Transforming growth factor-beta1 (TGF-beta1) is sufficient to induce fibrosis of rabbit corpus cavernosum in vivo

Lipopolysaccharide-preconditioned allogeneic adipose-derived stem cells improve erectile function in a rat model of bilateral cavernous nerve injury

Background

Erectile dysfunction (ED) often occurs due to cavernous nerve injury (CNI) after colorectal surgery. Cell-based therapies have great potential for the treatment of CNI-related ED; however, it needs to be optimised. In this study, we explored the therapeutic effects of lipopolysaccharide-preconditioned allogeneic adipose-derived stem cells (L-ADSCs) on CNI-induced ED in rats.

Results

The results of this in vitro study revealed that low-dose lipopolysaccharide could increase the viability of ADSCs, inhibit caspase 3 activation induced by hydrogen peroxide and promote cell migration. Compared with the ADSC supernatant, the L-ADSC supernatant could better reduce fibrosis in the corpus cavernosum smooth muscle cells induced by transforming growth factor-beta 1 protein. In the in vivo study, it was compared to ADSCs therapy, where the L-ADSCs therapy indicated that could better improve erectile function by increasing smooth muscle content and alleviating penile fibrosis in rats 2 weeks after CNI. The outcome may be related to the increase in the hepatocyte growth factor content in the corpus cavernosum and myelin basic protein in the major pelvic ganglion.

Conclusions

L-ADSC treatment may be a promising approach for restoring erectile function after CNI.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12610-022-00156-w.

Evaluation of Bi-Layer Silk Fibroin Grafts for Penile Tunica Albuginea Repair in a Rabbit Corporoplasty Model

The use of autologous tissue grafts for tunica albuginea repair in Peyronie's disease and congenital chordee is often restricted by limited tissue availability and donor site morbidity, therefore new biomaterial options are needed. In this study, bi-layer silk fibroin (BLSF) scaffolds were investigated to support functional tissue regeneration of tunica albuginea in a rabbit corporoplasty model. Eighteen adult male, New Zealand white rabbits were randomized to nonsurgical controls (NSC, N = 3), or subjected to corporoplasty with BLSF grafts (N = 5); decellularized small intestinal submucosa (SIS) matrices (N = 5); or autologous tunica vaginalis (TV) flaps (N = 5). End-point evaluations were cavernosography, cavernosometry, histological, immunohistochemical, and histomorphometric assessments. Maximum intracorporal pressures (ICP) following papaverine-induced erection were similar between all groups. Eighty percent of rabbits repaired with BLSF scaffolds or TV flaps achieved full rigid erections, compared to 40% of SIS reconstructed animals. Five-minute peak erections were maintained in 60% of BLSF rabbits, compared to 20% of SIS and TV flap reconstructed rabbits. Graft perforation occurred in 60% of TV group at maximum ICP compared to 20% of BLSF cohort. Neotissues supported by SIS and BLSF scaffolds were composed of collagen type I and elastin fibers similar to NSC. SIS and TV flaps showed significantly elevated levels of corporal fibrosis relative to NSC with a corresponding decrease in corporal smooth muscle cells expressing contractile proteins. BLSF biomaterials represent emerging platforms for corporoplasty and produce superior functional and histological outcomes in comparison to TV flaps and SIS matrices for tunica albuginea repair.

Optimal vacuum erectile device therapy regimen for penile rehabilitation in a bilateral cavernous nerve crush rat model

BACKGROUND

Vacuum erectile device (VED) therapy has been widely used in penile rehabilitation after radical prostatectomy; however, there is no consensus on the best regimen.

OBJECTIVES

To explore an optimal VED therapy regimen in bilateral cavernous nerve crush (BCNC) rat model.

MATERIALS AND METHODS

Adult male rats were used to measure the effects of different durations (1-30 min) of VED treatment on penile length, penile blood gas analysis, and adverse effects. Forty-eight adult male rats were randomly divided into Sham, BCNC, and VED treatment groups (2-3-2-3 min, 4-3-3 min, 5-5 min, and 10 min). Penile length, erectile function, and side effects were detected after VED treatment. Histopathological staining and Western blotting were performed to explore the cellular and molecular changes.

RESULTS

Prolongation of the duration of VED treatment significantly decreased the penile oxygen saturation, partial oxygen pressure, and arterial blood ratio (P < 0.05). Compared with the BCNC group, all VED treatment regimens partially reversed BCNC-induced penile shortening and erectile dysfunction (P < 0.0001), with the 4-3-3-min and 5-5-min treatment groups exhibiting more significant improvement than the 10-min and 2-3-2-3-min treatment groups (P < 0.0001). The mechanism may be related to the up-regulation of the smooth muscle cell/collagen ratio, endothelial nitric oxide synthase, and α-smooth muscle actin (all P < 0.0001); and the down-regulation of hypoxia-inducible factor-1α, transforming growth factor-β1, and apoptosis (all P < 0.0001). The incidence of adverse effects in the 2-3-2-3-min treatment group was the highest.

