Effectiveness of intracavernous delivery of adenovirus encoding Smad7 gene on erectile function in a mouse model of cavernous nerve injury

Testosterone attenuates senile cavernous fibrosis by regulating TGFβR1 and galectin-1 signaling pathways through miR-22-3p

Erectile dysfunction (ED) is a major health problem affecting a large proportion of the general population. Testosterone also plays a key role in sexual dysfunction. In this study, we found that testosterone can inhibit cavernous fibrosis by affecting the expression of miR-22-3p, providing a new basis for research and treatment of ED. Old and young rats were used to study the effects of testosterone on cavernous fibrosis. Hematoxylin and eosin (HE) and Masson's staining were used to observe the cavernous tissue. A luciferase assay was used to analyze the relationship between the miR-22-3p, TGFβR1, and Galectin-1 signaling pathways. CCK-8 and flow cytometry were used to detect the proliferation and apoptosis rates of cavernosum smooth muscle cells (CSMCs) following testosterone intervention. Immunohistochemical analysis was performed to examine the positive rate of caspase 3 and Ki67. IF was used to analyze the expression of collagen IV, MMP2, and α-SMA. The levels of GnRH, tT, LH, and F-TESTO in old rats increased after testosterone intervention. miR-22-3p inhibits the expression of TGFβR1 and Galectin-1. The protein expression of TGFβR1, Galectin-1, SMAD2, and p-SMAD2 was reduced by testosterone. The expression levels of α-SMA, collagen I, collagen IV, FN, and MMP2 in the cavernous tissues of old rats treated with testosterone were significantly reduced. The levels of caspase 3 and collagen IV decreased, and the levels of MMP2, Ki67, and α-SMA increased. Testosterone and miR-22-3p inhibit CSMC apoptosis and promote cell proliferation. Testosterone promoted the expression of miR-22-3p to interfere with the expression of the cavernous TGFβR1 and Galectin-1 signaling pathways. Testosterone can reduce cavernous fibrosis during the treatment of functional ED.

Molecular pathogenesis and treatment of cavernous nerve injury-induced erectile dysfunction: A narrative review

Introduction: Erectile dysfunction (ED) is a common complication after radical prostatectomy (RP), and it seriously affects the quality of life in patients and their partners. The primary trigger of postoperative ED is surgical injury to the cavernous nerves that control penile erection and run along the anterolateral aspect of the prostate. Despite the introduction and ongoing innovation of nerve-sparing techniques, a significant number of patients still suffer from moderate cavernous nerve injury (CNI), which is thought to be transient and reversible. Therefore, early postoperative penile rehabilitation therapy may salvage patients’ erectile function by promoting cavernous nerve regeneration and preventing penile structural alterations.

Aims: To present a comprehensive overview of the current molecular pathogenesis of CNI-induced ED, as well as novel therapeutic strategies and their potential mechanisms.

Methods: A literature search was performed using PubMed. Search terms included erectile dysfunction, cavernous nerve injury, pathogenesis, pathway, and treatment.

Results: The NOS/NO pathway, oxidative stress-related pathway, RhoA/ROCK pathway, transforming growth factor-β (TGF-β), sonic hedgehog (Shh), and hydrogen sulfide (H2S) are involved in the molecular pathogenesis of CNI-induced ED. Multiple neurotrophins, including brain-derived nerve growth factor (BDNF), glial cell line-derived neurotrophic factor (GDNF), and neurturin (NTN), were found to promote cavernous nerve regeneration. Emerging therapeutic approaches can be roughly summarized into four categories, namely small molecule and drug, stem cell-based therapy (SCT), micro-energy therapy and platelet-rich plasma (PRP) therapy.

Conclusion: These pathways collectively lead to the irreversible damage to the penile structure after CNI. The combined early rehabilitation strategies of promoting upstream nerve regeneration and recovering abnormal molecular signals of downstream penis are presumed to save patients’ erectile function after RP. In future studies, the cross-talk between these molecular pathways needs to be further clarified, and the questions of how denervation injury induces the molecular alterations in the penis also need to be addressed.

