Intracavernosal Injection of Vascular Endothelial Growth Factor Improves Erectile Function in Aged Rats

Radial Type Low-Intensity Extracorporeal Shockwave Therapy Enhances Penile Microvascular Perfusion in an Aging Rat Model: A Novel Interventional Strategy to Treat Erectile Dysfunction

PURPOSE

Physiological aging is associated with microvascular dysfunction, including in the penis, and this may contribute to age-related erectile dysfunction (ED). Low-intensity extracorporeal shockwave therapy (Li-ESWT) is a non-invasive intervention for ED, but its effect on penile microvascular function, remains unclear. Our objectives are to (i) evaluate the effect of Li-ESWT (specifically radial type ESWT [rESWT]) on penile microvascular perfusion (PMP) in aging rats, (ii) elucidate a possible mechanism, and (iii) evaluate its impact on angiogenic and smooth muscle biomarkers in cavernosal tissue.

MATERIALS AND METHODS

Male rats (n=9; 15-18 months) were anesthetized and subjected to rESWT while monitoring PMP. The nitric oxide (NO) pathway involvement was assessed by measuring the effect of rESWT on PMP following an intracavernosal injection of N(G)-nitroarginine methyl ester (L-NAME) (NO synthase inhibitor). To elucidate the cellular mechanism, another group of rats received repeated rESWT (n=4) or no treatment (n=4) three times/week for two weeks. Rats were euthanized at the end of the study and penile tissues were analyzed for angiogenic markers (vascular endothelial growth factor-A [VEGF-A], endothelial nitric oxide synthase [eNOS]) and smooth muscle content (α-actin) using immunostaining, Western blot, and quantitative polymerase chain reaction (qPCR).

RESULTS

rESWT resulted in more than a 2-fold increase in PMP (from 68.5 arbitrary units; 163.7 AU). L-NAME injection produced a <40%-50% decrease (185.3 to 101.0 AU) in rESWT-induced PMP response. Immunostaining revealed increased α-actin, eNOS, and VEGF-A in the cavernosum and these findings were confirmed by qPCR and Western blot results.

CONCLUSIONS

rESWT improved PMP, which may be mediated via increased VEGF expression, which stimulates the NO/cyclic guanosine monophosphate pathway, resulting in sustained PMP. rESWT devices could offer a safe, non-invasive treatment for age-related ED.

Regenerative therapies as a potential treatment of erectile dysfunction

Erectile dysfunction (ED) is the most common sexual dysfunction disease in adult males. ED can be caused by many factors, such as vascular disease, neuropathy, metabolic disturbances, psychosocial causes, and side effects of medications. Although current oral phosphodiesterase type 5 inhibitors can achieve a certain effect, they cause temporary dilatation of blood vessels with no curative treatment effects. Emerging targeted technologies, such as stem cell therapy, protein therapy, and low-intensity extracorporeal shock wave therapy (Li-ESWT), are being used to achieve more natural and long-lasting effects in treating ED. However, the development and application of these therapeutic methods are still in their infancy, and their pharmacological pathways and specific mechanisms have not been fully discovered. This article reviews the preclinical basic research progress of stem cells, proteins, and Li-ESWT therapy, as well as the current status of clinical application of Li-ESWT therapy.

Red Wine and Sexual Function in Men: An Original Point of View

Red wine is a rich source of nutrients whose biological properties have inspired numerous scientific studies. Indeed, it has been widely reported that there is a correlation between the positive health effects of moderate consumption of red wine and its phenolic content, which, due to its antioxidant activity, has proved to be useful in the improvement of various diseases, such as cardiovascular diseases, metabolic syndrome, cognitive disorders, depression, and cancer. It is a common opinion that the antioxidant activity of red wine is to be ascribed to its entire content of polyphenols, which act synergistically and not as a single component. Furthermore, this health-promoting effect of red wine can also be linked to its ethanol content, which has shown a wide array of biological properties. Beyond this evidence, very little is known about a possible correlation between moderate consumption of red wine and male sexual function. This brief review aimed to evaluate the effects of moderate consumption of red wine on erectile function. To accomplish this, Pubmed and Google Scholar databases were searched to retrieve the most relevant studies on this topic. The evidence so far collected has shown that red wine, if consumed in moderation, can be potentially beneficial for patients with erectile dysfunction as well as can positively influence reproductive function through mechanisms that depend on the vasorelaxant properties of red wine and its antioxidant properties.

Effects of Next-Generation Low-Energy Extracorporeal Shockwave Therapy on Erectile Dysfunction in an Animal Model of Diabetes

Purpose

Gene therapy, stem cell therapy, and low-energy extracorporeal shockwave therapy (ESWT) have been investigated as treatments for refractory erectile dysfunction (ED), but inconclusive evidence has been obtained. We investigated the effect of a next-generation electromagnetic cylinder ESWT device on an animal model of ED.

Materials and Methods

Diabetes mellitus (DM)-induced rats were divided into 3 groups: group 1, control; group 2, DM; and group 3, DM+ESWT. Rats were treated with ESWT 3 times a week for 2 weeks. After the treatment course, intracavernous pressure was measured and the corpus cavernosum and cavernous nerve were evaluated.

