Tissue
Engineering
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. [1999].
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.
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