An update on the current status and future prospects of erectile dysfunction following radical prostatectomy

BACKGROUND

Radical prostatectomy (RP) and radiation treatment are standard options for localized prostate cancer. Even though nerve-sparing techniques have been increasingly utilized in RP, erectile dysfunction (ED) due to neuropraxia remains a frequent complication. Erectile function recovery rates after RP remain unsatisfactory, and many men still suffer despite the availability of various therapies.

OBJECTIVE

This systematic review aims to summarize the current treatments for post-RP-ED, assess the underlying pathological mechanisms, and emphasize promising therapeutic strategies based on the evidence from basic research.

METHOD

Evaluation and review of articles on the relevant topic published between 2010 and 2021, which are indexed and listed in the PubMed database.

RESULTS

Phosphodiesterase type 5 inhibitors, intracavernosal and intraurethral injections, vacuum erection devices, pelvic muscle training, and surgical procedures are utilized for penile rehabilitation. Clinical trials evaluating the efficacy of erectogenic drugs in this setting are conflicting and far from being conclusive. The use of androgen deprivation therapy in certain scenarios after RP further exacerbates the already problematic situation and emphasizes the need for effective treatment strategies.

CONCLUSION

This article is a detailed overview focusing on the pathophysiology and mechanism of the nerve injury developed during RP and a compilation of various strategies to induce cavernous nerve regeneration to improve erectile function (EF). These strategies include stem cell therapy, gene therapy, growth factors, low-intensity extracorporeal shockwave therapy, immunophilins, and various pharmacological approaches that have induced improvements in EF in experimental models of cavernous nerve injury. Many of the mentioned strategies can improve EF following RP if transformed into clinically applicable safe, and effective techniques with reproducible outcomes.

Loxin Reduced the Inflammatory Response in the Liver and the Aortic Fatty Streak Formation in Mice Fed with a High-Fat Diet

Oxidized low-density lipoprotein (ox-LDL) is the most harmful form of cholesterol associated with vascular atherosclerosis and hepatic injury, mainly due to inflammatory cell infiltration and subsequent severe tissue injury. Lox-1 is the central ox-LDL receptor expressed in endothelial and immune cells, its activation regulating inflammatory cytokines and chemotactic factor secretion. Recently, a Lox-1 truncated protein isoform lacking the ox-LDL binding domain named LOXIN has been described. We have previously shown that LOXIN overexpression blocked Lox-1-mediated ox-LDL internalization in human endothelial progenitor cells in vitro. However, the functional role of LOXIN in targeting inflammation or tissue injury in vivo remains unknown. In this study, we investigate whether LOXIN modulated the expression of Lox-1 and reduced the inflammatory response in a high-fat-diet mice model. Results indicate that human LOXIN blocks Lox-1 mediated uptake of ox-LDL in H4-II-E-C3 cells. Furthermore, in vivo experiments showed that overexpression of LOXIN reduced both fatty streak lesions in the aorta and inflammation and fibrosis in the liver. These findings were associated with the down-regulation of Lox-1 in endothelial cells. Then, LOXIN prevents hepatic and aortic tissue damage in vivo associated with reduced Lox-1 expression in endothelial cells. We encourage future research to understand better the underlying molecular mechanisms and potential therapeutic use of LOXIN.

Administration of H2S improves erectile dysfunction by inhibiting phenotypic modulation of corpus cavernosum smooth muscle in bilateral cavernous nerve injury rats