Results

In the DM group, all parameters predicted to be significantly lower in the ED model had statistically significantly decreased (p<0.01). As a measurement of erectile function, intracavernous pressure was evaluated. The DM+ESWT group exhibited significantly restored erectile function compared to the DM group (p<0.05). Moreover, ESWT treatment restored smooth muscle content, as assessed by Masson's trichrome staining (p<0.05). Finally, corporal tissue and the dorsal nerve were evaluated by immunohistochemistry, Western blotting, and ELISA. After ESWT treatment, vascular endothelial growth factor (VEGF), endothelial nitric oxide synthase (eNOS), platelet endothelial cell adhesion molecule-1, cyclic guanosine monophosphate, and neuronal nitric oxide synthase (nNOS) expression levels were restored to levels in the DM group (p<0.05).

Conclusions

Electromagnetic cylinder ESWT device resulted in increased VEGF, nNOS, and eNOS expression; reduced smooth muscle atrophy; and increased endothelial cell regeneration in a DM-associated ED model. Our data suggest that safe and effective application could be possible in future clinical studies.

Aging and sexual health: getting to the problem

Erectile dysfunction (ED) is one of the most common disorders in male and is often associated with other age-related comorbidities. The aging process affects the structural organization and function of penile erectile components such as smooth muscle cell and vascular architecture. These modifications affect penile hemodynamics by impairing cavernosal smooth muscle cell relaxation, reducing penile elasticity, compliance and promoting fibrosis. This review aims to identify the mechanisms of ED in the penile aging process in experimental and clinical data. It also highlights areas that are in need of more research. The search strategies yielded total records screened from PubMed. Clarification of the molecular mechanisms that accompanies corpus cavernosum aging and aging-associated ED will aid new perspectives in the development of novel mechanism-based therapeutic approaches. Age is not a limiting factor for ED medical management, and it is never too late to treat. Hypogonadism should be managed regardless of age, and synergistic effects have been found during testosterone (T) replacement therapy when used along with oral phosphodiesterase-5 (PDE-5) inhibitors. Therefore, the clinical management of ED related to aging can be done by therapeutic interventions that include PDE-5 inhibitors, and other pharmacological treatments.

Anti-inflammatory and anti-fibrotic effects of annexin1 on erectile function after cavernous nerve injury in rats

The aim of this study was to investigate the effect of the anti-inflammatory and anti-fibrotic actions of ANX1 on erectile function (EF). Forty-eight male Wistar rats were randomly distributed into four equal groups: one group (sham operation-control) and three groups (bilateral cavernous nerve (CN) crush injury). Crush injury groups were treated prior to injury with an intravascular injection of either ANX1 (50 or 100 μg kg^-1) or vehicle. EF was assessed by CN electrical stimulation at 2 and 7 days after CN injury with histomorphometric and immunohistochemical analysis. ANX1 demonstrated functional preservation as the increase in intracavernous pressure (ICP). A dose-response relationship regarding the effect on penile tissue was confirmed, and preservation of the penile dorsal nerves and anti-apoptotic effects in the corpus cavernosum (real P-value vs injured control). ANX1 treatment prevented collagen deposition and smooth muscle loss in the penis. ANX1 normalized the expression of vascular endothelial growth factor and decreased tumor necrosis factor-α in the lumen of the blood vessels of the organ. ANX1 proved effective in preserving EF in a rat model of neurogenic erectile dysfunction. ANX1 treatment before CN injury in rats improved erectile recovery, enhanced vascular regeneration and preserved the micro-architecture of the corpus cavernosum. The clinical availability of this compound merits application in penile rehabilitation studies following radical prostatectomy.

Shengjing Capsule Improves Erectile Function Through Regulation of Nitric Oxide-induced Relaxation in Corpus Cavernosum Smooth Muscle in a Castrated Rat Model

OBJECTIVE

To evaluate the effects of Shengjing capsule on erectile function in a castrated rat model, and further to investigate the underlying molecular mechanism.

MATERIALS AND METHODS

Thirty male Sprague-Dawley rats were randomly divided into six groups (n = 5 per group), including sham group, castration group, testosterone replacement group, high-dose Shengjing capsule group, medium-dose Shengjing capsule group, and low-dose Shengjing capsule group. The weight of the body and androgen-sensitive organs, and the serum level of testosterone were assessed. Erectile function was evaluated using cavernous nerve electrical stimulation after treatment. Corpus cavernosum tissue was examined by Masson's trichrome staining, immunohistochemistry, quantitative reverse transcriptase-polymerase chain reaction, and Western blot.

RESULTS

Serum testosterone level, mean weights of body, and accessory sexual organs were not significantly different between Shengjing capsule treatment and the castration groups (P > .05 for all). Significant recovery of erectile function and the increased smooth muscle components were observed in the Shengjing capsule treatment group as compared with the castration group (P < .01 and P < .01, respectively). The gene and protein expression of 3 subtypes of nitric oxide synthase (NOS)-neuronal (nNOS), inducible (iNOS), and endothelial (eNOS) -in cavernous tissue in Shengjing capsule-treated rats were significantly higher than in the castration group (P < .05 for all). Phosphodiesterase type 5 messenger ribonucleic acid and protein expression in each group followed a trend similar to that of smooth muscle content.

CONCLUSION

These results show that Shengjing capsule improves the erectile function by protecting the smooth muscle content and enhancing NOS activity in penile tissues of castrated male rats.

