The new success of tissue engineering is a functioning penis

Scientists at the Institute of Regenerative Medicine at Wake Forest University Baptist Medical Center have grown functioning cavernous bodies from rabbit cells for the first time. A month after implantation, the rabbits fully recovered their sexual function, some of them even managed to have offspring. The results of the work will be published recently in the preliminary issue of the on-line version of the Proceedings of the National Academy of Sciences (Nov. 9-13).

The tissue grown by the researchers forms the so–called cavernous bodies of the penis - three oblong spongy formations that occupy most of the volume of the penis. These structures, interconnected by connective tissue and covered with skin, are filled with blood during an erection and provide an increase in penis size.

According to the director of the Institute, Professor Anthony Atala, it is obvious that further research is needed, but the results are very encouraging and indicate that the developed technology has great potential. The researchers hope that their proposed method will help patients with congenital anomalies, cancer and penile injuries, as well as with some types of erectile dysfunction in the future.

Until now, the restoration of the tissue of the cavernous bodies damaged as a result of injury or disease has been very problematic due to its unique structure and complex functioning. To date, there are no methods of replacing this tissue that would ensure the restoration of normal sexual function. Some specialists attempt surgical treatment, often representing multi-stage procedures, in some cases involving the implantation of a silicone prosthesis of the penis, but none of these procedures does not restore natural erectile function.

The researchers tried to solve this problem by creating a cavernous tissue suitable for transplantation in the laboratory. In earlier work, also carried out on rabbits, they managed to grow small segments of cavernous tissue, the functioning efficiency of which was 50% of the functioning efficiency of normal tissue. The aim of this work was to improve these results.

In their work, the scientists used methods that previously allowed them to become pioneers in growing human organs in the laboratory – they developed a technique for growing a bladder. Such artificial bladders have been implanted in almost 30 adults and children.

To create an artificial penis, scientists first isolated smooth muscle and endothelial cells from the cavernous tissue of animals (cells of these two types line the inner surface of blood vessels). The isolated cells were cultured under laboratory conditions in order to increase their number, after which they were introduced into a three-dimensional framework. A month after implantation of such a cage-seeded skeleton inside the animal's penis, the formation of structured tissue permeated with blood vessels began there.

The cells were injected into the scaffolds in two time-spaced stages, which made it possible to increase the number of injected smooth muscle cells by almost six times compared to earlier work. The authors consider this moment to be the key to the success of the latest experiment. During erection, relaxation of smooth muscle tissue, triggered by nitrogen oxide released by endothelial cells, provides blood flow to the penis. According to Professor Atala, increasing the density of smooth muscle cells allowed scientists to achieve sufficient blood pressure inside the tissue they constructed.

Functional testing of the implanted tissue already a month after the operation showed a normal level of intravascular pressure, stable blood flow, a normal reaction to relaxation caused by nitric oxide, as well as a normal outflow of venous blood after an erection.

After copulation of implanted males with females, spermatozoa were found in vaginal scrapings in eight of the twelve females, and four of them developed pregnancy.

Atala considers the results very encouraging, as they indicate the possibility of using tissue grown in laboratory conditions for reconstructive operations for men in need of them. Currently, the absence of cavernous tissue means that sexual function cannot be restored.

Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on Newswise: Scientists Successfully Grow Animal Penile Erectile Tissue in Lab

11.11.2009