Conclusion: What does all this mean? Further research is surely needed, but it may well be that we can achieve better medical results for large numbers of people in developing countries by focusing on nutritional and public-health interventions, rather than fancy new medications.
Problem: Depending on how you measure it (and the age of the people you survey), somewhere between 8 percent and 40 percent of American women suffer from urinary stress incontinence—the leakage of urine with physical exertion, sneezing, or coughing. The problem is more likely to occur as women age and after they have delivered babies.
Standard treatments: The famous Kegel exercises are usually tried first, but they don't work well for many patients. Women often go on to more invasive treatments like surgery or the injection of bulking agents to plump up the tissues around the neck of the bladder and help keep the urethral valve tightly closed. There is evidence that the surgery helps, but sometimes at the cost of side effects like a higher rate of urinary tract infections or the development of other complications, like leakage associated with the urge to urinate. In addition, as time passes the stress incontinence may return.
New research: A recent paper describes an entirely new approach to this problem, with impressive results. The researchers argue that the main cause of stress incontinence is a weakening of the muscle layer that almost surrounds the urethra below the bladder. (This weakening is the result of injury—often associated with childbirth—and a gradual dwindling of muscle cells as patients age.) As patients get older, the supportive tissue layer just below the lining of the urethra also thins and weakens.
Method: The study authors treated stress incontinence by strengthening the failing muscle layer and thickening and restoring the layer of tissue just underneath the lining of the urethra. They did this by collecting a small amount (about one-tenth of a teaspoon in volume) of muscle tissue through a small incision in the patient's upper arm. These tissues were cultivated in a laboratory for almost two months to develop a stock of muscle stem cells and fibroblast support cells. Then, they were passed up through the urethra to the proper level just below the bladder and injected in multiple tiny amounts through the urethral lining.
Findings: Forty-two women were randomly assigned to receive this treatment, and their results were compared with a control group of 21 women who were given a conventional treatment for stress incontinence: the injection of collagen, a bulking agent, into the tissues surrounding the urethra. There were no complications in either group. A year after the procedures, 90 percent of the women who received the cell treatment were cured of incontinence, compared with only 10 percent of the women treated with the bulking agent. (Of the four patients in the cell-treated group who were not completely recovered, three showed substantial improvement. In contrast, among the women given conventional treatment, besides the two successes, almost none of the remainder showed any improvement.) After three years, the results were unchanged. As you might expect, the quality of life was a lot better for the successfully treated women.
Conclusion: The treatment I've described is in a very early stage of development, but it's exciting and promising. I am particularly taken with it given what we know about the mechanism of incontinence, and as an example of a well-thought-out application of a hot new method, the use of adult-derived stem cells.