Decrease of the insulin-like growth factor-1 bioavailability in spontaneously hypertensive rats with erectile dysfunction

We investigated the role of insulin-like growth factor-1 (IGF-1) in spontaneously hypertensive rats with erectile dysfunction. Firstly, we evaluated intracavernous pressure. The bioavailability of IGF-1 at both mRNA and protein levels were measured by quantitative real-time PCR and Western blot respectively. Then, cavernous cyclic guanosine monophosphate concentrations were detected by enzyme-linked immunosorbent assay. The cavernosal pressure was significantly decreased in the hypertensive and the propranolol treatment groups compared to the normal control group (P < 0.01). Cavernous IGF-1 bioavailability and the concentrations of cavernous cyclic guanosine monophosphate were both significantly decreased in the hypertensive and the propranolol treatment groups compared to the normal control group (P < 0.01). This study suggests that an obvious decrease in cavernous IGF-1 levels might play an important role in spontaneously hypertensive rats with erectile dysfunction.

In vitro and in vivo evaluation of tissue-cultured mountain ginseng on penile erection

Background

Progressed tissue culture techniques have allowed us to easily obtain mass products of tissue-cultured mountain ginseng over 100 yr old (TCMG-100). We investigated the effects of TCMG-100 extract on erectile function using in vitro and in vivo studies.

Methods

To examine the relaxation effects and mechanisms of action of TCMG-100 on rabbit cavernosal strips evaluated in an organ bath. To investigate the long-term treatment effect of TCMG-100, 8-wk administration was performed. After administration of TCMG-100, intracavernosal pressure, cyclic guanosine monophosphate and nitric oxide (NO) levels of cavernosal tissue, serum testosterone level, histological observation of collagen fiber, endothelium, smooth muscle cell, and transforming growth factor-β1 were investigated.

Results

TCMG-100 extract displayed dose-dependent relaxation effects on precontracted rabbit corporal smooth muscle. The TCMG-100-induced relaxation was significantly reduced by removing the endothelium, and treatment with an NO synthase inhibitor or NO scavenger. Eight weeks of TCMG-100 administration increased intracavernosal pressure in a rat model. The levels of cyclic guanosine monophosphate and NO in the corpus callosum and serum testosterone level were also increased by TCMG-100 treatment. Furthermore, histological evaluation of collagen, smooth muscle, and endothelium showed increases in endothelium and smooth muscle, and a decrease in transforming growth factor-β1 expression.

Conclusion

These relaxation effects on corporal smooth muscle and increased erectile function suggest that TCMG-100 might be used as an alternative herbal medicine to improve erectile function.

Combination Therapy Using Human Adipose-derived Stem Cells on the Cavernous Nerve and Low-energy Shockwaves on the Corpus Cavernosum in a Rat Model of Post-prostatectomy Erectile Dysfunction

OBJECTIVE

To investigate combined therapeutic efficacy of human adipose-derived stem cells (h-ADSCs) application on injured cavernous nerve and low-energy shockwave therapy (SWT) on the corpus cavernosum in a rat model of post-prostatectomy erectile dysfunction.

MATERIALS AND METHODS

Rats were randomly divided into 5 groups: control, bilateral cavernous nerve injury (BCNI), adipose-derived stem cell (ADSC) (BCNI group with h-ADSCs on the cavernous nerve), SWT (BCNI group with low-energy SWT on the corpus cavernosum), and ADSC/SWT (BCNI group with a combination of h-ADSCs and low-energy SWT). After 4 weeks, erectile function was assessed using intracavernosal pressure. The cavernous nerves and penile tissue were evaluated through immunostaining, Western blotting, and a cyclic guanosine monophosphate assay.

RESULTS

ADSC/SWT significantly improved intracavernosal pressure compared to the other experimental group. ADSC had significantly increased β-III tubulin expression of the cavernous nerve, and SWT had a markedly enhanced vascular endothelial growth factor expression in corpus cavernosum. The ADSC/SWT group had a significantly increased in alpha smooth muscle actin content (P < .05), neural nitric oxide synthase (nNOS) of the dorsal penile nerve (P < .05), endothelial nitric oxide synthase (eNOS) protein expression (P < .05), and cyclic guanosine monophosphate level (P < .05) compared to the ADSC or SWT alone group. In addition, ADSC/SWT reduces the apoptotic index in the corpus cavernosum.

CONCLUSION

In this study, h-ADSCs showed an effect on the recovery of injured cavernous nerve and low-energy SWT improved angiogenesis in the corpus cavernosum. The h-ADSCs combined with low-energy SWT showed beneficial effect on the recovery of erectile function in a rat model of postprostatectomy erectile dysfunction.

Effects of insulin-like growth factor-1 on the relaxation responses of the cavernous smooth muscle from aged rats

OBJECTIVE

The aim of this study was determine whether intracavernosal injection (ICI) of insulin-like growth factor-1 (IGF-1) protein can improve corpus cavernosal smooth muscle relaxation in aging rats.

