Engineered Penile Erectile Tissue
In an advance that could one day provide replacement penile erectile tissue for patients with congenital abnormalities, penile cancer, traumatic injury and some cases of erectile dysfunction, Wake Forest University Baptist Medical Center researchers reported success completely replacing penile erectile tissue in animals.
In this first report of a functional engineered solid organ, the researchers described in the Proceedings of the National Academy of Sciences using cells from rabbits to engineer replacement penile erectile tissue in the laboratory. After implantation with the replacement tissue, the rabbits had normal sexual function and produced offspring. This is the most complete replacement of functional penile erectile tissue reported to date.
Further studies are required, of course, but the results suggest that the technology may be useful in the future for patients who need penile reconstruction,” said Anthony Atala, MD, chair of urology at Wake Forest Baptist and director of the Wake Forest Institute for Regenerative Medicine.
In an earlier study, also in rabbits, the team engineered short segments of erectile tissue that had 50 percent of the function of native tissue. The current study attempted to improve on those results. The Wake Forest Baptist team was the first in the world to engineer a human organ in the laboratory—bladders that have been implanted in almost 30 children and adults. Many of the same techniques used to build bladders were used in the current study. Smooth muscle and endothelial cells were harvested from the animals’ erectile tissue and cultured in the laboratory. Using a two-step process, the cells were injected into a three-dimensional scaffold that provided support while the cells developed.
As early as one month after implanting the scaffold, the organized penile tissue with vessel structures began to form. The cells were injected into scaffolds on two separate days, enabling them to hold almost six times as many smooth muscle cells as in the previous studies—which the scientists believe was a key to success. Functional testing of the implanted tissue showed that vessel pressure within the erectile tissue was normal, that blood flowed smoothly through it, that the response to nitric oxideinduced relaxation was normal as early as one month after implantation, and that veins drained normally after erection. When the animals with the engineered tissue mated with females, vaginal swabs contained sperm in eight of 12 instances and four of the 12 females were impregnated.
(Bioengineered corporal tissue for structural and functional restoration of the penis. Chen KL, Eberli D, Yoo JJ, Atala A. Proc Natl Acad Sci U S A. 2010 Feb 23;107(8):3346-50.)