A new study indicates that an injection of stem cells from a patient's own muscle can help restore control of a leaky bladder.

Stress incontinence symptoms improved in five out of seven women who got the experimental treatment, said senior investigator Dr. Michael Chancellor, a urologist at the University of Pittsburgh School of Medicine. None of the women had serious side effects.

"We just wanted to prove that it's feasible and safe, and to find ... improvement was terrific," he said. "It's like a bonus."

The findings were presented in Atlanta at the annual meeting of the American Urological Association.

Collaborators in Toronto, Ontario, performed the procedures for the study, which is the first of its kind in North America. About a week ago, Pitt researchers received federal approval to begin a similar trial here, Dr. Chancellor said.

In the protocol, a pea-sized biopsy of thigh muscle was taken from each participant. The sample was sent to Pittsburgh, where the stem cells were isolated and grown by Cook MyoSite Inc., which funded the project.

About 20 million cells were then sent back to Toronto to be injected into the patient.

Participant Sharon Tomlinson, of Pefferlaw, Ontario, who will soon turn 59, watched on a monitor as the doctor injected the cells into four areas around her urethra that had been numbed with local anesthetic. Like the biopsy, it was an outpatient procedure.

"It's probably the equivalent of getting a cavity done in the dentist's office," Dr. Chancellor explained.

For 10 years, Mrs. Tomlinson leaked urine when she laughed, coughed or sneezed.

"It just got so embarrassing," she said. "I would always take a change of clothes anywhere I went."

She tried strengthening her sphincter muscles with exercises, but that didn't help. She was reluctant to have an operation to fix the problem because many of her friends told her it didn't work well for them.

She's glad she took part in the study, which was led by Dr. Lesley Carr, a urologist at Sunnybrook Health Centre in Toronto. The injections appeared to work, and she no longer takes a change of clothes along when she goes out.

"I really started noticing a difference before my three-month checkup," Mrs. Tomlinson said. "I could laugh and not [have to] squeeze my legs and hold myself. Probably by my nine-month checkup, I was 100 percent."

Sheila McNeil, 66, of Stouffville, Ontario, did not have such a dramatic improvement, and plans to have surgery in the fall. She was the first patient to get the cells, and had the procedure repeated a year later after the researchers improved their technique.

"I still have a leaky bladder, but not nearly as bad as it was," Mrs. McNeil said. "It's better, but it's not how I want to live the rest of my life."

Dr. Carr said the next study phase will focus on determining the optimal number of stem cells for the procedure, and a second site will open in Alberta.

"It's very early but we're all really enthusiastic," she said. "We're impressed that as our techniques of injection evolved, we started to see definite improvements in the patients."

Dr. Chancellor said the Pittsburgh study could begin in the summer. About 50 women with stress incontinence will be needed to participate. He hopes to get approval to try the stem cell technique in as many men, who sometimes become incontinent after prostate cancer surgery.

About 13 million Americans, mostly women, have the condition, which may be caused by muscles weakened from frequent childbearing or pelvic surgery.