MATERIALS AND METHODS

Ten young (4-month-old) and 30 old (24-month-old) Sprague-Dawley male rats were enrolled in the study. The old rats were divided into three groups: vehicle-only (n = 10), IGF-1 1 µg/kg (n = 10) and IGF-1 10 µg/kg treatment groups (n = 10). After 4 weeks of single IGF-1 injection treatment, strips of corporal tissue were precontracted with phenylephrine, and dose-response curves were generated to evaluate endothelial-dependent [acetylcholine (ACh)], endothelial-independent [sodium nitroprusside (SNP)] and electrical field stimulation (EFS) vasoreactivity. The changes in percentage of cavernosal smooth muscle and the concentration of nitric oxide (NO) in penile tissue were also evaluated.

RESULTS

After IGF-1 treatment, the vasoreactivity was significantly improved in both the 1 µg/kg and the 10 µg/kg treatment groups compared with the vehicle-only group at 4 weeks in response to ACh, SNP and EFS (all p < 0.05). The percentage of cavernosal smooth muscle was increased in the IGF-1 treatment groups. The NO concentrations were increased after IGF-1 treatment.

CONCLUSIONS

These data demonstrate that ICI of IGF-1 can improve vasoreactivity via endothelium-dependent and endothelial-independent mechanisms in the corpus cavernosum of the aging rat.

shRNA constructs targeting IGFBP-3 alleviate age related erectile dysfunction in the rat

PURPOSE

We investigated whether injecting shRNA constructs targeting IGFBP-3 in the penis of old rats would improve erectile function.

MATERIALS AND METHODS

The most validated IGFBP-3 shRNA plasmid vector (pGPU6/GFP/Neo-shIGFBP-3) was prepared and injected in penile corpus cavernosum tissue. A total of 30 old (age 24 months) male Sprague Dawley® rats were randomly divided into 3 groups, including 10 each that received phosphate buffered saline only (100 μl), pGPU6/GFP/Neo-shNC (100 μg) and the most validated plasmid constructs pGPU6/GFP/Neo-shIGFBP-3 (100 μg). At 4 weeks the erectile response was measured as intracavernous pressure. The percent of smooth muscle in corpus cavernosum tissue was evaluated. Nitric oxide synthase activity and the cGMP concentration in penile tissue were also analyzed. IGFBP-3 was estimated in penile tissue by Western blot, real-time reverse transcriptase-polymerase chain reaction and immunohistochemistry.

RESULTS

pGPU6/GFP/Neo-shIGFBP-3 corrected the impaired erectile response in aged rats compared with the response in those injected with phosphate buffered saline and pGPU6/GFP/Neo-shNC (each p <0.01). The percent of cavernous smooth muscle was increased in the pGPU6/GFP/Neo-shIGFBP-3 group. Nitric oxide synthase activity and the cGMP concentration were also significantly increased in rats treated with pGPU6/GFP/Neo-shIGFBP-3. IGFBP-3 shRNA effectively reduced IGFBP-3 mRNA and protein expression in penile corpus cavernosum tissue.

CONCLUSIONS

Decreasing IGFBP-3 expression by plasmid expressed shRNA improved erectile function in aged rats. The therapy may modulate smooth muscle integrity and increase the cGMP concentration. This may be a new direction for treating erectile dysfunction in clinical practice.

Intracavernous administration of bone marrow mononuclear cells: a new method of treating erectile dysfunction?

While PDE5 inhibitors have revolutionized treatment of ED, approximately 30% of patients are non-responsive. A significant cause of this is vascular and smooth muscle dysfunction, as well as nerve atrophy. Autologous administration of bone marrow mononuclear cells (BMMC) has been performed in over 2000 cardiac patients without adverse effects, for stimulation of angiogenesis/regeneration. Despite its ease of access, and dependence on effective vasculature for function, comparatively little has been perform in terms of BMMC therapy for ED. Here we outline the rationale for use of autologous BMMC in patients with ED, as well as provide early safety data on the first use of this procedure clinically.

The therapeutic role of VEGF-expressing muscle-derived stem cells in acute penile cavernosal injury

INTRODUCTION

Traumatic penile injury is one of the urological emergencies. Surgery and conservative management are major treatment methods but are always accompanied by many complications.

AIM

To investigate the feasibility of repairing cavernous tissues in acute rabbit penile cavernosal injury model with vascular endothelial growth factor (VEGF)-expressing muscle-derived stem cells (MDSCs).

METHODS

MDSCs were isolated and transfected with hVEGF165 lentiviral gene vector in vitro. The expression of VEGF was confirmed using enzyme-linked immunosorbent assay (ELISA), Western blot, and real-time polymerase chain reaction (PCR) analyses. After animal models were constructed, animals were randomly divided into four groups, which were administrated with MDSCs/VEGF, MDSCs/vector, MDSCs, and normal saline, respectively. A month later, magnetic resonance imaging (MRI) and intracavernosal pressures (ICP) were performed on the animals. Then penile tissues were harvested and assayed with Western blot and immunohistochemistry.

MAIN OUTCOME MEASURES

Real-time PCR, Western blot, ELISA, immunohistochemistry, MRI, and ICP were performed in our experiments.

RESULTS

The expression of VEGF significantly increased in the VEGF-expressing MDSCs group compared with those in the MDSCs/vector and MDSCs groups. VEGF protein expression in the injury sites of cavernous tissues were significantly higher in the MDSCs/VEGF group compared with those in other three groups. Immunohistochemical staining showed that α-smooth muscle actin-positive cells, von Willebrand factor-positive cells and capillary density markedly increased in the MDSCs/VEGF group. Animals receiving MDSCs/VEGF showed a significant improvement in cavernosal contractile function and structural repair.

