Muscle cells taken from patients' own thighs could help reduce stress urinary incontinence according to a new study.

Most patients get help from exercises, behavioral training, and drug treatment; but many still leak often.

A new therapy takes muscle cells from the upper thigh and injects them into the sphincter muscle that controls urine flow. The idea is to stimulate growth of new sphincter muscle cells via growth signals sent by the injected cells.

The university of Toronto researcher Lesley K. Carr, and colleagues treated 29 women with one or two injections of thigh muscle cells at various doses.

All of the women were experiencing stress urinary incontinence that had not improved over a year of standard therapy.

Carr reported: 'Overall, urinary leaks were reduced after both injections.'

12 months after the muscle-cell injections over three-fourths of the women said they had fewer stress leaks and less urinary urgency.

However, one woman had worse incontinence than she had before. Although they weren't classed as "serious," there was pain and bruising in the thigh, pain at the site of injection, and "mild and self-limiting urinary retention and urinary tract infection."

Despite these issues, 86% of patients chose to have a second muscle cell injection three months after the first.

An American Urological Association spokesman, said the study confirmed the muscle-cell treatment to be safe and effective:

'It is important to note that this therapy has few side effects and seems to improve symptoms for most patients in whom other therapies failed.'