Chronic treatment with a combination of hepatocyte growth factor and JNK inhibitor ameliorates cavernosal veno-occlusive dysfunction: a rat model of cavernous nerve injury

Background: Structural alterations of the penis, including cavernosal apoptosis and fibrosis, induce venous leakage into the corpus cavernosum or cavernosal veno-occlusive dysfunction, a key pathophysiology associated with erectile dysfunction after radical prostatectomy. We hypothesized that the effect of JNK inhibitors on reducing apoptosis and hepatocyte growth factor (HGF) on inducing tissue regeneration could be another treatment mechanism of erectile dysfunction after radical prostatectomy. Aim: To investigate whether JNK inhibition combined with intracavernosal administration of HGF can completely preserve cavernosal veno-occlusive function (CVOF) in a rat model of erectile dysfunction induced via bilateral cavernosal nerve crush injury (CNCI). Methods: A total of 42 male Sprague-Dawley rats were randomly assigned to sham control (group S), CNCI (group I), and CNCI treated with a combination of JNK inhibitor and HGF (group J + H) for 5 weeks after surgery. Outcomes: Rats in each group were evaluated via dynamic infusion cavernosometry (DIC), caspase-3 activity assay, Masson trichrome staining, immunohistochemical staining of α-smooth muscle actin, and immunoblotting at 5 weeks after surgery. Results: Regarding CVOF, group I showed decreased papaverine response, increased maintenance, and drop rates of DIC when compared with group S. Group J + H showed significant improvement in the 3 DIC parameters vs group I. No differences in the 3 DIC parameters were found between group J + H and group S. Regarding the structural integrity of the corpus cavernosum, group I showed increased caspase-3 activity, decreased smooth muscle (SM):collagen ratio, decreased SM content, decreased protein expression of PECAM-1, and decreased phosphorylation of c-Jun and c-Met. Group J + H showed significant attenuation in histologic and molecular derangement as compared with group I. There were no differences in caspase-3 activity, SM content, SM:collagen ratio, PECAM-1 protein expression, c-Jun phosphorylation, and c-Met phosphorylation between groups J + H and S. Clinical Implications: Our results suggest that antiapoptotic and regenerative therapy for the corpus cavernosum is a potential mechanism of penile rehabilitation after radical prostatectomy. Strengths and Limitations: This study provides evidence that combination treatment of JNK inhibitor and HGF preserves erectile function by restoring corporal SM and endothelium. However, additional human studies are needed to confirm the clinical effect. Conclusion: Chronic treatment with JNK inhibitor and HGF may preserve CVOF to levels comparable to sham control by preserving the structural integrity of the corpus cavernosum and so represents a potential therapeutic option for preventing the development of cavernosal veno-occlusive dysfunction.