DISCUSSION

The commonly used VED therapy regimens maintained erectile function and penile length of BCNC rat by relieving hypoxia and fibrosis, and no further benefits were observed with increased treatment frequency or prolonged treatment duration.

CONCLUSION

Two consecutive 5-min treatments with a short interval is the optimal VED therapy regimen for penile rehabilitation in BCNC rat model.

N-acetylcysteine maintains penile length and erectile function in bilateral cavernous nerve crush rat model by reducing penile fibrosis

Penile length shortening and erectile dysfunction are common complications after radical prostatectomy. Various methods have been used to maintain erectile function, but less attention has been paid to preserving penis length. N-acetylcysteine (NAC) has the effect of antioxidation and antifibrotic, which may be beneficial to improve those postoperative complications. This study investigated the effect of NAC on maintaining the penile length and the erectile function after bilateral cavernous nerve crush (BCNC) and its underlying mechanism. Twenty-four male rats were randomly divided into three groups: control group, BCNC group, and BCNC + NAC group. NAC or equal volume of saline was daily administrated by intragastric gavage for 4 weeks. The initial and end penile lengths were measured. Intracavernosal pressure/mean arterial pressure (ICP/MAP) ratio was calculated to assess erectile function. Hematoxylin–eosin staining, Masson's trichrome staining, immunohistochemistry, and Western blot were performed to explore cellular and molecular changes of the penis. Compared to the BCNC group, the penile length, ICP/MAP ratio and smooth muscle/collagen ratio in the BCNC + NAC group were improved significantly (all P < 0.05), and the expressions of endothelial nitric oxide synthase, α-smooth muscle actin, glutathione, and glutathione peroxidase 1 were significantly increased after NAC treated (all P < 0.05), along with the decreased expressions of hypoxia-inducible factor-1α, transforming growth factor-β1, collagen I, collagen III, collagen IV, malonaldehyde, and lysine oxidase (all P < 0.05). This study demonstrated that NAC could maintain penile length and partly improve erectile function. Possible mechanism is directly and/or indirectly related to antihypoxic and antifibrosis.

Course of transforming growth factor ß1 in the systemic and cavernous blood of healthy males through different penile conditions

Studies on erectile dysfunction (ED) have revealed a relationship between smooth muscle atrophy and the accumulation of collagen in the corpus cavernosum (CC). Transforming growth factor ß1 (TGF ß1) is a cytokine which has been proposed to be involved in the fibrotic process in the CC. We aimed to evaluate the course of TGF ß1 in the systemic and cavernous blood of 17 healthy males through different phases of the sexual arousal response (exemplified by the penile conditions flaccidity, tumescence, rigidity and detumescence). An enzyme-linked immunoassay was used to measure the concentration of TGF ß1 (ng/ml) in both the systemic and cavernous blood at the stages of flaccidity, tumescence and detumescence. TGF levels were significantly higher in the cavernous compartment than in the systemic blood. A linear decrease was evident in the cavernous blood when the flaccid penis became tumescent (24.3 ± 14.5 to 13.9 ± 6.5) and rigid (to 8.7 ± 3.1). At detumescence, TGF increased to 18.3 ± 10.4. In contrast, the levels in the systemic circulation remained unchanged. The results are in support of the hypothesis that the concentration of TGF ß1 in the CC is regulated by adequate blood flow and oxygenation.

Fibrotic protein expression profiles in penile tissue of patients with erectile dysfunction

OBJECTIVE

To characterize transforming growth factor beta 1 (TGFβ1) and related signaling pathway proteins in a large cohort of human penile tissue (HPT) samples.

METHODS

HPT was collected from patients undergoing penile prosthesis implantation for erectile dysfunction (ED) and divided into the following 2 groups: postradical prostatectomy ED (RP-ED; n = 57) and organic ED (O-ED; n = 30). HPT from patients undergoing partial penectomy without ED was used as controls (CON; n = 6). Western blot analysis was performed to investigate the protein expressions of TGFβ1, thrombospondin 1 (TSP1; an activator of TGFβ1), fibronectin (an extracellular matrix glycoprotein induced by TGFβ1), and a family of transcriptional factors activated by TGFβ1 (Smad2, phospho-Smad2-serine-465/467 [pSmad2], Smad3, phospho-Smad3-serine-423/425 [pSmad3]).

