Lab-grown penises are ready for human trials
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They've already created lab-grown kidneys, hearts, and vaginas, and now a team of bioengineering specialists at the Wake Forest Institute for Regenerative Medicine in the US is working on getting their lab-grown penises approved for human testing.

Led by Anthony Atala, director of the Wake Forest Institute, the researchers started out by crafting penises for rabbit subjects back in 2008. The process begins with the researchers taking cells from the remainder of the recipient's penis and growing them in the lab for four to six weeks. This ensures that the risk of the recipient's body rejecting the new organ will be low. They also take a donor penis, wash it with detergent to kill all the living cells, and use this as a collagen frame - or scaffold - on which to build their new penis. 

To make sure the lab-grown penis is actually functional when transplanted onto a recipient, the team built each one by layering endothelial cells - which line the interior surface of blood vessels - on top of smooth muscle cells. Of the 12 male rabbits that received the team's lab-grown penises, each one ended up mating with a female as soon as they were put in contact, and four of these interactions resulted in pregnancies. 

"The rabbit studies were very encouraging,” Atala told Dari Mohammadi at The Guardian, "but to get approval for humans we need all the safety and quality assurance data, we need to show that the materials aren't toxic, and we have to spell out the manufacturing process, step by step.”

While hospitals already have an option for human patients in need of a replacement penis, it’s by no means ideal, as Mohammadi explains:

"At present, the only treatment option for these men is to have a penis constructed with skin and muscle from their thigh or forearm. Sexual function can be restored with a penile prosthetic placed inside. The prosthetics can be either malleable rods, with the penis left in a permanently semi-rigid state and thus difficult to conceal, or inflatable rods, which have a saline pump housed in the scrotum. Both technologies have been around since the 1970s. The aesthetics are crude and penetration is awkward.”

Atala’s team has been specialising in lab-grown tissues and organs for over 10 years, and are right now working on 30 different kinds, including the first ever lab-grown human bladder, which they created in 1999, and the first lab-grown vagina, developed in 2005. 

They’re now in the process of getting approval from the US Food and Drug Administration to start human testing on their lab-grown penises within the next five years. They've so far built six human penises that are ready for transplantation, as soon as they get approval. If the trials prove a success, the technique will be made available in hospitals around the world, using penises from deceased donors for the scaffolding. 

"Our target is to get the organs into patients with injuries or congenital abnormalities,” Atala told The Guardian. His work has been funded by the US Armed Forces Institute of Regenerative Medicine, so one group he hopes to help with this technology is soldiers who have sustained severe injuries on the battlefield. He also hopes to assist people who have been born with a disorder known as ambiguous genitalia, which is often treated by removing the male genitals altogether, and essentially forces a male to grow up as a female.

"Imagine being genetically male but living as a woman," Atala told Becky Ferreira at Motherboard. "It's a firmly devastating problem that we hope to help with."