World First: Scientists Printed Penises For Pigs And Restored Their Erections

A 3D-printed penis implant has restored erectile function to rabbits and pigs in a world first.

Pigs with damage to their penile tissue that received the one-of-a-kind surgery not only achieved erections, their rates of successfully producing offspring increased from 25 percent to 100 percent.

The penis has one of the most complex vascular network structures in the human body. For years now, researchers have been working on a model of the corpus cavernosum, the spongy tissue of the penile shaft, that could help those with erectile defects.

The recent study by a team from China, the US, and Japan presents a new physiological model that can reproduce erections in large, living animals.

To create the model, researchers mimicked the corpus cavernosum through the creation of a hydrogel-based scaffolding – one that is strong enough to withstand the internal pressure when the structure fills with blood.

The team then seeded the scaffolding with pig or rabbit endothelial cells, which are the main cells that line blood vessels. Endothelial cells (ECs) can create an "adaptable life-support system" in vessel-rich tissues, helping restore and improve function.

To test this idea out in the corpus cavernosum of Bama pigs and New Zealand rabbits, researchers implanted the hydrogel and ECs into dozens of animals with erectile defects.

Some rabbits and pigs received the artificial penis implant without ECs, but those that received the ECs and the implant showed better erectile function overall. In fact, their outcomes approached that of an animal without erectile dysfunction.

"These findings indicate that the implants markedly improved functional recovery, and the combination with ECs further enhanced this effect, demonstrating notable improvements in tissue regeneration and functional recovery," write the authors, led by biological engineer Zhenxing Wang from South China University of Technology.

"The fertility of the EC groups demonstrates the recovery of erectile function and the ability to ejaculate, suggesting the restoration of the cavernous tissue in the treated males."

Pigs that received the EC model, for instance, showed low inflammation levels after surgery, and as the hydrogel scaffolding degraded at the defect site, new tissue progressively formed.

When the pigs were allowed to breed a few weeks after surgery, pregnancy rates rose from just 25 percent in the defect group to 75 percent in the implant without ECs group.

Male pigs that received the implant with ECs successfully impregnated every single female pig they mated with.

The new penis model may prove useful in the future treatment of human erectile dysfunction and diseases that scar the deeper tissues of the penis, causing painful erections.

It could also help inform the development of other artificial, vessel-rich organs, like the heart.

"Currently, developing transplant materials that support nerve regeneration and effectively integrate with the host's urethra and vascular networks presents a major challenge," the authors write.

"These approaches could help overcome current obstacles in repairing large-scale penile injuries."

Some studies suggest that more than half of men aged 40 to 70 experience mild to moderate erectile dysfunction that increases with age, and while the condition is treatable, it is not always curable.

"These findings underscore the potential clinical applications of biomimetic corpus cavernosum for the treatment of penile injuries," conclude Wang and colleagues.

"Furthermore, this study advances the clinical application of 3D-printed artificial tissue organs."

The study was published in Nature Biomedical Engineering.