Neuroscientists and engineers have developed a soft, implantable device that could detect overactivity in the bladder and use light from biointegrated LEDs to reduce the urge to urinate for people with bladder problems. This has been shown to reduce symptoms in rats and could potentially replace current medication and electronic stimulators in the future.
In the study, published in Nature, a team of researchers from Washington University School of Medicine (MO, USA), the University of Illinois at Urbana-Champaign (IL, USA) and Northwestern University (IL, USA) collaborated to create the implantable device, which was shown to control urination in laboratory rats. Previously, bladder problems including pain, burning and frequent urination have been treated using electronic stimulators that send a current to nerves in the bladder. While these implants improve incontinence, they may also disrupt normal nerve signaling in other organs.
“There definitely is benefit to that sort of nerve stimulation,” commented Robert Gereau IV, Washington University School of Medicine . “But there also are some off-target side effects that result from a lack of specificity with those older devices.”
The new device was implanted into the laboratory rats around the bladder, like a belt, through minor surgery. This allowed the belt to expand and contract as the bladder filled and emptied. Opsins, proteins carried by a virus that binds to nerve cells in the bladder, were then injected into the rats’ bladders. This caused the nerve cells to become sensitive to light signals allowing the researchers to control their behavior through optogenetics.
The team were able to read information from the implanted device in real-time using blue-tooth communication to signal an external device. Then an algorithm was applied to allow the researchers to detect filling and emptying of the rats’ bladder.
“When the bladder is emptying too often, the external device sends a signal that activates micro-LEDs on the bladder band device and the lights then shine on sensory neurons in the bladder. This reduces the activity of the sensory neurons and restores normal bladder function,” explained Gereau.
The team hopes a similar approach using larger devices implanted by catheters could be used in humans to control bladder problems.
“We’re excited about these results. This example brings together the key elements of an autonomous, implantable system that can operate in synchrony with the body to improve health: a precision biophysical sensor of organ activity; a noninvasive means to modulate that activity; a soft, battery-free module for wireless communication and control; and data analytics algorithms for closed-loop operation,” commented John Rogers, Northwestern University.
The team expect to trail similar devices in larger animals, however, further research into the viruses used to generate light-sensitivity in organ cells is required. It is also believed that a similar approach could be used in other parts of the body to treat conditions such as chronic pain and insulin secretion in diabetics.
“We don’t yet know whether we can achieve stable expression of the opsins using the viral approach and, more importantly, whether this will be safe over the long term,” Gereau concluded. “That issue needs to be tested in preclinical models and early clinical trials to make sure the strategy is completely safe.”
Sources: Mickle AD, Won SM, Noh KN et al. A wireless closed-loop system for optogenetic peripheral neuromodulation. Nat. (2019); www.eurekalert.org/pub_releases/2019-01/wuso-tid122818.php