RECONSTRUCTIVE UROLOGY

Tunica albuginea acellular matrix graft for penile reconstruction in the rabbit: a model for treating Peyronie’s disease
Wefer J, Schlote N, Sekido N, Sievert K-D, Wefer AE, Nunes L, Bakircioglu ME, Dahiya R, Tanagho EA
Departments of Urology and Radiology, University of California School of Medicine, San Francisco, California, USA
BJU Int. 2002; 90:326-31

• Objective: To evaluate the use of an acellular matrix graft of the tunica albuginea for functional penile reconstruction in severe cases of Peyronie’s disease.
• Materials and Methods: In 18 rabbits, an acellular matrix graft of the tunica albuginea was used to cover a 4x8 mm tunical defect, and six animals each were killed 1, 3 and 6 months later; four unoperated animals served as histological controls. Before death an erection was induced by papaverine, with the quality classified on a scale of 0–5, and cavernosography performed. After death the penis was prepared for histological study, and the cell number, collagen and elastic fiber content evaluated in the regenerated matrix, and in control specimens and four unimplanted matrices.
• Results: Of 18 experimental animals, 11 had normal erections before death, four had slight penile deviation and three developed no erection. Failure was caused by severe postoperative haematoma, resulting in scar tissue. There was no graft rejection. Histologically there was no difference between natural and regenerated tunica. The collagen content and cell number were not significantly different in regenerated and control samples. There were significantly fewer elastic fibers in the unimplanted grafts and the 1-month group, but in later samples this difference was no longer evident.
• Conclusion: The homologous acellular matrix graft of the tunica albuginea warrants further evaluation as an alternative treatment in Peyronie’s disease, despite some postoperative failures. The advantage of this orthotopic biomaterial is its rapid integration, with no rejection.
  
  
• Editorial Comment
  Various tissues and materials have been tried with variable success in the reconstruction or surgical repair of penile diseases. Many of the flaps are usually incorporated into the well vascularized surrounding of the penile structures. But apart from closing a defect of the corpus cavernosum after, e.g. excision of a plaque, none of them could reliably imitate all features of cavernous tissue. Strength, elasticity, venous tightness and controlled venous leakage are qualities which are difficult to substitute by tissues such as fascia or dermis.
  Recently artificial biomatrices have proven to be successful clinically in closing surgical defects of patients suffering from Peyronie’s disease. Among those a collagenous fleece usually used for surgical hemostasis seems to be a good scaffold along which cavernous tissue may regenerate (1). Another attempt, although not yet proven clinically to be useful, is tissue engineering.
  Wefer and collaborators from San Francisco have previously shown the possibilities of using acellular matrix for reconstruction in the lower urinary tract. The advantage of acellular matrix would be that cellular regeneration is based on the native scaffold of the respective organ. This matrix therefore already has the qualities of resembling very closely the organ to be reconstructed. If tunica albuginea acellular matrix is a viable option for penile reconstruction, further interesting options may ensue. One could be the use of healthy corpus cavernosum from cadavers for the treatment of erectile dysfunction. However, before we are ready to speculate about future projects like that it has to be demonstrated that homologous penile acellular matrix craft works also in the human setting.

Reference
1. Lahme S, Gotz T, Bichler KH: Collagen fleece for defect coverage following plaque excision in patients with Peyronie’s disease. Eur Urol. 2002; 41:401-5.

Dr. Arnulf Stenzl
Professor and Chairman of Urology
Eberhard-Karls-University Tuebingen
Tuebingen, Germany