CONCLUSIONS

The transplantation of VEGF-expressing MDSCs could repair the actuely injured cavernous tissue. We believed that it could be a novel therapeutic strategy for acute rabbit penile cavernosal injury.

Up-regulation of VEGF by small activator RNA in human corpus cavernosum smooth muscle cells

INTRODUCTION

Functional failure of smooth muscle cells and endothelial cells in corpus cavernosum contributes to erectile dysfunction (ED) in aging men. Given that vascular endothelial growth factor (VEGF) may improve the function of smooth muscle cells and endothelial cells through different mechanisms, it is thus expected that increasing the expression of VEGF may have beneficial effects on erectile function.

AIM

The aim of this article is to explore the possibility that VEGF can be induced by ribonucleic acid activation (RNAa) technology, and VEGF induction by RNAa has the potential of treating ED.

METHODS

Primary human corpus cavernosum smooth muscle cells (CCSMCs) were isolated and cultured in vitro. The expression of α-smooth muscle actin was detected by immunohistochemistry to identify CCSMCs. A previously identified VEGF promoter-targeted small activator RNA (saRNA, double-stranded [ds]VEGF-706) and a negative control dsRNA were chemically synthesized. Cultured human CCSMCs were transfected with the saRNAs. The expression of VEGF messenger RNA (mRNA) and protein in transfected CCSMCs was evaluated by real-time polymerase chain reaction (RT-PCR) and Western blotting assay, respectively. Immunofluorescent staining was also used to confirm VEGF protein expression in cultured CCSMCs.

MAIN OUTCOME MEASURE

The expression of VEGF was assessed by RT quantitative PCR, Western blotting, and immunofluorescence assays.

RESULTS

After transfection, RT quantitative PCR analysis showed that the expression of VEGF mRNA was significantly induced in dsVEGF-706 transfected cells compared with cells receiving control treatments (P < 0.05). Consistent with mRNA induction, Western blotting and immunofluorescence analysis showed that VEGF protein expression was also induced by dsVEGF-706.

CONCLUSION

VEGF expression can be activated by RNAa in primary human CCSMCs, suggesting a potential application of RNAa-mediated VEGF activation for the treatment of ED.

Impact of systemically active neurohumoral factors on the erectile response of the rat

INTRODUCTION

Mean arterial pressure (MAP) and specific regulation of penile blood flow are the primary determinants of an erection. While this concept is well recognized, the differential relationship between systemically acting vasoactive factors on arterial pressure and erectile responses is not well described.

AIM

The aim of this study was to determine how the modification of systemic levels of neurohumoral factors impacts on the magnitude and efficiency of the erectile response.

MAIN OUTCOME MEASURES

The main outcome measures for this study are changes in MAP and intracavernosal pressure (ICP) following electrostimulation of the cavernous nerve.

METHODS

Anesthetized adult, male Sprague-Dawley rats were catheterized for measuring MAP (carotid), ICP, and drug administration (vena cava). Erections were induced via cavernous nerve electrostimulation. Vasoactive drug infusions were used to produce changes in MAP levels including: hexamethonium, angiotensin II (ANGII)±hexamethonium, methoxamine±hexamethonium, losartan, MAHMA NONOate, and terbutaline.

RESULTS

In general, ICP and MAP were linearly correlated regardless of treatment. Hexamethonium markedly dropped MAP and proportionately decreased the magnitude of the erectile response. ANGII or methoxamine given to hexamethonium-pretreated or untreated rats increased MAP similarly, but produced contrasting effects on erectile responses. ANGII-induced pressor responses were associated with increased erectile responses whereas all methoxamine treatments markedly decreased erectile responses. Depressor changes with losartan or terbutaline, but not MAHMA NONOate, also impacted negatively on the efficiency of the erectile responses at lower arterial pressures.

CONCLUSIONS

In general, the magnitude of the erectile responses was found to be dependent upon the level of MAP, although the mechanism by which arterial pressure was changed impacted substantially on the characteristics of the relationship. The major finding was that circulation-wide α-adrenoceptor stimulation was extremely deleterious to erectile responses whereas global stimulation of ANG II receptors was actually proerectile. Overall, the results indicate that neurohumoral specificity in systemic hemodynamic control is also critical in establishing the optimal erectile environment in rats.

Effects of androgen on the expression of vascular endothelial growth factor in the penile corpus cavernosum

OBJECTIVES

To investigate the effect of orchiectomy and androgen replacement on the expression of vascular endothelial growth factor (VEGF) in rat penile tissue.

MATERIAL AND METHODS

Adult male Sprague-Dawley rats (12 weeks old) were left intact (control) or surgically castrated. Orchiectomized rats were left untreated or received testosterone propionate (TP) for 7 days, beginning 1 or 2 weeks after castration. Erectile function was assessed by measuring intracavernosal pressure in response to cavernous nerve stimulation, and the expression of VEGF protein and mRNA was determined by immunohistochemistry, Western blot analysis, and reverse transcriptase-polymerase chain reaction. Serum testosterone values were measured in each animal by radioimmunoassay.

