A mouse model of cavernous nerve injury-induced erectile dysfunction: functional and morphological characterization of the corpus cavernosum.

With the advent of genetically engineered mice, it seems important to develop a mouse model of cavernous nerve injury (CNI). To establish a mouse model of CNI induced either by nerve crushing or by neurectomy and to evaluate time-dependent derangements in penile hemodynamics in vivo and subsequent histologic alterations in the cavernous tissue. Twelve-week-old C57BL/6J mice were divided into 4 groups (N=36 per group): control, sham operation, bilateral cavernous nerve crush, and bilateral cavernous neurectomy group. Three days and 1, 2, 4, 8, and 12 weeks after CNI, erectile function was measured by electrical stimulation of the cavernous nerve. The penis was then harvested and TUNEL was performed. Immunohistochemical analysis was performed assaying for caspase-3, transforming growth factor-β1 (TGF-β1), phospho-Smad2, PECAM-1, factor VIII, and smooth muscle α-actin. The numbers of apoptotic cells and phospho-Smad2-immunopositive cells in endothelial cells or smooth muscle cells were counted. Erectile function was significantly less in the cavernous nerve crushing and neurectomy groups than in the control or sham group. This difference was observed at the earliest time point assayed (day 3) and persisted up to 4 weeks after nerve crushing and to 12 weeks after neurectomy. The apoptotic index peaked at 1 or 2 weeks after CNI and decreased thereafter. Cavernous TGF-β1 and phospho-Smad expression was also increased after CNI. The numbers of apoptotic cells and phospho-Smad2-immunopositive cells in cavernous endothelial cells and smooth muscle cells were significantly greater in the cavernous nerve crush and cavernous neurectomy groups than in the control or sham group. Conclusion.  The mouse is a useful model for studying pathophysiologic mechanisms involved in erectile dysfunction after CNI. Early intervention to prevent apoptosis in smooth muscle cells and endothelial cells or to inhibit cavernous tissue fibrosis is required to restore erectile function.

Jin HR ，Chung YG ，Kim WJ ，Zhang LW ，Piao S ，Tuvshintur B ，Yin GN ，Shin SH ，Tumurbaatar M ，Han JY ，Ryu JK ，Suh JK ... -  《-》

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

Men with erectile dysfunction (ED) respond poorly to oral phosphodiesterase-5 inhibitors following radical prostatectomy. Recent studies have reported that up-regulation of transforming growth factor-β1 (TGF-β1) and activation of the Smad signaling pathway play important roles in cavernous fibrosis and in the deterioration of erectile function in a mouse model of cavernous nerve injury (CNI) and in patients with spinal cord injury. The mothers against decapentaplegic homolog 7 (Smad7) is known to inhibit the phosphorylation of Smad2 and Smad3. To investigate the effectiveness of adenoviruses encoding Smad7 gene (Ad-Smad7) on erectile function in a mouse model of CNI. Twelve-week-old C57BL/6J mice were used and distributed into 7 groups: sham operation group, untreated CNI group, and CNI groups receiving a single intracavernous injection of adenovirus encoding LacZ (1 × 10(8) virus particles [vp]/20 μL) or adenovirus encoding Smad7 (Ad-Smad7; 1 × 10(7), 1 × 10(8), 2 × 10(8), or 1 × 10(9) vp/20 μL). Two weeks after bilateral cavernous nerve crushing and treatment, erectile function was measured by electrical stimulation of the cavernous nerve. The penis was harvested for histologic examinations and Western blot analysis. The highest erectile response was noted in CNI mice treated with Ad-Smad7 at a dose of 1 × 10(8)  vp, which reached up to 82-85% of sham control values. Local delivery of Ad-Smad7 significantly decreased endothelial cell apoptosis and the production of extracellular matrix proteins, including plasminogen activator inhibitor-1, fibronectin, collagen I, and collagen IV, and induced endothelial nitric oxide synthase phosphorylation in the corpus cavernosum tissue of CNI mice. The adenovirus-mediated gene transfer of Smad7 successfully restored erectile function by enhancing endothelial cell function and through antifibrotic effects. These findings suggest that inhibition of the TGF-β signaling pathway by use of Smad7 may represent a promising therapeutic strategy for ED induced by radical prostatectomy.

Song KM ，Chung JS ，Choi MJ ，Jin HR ，Yin GN ，Kwon MH ，Park JM ，Kim WJ ，Lee SJ ，Kim SJ ，Ryu JK ，Suh JK ... -  《-》

Increased cavernous expression of transforming growth factor-β1 and activation of the Smad signaling pathway affects erectile dysfunction in men with spinal cord injury.

