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

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. 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. 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. 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.

Various reconstructive procedures have been attempted to restore a cosmetically acceptable phallus that would allow normal reproductive, sexual, and urinary function in patients requiring penile reconstruction. However, these procedures are limited by a shortage of native penile tissue. We previously demonstrated that a short segment of the penile corporal body can be replaced using naturally derived collagen matrices with autologous cells. In the current study, we examined the feasibility of engineering the entire pendular penile corporal bodies in a rabbit model. Neocorpora were engineered from cavernosal collagen matrices seeded with autologous cells using a multistep static/dynamic procedure, and these were implanted to replace the excised corpora. The bioengineered corpora demonstrated structural and functional parameters similar to native tissue and male rabbits receiving the bilateral implants were able to successfully impregnate females. This study demonstrates that neocorpora can be engineered for total pendular penile corporal body replacement. This technology has considerable potential for patients requiring penile reconstruction.

Graft surgery for Peyronie's disease (PD) is associated with significant long-term risks. To evaluate the clinical and functional outcomes of graft repairs with a minimum of 5-year follow-up. A retrospective review of database and third party telephone survey was undertaken in all men who underwent reconstructive graft procedures for PD between May 1999 and May 2005. Patient demographics, International Index of Erectile Function (IIEF-5) scores, and penile Doppler ultrasonography were performed preoperative. Follow-up assessments included surgical outcomes and overall patient satisfactions. A total of 86 patients with an average age of 54.6 (34 to 73) years underwent Peyronie's graft repair. The average follow-up was 98 (61 to 120) months. Twenty patients received dermal graft whereas 33 patients underwent Tutoplast graft and 33 patients had Stratasis small intestinal submucosa graft. Penile curvature greater than 60 degrees was more common in the Tutoplast and Stratasis groups. Twelve patients used phosphodiesterase type 5 inhibitors or intracavenous agents preoperatively. At the time of review, only 46 (53%) patients were able to be contacted and consented for telephone interview. Although 6 months of postoperative follow-up showed excellent resolution, or significantly less, penile curvature, this figures decreased to 50% in dermal, 87% in Tutoplast, and 76% in Stratasis patients. Further penile length shortening was also reported on patient self-assessment at the recent follow-up. Worsening of IIEF-5 scores were noted with the development of erectile dysfunction was more pronounced in the diabetic cohort (P<0.01). The overall satisfaction on a 5-point scale was 2.6 with more than 65% of patients dissatisfied with the outcomes of the Peyronie's graft surgery. The recurrence of penile curvature, penile length loss, and the new-onset of ED are not uncommon sequelae and are associated with a significant patient dissatisfaction rate when a 5-year follow-up is achieved. © 2010 International Society for Sexual Medicine.