Novel image analysis of corpus cavernous tissue in impotent men

Pathophysiology and Grayscale Ultrasonography of Penile Corporal Fibrosis

INTRODUCTION

Penile corporal fibrosis may occur secondary to explantation of an infected penile prosthesis, severe penile trauma, refractory low-flow priapism, Peyronie's disease, or chronic intra-cavernous injection of vasoactive drugs. Other etiologies of corporal fibrosis, presenting primarily with erectile dysfunction, can develop in chronic smokers, hypertensive patients, alcoholics, diabetics, and after radical prostatectomy. Corporal erectile tissue fibrosis is a significant pathophysiologic component of erectile dysfunction; however, current ultrasound-based penile imaging protocols do not directly assess it.

OBJECTIVE

To determine if grayscale ultrasonography (US) is a suitable imaging modality to identify and assess penile corporal erectile tissue fibrosis.

METHODS

A PubMed literature review was performed for studies that detailed ultrasonographic methods and findings of pathologies causing penile corporal fibrosis. Our main outcome measure was the ultrasonographic findings of pathologies causing penile corporal fibrosis.

RESULTS

Grayscale US demonstrates the capability to detect and localize the fibrotic changes of the corpora cavernosa. Ultrasonographic findings capture penile corporal tissue heterogeneity including diffuse, circumscribed, or localized patterns.

CONCLUSION

Overall, grayscale US may be a useful and convenient imaging modality to assess penile corporal fibrosis secondary to explantation of an infected penile prosthesis, priapism, penile trauma, chronic intra-cavernous injection of vasoactive drugs, diabetes, Peyronie's disease, and vascular disease. While limited by the skill and knowledge of the US operator, the combined knowledge of pathophysiology and US may help clinicians identify and manage the underlying etiology of penile corporal fibrosis. Kim J, Drury R, Morenas R et al. Pathophysiology and Grayscale Ultrasonography of Penile Corporal Fibrosis. Sex Med Rev 2022;10:99-107.

Age-related morphological changes in smooth muscle and collagen content in human corpus cavernosum

INTRODUCTION

Aging process has been related to erectile dysfunction (ED) possibly due to morphological changes in corpus cavernosum among many other causes.

AIM

To evaluate smooth muscle and collagen content in human corpus cavernosum and to correlate it to age.

METHODS

Cadaveric human cavernosal tissue was collected during the period of 1 year. Morphological analysis of a whole corpus cavernosum was performed in tissue sections stained with Masson's trichromic method to differentiate smooth muscle (red) from collagen (blue) content.

MAIN OUTCOME MEASURES

Analysis was performed with specialized micrographs image analysis software. Pearson's correlation test was used to establish correlation between corpus cavernosum morphology (smooth muscle and collagen content) and age.

RESULTS

A total sample of 89 tissues from different male cadavers were analyzed. The average age of the sample was 49.2 ± 19.1 years, with a range between 14 and 90 years. There was a statistically significant inverse correlation between age and the percentage of smooth muscle content (P = 0.012), direct correlation between age and percentage of collagen content (P = 0.019), and inverse correlation between age and the ratio of smooth muscle : collagen content (P = 0.007).

CONCLUSIONS

Age-related morphological changes in terms of smooth muscle and collagen content are observed in human corpus cavernosum as a possible contributing factor to the development of ED.

Apoptosis of corpus cavernosum in patients with organic erectile dysfunction

OBJECTIVES

It has been reported that apoptosis of penile erectile tissue occurs after penile denervation, castration, and diabetes mellitus in animal studies. Aim of this study was to investigate apoptosis in corpora cavernosa of patients with organic erectile dysfunction (ED).

METHODS

Cavernous biopsies were obtained from 38 patients with erectile dysfunction and 10 patients with normal erectile function. Apoptosis of tissues were determined via terminal deoxyuridine nucleotide end labeling method by using flow cytometry.

RESULTS

The mean ages of patients with ED and control patients were 50.65 +/- 2.27, and 32.43 +/- 2.90 years, respectively (P = 0.0001). Patients with ED were set in two groups as more than 50 years old and less than 50 years old for further analysis of age factor on apoptosis. The mean % apoptosis of ED patients was 26.22 +/- 2.79 and control group was 11.26 +/- 3.79, (P = 0.032). Mean fluorescence intensity (MFI) values were also 17.41 +/- 3.21 and 6.59 +/- 2.28, respectively (P = 0.039). MFI and % apoptosis values were not statistically significant different neither between the patients groups nor between the control and patients < or = 50 years old (P > 0.05).

CONCLUSIONS

We did not find any statistically significant difference with respect to apoptosis rates when we compared neither control group with < or = 50 years old patients nor patients groups of ED. Because of this we did not have enough data to say that apoptosis has a prominent role on the development of ED independently from other factors. However, further studies are necessary to clarify the role of apoptosis in erectile dysfunction.

