Artificial tissue reverses erectile dysfunction in pigs

The synthetic penile tissue restored erectile function “immediately.”

Researchers in China have reversed erectile dysfunction in pigs using artificial tissue that repairs penile injury, a breakthrough they say may lead to improved treatment options for humans with this condition.

Treating penile injury

The failure to maintain a stable erection during sex, otherwise known as erectile dysfunction (ED), is a widespread condition affecting about half of all men aged between 40 and 70 years old at some point in their lives. Having far-reaching consequences, ED can cause stress, depression, as well as trouble conceiving offspring. Yet, it is both under-recognized and under-reported.

“We noticed that this is an area that has received little attention, yet the related need is huge,” said study co-author Xuetao Shi from the South China University of Technology in an interview with The Independent.

Adding to this complication, the causes of this widespread condition can be both mentally or physically-based, with many diseases or accidents causing injury to the structures that make up penile tissue. One of these vulnerable structures is the tunica albuginea-a protective, elastic layer surrounding the erectile tissue that pumps blood to the organ to maintain an erection.

 Although clinicians can treat damaged tunica albuginea tissue in the penis using patches of other tissues in the patient’s body, this method comes with disadvantages. In this situation, their structures are different from native tunica albuginea, making it difficult for these patches to replace this tissue perfectly. The host’s immune system can even reject them in some cases. 

The current study reports the development of Artificial Tunica Albuginea (ATA), made up of hydrogels arranged in a structure similar to the natural version. When tested in Bama miniature pigs with injuries to the tunica albuginea, the ATA restored erectile function.

Commenting on their breakthrough, Shi says, “We largely foresaw the problems and results of the ATA construction process, but we were still surprised by the results in the animal experiments, where the penis regained normal erection immediately after the use of ATA.”

How did they do it?

In mammals, the tunica albuginea in the penis is a structure comprising a double layer of ‘crimped’ collagen that undergoes straightening and stretching during erection to mediate a soft-to-firm transition. Often damaged by disease or physical injury, this structure is also affected by a broken penis.

To mimic this tissue as closely as possible, the scientists decided to create a safe and synthetic material that is pliable when the penis isn’t erect and then quickly becomes rigid during an erection.

They achieved this by using a polyvinyl alcohol gel consisting of uniform crimped fiber structures that expand and straighten with a saline injection to mimic the natural tissue. The scientists selected this type of gel as it is isotropic, meaning its arrangement is highly uniform in all orientations, much like the tunica albuginea found in the mammalian body. Consequently, the resultant ATA has biomechanical properties very close to its natural counterpart.

Specifically, these mechanical features include rapid ‘stiffening’ due to strain and deformation, excellent fatigue resistance to sustain multiple erections, and the strength to withstand suturing (the current method of implantation).

“The greatest advantage of the ATA we report is that it achieves tissue-like functions by mimicking the microstructure of natural tissues,” Shi says. He also feels their technology isn’t limited to the repair of the tunica albuginea “but can be extended to many other load-bearing tissues.”

Is it safe?

To evaluate this, the researchers analyzed the effect of the ATA patches after one month in the pigs. Data indicated that although it didn’t restore the microstructure of the natural tissue, it did develop fibrosis, a type of wound healing where tissue thickens and becomes stiffer. The team says this type of tissue is comparable to that found in native structures and allowed the treated pigs to achieve a normal erection after researchers injected the penis with saline.

“The results one month after the procedure showed that the ATA group achieved good, though not perfect, repair results,” said Shi.

In an interview with Gizmodo, he concedes that as encouraging as these results are, this technology is still only in its infancy, with a lot more work to do before the ATA can move to human trials. One of their first tasks will be to evaluate the material’s long-term effectiveness and safety, as it will need a lifespan of at least three to five years in the body.

Shi says they could also improve how the material is implanted into the penis as they’re using a simple suture presently. He also points out that even if the ATA passes these tests, it’s still only one piece of the puzzle, as injured penises are often damaged in several ways, not just along the tunica albuginea.

For the future, the team plans on refining its technology to encompass all tissues and nerves damaged in penile injury. They also hope to use their ATA platform to repair other tissues, such as those found in the bladder and heart – adjusting the material depending on the tissue type.