RESULTS

Expressions of TGFβ1 and TSP1 were significantly higher in RP-ED (P <.05) and O-ED (P <.05) groups compared with that of the CON group and were not different between either ED groups. Expressions of Smad2, pSmad2, Smad3, pSmad3, and fibronectin were similar among all groups. Within the RP-ED group, a subgroup analysis showed that time from RP to penile prosthesis implantation was related to increased expression of pSmad2 (P <.05), and previous history of intracavernosal injection was related to increased expression of TGFβ1 (P <.05).

CONCLUSION

Our results demonstrate that TSP1- and TGFβ1-dependent fibrotic changes occur in penile tissue in patients with ED regardless of etiology. The unchanged expression of the Smad transcriptional factors may be reconciled by a Smad-independent downstream signaling pathway transmitting TGFβ1 signals.

P144, A TGF-β1 antagonist peptide, synergizes with sildenafil and enhances erectile response via amelioration of cavernosal fibrosis in diabetic rats

INTRODUCTION

Patients with diabetes exhibit more severe erectile dysfunction (ED) and are less responsive to first-line oral phosphodiesterase type 5 inhibitor (PDE5i). It has been suggested that increased collagen deposition and reduced smooth muscle content in the corpus cavernosum are important mechanisms for diabetes-associated ED and that transforming growth factor-β1 (TGF-β1) is a potent fibrotic factor responsible for the structural alterations in the corpus cavernosum.

AIMS

The aims of this study are to determine whether activation of TGF-β1 and its downstream pathways is responsible for the reduced efficacy of the PDE5is in diabetic ED via abnormalities in cavernosal structures and to investigate the synergistic effects of the TGF-β1 antagonist P144 and sildenafil on erectile response.

METHODS

Six weeks after inducting diabetes with streptozotocin in male Sprague-Dawley rats, age-matched control and diabetic rats were treated with vehicle, sildenafil, or P144 alone or in combination for 4 weeks, respectively.

MAIN OUTCOME MEASURES

Intracavernous pressure, dynamic infusion cavernosometry, and histological and molecular alterations of the corpus cavernosum were analyzed.

RESULTS

Diabetic rats exhibited a decreased erectile response, severe corporal veno-occlusive dysfunction (CVOD), and structural alterations including cavernosal fibrosis and decreased smooth muscle content. Expression and activation of TGF-β1 and its downstream Smad and non-Smad pathways increased in diabetic rats. Treatment with sildenafil showed modest effect on erectile response and a less suppressive effect on CVOD, cavernosal fibrosis, and molecular alterations. Treatment with P144 had lower effect on erectile response, even greatly improved the histological and molecular alterations and CVOD than sildenafil. The combined treatment with P144 and sildenafil effectively restored erectile response, CVOD, and histological and molecular alterations.

CONCLUSION

An insufficient suppressive effect of sildenafil on cavernosal fibrosis, severe CVOD, and TGF-β1 pathways was implicated in reduced efficacy of the PDE5i in diabetic ED. Treatment with P144 synergized sildenafil and significantly increased erectile response by the potential antifibrotic activity.

Recombinant lysyl oxidase propeptide protein inhibits growth and promotes apoptosis of pre-existing murine breast cancer xenografts

Lysyl oxidase propeptide (LOX-PP) ectopic overexpression inhibits the growth of cancer xenografts. Here the ability and mode of action of purified recombinant LOX-PP (rLOX-PP) protein to inhibit the growth of pre-existing xenografts was determined. Experimental approaches employed were direct intratumoral injection (i.t.) of rLOX-PP protein into murine breast cancer NF639 xenografts, and application of a slow release formulation of rLOX-PP implanted adjacent to tumors in NCR nu/nu mice (n = 10). Tumors were monitored for growth, and after sacrifice were subjected to immunohistochemical and Western blot analyses for several markers of proliferation, apoptosis, and for rLOX-PP itself. Direct i.t. injection of rLOX-PP significantly reduced tumor volume on days 20, 22 and 25 and tumor weight at harvest on day 25 by 30% compared to control. Implantation of beads preloaded with 35 micrograms rLOX-PP (n = 10) in vivo reduced tumor volume and weight at sacrifice when compared to empty beads (p<0.05). A 30% reduction of tumor volume on days 22 and 25 (p<0.05) and final tumor weight on day 25 (p<0.05) were observed with a reduced tumor growth rate of 60% after implantation. rLOX-PP significantly reduced the expression of proliferation markers and Erk1/2 MAP kinase activation, while prominent increases in apoptosis markers were observed. rLOX-PP was detected by immunohistochemistry in harvested rLOX-PP tumors, but not in controls. Data provide pre-clinical findings that support proof of principle for the therapeutic anti-cancer potential of rLOX-PP protein formulations.

