|Anthony Atala and his team is growing bioengineered|
penises in the lab.
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. The work will fulfil a real need for men who have lost their penis through genital defects, traumatic injury, surgery for aggressive penile cancer. 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.
Another option is a penis transplant from another individual, but this carries a risk of immunological rejection. The chance of organ death can be lessened with anti-rejection drugs, but these drugs have serious side-effects. Transplants can also have a psychological impact, especially with an organ as intimate as the penis. In 2006, a Chinese man was the first to receive a donor penis; two weeks after the 15-hour operation, surgeons removed the transplanted organ on the request of both the patient and his partner.
In 2006, the research team announced the first successful bioengineered organ transplant, a bladder, which had been implanted into seven patients in 1999. Earlier this year they announced the successful follow-up of four women given bioengineered vaginas in 2005-2008. Despite these successes, the penis is proving trickier.
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.
The research team has made encouraging progress. They have engineered half a dozen human penises. Although they are not yet ready for transplanting, the team is assessing the structures for safety and effectiveness. One machine squashes, stretches and twists them to make sure they can stand up to the wear of everyday life; another pumps fluid into them to test erections. Sliced segments are tested at the genetic, cellular and physiological level.
Please read the entire story of Anthony Atala and his team in The Guardian.