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CT scan of a rat with a small implanted device.
This CT scan of a rat shows a small device implanted around the bladder. The device uses light signals from tiny LEDs to activate nerve cells in the bladder and control problems such as incontinence and overactive bladder. (Credit: Washington University School of Medicine)

A team of neuroscientists and engineers has developed a tiny, implantable device that has potential to help people with bladder problems bypass the need for medication or electronic stimulators. The team created a soft, implantable device that can detect overactivity in the bladder and then use light from tiny, biointegrated LEDs to tamp down the urge to urinate.

The device works in laboratory rats and one day may help people who suffer incontinence or frequently feel the need to urinate.

Overactive bladder, pain, burning and a frequent need to urinate are common and distressing problems. For about 30 years, many with severe bladder problems have been treated with stimulators that send an electric current to the nerve that controls the bladder. Such implants improve incontinence and overactive bladder, but they also can disrupt normal nerve signaling to other organs.

During a minor surgical procedure, they implant a soft, stretchy belt-like device around the bladder. As the bladder fills and empties, the belt expands and contracts. The researchers also inject proteins called opsins into the animals’ bladders. The opsins are carried by a virus that binds to nerve cells in the bladder, making those cells sensitive to light signals. This allows the researchers to use optogenetics — the use of light to control cell behavior in living tissue — to activate those cells.

Using blue-tooth communication to signal an external hand-held device, the scientists can read information in real time and, using a simple algorithm, detect when the bladder is full, when the animal has emptied its bladder, and when bladder emptying is occurring too frequently.

Closed-loop operation essentially means the device delivers the therapy only when it detects a problem. When the behavior is normalized, the micro-LEDs are turned off, and therapy can be discontinued.

The researchers also believe the strategy could be used in other parts of the body — treating chronic pain, for example, or using light to stimulate cells in the pancreas to secrete insulin. One hurdle, however, involves the viruses used to get light-sensitive proteins to bind to cells in organs.

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