RESULTS

Serum androgen levels decreased significantly in castrated animals, whereas TP injection normalized the serum levels of testosterone. Intracavernosal pressure was significantly decreased in untreated castrated rats (31.3 ± 15.7% at 2 weeks postcastration; 18.6 ± 4.6% at 3 weeks postcastration) compared with intact controls (58.0 ± 11.4% and 58.9 ± 8.2%, respectively). Erectile function was normalized in androgen-replaced rats, irrespective of treatment was initiation 1 or 2 weeks after orchiectomy. The expression of VEGF protein and mRNA was decreased in the corpus cavernosum of castrated animals compared with controls, whereas androgen replacement normalized the expression of VEGF. These results were consistently observed by all 3 methods of assessment.

CONCLUSIONS

These data suggest that androgen regulates the expression of VEGF in rat penile corpus cavernosum and confirms the importance of androgens in the maintenance of erectile function.

Transplantation of nonhematopoietic adult bone marrow stem/progenitor cells isolated by p75 nerve growth factor receptor into the penis rescues erectile function in a rat model of cavernous nerve injury

PURPOSE

Radical prostatectomy for prostate cancer frequently results in erectile dysfunction and decreased quality of life. We investigated the effects of transplanting nonhematopoietic adult bone marrow stem/progenitor cells (multipotent stromal cells) into the corpus cavernosum in a rat model of bilateral cavernous nerve crush injury.

MATERIALS AND METHODS

Multipotent stromal cells were isolated from the bone marrow of transgenic green fluorescent protein rats by plastic adherence (rat multipotent stromal cells) or magnetic activated cell sorting using antibodies against p75 low affinity nerve growth factor receptor (p75 derived multipotent stromal cells). Bilateral cavernous nerve crush injury was induced in adult male Sprague-Dawley rats. Immediately after injury 8 rats each were injected intracavernously with phosphate buffered saline (vehicle control), fibroblasts (cell control), rat multipotent stromal cells (cell treatment) or p75 derived multipotent stromal cells (cell treatment). Another 8 rats underwent sham operation (phosphate buffered saline injection). Four weeks after the procedures we assessed erectile function by measuring the intracavernous-to-mean arterial pressure ratio and total intracavernous pressure during cavernous nerve stimulation.

RESULTS

Intracavernous injection of p75 derived multipotent stromal cells after bilateral cavernous nerve crush injury resulted in a significantly higher mean intracavernous-to-mean arterial pressure ratio and total intracavernous pressure compared with all other groups except the sham operated group (p <0.05). Rats injected with typical multipotent stromal cells had partial erectile function rescue compared with animals that received p75 derived multipotent stromal cells. Fibroblast (cell control) and phosphate buffered saline (vehicle control) injection did not improve erectile function. Enzyme-linked immunosorbent assay suggested that basic fibroblast growth factor secreted by p75 derived multipotent stromal cells protected the cavernous nerve after bilateral cavernous nerve crush injury.

CONCLUSIONS

Transplantation of adult stem/progenitor cells may provide an effective treatment for erectile dysfunction after radical prostatectomy.

Does regular consumption of green tea influence expression of vascular endothelial growth factor and its receptor in aged rat erectile tissue? Possible implications for vasculogenic erectile dysfunction progression

Erectile dysfunction (ED) is a highly prevalent disease affecting millions of men worldwide with a tendency for widespread increase. ED is now considered an early manifestation of atherosclerosis and, consequently, a precursor of systemic vascular disease. Atherosclerosis and ED share potentially modifiable risk factors, as smoking or high-fat food intake, but it is unclear how regular consumption of anti-oxidant rich drinks, which exhibit recognised anti-atherosclerotic features, affects ED progression. The objective of this study was to evaluate the modulating effects of chronic consumption of catechin-rich beverages on the vascular structure of the rat corpus cavernosum, and how this could contribute to delay or prevention of the onset of ED. Male Wistar rats aged 12 months were treated with green tea (GT) or a green tea extract solution (GTE) as the only liquid source for 6 months. Consumption of GT and GTE led to decreased plasma androgen levels without any significant change in plasma lipid levels. A reduction in corpus cavernosum intracellular storage of lipids, associated with decreased expression of vascular endothelial growth factor (VEGF) and its receptor VEGFR2 in endothelial cells, was observed. Taken together, these results suggest diminished atherosclerotic progression in cavernous tissue. However, functional studies will be necessary to elucidate if catechin-rich beverages are useful compounds in the prevention of deleterious vascular events associated with ED. It was also demonstrated that regular consumption of catechins reduces atherosclerotic progression and mortality due to cardiovascular disease. The results reported here suggest diminished atherosclerotic progression in cavernous tissue in aged rats following chronic ingestion of catechin-rich beverages.

High cholesterol feeding in C57/Blc6 mice alters expression within the VEGF receptor-ligand family in corporal tissue

INTRODUCTION

Angiogenesis, the growth and proliferation of blood vessels from existing vascular structures, is mediated by many cytokine growth factors and receptors, among the most important are the vascular endothelial growth factor (VEGF) family.

AIM

Decreases in VEGF receptor signaling have been linked to abnormalities in vasoreactivity in corporal tissue, but it is unknown if alterations in the VEGF ligands and/or receptors contribute to this process.