Preclinical evidence for the benefits of penile rehabilitation therapy following nerve-sparing radical prostatectomy

Erectile dysfunction following radical prostatectomy remains a frequent problem despite the development of nerve-sparing techniques. This erectile dysfunction is believed to be neurogenic, enhanced by hypoxia-induced structural changes which result in additional veno-occlusive dysfunction. Recently, daily use of intracavernous vasoactive substances and oral use of PDE5-inhibitors have been clinically studied for treatment of postprostatectomy erectile dysfunction. Since these studies showed benefits of “penile rehabilitation therapy,” these effects have been studied in a preclinical setting. We reviewed experimental literature on erectile tissue preserving and neuroregenerative treatment strategies, and found that preservation of the erectile tissue by the use of intracavernous nitric oxide donors or vasoactive substances, oral PDE5-inhibitors, and hyperbaric oxygen therapy improved erectile function by antifibrotic effects and preservation of smooth muscle. Furthermore, neuroregenerative strategies using neuroimmunophilin ligands, neurotrophins, growth factors, and stem cell therapy show improved erectile function by preservation of NOS-containing nerve fibers.

Priapism: New concepts in the pathophysiology and new treatment strategies

Priapism is defined as prolonged and persistent erection of the penis without sexual stimulation. This is a poorly understood disease process, and we have little information on the etiology and pathophysiology of this erectile disorder. Two main types of priapism exist: low-flow (ischemic) and high-flow (nonischemic) priapism. When the physician first diagnoses which type of priapism exists, distinguishing the type of priapic event is paramount in order to choose the correct treatment options. Until recently, we had not sufficiently understood the pathogenesis of this erectile disorder and therefore, could not effectively manage its pathologic consequences of erectile tissue damage and erectile dysfunction. In this review, the proposed pathogenesis of ischemic priapism is reviewed, and a survey regarding novel treatment modalities is given.

Physiology of penile erection and pathophysiology of erectile dysfunction

This article reviews the physiology of penile erection, the components of erectile function, and the pathophysiology of erectile dysfunction. The molecular and clinical under-standing of erectile function continues to gain ground at a particularly fast rate. Advances in gene discovery have aided greatly in working knowledge of smooth muscle relaxation/contraction pathways. The understanding of the nitric oxide pathway has aided not only in the molecular understanding of the tumescence but also greatly in the therapy of erectile dysfunction.

Establishment of Penile Fibrosis Model in a Rat Using Mouse NIH 3T3 Fibroblasts Expressing Transforming Growth Factor β11

Transforming growth factor (TGF) beta1 has been suggested to have an important role in cavernous fibrosis and resultant erectile dysfunction. For further elucidation of TGFbeta1 signaling in association with cavernous fibrosis, we developed a rat model of cavernous fibrosis using TGFbeta1-producing NIH 3T3 fibroblasts (NIH 3T3-TGFbeta1). The NIH 3T3-TGFbeta1 cells were injected into male Sprague-Dawley rats intracavernously. Masson trichrome staining at 20 days postinjection showed multiple fibrous scars in the rats injected with the NIH 3T3-TGFbeta1 cells (group 3), whereas no histological evidence of cavernous fibrosis was found in the control rats (group 1) or the recombinant human TGFbeta1 protein-injected rats (group 2). Immunohistochemical staining revealed a higher expression of TGFbeta1 and its type II receptor in group 3 than in groups 1 and 2. Electrostimulation of the cavernous nerve revealed that the maximal intracavernous pressure was significantly lower in group 3 than in groups 1 and 2 (P < 0.01). The expression of transgenic TGFbeta1 mRNA continued to 10 days after injection of the cells. The NIH 3T3-TGFbeta1 cells sufficiently induced relatively long-lasting cavernous fibrosis. This novel animal model may contribute to future investigations of the pathogenesis of penile fibrosis associated with TGFbeta1 signaling and the development of new therapeutics targeting this pathway.

Pathophysiology of Erectile Dysfunction

INTRODUCTION

Multiple regulatory systems are involved in normal erectile function. Disruption of psychological, neurological, hormonal, vascular, and cavernosal factors, individually, or in combination, can induced erectile dysfunction (ED). The contribution of neurogenic, vascular, and cavernosal factors was thoroughly reviewed by our committee, while psychological and hormonal factors contributing to ED were evaluated by other committees.

AIM

To provide state of the art knowledge on the physiology of ED.