Phenotypic modulation of Corpus Cavernosum Smooth Muscle Cells (CCSMCs) is an important step in the development and progression of bilateral cavernous nerve injury induced erectile dysfunction (BCNI-ED). To investigate the effect of exogenous hydrogen sulfide (H2S) on the phenotypic modulation of CCSMCs in BCNI-ED rats, a total of 18 male Sprague-Dawley rats were equally divided into 3 groups, including sham-operated (Sham) group, BCNI group and BCNI treated with NaHS (BCNI + NaHS) group. The treated group received intraperitoneal injection of NaHS (100 μmol kg-1day-1) for 4 weeks starting day 1 postoperatively. Erectile function was measured by the ratio of intracavernous pressure (ICP)/mean arterial pressure (MAP), and relevant tissues were harvested for Immunohistochemistry, Hematoxylin and eosin (H&E), Masson's trichrome staining, H2S fluorescent probe WSP-1 and Western blot. The primary CCSMCs were isolated and pretreatment with NaHS before exposed to PDGF-BB (platelet-derived growth factor). Relative expression mRNA and protein of phenotypic biomarkers, RhoA, ROCK-1 and cell cycle proteins were detected. Cystathionine-β-synthase (CBS) and cystathionine-γ-lyase (CSE), 3-mercaptopyruvate sulfurtransferase (3-MST) and H2S levels in penile tissue was significantly decreased in the BCNI group compared with the Sham group. Compared with the BCNI group, administration of NaHS significantly increased the ratio of ICP/MAP, ratio of smooth muscle to collagen, expressions of a-SMA, calponin and decreased the expression of OPN, collagen-I, RhoA, ROCK1 in the penile tissue. PDGF-BB-treated CCSMCs exhibited higher expression of OPN, RhoA, ROCK1, and lower α-SMA, calponin, which were attenuated by NaHS pretreatment. NaHS suppressed RhoA/ROCK activity and decreased the expression of CDK2, Cyclin E1, while increased the expression of P27kip1 induced by PDGF-BB in CCSMCs. Taken together, this study indicated that exogenous H2S inhibited the phenotypic modulation of CCSMCs by suppressing RhoA/ROCK1 signaling and affecting its downstream factor, CDK2, Cyclin E1, P27kip1, thereby improved BCNI rat erectile function.

[Exogenous hydrogen sulfide improves erectile dysfunction by inhibiting apoptosis of corpus cavernosum smooth muscle cells in rats with cavernous nerve injury]

OBJECTIVE

To explore the effects of exogenous hydrogen sulfide (H2S) on apoptosis of corpus cavernosum smooth muscle cells (CCSMCs) and erectile dysfunction (ED) in rats with bilateral cavernous nerve injury (BCNI).

METHODS

Twentyfour male SD rats were randomly divided into 3 groups (n=8):sham operation group, bilateral cavernous nerve injury group (BCNI group) and H2S intervention group (BCNI+NaHS group). In BCNI and BCNI+NaHS groups, BCNI was induced by clamp injury of the bilateral cavernous nerves, and the rats were subjected to daily intraperitoneal injection of normal saline and 100 μmol/kg NaHS solution for 4 weeks, respectively. After the treatment, the intracavernous pressure (ICP) and mean arterial pressure (MAP), ) of the rats were measured. Western blotting was used to detect the expressions of cystathionine β synthetase (CBS), cystathionine γ lyase (CSE), α-SMA, collagen-I, caspase-3, Bax and Bcl-2 in the penile cavernous tissue, and the expressions of CBS and CSE were also detected immunohistochemically. The ratio of cavernous smooth muscle to collagen was detected using Masson's Trichrome staining. The apoptosis level of CCSMC was detected by TUNEL + α-SMA immunofluorescence double staining.

RESULTS

After 4 weeks of treatment, the rats in BCNI+NaHS group showed a significantly higher ICP/MAP ratio than those in BCNI group (P < 0.05). The results of Masson's Trichrome staining showed that the ratio of cavernous smooth muscle/collagen was significantly higher in BCNI + NaHS group than in BCNI group (P < 0.05). Western blotting showed a significantly higher expression of α-SMA protein but a lower expression of collagen-I protein in BCNI + NaHS group than in BCNI group (P < 0.05). TUNEL+α-SMA immunofluorescence double staining revealed a significantly lower number of apoptotic CCSMCs in BCNI+NaHS group than in BCNI group (P < 0.05). Compared with those in BCNI group, the rats in BCNI+NaHS group had significantly decreased expressions of caspase-3 and Bax proteins (P < 0.05) with significantly enhanced Bcl-2 protein expression and an increased Bcl-2/Bax ratio (P < 0.05). The expressions of CBS and CSE were significantly lower in BCNI group than in the other two groups (P < 0.05).

