoplasm of smooth muscle cells (SMCs) and endothelial cells (ECs) in the CC. The expression of NLRP3, ASC, Caspase-1p20, GSDMD-N, IL-1β, TGF-β1, collagen-I, and collagen-III was significantly increased in castration groups when compared with other groups (p < 0.01). The proportion of pyroptotic cells in the CC was increased significantly in castration groups when compared with other groups (p < 0.05).

DISCUSSION AND CONCLUSION

Low androgen status inhibits erectile function of rats by promoting CC fibrosis and reducing NO synthesis through pyroptosis of SMCs and ECs in the CC.

Revisiting the Regenerative Therapeutic Advances Towards Erectile Dysfunction

Erectile dysfunction (ED) is an inability to attain or maintain adequate penile erection for successful vaginal intercourse, leading to sexual and relationship dissatisfaction. To combat ED, various surgical and non-surgical approaches have been developed in the past to restore erectile functions. These therapeutic interventions exhibit significant impact in providing relief to patients; however, due to their associated adverse effects and lack of long-term efficacy, newer modalities such as regenerative therapeutics have gained attention due to their safe and prolonged efficacy. Stem cells and platelet-derived biomaterials contained in platelet-rich plasma (PRP) are thriving as some of the major therapeutic regenerative agents. In recent years, various preclinical and clinical studies have evaluated the individual, as well as combined of stem cells and PRP to restore erectile function. Being rich in growth factors, chemokines, and angiogenic factors, both stem cells and PRP play a crucial role in regenerating nerve cells, myelination of axons, homing and migration of progenitor cells, and anti-fibrosis and anti-apoptosis of damaged cavernous nerve in corporal tissues. Further, platelet-derived biomaterials have been proven to be a biological supplement for enhancing the proliferative and differentiation potential of stem cells towards neurogenic fate. Therefore, this article comprehensively analyzes the progresses of these regenerative therapies for ED.

The Etiology of Peyronie's Disease: Pathogenesis and Genetic Contributions

INTRODUCTION

Peyronie's disease (PD) is a chronic fibrosing condition that contributes to penile deformity, curvature, and pain. Initial familial studies demonstrated potential genetic links to PD. Since that time, very few investigations have significantly advanced the science in this area. Hence, there is a large opportunity and significant need to better study the underlying genomics and pathogenesis of PD.

AIM

To summarize the current genomic literature relevant to PD.

METHODS

A review was performed of all PubMed-indexed literature from 1970-2018 relating to the pathophysiology and genetics of PD. Key findings were categorically summarized to include epidemiology, risk factors, inheritance patterns, chromosomal instability, genetic associations, epigenetics, differential gene expression, and preclinical models of PD.

MAIN OUTCOME MEASURES

Summary of the current literature on the genetics of PD.

RESULTS

PD is a common condition and has several known risk factors and comorbid disease associations. Although men with PD are believed to be genetically predisposed, there are likely several subtypes of the condition, each with varied pathophysiological disorders and contributing factors. Available data suggest that PD is associated with underlying genetic instability, including dysregulation of genes relating to fibrosis and cellular degradation, thus, resulting in abnormal plaque development and penile deformity. Preclinical models, including cell cultures and rat models, demonstrate several consistencies with PD clinical and histopathologic characteristics; however, an ideal model with spontaneous development of PD is lacking.

CONCLUSION

Based on limited data, PD likely represents a heterogeneous condition, with both heritable and environmentally-driven epigenetic factors contributing to its development and progression. However, there remains a significant gap in the literature on the underlying cause and pathophysiology of the condition, suggesting a substantial need for further investigation and study. Sharma KL, Alom M, Trost L. The Etiology of Peyronie's Disease: Pathogenesis and Genetic Contributions. Sex Med Rev 2020;8:314-323.

Effect of HongJing I in Treating Erectile Function and Regulating RhoA Pathway in a Rat Model of Bilateral Cavernous Nerve Injury

HongJing I (HJI), a traditional Chinese herbal formula, has been confirmed to be effective for the clinical treatment of erectile dysfunction (ED). However, the mechanism of action of HJI remains unclear. Here, we aimed to investigate the effect and underlying mechanisms of HJI against ED in a rat model of bilateral cavernous nerve injury (BCNI). Rats were divided into five groups: normal control (NC), BCNI-induced ED model (M), M + low-dose HJI (HL), M + medium-dose HJI (HM), and M + high-dose HJI (HH). All groups were treated with normal saline or the relevant drug for 28 consecutive days after inducing BCNI-ED. At the end of the treatment period, the intracavernous pressure (ICP) was recorded, and histological examination was conducted using Masson's trichrome staining. Immunofluorescence staining and western blotting were applied to detect the changes in fibrosis protein and Ras homolog A (RhoA), Rho-associated protein kinase 1 (ROCK1), and ROCK2 expression. We found that HJI effectively improved the ICP in the treatment groups. In addition, RhoA, ROCK1, and ROCK2 expression levels were increased upon BCNI-ED induction, and HJI successfully inhibited cavernosum fibrosis and the activation of RhoA/ROCK2 signaling. Overall, these results suggest that the effects of HJI in attenuating ED may be caused, at least in part, by the suppression of RhoA/ROCK2 signaling and alleviation of fibrosis. However, the precise mechanism surrounding this requires further investigation in future studies.

Comparison of the effects of pentoxifylline, simvastatin, tamoxifen, and losartan on cavernous bodies after penile fracture in rats: a stereological study

Penile fracture (PF) is described as a rupture and fibrosis of the cavernous bodies. This study aimed to collect quantitative data on the impacts of pentoxifylline, simvastatin, tamoxifen, and losartan on cavernous body structure after PF. The rats were divided into six groups. The control group received anesthesia and incision without actual PF. The other groups (second to sixth) underwent PF induction in addition to administration of distilled water, pentoxifylline (200 mg/kg/day), simvastatin (40 mg/kg/day), tamoxifen (10 mg/kg/day), and losartan (20 mg/kg/day) for 8 weeks. The volumes of cavernous bodies, collagen bundles, and vessels and number of fibroblasts were increased significantly in the PF group in comparison to the control rats (p < 0.01), indicating a fibrotic process. Moreover, the mean volume of the cavernous bodies decreased in the groups with PF that received pentoxifylline, simvastatin, tamoxifen, or losartan when compared with the PF group. However, the volumes of the collagen bundles and vessels as well as the population of fibroblasts remained at the control level or even lower in PF plus pentoxifylline, simvastatin, tamoxifen, and losartan groups. This indicated the anti-fibrotic effects of the four drugs. It can be concluded that pentoxifylline, simvastatin, tamoxifen, and losartan could reduce fibrosis activities by minimizing the formation of collagen bundles and vessels as well as decreasing the population of fibroblasts 8 weeks after PF. Yet, losartan brought about a better outcome compared with the other chemicals.