Transforming growth factor-β1 (TGF-β1) is implicated in bladder fibrosis after spinal cord injury (SCI) and in the fibrosis in the corpus cavernosum tissue after cavernous nerve injury. We investigated the differential expression of TGF-β1 and the Smad transcription factor, the key molecule for the initiation of TGF-β-mediated fibrosis, in cavernous tissue from SCI patients. After obtaining informed consent and approval from the patients and our institutional review board, we enrolled 5 patients with psychogenic erectile dysfunction (ED) (mean age 36.8 years; range 20-50 years) and 10 patients with neurogenic ED from SCI (mean age 38.8 years; range 18-50 years). Cavernous tissues were obtained by percutaneous biopsy and stained with Masson trichrome, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling (TUNEL), or antibodies to TGF-β1 and phospho-Smad2. Semi-quantitative analysis of TGF-β1 and phospho-Smad2 was performed, and the numbers of apoptotic cells were counted. We also quantified the cavernous collagen area with the use of an image analyzer system. The expression of TGF-β1 and phospho-Smad2 protein was significantly higher in the SCI group than in the psychogenic group. The TUNEL assay revealed a higher apoptotic index in the SCI group than in the psychogenic group. Higher TGF-β1 and phospho-Smad2 expression and more apoptotic cells were noted mainly in endothelial cells, smooth muscle cells, and fibroblasts of the SCI group. Double labeling of cavernous tissue with TUNEL and antibody to phospho-Smad2 revealed that most TUNEL-positive cells showed immunoreactivity to phospho-Smad2 staining. Cavernous collagen content was significantly greater in the SCI group than in the psychogenic group. Upregulation of TGF-β1 and activation of the Smad signaling pathway may play important roles in SCI-induced cavernous fibrosis and deterioration of erectile function, which warrants early pharmacological intervention to protect erectile tissue from irreversible damage.

Shin TY ，Ryu JK ，Jin HR ，Piao S ，Tumurbaatar M ，Yin GN ，Shin SH ，Kwon MH ，Song KM ，Fang ZH ，Han JY ，Kim WJ ，Suh JK ... -  《-》

Functional and morphologic characterizations of the diabetic mouse corpus cavernosum: comparison of a multiple low-dose and a single high-dose streptozotocin protocols.

Jin HR ，Kim WJ ，Song JS ，Choi MJ ，Piao S ，Shin SH ，Tumurbaatar M ，Tuvshintur B ，Nam MS ，Ryu JK ，Suh JK ... -  《-》

Nerve injury-induced protein 1 (Ninjurin-1) is a novel therapeutic target for cavernous nerve injury-induced erectile dysfunction in mice.

Radical prostatectomy for prostate cancer can not only induce cavernous nerve injury (CNI) but also result in structural changes in the cavernous tissues. Nerve injury-induced protein 1, Ninjurin-1 (Ninj1), is known to be involved in neuroinflammatory processes and to be related to vascular regression during the embryonic period. The study aims to determine whether and how Ninj1 neutralizing antibody (Ninj1-Ab) restores erectile function in mice with CNI. Twelve-week-old C57BL/6J mice were used and distributed into four groups: sham operation group and CNI groups receiving a single intracavernous injection of immunoglobulin G (IgG) control antibody, low-dose Ninj1-Ab (1.0 μg/20 μL), or high-dose Ninj1-Ab (2.5 μg/20 μL). One week after bilateral cavernous nerve crush, erectile function was measured by electrical stimulation of the cavernous nerve. The penis was harvested for histologic examinations and Western blot analysis. The cavernous expression of Ninj1 protein was upregulated up to 7 days after CNI and returned to baseline levels thereafter. Local delivery of Ninj1-Ab significantly increased penile neuronal nitric oxide synthase and neurofilament contents, induced cavernous endothelial proliferation and phosphorylation of Akt and endothelial nitric oxide synthase, and decreased endothelial cell apoptosis in the CNI mice by upregulating angiopoietin-1 and downregulating angiopoietin-2. High-dose Ninj1-Ab induced profound restoration of erectile function in the CNI mice (91% of sham control values), whereas low-dose Ninj1-Ab elicited partial improvement. The dual neurotrophic and angiogenic effects of Ninj1 blockade may provide a good opportunity for treating erectile dysfunction resulting from radical prostatectomy.

Yin GN ，Kim WJ ，Jin HR ，Kwon MH ，Song KM ，Choi MJ ，Park JM ，Das ND ，Kwon KD ，Batbold D ，Kim KW ，Ryu JK ，Suh JK ... -  《-》