"If we can engineer and replace this tissue
(penis), these men can have erections again," said Yoo,
Scientist’s makes progress, grows penises which
can be used by people who have undergone surgery for aggressive cancer or
suffered traumatic injury.
Researchers at the Wake Forest Institute for
Regenerative Medicine in Winston-Salem, North Carolina, are testing engineered
penises for safety, function and durability. They hope to receive approval from
the US Food and Drug Administration to be tested on humans.
Professor Anthony Atala, director of the
institute, oversaw the team's successful engineering of penises for
rabbits in
2008. "The rabbit studies were very encouraging," he said, "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."
The penises would be grown using a patient's own
cells to avoid the high risk of immunological rejection after organ
transplantation from another individual. Cells taken from the remainder of the
patient's penis would be grown in culture for four to six weeks.
For the structure, they wash a donor penis in a
mild detergent to remove all donor cells. After two weeks a collagen scaffold
of the penis is left, on to which they seed the patient's cultured cells –
smooth muscle cells first, then endothelial cells, which line the blood
vessels. Because the method uses a patient's own penis-specific cells, the
technology will not be suitable for female-to-male sex reassignment surgery.
"Our target is to get the organs into
patients with injuries or congenital abnormalities," said Atala, whose
work is funded by the US Armed Forces Institute of Regenerative Medicine, which
hopes to use the technology to help soldiers who sustain battlefield injuries.
As a paediatric urological surgeon, Atala began
his work in 1992 to help children born with genital abnormalities. Because of a
lack of available tissue for reconstructive surgery, baby boys with ambiguous
genitalia are often given a sex-change at birth, leading to much psychological
anguish in later life. "Imagine being genetically male but living as a
woman," he said. "It's a firmly devastating problem that we hope to
help with."
Asif Muneer, a consultant urological surgeon and
andrologist at University College hospital, London, said the technology, if
successful, would offer a huge advance over current treatment strategies for
men with penile cancer and traumatic injuries. At present, men can have a penis
reconstructed using a flap from their forearm or thigh, with a penile
prosthetic implanted to simulate an erection.
"My concern is that they might struggle to
recreate a natural erection," he said. "Erectile function is a
coordinated neurophysiological process starting in the brain, so I wonder if
they can reproduce that function or whether this is just an aesthetic
improvement. That will be their challenge."
Atala's team are working on 30 different types of
tissues and organs, including the kidney and heart. They bioengineered and
transplanted the first human bladder in 1999, the first urethra in 2004 and the
first vagina in 2005.
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