METHODS

An international consultation in collaboration with the major urology and sexual medicine associations assembled over 200 multidisciplinary experts from 60 countries into 17 committees. Committee members established specific objectives and scopes for various male and female sexual medicine topics. The recommendations concerning state-of-the-art knowledge in the respective sexual medicine topic represent the opinion of experts from five different continents developed in a process over a 2-year period. Concerning the pathophysiology of ED committee, there were seven experts from five different countries.

MAIN OUTCOME MEASURE

Expert opinion was based on the grading of evidence-based medical literature, widespread internal committee discussion, public presentation, and debate.

RESULTS

The epidemiology and classification of neurogenic ED was reviewed. The evidence for the association between vascular ED and atherosclerosis/hypercholesterolemia, hypertension and diabetes was evaluated. In addition, the pathophysiological mechanisms implicated in vascular ED were defined, including: arterial remodeling, increased vasoconstriction, impaired neurogenic vasodilatation, and impaired endothelium-dependent vasodilatation. The possible mechanisms underlying the association between chronic renal failure and ED were also evaluated as well as the evidence supporting the association of ED with various classes of medications.

CONCLUSIONS

A better understanding of how diseases interfere with the physiological mechanisms that regulate penile erection has been achieved over the last few years, which helps establish a strategy for the prevention and treatment of ED.

Vardenafil is effective and well-tolerated for treating erectile dysfunction in a broad population of men, irrespective of age

OBJECTIVES

To assess the efficacy and safety of vardenafil in the treatment of erectile dysfunction (ED) in men of different age groups.

PATIENTS AND METHODS

In a retrospective pooled subgroup analysis of randomized, double-blind, placebo-controlled studies, men from the general population with ED received either placebo or vardenafil 5, 10 or 20 mg over 12 weeks. Efficacy variables included the erectile function (EF) domain score from The International Index of Erectile Function, diary response rates to questions on vaginal penetration and maintenance of erection, and positive responses to the Global Assessment Question (GAQ) "Has the treatment you have been taking over the past 4 weeks improved your erections?'. The 1385 men were grouped by age (< 45, 45-64 and > or =65 years).

RESULTS

At 12 weeks the EF domain scores approached 20 with vardenafil and 14 with placebo in men aged > or = 65 years (P < 0.03 vardenafil 5 mg vs placebo, P < 0.001 vardenafil 10 and 20 mg vs placebo). The corresponding scores were 22 and 14 in men aged 45-64 years and up to 24 and 16 in those aged <45 years (P < 0.03 vardenafil 5 mg vs placebo, P < 0.001 vardenafil 10 and 20 mg vs placebo). Vardenafil generated positive GAQ responses in approximately 71%, 76% and 85% of men aged <45, 45-64 and > or = 65 years (P < or = 0.001 vardenafil vs placebo). The corresponding placebo rates were 23%, 25% and 34%. The most common treatment-emergent adverse events were headache, rhinitis, flushing and dyspepsia, which were mild to moderate, transient and unrelated to age.

CONCLUSION

Vardenafil is an effective and generally well-tolerated treatment for ED, irrespective of age.

Oxygenation Status of the Cavernosal Tissue after the Direct Action of the Vacuum Device

This study aims at comparing the oxygenation status of the cavernosal tissue after the direct action of the Vacuum device (VD) preceded or not by administration of Sildenafil. Patients and methods. We enrolled thirty patients who had undergone perineal radical prostatectomy. After four weeks from surgery we evaluated oxygen pressure (pO2), carbon dioxide pressure (pCO2) and O2 saturation in cavernosal blood. The pts were divided in 2 groups: 15 pts used only Vacuum device (first group), while the other 15 took Sildenafil 50 mg one hour before the exercise with VD (second group) for approximately 30 minutes without constriction band. Cavernous blood gas analyses pre- e post-exercising with the VD were repeated at the end of the complete 3-month rehabilitation program. The data obtained were processed by statistical analysis using the Student t test.

Results

During flaccidity at baseline, average levels of pO2, pCO2 and O2% saturation rates were respectively 30.07+/-2.91, 39.60+/-6.47, and 65.93+/-2.15 in the first group and 31.20+/-8.1, 42.64+/-7.64 and 52.87+/-8.95 in the second group. Mean values of pO2 rates increased after both treatments with higher oxygenation levels in the second group. At the end of the study pO2 and O2 saturation levels in the second group were found to be 68.5+/-6.87 (p>0.05) and 92.8+/- 2.66 (n.s.) versus levels of 63.8+/- 4.61 and 91.6+/-2.79 in the first group. No significant variations were found in partial CO2 pressure between the two groups (38.13+/-3.52 vs 38. 13+/-6.62).

