A group of Wake Forest University researchers has grown fully functional penile erectile tissue in rabbits, using a procedure that one day may be used to treat erectile dysfunction in men.
Dr. Anthony Atala said yesterday that he has been researching growth of the tissue for 18 years. In earlier experiments, the researchers were able to restore about 50 percent of the male rabbit's function.
But in results released yesterday in the online edition of the Proceedings of the National Academy of Sciences, the researchers reported that they were able to restore fully the erectile tissue of the penises of lab rabbits, giving the animals the ability to have sex and even produce offspring.
The research was done at Wake Forest University Baptist Medical Center's Institute for Regenerative Medicine.
Rabbits were used because of the similarity of their penile cells compared to humans, Atala said.
In the experiments, when the animals with engineered tissue mated with females, sperm was detected on vaginal swabs in eight of 12 samples, and four of the female rabbits were impregnated.
The research marks the latest breakthrough for the regenerative center and Atala, who was recruited to Wake Forest from Harvard University in 2004. Since then, the number of scientists, researchers and technicians on the center's staff has almost quadrupled, and numbers almost 100 people now, said Karen Richardson, a Wake Forest Baptist spokeswoman.
In 2005, scientists at the Regenerative Medicine Center announced that they had grown fat, muscle and bone cells using stem cells isolated from human skin. The next year, researchers had engineered tissues to rebuild human bladders. To date, those bladders have been implanted in almost 30 patients.
Atala said that growing skin tissue was relatively simple because the tissues are flat. Hollow organs such as the bladder are harder because they are more complex.
He said that the most complex and difficult tissues to grow in the lab are for solid organs such as the penis, in part because they require so many more cells than other types of tissues in order to have adequate blood supply.
Researchers first harvested smooth muscle cells and endothelial cells, the same type of cells that line blood vessels, from the animals' erectile tissue. They multiplied those cells in the lab and then injected the cells into a three-dimensional scaffold that provided support while the cells developed. When they implanted the scaffold, organized tissue with vessel structure began to form as soon as one month later.
Atala said that the department will now work to see if the results can be replicated using human penile tissue.
"We're going to be doing that experimentally at our center," he said.
If those experiments are successful, they could help address a wide variety of problems.
The tissue could be used to help treat congenital abnormalities or help men whose penises have been damaged by surgery or injury.
Atala said that there may also be a benefit of growing new tissue for the up to 25 percent of men with erectile dysfunction who do not respond to drug treatments.
"A lack of erectile tissue currently prevents us from restoring sexual functions to these patients," he said.
Atala said that he knows there will be interest in the results from some who may be interested in the potential for male enhancement. Atala said he's more interested in the potential medical benefits of the research than the cosmetic ones. Using the engineered penile tissues for cosmetic reasons would require surgery, which always involves some risk, Atala said.
"There are so many medical conditions that could benefit," he said.
pgarber@wsjournal.com
727-7327
Email
Facebook
Google
Twitter
Favorites
More
Advertisement