MAIN OUTCOME MEASURES

We sought to determine changes in vasoreactivity and the expression of the family of VEGF ligands and receptors in corporal tissue with cholesterol feeding in C57BL6 mice. Methods. Twenty-four mice (N = 8/group) were fed a normal diet (Group 1) or a 1.25% high cholesterol diet for 4 (Group 2) or 12 (Group 3) weeks. Isometric tension studies were performed on corporal strips and dose response curves were generated to evaluate endothelium-dependent and endothelium-independent vasoreactivities. Levels of VEGF-A, B, C, D, VEGF receptors (VEGFRs) were detected by PCR (polymerase chain reaction) and/or western blot/enzyme-linked immunosorbent assay (ELISA). Endothelial and smooth muscle cell contents were determined by immunohistochemistry.

RESULTS

At 4 weeks there was a small but significant decrease in endothelium-dependent vasoreactivity. Both mRNA and protein levels of VEGFR-1 were decreased, while VEGF-B was increased in Group 2 vs. Group 1, with no change in VEGF-A or endothelial cell content. By 12 weeks, decreases in both endothelium-dependent and endothelium-independent vasoreactivity were evident with decrease in most VEGF ligands (except VEGF-B), receptors, and receptor signaling.

CONCLUSIONS

Cholesterol feeding in C57BL6 mice results in alterations in the VEGF receptor-ligand family that may initially serve to limit the degree of vascular injury but these adaptations fail with the continuation of cholesterol feeding.

Insulin-like growth factor-1 restores erectile function in aged rats: modulation the integrity of smooth muscle and nitric oxide-cyclic guanosine monophosphate signaling activity

INTRODUCTION

Insulin-like growth factor-1 (IGF-1) is one of the growth factors that have a wide range of biologic effects. We have confirmed that gene transfer of IGF-1 to the penis could improve erectile capacity. However, there are some limitations in gene therapies, such as toxicity or a risk of insertional mutagenesis. Protein treatment may be another choice for decreasing these risks.

AIM

To investigate whether intracavernosal injection of IGF-1 protein can restore erectile function in the aging rat.

MAIN OUTCOME MEASURES

Erectile responses, morphological changes, and nitric oxide-cyclic guanosine monophosphate (NO-cGMP) signaling pathways-related marker were determined.

METHODS

Ten young (4 months) and 30 old (24 months) Sprague-Dawley male rats were enrolled in this study. The old rats were divided into three groups: vehicle-only (N = 10), IGF-1 1 microg/kg (N = 10) and IGF-1 10 microg/kg treatment group (N = 10). After 4 and 8 weeks of single IGF-1 injection treatment, intracavernous pressure (ICP) responses with electrical stimulation to the cavernous nerve were evaluated. The percent of smooth muscle in corpus cavernosum tissue, the expression of mRNA and protein of endothelial nitric oxide synthase (eNOS) were also evaluated. The activity of nitric oxide synthase (NOS) and concentration of guanosine 3',5'-cyclic-monophosphate (cGMP) that act upon the major NO-cGMP signaling pathways in penile tissue were also analyzed.

RESULTS

After IGF-1 treatment, the ICP responses was significantly increased as the young control group in both the IGF-1 1 microg/kg and the IGF-1 10 microg/kg group compared with the vehicle-only group at 4 and 8 weeks (P < 0.05). Masson's trichrom staining showed the percentage of cavernosal smooth muscle was increased in IGF-1 treatment group. IGF-1 increased e-NOS expression. NOS activities and cGMP concentrations were also significantly increased in IGF-1 treatment rats.

CONCLUSIONS

IGF-1 improved erectile function in aged rats via restoration the integrity of smooth muscle of corpus cavernosum and modulation of NO-cGMP pathways.

Long-term treatment of erectile dysfunction with a phosphodiesterase-5 inhibitor and dose optimization based on nocturnal penile tumescence

OBJECTIVE

To test the hypothesis that a variable dosage of the oral phosphodiesterase type 5 (PDE5) inhibitor sildenafil (25, 50, 100 mg) or vardenafil (5, 10, 25 mg) determined according to results obtained from nocturnal penile tumescence and rigidity (NPTR, RigiScan), given nightly for 1 year, can improve spontaneous erectile function (EF) in men with mild-to-moderate arteriogenic erectile dysfunction (ED); this regimen was compared with a fixed daily dosage of sildenafil 25 mg or vardenafil 5 mg.

PATIENTS AND METHODS

In a prospective open-label, parallel-group trial 154 men with ED were randomized either to fixed low-dose sildenafil 25 mg or vardenafil 5 mg (group 1) or to the lowest erectile dosage of sildenafil (25, 50 or 100 mg) or vardenafil (5, 10 or 20 mg) (group 2) provoking an erectile event as measured by NPTR nightly for 1 year. The EF domain of the International Index of Erectile Function (IIEF) was assessed before and 1 year after the beginning of treatment, and at 4 weeks after ending treatment.

RESULTS

After 1 year, 27 of 63 (64%) evaluable men in group 1 had an EF domain score in the normal range, vs 46 of 61 (75%) men in group 2. After the subsequent 4-week wash-out phase, both groups continued to have improved EF domain scores; 22 of 63 (35%) men in group 1 still had a score in the normal range, whereas 38 of 61 (62%) in group 2 had a normal score. The EF domain score in group 1 and 2 improved significantly after 1 year of treatment, from 13.6 to 18.9, and 15.1 to 23.9, respectively (P < 0.01). After the subsequent 4-week wash-out phase, men from both groups maintained this significant level of EF, at 17.1 and 22.4, respectively (P < 0.05).