Conclusions

In patients presenting with ED after radical prostatectomy, treatment with exercising of erectile tissue by means of an intermittent Vacuum device without constriction band can locally improve oxygenation levels. The addition of Sildenafil offers a further increase of oxygenation levels in the cavernosal tissue.

TGF-beta1 neutralizing antibodies decrease the fibrotic effects of ischemic priapism

The objective of this study was to evaluate the possible role of transforming growth factor beta 1 (TGF-beta1) antibodies (ab) for the prevention of fibrotic effects of priapism in a rat model. In total, 30 adult Sprague-Dawley rats were divided into five groups. Priapism with 6 h (group 1), priapism with 6 h+ab (group 2), priapism with 24 h (group 3), priapism with 24 h+ab (group 4) and control (group 5). Priapism was induced with a vacuum erection device and a rubber band was placed at the base of the erect penis. At 1 h after the initiation of priapism, TGF-beta1 antibodies were given intracavernosaly. All rats underwent electrical stimulation of the cavernous nerve after 8 weeks. Intracavernous and systemic blood pressures were measured during the procedure. Rats in group 1 showed significantly higher (intracavernosal pressure (ICP) pressures to cavernous nerve stimulation and had higher ICP/BP ratios when compared to other groups. Similarly, histopathologic examination revealed less fibrosis in group 2, compared with the other groups. Consequently, TGF-beta1 antibodies antagonise the fibrotic effects of TGF-beta1, especially in cases with duration of priapism less than 6 h.

The effect of PDE5 inhibition on the erectile function in streptozotocin-induced diabetic rats

The aim of this study was to assess the effect of phosphodiesterase 5 inhibitor, DA-8159, on erectile function throughout the quantitative analysis of vascular endothelial cell, smooth muscle (SM), TGF-beta1 expression in rat corpus cavernosum and measurement of intracavernous pressure (ICP) in diabetic rats. DA-8159 (0, 5, 10, 20 mg/kg) was administered orally once a day to diabetic rats. After 8 weeks, immunohistochemistry and computerized image analysis were performed to quantify the percent area within the Corpora Cavernosa occupied by the endothelial cells, SM cells and fibrotic tissues. ICP/mean arterial pressure (MAP) was also measured by electrostimulation of the cavernous nerve. Diabetic rats showed a significant decrease in the SM and endothelial cell content, and an increase in the TGF-beta1 expression level within the cavernosa areas compared to the normal rats. The mean cavernous SM, endothelial cell content and TGF-beta1 expression level were 9.7+/-0.7, 4.5+/-0.7 and 17.9+/-2.1%, respectively. DA-8159 prevented reduction of SM (12.3+/-0.4% (5 mg/kg), 13.8+/-0.4% (20 mg/kg)) and endothelial cell content (5.6+/-0.5% (5 mg/kg), 6.3+/-0.6% (20 mg/kg)). Immunoreactivity of TGF-beta1 and intracorporal fibrosis were also significantly lower in DA-8159-treated groups (11.8+/-1.2% (5 mg/kg), 9.5+/-1.1% (20 mg/kg)). Electrostimulation of the cavernous nerve induced significant increase in maximum ICP (62.2+/-13.6 mmHg in 10 mg/kg vs 37.5+/-17.5 mmHg in diabetic group) and area under the curve of the ratio of ICP/MAP (8891.09+/-1957 in 10 mg/kg vs 6315.87+/-2272 in diabetic group). These results suggest that subchronic treatment of DA-8159 can prevent the development of erectile dysfunction (ED), and provides a rationale for the use of DA-8159 as treatment of diabetic ED.

Expression of cavernous transforming growth factor-beta1 and its Type II Receptor in patients with erectile dysfunction

It has been hypothesized that transforming growth factor-beta1 (TGF-beta1) signalling is involved in erectile dysfunction (ED). This study was undertaken to elucidate in detail whether expression of TGF-beta1 and its type II receptor is clinically related to various causes of ED. Fifty-four patients with ED and 24 potent men were the subjects of this study. After multidisciplinary work-up, the ED was classified as psychogenic (n = 6), neurogenic (n = 15), or vasculogenic (n = 33). In every subject, percutaneous cavernous biopsy was performed using a Biopty gun. Masson's trichrome staining was used to quantitate collagen fibres and immunohistochemical staining to evaluate both TGF-beta1 and its type II receptor by scoring the intensity of immunoreactivity (score 0-6). Collagen fibres were significantly more abundant in men with vasculogenic ED (72.7 +/- 17.7%) than in control subjects (43.3 +/- 11.2%) or those with psychogenic (45.0 +/- 12.2%) or neurogenic (51.3 +/- 20.3%) ED (p < 0.01). Expression of TGF-beta1 was significantly greater in vasculogenic ED (4.3 +/- 1.3) than in the control subjects (2.4 +/- 0.9) or psychogenic ED (2.0 +/- 0.6) groups (p < 0.01). Type II receptor expression was also significantly increased in vasculogenic ED (3.9 +/- 1.3) compared with control (2.2 +/- 0.7) and psychogenic (2.2 +/- 0.8) or neurogenic (2.6 +/- 1.3) ED (p < 0.01). Of the ED groups, both the hyperlipidaemia and the atherosclerosis patients showed significantly more fibrosis than those without the condition (p < 0.05). The abundance of collagen fibres correlated well with both TGF-beta1 expression (gamma = 0.81; p < 0.001) and receptor II expression (gamma = 0.83; p < 0.001). These results suggest that TGF-beta1 and its receptor II pathway are involved in cavernous fibrosis and ED in man. Patients with vascular risk factors such as hyperlipidaemia and atherosclerosis are liable to ED by activation of this pathway.

