Scientists invent 3D-printed penis implant to restore erections — and it works in rabbits and pigs

3D-printed penises could be used to cure erectile dysfunction, scientists say.

In a study published March 4 in the journal Nature Biomedical Engineering, researchers 3D-printed a model penis using a special type of hydrogel that successfully became erect just like a natural one.

They then implanted parts of the model penis into rabbits and pigs with erectile issues, and after only a few weeks, the animals were able to mate and reproduce. This technology could one day be used to help humans with penis injuries and erectile dysfunction, the researchers say.

Natural penises are made up of two columns of erectile tissue named the corpora cavernosa, which run side-by-side along the upper length of the shaft. Below them lies a single column of erectile tissue called the corpus spongiosum, which surrounds the urethra. A tough, fibrous layer of tissue called the tunica albuginea coats the corpora cavernosa and holds the two columns together.

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Upon arousal, the arteries in the penis dilate, allowing blood to flow into the corpora cavernosa. This causes the tissue to swell, held taut within the tunica albuginea, and the penis becomes erect. The expanding corpora cavernosa also compresses the veins that drain blood from the penis against the firm tunica albuginea, trapping the blood inside and maintaining an erection.

Sometimes, people struggle to achieve or maintain an erection — known as erectile dysfunction — which can be caused by a range of issues such as nerve damage, hormone issues, or problems with blood flow due to damage to the tunica albuginea or corpora cavernosa. The condition is very common, with an estimated 40% of cisgender men over the age of 40 and 70% over the age of 70 reporting erectile dysfunction, according to the National Institutes of Health. The condition particularly affects older men.

A condition named Peyronie’s disease, caused by fibrous scar tissue inside the tunica albuginea, can also lead to erectile dysfunction or a curved, painful erection, and is thought to affect between 6 and 10% of men, according to the British Association of Urological Surgeons. Both erectile dysfunction and Peyronie’s disease can affect physical and mental well-being, sexual function, and overall quality of life.

In the latest study, the researchers 3D-printed the main structures of the penis using a soft, water-based material called hydrogel that can expand and retain water, creating a model of the corpora cavernosa, corpus spongiosum and tunica albuginea coating. This model successfully became erect when flooded with a blood substitute, and allowed the researchers to study the structural issues that can lead to erectile dysfunction.

The researchers modified the printed models of the corpora cavernosa by growing cells from inside the penis of a rabbit within them, and then transplanted them into the penises of rabbits with penile issues. They also did the same with pigs, seeding the model with cells from pigs. This seeding of the model with cells from natural penises was to prevent the animals’ immune systems from rejecting the implant. Within only a few weeks, they found that the implanted animals could achieve erections, have sex and successfully sire offspring.

“These findings underscore the potential clinical applications of biomimetic corpus cavernosum (BCC) for the treatment of penile injuries,” the researchers wrote in the paper. “Furthermore, this study advances the clinical application of 3D-printed artificial tissue organs.”

The researchers note that this model is not a perfect replacement for a true penis transplant from another human, as it does not replace damaged nerves, blood vessels, or the urethra. However, despite this, they hope that in the future they can develop 3D-printed penis models that do include these important structures.

This method could then be used in place of human penile transplants, which have only been performed a small number of times, and face a range of issues with immune rejection and regaining full sensation and erectile function.

“Future research could explore design strategies aimed at inducing nerve regeneration and embedding artificial blood vessels and urethral structures within the implants,” the researchers wrote. “These approaches could help overcome current obstacles in repairing large-scale penile injuries.”