CONCLUSIONS

Exogenous H2S enhance the expression of the classic apoptotic protein Bcl-2 and reduces apoptosis of CCSMC to improve the erectile function in rats with BCNI.

A potential treatment of low intensity pulsed ultrasound on cavernous nerve injury for erectile dysfunction

Erectile dysfunction after nerve injury is a common disease after radical prostatectomy. Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin family, which plays an important role in the survival of existing neurons, the differentiation of new neurons, and synaptic plasticity. It has been demonstrated that low-intensity pulsed ultrasound (LIPUS) accelerates bone healing and axonal regeneration after injury. LIPUS may also be able to stimulate neuronal activity and enhance the levels of neurotrophic factors. Evidence suggests that elevated levels of BDNF in the brain have protective effects against neurodegenerative diseases. Previous studies have shown that the treatment on cavernous nerve injury repair, and protective effect plus neuro-regeneration effect by low-intensity pulsed ultrasound. They shared the similar mechanism including several trophic factors stimulation, Pl3K/akt pathway activation, and anti-fibrosis mechanism. We hypothesized that due to its combined neuroregenerative and protective effects, the non-invasive and easy-to-use method of LIPUS stimulation could have a therapeutic effect on erectile dysfunction stemming from cavernous nerve injury.

Maintenance of the contractile phenotype in corpus cavernosum smooth muscle cells by Myocardin gene therapy ameliorates erectile dysfunction in bilateral cavernous nerve injury rats

The pathophysiology of erectile dysfunction post radical prostatectomy is not clearly clarified, and the low efficacy of traditional PDE5i treatment remains a major complaint in contemporary practice. This study aimed to demonstrate phenotypic modulation in bilateral cavernous nerve injury (BCNI) rats within 7 days, and subsequently validate gene therapy with Myocardin (Mycod) by maintaining a contractile phenotype in corpus cavernosum smooth muscle cells. Initially, 36 male rats were randomly divided into BCNI and negative control (NC) groups for histological and phenotypic molecular measurements at 3, 5, and 7 days. Afterwards, an additional 30 rats received a single intra-cavernous injection of 50 μL PBS, Ad-Myocd (1 × 1011  pfu/ml) or Ad-vector for 10 animals each, namely the NC+PBS, BCNI+Ad-Myocd, and BCNI+Ad-vector groups. Finally, the validity and mechanism of Myocd transfection was explored at 21 days in vivo and 48 h in vitro. Western blotting showed canonical declines in Myocd, α-SMA, and Calponin expression, as well as elevated Osteopontin (OPN) expression, before corporeal morphological and SM-to-collagen ratio changes at day 5 after injury. Overexpression of Myocd maintained the contractile phenotype of corpus cavernosum smooth muscle cells, ameliorated bilateral cavernous nerve injury rat erectile dysfunction, as well as promoted cell contractility and suppressed proliferative capacity. Simultaneously, confocal imaging revealed up-regulation and co-localization of serum response factor in gene-transferred cells. In conclusion, our study is the first to investigate corpus cavernosum smooth muscle cells phenotypes in the early stages of cavernous injury model rats, and Myocd reversed phenotypic modulation by activating serum response factor. The experimental results demonstrated the validity of gene therapy for erectile dysfunction.