Vasculogenic erectile dysfunction: newer therapeutic strategies

PURPOSE

Despite recent advances in therapy, reversal of vasculogenic erectile dysfunction (ED) is rarely possible. A review of vasculogenic ED may further our understanding of the underlying pathophysiology and help develop more effective curative therapy.

MATERIALS AND METHODS

We reviewed the mechanisms of vasculogenic erectile dysfunction and discuss the therapies currently available or being developed for possible future use.

RESULTS

Penile erection is a complex neurovascular phenomenon that may be affected by hypercholesterolemia, atherosclerotic vascular occlusive disease, veno-occlusive dysfunction and cavernosal fibrosis. Animal models of diffuse pelvic atherosclerosis can be maintained by feeding oral cholesterol and injuring the arterial endothelium. Impaired inflow may be addressed by penile revascularization but this strategy is applicable only in select cases. Neovascularization using vascular growth factors has recently been demonstrated to be feasible in animal models. Permanent reversal of impaired cavernosal relaxation requires control of hypercholesterolemia and lifestyle changes, such as smoking cessation. Cavernosal fibrosis may be reversible via some of the same approaches used in treating Peyronie's disease but to date little clinical success has been reported. Venous ligation appears to have a limited role in treating veno-occlusive dysfunction only in highly selected men with minimal cavernosal smooth muscle dysfunction. Hypoxemia, sleep apnea and respiratory failure may also affect erectile dysfunction. However, little attention has been paid to oxygen as therapy for ED.

CONCLUSIONS

Current therapy, while effective in circumventing vasculogenic ED, is relatively ineffective in permanently reversing the condition. Further research aimed at long-term treatment strategies in vasculogenic ED is needed.

Small intestinal submucosa as a tunica albuginea graft material

PURPOSE

We evaluated the morphological, immunological and functional response to small intestinal submucosa grafting of the tunica albuginea to determine its potential as a grafting material for penile surgery.

MATERIALS AND METHODS

Male New Zealand White rabbits underwent a sham procedure (6) or tunical excision and grafting with small intestinal submucosa (6). The erectile response to the intracavernous vasoactive agents sodium nitroprusside plus a papaverine, phentolamine and prostaglandin E1 combination (Sigma Chemical Co., St. Louis, Missouri) was evaluated 45-day postoperatively. The area under the graft was evaluated for stromal collagen and smooth muscle content by Masson's trichrome stain. Protein expression of smooth muscle specific alpha-actin and the inflammatory markers inducible nitric oxide synthase (NOS) and transforming growth factor-beta1 (TGF-beta1) was evaluated by immunohistochemical methods. Total RNA was extracted from the corpora cavernosum underlying the small intestinal submucosa graft and reverse transcriptase-polymerase chain reaction (RT-PCR) was done using an Access system (Promega, Madison, Wisconsin) with gene specific primers for inducible NOS, TGF-beta1 and vascular endothelial growth factor (VEGF).

RESULTS

Grafting of the tunica albuginea with small intestinal submucosa had no significant effect on the magnitude or duration of the erectile response to intracavernous vasoactive agents. Histological examination demonstrated no inflammatory changes in the tunica albuginea or corporeal tissue underlying the area of the small intestinal submucosa graft and there was no appreciable alteration in smooth muscle or collagen content. The 2 groups showed intense positive immunostaining to alpha-actin. Weak expression of TGF-beta1 predominantly associated with smooth muscle fibers was identified in the 2 groups of rabbits by immunostaining and RT-PCR. No significant inducible NOS was detected by immunostaining or RT-PCR in either group. Strong VEGF expression was observed in grafted rabbits. The most noticeable (3-fold) increase in expression was detected in splice variant 165.

