Over the past decade, physicians and scientists have been working to engineer a biological substitute to replace injured, diseased or malfunctioning organs. As applied to urology, much research and development has been seen in the arena of tissue engineering for corporal bodies and tunica albuginea replacement and repair. The construction of a biological penile prosthesis has gained much interest in the urologic community. The first known biological reconstruction of the phallus for impotence had its origin in 1936, when use of bone cartilage, the 'artificial os penis' was used to create scaffolding for post traumatic penile reconstruction [Bretan, 1989]. However, as it functioned poorly and had aberrant cosmetic results, this methodology of reconstruction fell out of favor [Patel and Atala, 2011; Yoo et al. 1999]. In 1998, Yoo and colleagues were able to demonstrate the ability to grow cartilaginous rods produced by seeding bovine chondrocytes onto a polyglycolic acid polymer infrastructure [Yoo et al. 1998]. Later studies performed by the same group demonstrated successful implantation of the biologically grown cartilage rods into the corporal spaces of rabbits (Figure 5) [Yoo et al. 1999]. The creation of a neo corpora by seeding human corporeal smooth muscle cells on polymer scaffolds was later demonstrated by the research conducted by Kershen and colleagues [Kershenet al. 2002].
Figure 5: Demonstration of autologous engineered cartilage rods before and after implantation into the corporal spaces of rabbits. Source: Yoo et al. .
Further studies by Chen and colleagues examined the ability to bioengineer entire pendular penile bodies in a rabbit model. By implanting smooth muscle cells and endothelial cells seeded onto three-dimensional (3D) corporal collagen matrices into excised pendular penile corpora cavities in a rabbit model, they were able to demonstrate the creation of a neo corpora that exhibited good intracorporeal pressures to attain erection, induced relaxation by exposure to NO and carbachol, and mating assessments that revealed an 83% intravaginal ejaculation rate [Chen et al. 2010].
Such research and development has given encouraging hope and direction for individuals with ED due to congenital penile anomalies, penile cancer and penile injury with the possibility of being able to provide a biological substitute. No human tests have been performed, yet the future of such technology is bright and may bring an alternative to implantation of the mechanical penile prosthesis.