Gene Therapy Offers Hope of New Lease on Sex Life
Five days after the injections, the rats underwent nerve stimulation to simulate a normal erection, and their responses were compared with those of other rats one-third their age. The researchers found that older animals that received the adenovirus had erectile responses comparable to those of young rats. In contrast, older rats injected with a different gene not associated with erectile function had no significant improvements in function.
The researchers also found evidence that the virus continued to be present in penile tissue for up to 30 days, suggesting that the therapy, if found to be safe and effective in humans, could be delivered once a month rather than before every episode of sexual intercourse -- no doubt a welcome prospect to men who are squeamish about the idea of penile injections.
But a urologist who studies gene therapy for erectile dysfunction tells WebMD that there are several drawbacks to using adenoviruses as carriers for genes.
"As a strategy in humans, I think adenovirus has some drawbacks in that it's inflammatory, and usually repeated doses will cause [an immune system reaction]. I think we need to keep trying different genes, and we also need to start looking at long-term strategies for gene expression, because these are [temporary] and won't be permanently incorporated into the penis," says Hunter Wessells, MD, associate professor of urology at the University of Washington School of Medicine in Seattle.
Craig F. Donatucci, MD, a urologist who specializes in research and treatment of erectile dysfunction at Duke University Medical Center in Chapel Hill, N.C., tells WebMD that "conceptually it makes sense, because you fix the problem, but then you have the issue about the dangers of [adenoviruses]."
Donatucci points to the 1999 death of a patient at the University of Pennsylvania who was undergoing experimental gene therapy with an adenovirus for correcting a lifelong metabolic disorder. "If you're talking just about erectile failure, what's your safety level? Where do you set that?" he asks. "From a general philosophical viewpoint, it's very attractive to think of gene therapy in the future, putting in some form of gene therapy, but realistically, it's a long way from happening."