CONCLUSIONS

Small intestinal submucosa grafting of the tunica albuginea preserves the duration and magnitude of the erectile response to vasoactive agents. This type of tunical grafting does not stimulate a significant inflammatory response, or cause corporeal fibrosis or loss of cavernous smooth muscle content. Stimulating VEGF may facilitate wound healing and the maintenance of normal erectile function.

Diabetes mellitus induces vaginal tissue fibrosis by TGF-beta 1 expression in the rat model

The commonly reported sexual problem in women with diabetes mellitus is lack of vaginal lubrication. It is our hypothesis that reduced vaginal lubrication in diabetic women may result from the structural changes of the vagina. The aim of this study was to investigate in the diabetic rat model the vaginal structures using histochemistry and the expression of TGF-beta 1 using immunohistochemistry. Twenty female Sprague-Dawley rats (200-210 g) were divided into two groups: control and experimental. The experimental group (n = 10) received intravenous injection of streptozotocin (50 mg/kg). After 4 weeks, blood glucose levels were measured, and the vagina of the rat was excised. Serial sections of the vagina were used to perform hematoxylin and eosin (H & E) and Masson's trichrome stains, and for immunohistochemistry to identify TGF-beta 1 expression. The mean blood glucose concentrations were 67 +/- 11 mg/dL (range; 50-85) in the control group and 522 +/- 61 mg/dl (range; 429-590) in the experimental group. In the diabetic animals, vaginal tissue revealed reduced epithelial layers and decreased vaginal submucosal vasculatures compared to the control animals. The collagen connective tissue in the submucosal area of the diabetic animal tissue showed a dense and irregular, distorted arrangement. The immunoreactivity of TGF-beta 1 in the diabetic animals was prominent in the collagen connective tissue, fibroblasts, and smooth muscle fibers, whereas no immunoactivity was detected in the vaginal structures of the control animals. Diabetes mellitus may induce vaginal tissue fibrosis by TGF-beta 1 expression in the rat model. This implies that reduced vaginal lubrication in the diabetic women may result from the structural changes of the vagina.

O2-dependent prostanoid synthesis activates functional PGE receptors on corpus cavernosum smooth muscle

We have previously demonstrated that decreased O2 tension inhibits prostaglandin synthesis from human corpus cavernosum smooth muscle cells in static culture over 8-18 h (R. B. Moreland et al., Molecular Urology 2: 41-47, 1998). In this report, an experimental system was designed that allowed determination of the effects of O2 tension changes over the time frame of physiological penile erection. Human corpus cavernosum smooth muscle cells were cultured on microcarrier beads in enclosed stirrer flasks so that rapid changes of O2 tension could be modulated. After 18 h of equilibration at 30-40 mmHg to simulate blood PO2 at penile flaccidity, O2 tension was increased to 100 mmHg for 1 h and then returned to 30-40 mmHg. Media samples were withdrawn for prostanoid synthesis and cell samples were taken for cAMP determinations. After 18 h of 30-40 mmHg PO2 values, prostanoid synthesis by human corpus cavernosum smooth muscle cells was low (0.1-0.7 pmol/10(6) cells). When PO2 was increased to 100 mmHg, a rapid increase in PGE2 >> PGF2alpha > PGD2 was observed (thromboxane A2 was undetectable), which peaked at 5.7 pmol PGE2/10(6) cells. Increased O2 tension correlated with increased PGE2 and increased intracellular synthesis of cAMP. The prostaglandin G/H synthase inhibitor indomethacin or the E prostanoid (EP2)-selective antagonist AH-6809 each inhibited the O2-tension-dependent increases in cAMP. These data support a role of differential O2 tension in the penis in the smooth muscle synthesis of PGE2, which in turn increases cAMP synthesis via EP2 receptors.

Sildenafil improves nocturnal penile erections in organic impotence

We studied the effects of sildenafil on nocturnal penile erections. We prospectively evaluated 36 patients with organic or psychogenic impotence and 5 normal, potent men. All patients completed 3 sessions of consecutive nights using the RigiScan Plus device. The first two nights the patients were asked to take placebo before the session and to take 50 mg of sildenafil before the third session. In the organic impotence group the use of sildenafil induced a significant improvement in time of rigidity 60-100%, rigidity and tumescence activity unit values and rigidity and tumescence activity unit values per hour in the tip and base. In the psychogenic impotence group it caused significant improvement only in rigidity activity unit per hour in the tip. In the potent men, changes were statistically insignificant. Sildenafil improves nocturnal penile erectile activity in organic impotence. Our study shows that phosphodiesterase inhibitors can improve penile erections not induced by sexual stimulation.