Stem cells rebuild bladder control

Using a patient’s own stem cells to rebuild feeble bladder-control muscles may provide lasting relief from the embarrassing and inconvenient symptoms of urinary incontinence, a new study reveals.

Activity-induced incontinence – a tiny tinkle when a person laughs or jogs, for example – is very common, affecting an estimated 10% to 35% of women globally. Also called stress incontinence, the loss of control is due to shrinking muscles in the bladder, sphincter, and urethra wall and becomes more likely as women age.

In 1995, US sufferers alone spent $12.4 billion on drugs, adult incontinence pads and corrective surgeries. But even surgical treatments, such as collagen or liquid plastic injections to bulk up the urethra, are not permanent and can make it difficult to urinate.

So Ferdinand Frauscher and his colleagues at University Hospital, Innsbruck, Austria wanted to see if stem cells could put the muscle power back, to re-establish natural control.

Bladder controlled experiment

The team removed a cube of muscle tissue, 4 millimetres to a side, from the biceps of 20 women, ranging in age from 36 to 84. Stem cells from the tissue were extracted and then grown in culture for six weeks, producing about 50 million myoblasts — the precursors of muscle fibres.

“If you just inject 100,000 cells you can forget it. If you want to get a strong [bladder] sphincter muscle you must use a really large number of cells,” says Frauscher.

Frauscher’s team injected the myoblasts into the urethra wall and bladder sphincter of each woman, using real-time ultrasound to make sure the cells made contact with their target. This contact is crucial as myoblasts need to be “told” in which direction they should grow by existing muscle fibres. The muscle-tissue extraction and stem-cell injection procedures each took about 15 minutes under local anaesthetic.

Within 24 hours, 90% of the women had no urinary leakage. After two weeks, both doctor and patient could a see a marked increase in muscle tissue and contraction power under the ultrasound.

Now, more than a later year, 18 of the 20 women have maintained full control over their bladders, says Frauscher, who presented the results at the Radiological Society of North America meeting in Chicago on Monday. The team is currently treating eight to 10 women per week and long waiting lists are building up.

Christopher Woodhouse, at the Institute of Urology and Nephrology, University College London, is optimistic about the work. “At the moment, only God can make a sphincter. If you can make a muscle that relaxes and contracts in response to the body’s normal mechanisms, it would be a huge advance,” he told New Scientist.

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