The genitourinary system is exposed to a variety of possible injuries from the time the fetus develops. Aside from congenital abnormalities, individuals may also suffer from other disorders, such as cancer, trauma, infection, iatrogenic injuries, or other conditions that may lead to genitourinary organ damage or loss, requiring eventual reconstruction.

Whenever there is a lack of native urologic tissue, reconstruction is usually performed with native nonurologic tissues, such as skin, gastrointestinal segments, or mucosa from multiple body sites.<sup>14 Atala A., Retik A.B. Hypospadias Reconstructive Urologic Surgery Baltimore: Williams and Wilkins (1997). 

Cliccare qui per andare alla sezione Riferimenti, 45 Retik A.B., Bauer S.B., Mandell J. , e al. Management of severe hypospadias with a 2-stage repair J Urol 1994 ;  152 : 749

Cliccare qui per andare alla sezione Riferimenti</sup> The use of native nonurologic tissues in the genitourinary tract is common, due to a lack of a better alternative, despite the known possible adverse effects. For example, the use of bowel in genitourinary reconstruction is associated with a variety of complications.<sup>15 Atala A., Retik A. Pediatric urology: Future perspectives Clincial Urology Philadelphia: JB Lippincott (1994).  507

Cliccare qui per andare alla sezione Riferimenti</sup> These include metabolic abnormalities, infection, perforation, urolithiasis, increased mucous production, and malignancy. Alternative approaches are constantly being explored in order to overcome the problems associated with the incorporation of nonurologic segments into the urinary tract.

Due to the complications associated with the use of native nonurologic tissues, such as gastrointestinal segments for genitourinary reconstruction, many investigators have sought to use synthetic materials as an alternative. The most common type of synthetic prostheses for urologic use are made of silicone. Silicone prostheses have been used for the treatment of urinary incontinence (artificial urinary sphincter)<sup>34 Levesque P.E., Bauer S.B., Atala A. , e al. Ten year experience with the artificial urinary sphincter in children J Urol 1996 ;  156 : 625

Cliccare qui per andare alla sezione Riferimenti</sup>; vesicoureteral reflux (detachable balloon system, silicone microparticles)<sup>13 Atala A., Peters C.A., Retik A.B., Mandell J. Endoscopic treatment of vesicoureteral reflux with a self-detachable balloon system J Urol 1992 ;  148 : 724

Cliccare qui per andare alla sezione Riferimenti, 22 Buckley J.F., Scott R., Aitchison M. , e al. Periurethral microparticulate silicone injection for stress incontinence and vesicoureteric reflux Min Inv Ther 1991 ;  1 (suppl 1) : 72

Cliccare qui per andare alla sezione Riferimenti</sup>; and impotence (penile prostheses).<sup>46 Riehmann M., Gasser T.C., Bruskewitz R.C. The hydroflex penile prosthesis: A test case for the introduction of new urological technology J Urol 1993 ;  149 : 1304

Cliccare qui per andare alla sezione Riferimenti</sup> In some disease states, such as urinary incontinence or vesicoureteral reflux, artificial agents (Teflon paste, glass microparticles) have been used as injectable bulking substances; however, these substances are not entirely biocompatible.<sup>2 Atala A. Non-autologous substance in VUR and incontinence therapy Dialogues in Pediatric Urology 1994 ;  17 : 12

Cliccare qui per andare alla sezione Riferimenti, 4 Atala A. Use of non-autologous substances in VUR and incontinence treatment Dialogues in Pediatric Urology 1994 ;  17 : 11

Cliccare qui per andare alla sezione Riferimenti</sup> The literature is replete with a wide array of complications (i.e., device malfunction, infection, and so forth) associated with these artificial devices.

Other natural tissues and synthetic materials that have been tried previously in experimental and clinical settings include omentum, peritoneum, seromuscular grafts, de-epithelialized segments of bowel, and polyvinyl sponge.<sup>15 Atala A., Retik A. Pediatric urology: Future perspectives Clincial Urology Philadelphia: JB Lippincott (1994).  507

Cliccare qui per andare alla sezione Riferimenti</sup> These attempts have usually failed. It is evident that urothelial to urothelial anastomoses are preferable functionally. The limited amount of autologous urothelial tissue for reconstruction, however, generally precludes this option. There is a critical need for tissues to replace lost and functionally deficient genitourinary tissues.<sup>3 Atala A. Tissue engineering in the urinary tract Dialogues in Pediatric Urology 1995 ;  18 : 1

Cliccare qui per andare alla sezione Riferimenti</sup> Engineering tissues using selective cell transplantation<sup>32 Langer R., Vacanti J.P. Tissue engineering Science 1993 ;  260 : 920

Cliccare qui per andare alla sezione Riferimenti</sup> may provide a means to create functional new genitourinary tissues.