Comparative analysis of the penis corpora cavernosa in controls and patients with erectile dysfunction

OBJECTIVE

To evaluate the presence of structural disorders of the corpora cavernosa in patients with erectile dysfunction (ED), as despite new drugs being effective in many men with ED, some aspects of structural disorders of the corpora cavernosa remain unknown.

MATERIALS AND METHODS

Biopsy specimens were taken from the corpora cavernosa of seven patients (mean age 57.8 years, range 51-72) with severe ED who had a penile prosthesis implanted. The controls tissues were fragments of corpora cavernosa obtained from autopsies of six men (mean age 52.3 years, range 40-66) who died from causes unrelated to the urogenital system. For light microscopy, the specimens were processed routinely to paraffin wax, and by immunohistochemistry to evaluate elastic fibres, and by Masson's trichrome to analyse collagen and smooth muscle fibres. Stereological methods were used to quantitatively evaluate the different elements (as a percentage).

RESULTS

The percentages of the different elements in the human penis of controls and men with ED, respectively, were: elastic fibres 13.2% and 9.1%; collagen fibres 40.8% and 41.6%; and smooth muscle, 40.4% and 42%.

CONCLUSIONS

In patients with ED there was a statistically significant reduction in the percentage of elastic fibres, but no statistically significant difference in collagen and smooth muscle fibres, and no appreciable differences in collagen distribution between the groups.

Histological alterations in cavernous tissue after radical prostatectomy

PURPOSE

Radical prostatectomy often results in erectile dysfunction because of lesions to the erectile nerves. In this study we evaluated histomorphological alterations in cavernous smooth muscle and collagen content after radical prostatectomy.

MATERIALS AND METHODS

A total of 19 patients between 57 and 69 years old with prostate adenocarcinoma and normal erectile function, as reported and validated by RigiScan (UroHealth Systems, Laguna Niguel, California) testing, underwent corpora cavernosa biopsy in the operating room before radical prostatectomy, and 2 and 12 months after surgery. No patient underwent hormone therapy before or after surgery and none was diabetic. Elastic fibers (manual counting), muscle specific actin (immunostaining) and collagen content (computerized morphometric imaging) were measured in the 3 biopsies.

RESULTS

In all cases the first postoperative histological assessment revealed some disorganization. Trabecular elastic fibers (p <0.0003) and smooth muscle fibers were decreased and collagen content was significantly increased (p <0.0003) compared with preoperative biopsies. One year after surgery elastic fibers (p <0.0003) and smooth muscle fibers were decreased and collagen content was significantly increased (p <0.0003) compared with the first postoperative biopsy. Moreover, organized collagen and trabecular protocollagen deposits were increased.

CONCLUSIONS

Progressive fibrosis in the corpora cavernosa after radical prostatectomy probably results from denervation and/or an ischemic process, which is caused in turn by the ligation of anomalous pudendal artery branches or of venous plexuses that drain to or from the corpora cavernosa. Fibrosis and the subsequent loss in elasticity and function of erectile tissue probably together cause erectile dysfunction.

COMPOSITIONAL CHANGES OF COLLAGEN AND GLYCOSAMINOGLYCANS IN THE TUNICA ALBUGINEA AND CORPUS CAVERNOSUM FROM THE HUMAN PENIS DURING THE FETAL AND POSTNATAL PERIODS

PURPOSE

We investigated the composition of collagen and glycosaminoglycans (GAGs) in the corpus cavernosum (CC) and tunica albuginea (TA) of normal human penises.

MATERIALS AND METHODS

Penises were obtained from a 6-month-old child (group 1), a 2-year-old child (group 2), 18 to 34-year-old adults (group 3), 37 to 53-year-old adults (group 4) and 22 fetuses at 17.2 to 33.3 menstrual weeks (group 5). Total GAG and collagen concentrations were expressed per mg dry tissue and proportions of GAG species were determined by agarose electrophoresis and ion exchange chromatography.

RESULTS

The GAG concentration in group 1 CC and TA was 1.32 and 0.52 microg/mg, respectively, and thereafter it increased noticeably. TA collagen concentration followed a similar pattern. TA had more collagen than CC in groups 3 (mean +/- SD 93.41 +/- 6.17 vs 53.77 +/- 11.18 microg/mg, p <0.001) and 4 (89.94 +/- 5.53 vs 55.39 +/- 5.89 microg/mg, p <0.01). In these groups TA and CC differed markedly in the proportion of hyaluronan, heparan sulfate and dermatan sulfate. In TA group 4 had slightly less hyaluronan and more chondroitin sulfate than group 3 but in CC the GAG proportions were similar. Collagen content in the whole fetal penis correlated with gestational age (r = 0.78, p <0.001).

CONCLUSIONS

Collagen and the GAG concentration in the human penis undergo extensive modifications during development and shortly after birth but from ages 2 to approximately 46 years changes are limited to the proportion of GAG species in TA from older individuals. Reflecting diverse biomechanical roles, the extracellular matrix of CC and TA are markedly different.