Research in pharmacotherapy for erectile dysfunction

Although oral phosphodiesterase-5 (PDE5) inhibitors are generally accepted as an effective therapy for erectile dysfunction (ED), men with ED from diabetes or radical prostatectomy respond poorly to these drugs. Many researchers have tried to develop novel therapeutics that target alternative molecular pathways. A group of therapeutics belongs to centrally acting agents that target dopamine and melanocortin receptors. The other one is the peripherally acting agents that target soluble guanylate cyclase, Rho-kinase pathway, and Maxi-K channel, etc. Also, a variety of preclinical studies by the application of biotherapies in the concept of therapeutic angiogenesis or neural regeneration as well as anti-fibrosis to regenerate damaged erectile tissue have been reported. This article will address the current therapeutic targets for ED under clinical or preclinical development, including pharmacotherapy and biotherapy which comprises protein therapy and gene therapy. In spite of numerous clinical trials that target alternative pathways, these agents have yet to reach the market. The results from preclinical studies targeting therapeutic angiogenesis, neural regeneration, and anti-fibrosis are promising.

Effect of SMAD7 gene overexpression on TGF-β1-induced profibrotic responses in fibroblasts derived from Peyronie's plaque

Transforming growth factor-β1 (TGF-β1) has been identified as one of the most important fibrogenic cytokines associated with Peyronie's disease (PD). The mothers against decapentaplegic homolog 7 (SMAD7) is an inhibitory Smad protein that blocks TGF-β signaling pathway. The aim of this study was to examine the anti-fibrotic effect of the SMAD7 gene in primary fibroblasts derived from human PD plaques. PD fibroblasts were pretreated with the SMAD7 gene and then stimulated with TGF-β1. Treated fibroblasts were used for Western blotting, fluorescent immunocytochemistry, hydroxyproline determination, and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling assays. Overexpression of the SMAD7 gene inhibited TGF-β1-induced phosphorylation and nuclear translocation of SMAD2 and SMAD3, transdifferentiation of fibroblasts into myofibroblasts, and quashed TGF-β1-induced production of extracellular matrix protein and hydroxyproline. Overexpression of the SMAD7 gene decreased the expression of cyclin D1 (a positive cell cycle regulator) and induced the expression of poly (ADP-ribose) polymerase 1, which is known to terminate Smad-mediated transcription, in PD fibroblasts. These findings suggest that the blocking of the TGF-β pathway by use of SMAD7 may be a promising therapeutic strategy for the treatment of PD.

Hepatocyte growth factor-modified adipose tissue-derived stem cells improve erectile function in streptozotocin-induced diabetic rats

TGFβ1-Smad signaling pathway is closely related to various tissues fibrosis. Hepatocyte growth factor (HGF) has been shown to antagonize TGFβ1-Smad signaling and may improve kidney tissue fibrosis in diabetic models. Penile fibrosis is a pathological condition which occurs during diabetic erectile dysfunction (ED). The aim of this study was to examine the effect of the treatment of ED in diabetic rats with a combination of HGF and adipose tissue-derived stem cells (ADSC). In this diabetes model, rats were injected intraperitoneally with 60 mg streptozotocin (STZ) to induce diabetes. Three months later, the diabetic rats were divided into a negative control(NC) group, an ADSC-treated group and an ADSC + HGF-treated group while normal rats were assigned into a sham group. Rats in the sham and NC groups were injected in the corpus cavernosum with phosphate-buffered saline, while rats in the other groups were injected with either ADSC or ADSC + HGF. One month later, erectile function was examined in each group and penile tissues were collected for experiments. The expression of smooth muscle actin (SMA) and platelet-endothelial cell adhesion molecule-1 (PECAM-1) was analyzed by Western blotting. The smooth muscle and collagen deposition in corpus cavernosum was evaluated by Masson staining, while endothelial changes were assessed immunohistochemically. Cell apoptosis was detected by the TdT-mediated dUTP nick-end labeling (TUNEL) assay. The results revealed that ADSC alone can significantly improve erectile function in diabetic rats, but in combination with HGF the improvement was more prominent, showing higher content of smooth muscle and endothelial cells and lower cell apoptotic index in corpus cavernosum. Treatment with HGF can significantly enhance the beneficial effect of ADSC on erectile function in diabetic rats, and this effect might be closely related to the down-regulation of TGFβ1-Smad signaling.