Penis implant brings hopes to thousands

An unusual organ implant grown in the laboratory and rigorously tested on highly-sexed male rabbits could bring new hope to thousands of men.

Scientists in the US completely rebuilt the "stiffening" elements of the penis from donor cells - and showed that they worked.

Rabbits given the implants attempted to mate within one minute of being introduced to a female partner, and 83 per cent succeeded.

Study leader Professor Anthony Atala, director of the Institute for Regenerative Medicine at Wake Forest University in New Carolina, said: "Our results are encouraging and suggest that the technology has considerable potential for patients who need penile reconstruction.

"Our hope is that patients with congenital abnormalities, penile cancer, traumatic injury and some cases of erectile dysfunction will benefit from this technology in the future."

The mammalian penis is a surprisingly complex organ which once damaged is difficult to repair.

Erections are achieved by means of two sponge-like cylinders, or "corporal bodies", on each side of the penis that fill with blood.

Disease and injury can lead to loss of the erectile tissue, which may also waste away if no erections occur for too long. This is a risk faced by patients who have had surgery for prostate cancer.

In extreme cases artificial silicone rods can be implanted into the penis but they do not function in a natural way.

The new research focused on growing new erectile tissue in the laboratory from seeded cells.

First smooth muscle cells and endothelial cells, similar to those lining blood vessels, were harvested from the erectile tissue of male rabbits.

Using a two-step process, these were then grown on a three-dimensional collagen "scaffolds" bathed in chemicals.

Finally the scaffolds holding the developing cells were implanted into the penises of rabbits whose erectile tissue had been surgically removed.

A month after the implants were inserted organised tissue with blood vessel structures began to form.

Laboratory tests showed that the biological responses of the erectile tissue were normal. During an erection, the release of nitric oxide from endothelial cells leads to a relaxation of smooth muscle tissue and an influx of blood.

The scientists used the implants to replace whole corporal bodies in 12 male white rabbits.

The acid test came when the rabbits were introduced to female partners. All attempted to mate within one minute, and vaginal swabs showed that 10 of them (83 per cent) managed to transfer sperm into the females. This occurred as early as one month after the implants were inserted.

Most of an equal number of male rabbits lacking erectile tissue that did not receive implants made no attempt to mate. None of them succeeded in transferring sperm.

The same team was the first in the world to engineer a rudimentary human organ in the laboratory. Bladders constructed by the Wake Forest scientists have been implanted in almost 30 children and adults.

The research was published today in the journal Proceedings of the National Academy of Sciences