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Stem cells instead of Viagra?
SEOUL, South Korea—Ever since Viagra hit the markets in 1998, men with erectile dysfunction (ED) have had access to oral medications that in a majority of cases are remarkably effective. But not in all cases; roughly 20 percent of men with ED remain unresponsive to oral phosphodiesterase type 5 inhibitors like Viagra and other forms of available treatment. And men who have undergone prostatectomy as treatment for prostate cancer are much less likely to see results from oral medication. It is these men who are most likely to benefit from the promising findings of a new study into the potential of using the byproduct of liposuction to treat ED.
The study, a collaboration between Asan Medical Center and University of Ulsan College of Medicine in South Korea, compared the effectiveness in rats of two different methods of using stem cells to treat ED caused by damage to the cavernous nerve (CN), which facilitates erection and is sometimes injured during radical prostatectomy. One of the methods that was studied uses stem cells derived from uncultured stromal vascular fraction (SVF), a byproduct of liposuction. The other method uses adipose-derived stem cells (ADSCs) that are cultured in the lab.
Many published studies have explored the potential for using stem cells to treat ED. Until now, however, no study has reported side-by-side comparisons of the effectiveness of uncultured SVF versus cultured ADSCs for treating ED. “This first study to compare two types of cells derived from fat tissue in a rat model of erectile dysfunction after prostate cancer surgery is an important step in identifying effective new treatments for this condition,” said Anthony Atala, director of the Wake Forest Institute for Regenerative Medicine and editor-in-chief of STEM CELLS Translational Medicine, which published the study.
ADSCs, which are harvested from fat, are an attractive source of stem cells for several reasons. First, they are not only abundant but can also be easily obtained using minimally invasive liposuction. Secondly, they also have characteristics similar to bone marrow-derived stem cells in terms of their potential for self-renewal and multipotency. Moreover, ADSCs retain their ability to divide and grow longer than bone marrow-derived stem cells, which may be beneficial in treating chronic conditions.
Cultured ADSCs also have limitations, however. These shortcomings include the cost and time required to culture them, their potential for contamination, the possibility they will undergo changes in cell characteristics during culturing procedures and their tendency to sometimes form tumors. To avoid these risks, uncultured SVF has emerged as an easier and safer way to use stem and progenitor cells derived from fat tissue.
The study, led by Drs. Dalsan You and Choung- Soo Kim, involved testing the cells in 40 rats, some with injured cavernous nerves and some with healthy cavernous nerves. One group of animals was injected with cultured ADSCs, another received uncultured SVF and a control group received no stem cells. Four weeks later, the two groups of rats that were treated with stem cells experienced significantly improved erection function when compared to the control group. Both types of stem cell types also significantly increased the number of neuronal nitric oxide synthase-positive nerve fibers, suggesting that they stimulated nerve regeneration.
But there were significant differences in the effects of the two types of stem cells on the rats. The scientists reported that cells coming from uncultured SVF outperformed the cultured ADSCs in terms of the ratio of smooth muscle-to-collagen ratio achieved and the endothelial cell content in the blood vessels, which are both important factors in repairing ED.
The scientists intend to follow up on their study by looking at other aspects of the potential for stem cell therapy to cure ED. “Further research is now ongoing to determine the optimal protocol for cellular therapy of ED following CN injury,” said You. “We want to follow the progress of the animals over the long term and also we want to see what happens with multiple stem cell injections, rather than just the one given in this study.”