This is making news all over the place. From The Guardian:
The Lab-Grown Penis: Approaching a Medical Milestone
After more than 20 years of research, a team of scientists are bioengineering penises in the lab which may soon be transplanted safely on to patients. It is an extraordinary medical endeavour that has implications for a wide range of disorders.
Gathered around an enclosure at the Wake Forest Institute for Regenerative Medicine in North Carolina in 2008, Anthony Atala and his colleagues watched anxiously to see if two rabbits would have sex. The suspense was short-lived: within a minute of being put together, the male mounted the female and successfully mated.
While it’s not clear what the rabbits made of the moment, for Atala it was definitely special. It was proof that a concept he’d been working on since 1992 – that penises could be grown in a laboratory and transplanted to humans – was theoretically possible. The male rabbit was one of 12 for which he had bioengineered a penis; all tried to mate; in eight there was proof of ejaculation; four went on to produce offspring.
The media’s coverage of Atala’s announcement a year later was understandably excited. Not just because of the novelty of a man growing penises in a laboratory, but because his work would fulfil a real need for men who have lost their penis through genital defects, traumatic injury, surgery for aggressive penile cancer, or even jilted lovers exacting revenge.
[…]
Organs increase in architectural complexity as they go from flat structures such as skin, cylindrical structures such as the vagina, to hollow non-tubular organs such as the bladder. As a solid organ, the penis tops this list in both density of cells and structural complexity. It consists of a spongy erectile tissue unique to it. During an erection, signals from the nerves trigger blood vessels to dilate, filling this spongy tissue with blood and causing the penis to lengthen and stiffen.
“We were completely stuck,” says Atala of the first few years of research in the early 90s. “Even the idea of the field of regenerative medicine was brand new at the time. We had no idea how to make this structure, let alone make it so it would perform like the natural organ.” Then, in 1994, he figured he could take a helping hand from Mother Nature. Using a technique pioneered for biological skin dressings, he would take a donor penis and soak it in a mild detergent of enzymes for a couple of weeks to wash away the donor cells.
“You’re left with a mostly collagen scaffold – a skeleton if you like, that looks and feels just like the organ,” explains James Yoo, one of Atala’s collaborators at the institute. “Think of it like a building. If you remove all the furniture and the people, you’re still left with the main structure of the building. Then you replace the tenants with new ones. That’s the whole idea. It’s just that the building is a penis and the tenants are cells.”