CONCLUSION

Nightly PDE5-inhibitor treatment 1 year in a dosage determined by NPTR measurements results in better EF than giving a fixed dosage of sildenafil (25 mg) or vardenafil (5 mg). This improvement persisted for >4 weeks beyond the end of treatment. The results from this open-label, randomized trial warrant verification under double-blind, placebo-controlled conditions.

Modulation of in vitro and in vivo angiogenesis by alternagin-C, a disintegrin-like protein from Bothrops alternatus snake venom and by a peptide derived from its sequence

We have previously demonstrated that alternagin-C (ALT-C), a disintegrin-like protein from the venom of the Brazilian snake Bothrops alternatus, induces human vascular endothelial cell (HUVEC) proliferation by up-regulating the expression of vascular endothelial growth factor (VEGF). Here, we show that ALT-C is also able to induce in vivo angiogenesis using the model of matrigel plug in nude mice. Fibroblast growth factor (FGF) alone or supplemented with ALT-C was mixed with melted matrigel and subcutaneously injected in nude mice. After two weeks, the matrigel plugs were removed and analyzed to verify endothelial cell migration and new vessel formation. ALT-C (1 and 10 ng) strongly induced endothelial cell migration as well as the formation of new vessels. However, in higher concentrations, ALT-C strongly inhibited angiogenesis. In low concentrations (1 and 10nM), ALT-C also up-regulates the expression of VEGF receptor 2 (VEGFR2, KDR) mostly after 48 h, but it did not affect VEGFR1 (Ftl-1) in HUVEC cells as demonstrated by real-time PCR analysis. However, in higher concentrations (100 nM) the expression of both receptors is down-regulated. A peptide derived from ALT-C primary structure also affects HUVEC proliferation in vitro and angiogenesis in vivo. In conclusion, the present study shows for the first time the in vivo angiogenesis induced by a disintegrin-like molecule and the modulation of VEGFRs as well.

Improved spontaneous erectile function in men with mild-to-moderate arteriogenic erectile dysfunction treated with a nightly dose of sildenafil for one year: a randomized trial

AIM

To test the hypothesis that sildenafil (50 mg nightly for one year) can improve spontaneous erectile function (EF) in men with mild-to-moderate arteriogenic erectile dysfunction (ED) responsive to erectogenic treatment.

METHODS

In a prospective open-label trial, 112 men with ED were randomized to sildenafil 50 mg nightly or sildenafil 50 or 100 mg as needed for 12 months, followed by one-month and 6-month non-medicated periods. Non-randomized, non-medicated men with ED were also assessed. The EF domain of the International Index of Erectile Function (IIEF EF) and the peak systolic velocity (PSV) of penile cavernous arteries were used to measure the efficacy.

RESULTS

After sildenafil treatment and a subsequent non-medicated month, IIEF EF was normal in 29 of 48 (60.4%, 95% confidence interval [CI]: 45.3-74.2%) of the nightly group vs. 4 of 49 (8.2%, 95% CI: 2.3-19.6%) of the as-needed group. PSV improved by 11.2 cm/s (95% CI: 4.7-21.4; P=0.012) in the nightly group but only by 3.4 cm/s (-5.1-14.7; P=0.435) in the as-needed group. IIEF EF normalized in 1 of 18 (5.6%, 95% CI: 0.1-27.3%) non-medicated men and the PSV declined slightly. Six months after treatment, the IIEF EF remained normal and PSV was stabilized in most (28/29, 97%) nightly group men who had initially normalized.

CONCLUSION

Sildenafil nightly for one year resulted in ED regression that persisted well beyond the end of treatment, so that spontaneous EF was characterized as normal on the IIEF in most men. The results from this open-label, randomized trial warrant verification under double-blind, placebo-controlled conditions.

Aging and Orchidectomy Modulate Expression of VEGF Receptors (Flt-1 and Flk-1) on Corpus Cavernosum of the Rat

Aging and hypogonadic states are known risk factors for erectile dysfunction (ED), contributing together to vascular damage of penile tissue. In the present study, VEGF-specific membrane receptor (VEGFR-1/Flt-1 and VEGFR-2/Flk-1) expression was studied by confocal immunofluorescence in the corpus cavernosum of control rats, rats aged 12 and 18 months, and orchidectomized Wistar rats (90 days of bilateral orchidectomy). Immunocytochemical results demonstrated VEGFR-2 expression restricted to the endothelium in both control and orchidectomized rats. Aged animals (12 and 18 months) presented enlarged vessels with intense VEGFR-2 endothelial staining. On the other hand, VEGFR-1 was demonstrated in smooth muscle fibers, particularly in those that surround vessel endothelium, the endothelial expression being very low in control and orchidectomized rats. However, in the aged rats, a shift resulting in a VEGFR-1 and VEGFR-2 co-localization in the endothelial cell was observed. The findings suggest an upregulation of VEGFR-1 in the corpora cavernosa during aging in the rat, which is evident from an increased expression by endothelial cells.