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.

Erectile dysfunction: etiology, evaluation, and treatment options

The evaluation and treatment of male sexual dysfunction has evolved into a more extensive evaluation. This new evaluation should now include evaluation of hypogonadism, ejaculatory function, lower urinary tract symptoms, and depression. The evaluation may be readily accomplished with the use of questionnaires. The management of these entities is discussed, including the novel phosphodiesterase-5 for male erectile dysfunction. Inclusion of the partner in the evaluation and management scheme will provide added benefit and may produce a better outcome.

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.

Erectile dysfunction in the elderly: epidemiology, etiology and approaches to treatment

PURPOSE

Erectile dysfunction is experienced at least some of the time by most men who have reached 45 years of age, and it is projected to affect 322 million men worldwide by 2025. The prevalence of erectile dysfunction is high in men of all ages and increases greatly in the elderly.

MATERIALS AND METHODS

This paper reviews the epidemiology of erectile dysfunction with an emphasis on the experience of older men, normal age related changes in the structure and function of the penis that may contribute to increased risk with age, how the accumulation of risk factors with age may contribute to the high prevalence of the disease in older men, and established and emerging therapies. The normal aging process and age related risk factor accumulation contribute to the increased prevalence of erectile dysfunction in the elderly.

RESULTS

Remarkable progress has been made in the treatment of erectile dysfunction. At present inhibition of phosphodiesterase 5 with oral agents such as sildenafil would appear to be the initial treatment of choice. These drugs have been shown to be safe and effective, and sildenafil has demonstrated efficacy in patients with many of the comorbidities observed in older men with erectile dysfunction. New treatments, in particular transfection with genes for key mediators of erectile function that are known to be down-regulated in elderly men, also hold promise.

CONCLUSIONS

Further research into the neural, vascular and molecular mechanisms involved in penile erection will lead to the development of even safer, more effective and more convenient therapies for men with erectile dysfunction.

Gene expression in Peyronie's disease

Currently, surgical intervention is the only efficacious treatment for Peyronie's disease (PD), a fibromatosis of the tunica albuginea of the penis. Therapies based on the molecular pathways for this disease could provide alternatives to surgical treatment but only recently has the pathophysiology of the Peyronie's disease plaque been investigated at the molecular level. In this review, we examine the current knowledge of gene expression in the PD plaque and the relationship of PD with other fibrotic conditions such as Dupytren's disease. TGFbeta1, along with other growth factors, pro-fibrotic genes, and collagen, are expressed in fibroblasts and myofibroblasts. Myofibroblasts are normally involved in wound contracture and largely eliminated via apoptosis during the late stages of wound remodeling. In the PD plaque, however, these cells persist and may play an important role in the PD plaque fibrosis. The expression levels of TGFbeta1 and pro- and anti-fibrotic gene products, along with the nitric oxide/reactive oxygen species (NO/ROS) ratio in the tunica albuginea, appear to be essential for the formation and progression of the PD plaque and effect the expression of multiple genes. This can be assessed with the recently developed DNA-based chip arrays and results with the PD plaque have been encouraging. OSF-1 (osteoblast recruitment), MCP-1 (macrophage recruitment), procollagenase IV (collagenase degradation), and other fibrotic genes have been identified as being possible candidate regulatory genes. Finally, possible therapeutic avenues for gene-based therapy in the treatment of PD are discussed that may eventually reduce the need for surgical intervention.

Age-associated changes in collagen content and its subtypes within rat corpora cavernosa with computerized histomorphometric analysis

OBJECTIVES

To study the age-associated changes in the percentage of collagen and subtypes I, III, and IV within the corpora cavernosa in a rat model.

METHODS

The corpora cavernosa tissues were obtained from 30 male Wistar rats at three different ages. Processed with Masson's trichrome staining for collagen and with immunohistochemical staining for the collagen subtypes, the values of the collagen percentage, the percentage of area, and relative proportion of each collagen subtype within the rat corpora cavernosa were measured using an automatic image analysis system. The relationships between an increase in age and these parameters were analyzed.

RESULTS

The percentage of collagen within the corpora cavernosa was higher in the old rats (80 weeks) than in the young (20 weeks) and intermediate-age (40 weeks) rats (P = 0.02 and P = 0.25, respectively) and significantly increased with age (P = 0.021). The values of the percentage of area of collagen subtypes III and IV also increased significantly with age (P = 0.039 and P = 0.019, respectively). The value of the percentage of area of collagen subtype I was not significantly increased (P = 0.159). Also, no significant differences were found in the relative proportions of all three collagen subtypes with age among the three age groups.

CONCLUSIONS

The percentages of collagen within rat corpora cavernosa significantly increased, but not strongly, with age, especially collagen subtypes III and IV. However, the relative proportion of each subtype did not change with age. Therefore, we conclude that the amount of collagen may only partly contribute to erectile dysfunction in the aging process of the rat.