Engineers develop vibrating, ingestible capsule that could help treat obesity

When you eat a large meal, your stomach sends signals to your brain that create a feeling of fullness, which helps you realize it’s time to stop eating. A stomach full of fluid can also send these messages, which is why dieters are often advised to drink a glass of water before eating.

Now MIT engineers have developed a new way to take advantage of this phenomenon, using an ingestible capsule that vibrates in the stomach. These vibrations activate the same stretch receptors that detect when the stomach is distended, creating an illusory feeling of fullness.

The team’s work is published in Scientists progress.

In animals given this pill 20 minutes before eating, researchers found that this treatment not only stimulated the release of hormones signaling satiety, but also reduced the animals’ food consumption by about 40 percent. Scientists still have much to learn about the mechanisms that influence human weight, but if further research suggests that this technology could be used safely in humans, such a pill could offer a minimally invasive way to treat weight loss. obesity, researchers say.

“For someone who wants to lose weight or control their appetite, it could be taken before every meal,” says Shriya Srinivasan Ph.D., a former MIT graduate student and postdoctoral fellow who is now an assistant professor of bioengineering at the Harvard University. “This could be really interesting in the sense that it would provide an option that could minimize the side effects that we see with other pharmacological treatments.”

Srinivasan is the lead author of the new study. Giovanni Traverso, associate professor of mechanical engineering at MIT and gastroenterologist at Brigham and Women’s Hospital, is the senior author of the paper.

A feeling of fullness

When the stomach stretches, specialized cells called mechanoreceptors detect this stretch and send signals to the brain via the vagus nerve. As a result, the brain stimulates the production of insulin, as well as hormones such as C-peptide, Pyy and GLP-1. All of these hormones work together to help people digest their food, feel full, and stop eating. At the same time, levels of ghrelin, a hunger-promoting hormone, decrease.

While he was a graduate student at MIT, Srinivasan became interested in the idea of ​​controlling this process through vibration, artificially stretching the mechanoreceptors that line the stomach. Previous research has shown that vibrations applied to a muscle can make the muscle appear to have stretched further than it actually is.

“I wondered if we could activate the stretch receptors in the stomach by vibrating them and making them perceive that the entire stomach had been expanded, to create an illusory sensation of distension that could modulate hormones and eating habits,” says Srinivasan.

As a postdoctoral fellow at MIT’s Koch Institute for Integrative Cancer Research, Srinivasan worked closely with Traverso’s lab, which developed many novel approaches for oral drug delivery and electronic devices . For this study, Srinivasan, Traverso and a team of researchers designed a capsule the size of a multivitamin, which includes a vibrating element. When the pill, powered by a small silver oxide battery, reaches the stomach, acidic gastric fluids dissolve a gelatinous membrane that covers the capsule, completing the electronic circuit that activates the vibrating motor.

In an animal study, researchers showed that once the pill begins to vibrate, it activates mechanoreceptors, which send signals to the brain through stimulation of the vagus nerve. The researchers tracked hormone levels during periods when the device vibrated and found that they mirrored the patterns of hormone release seen after a meal, even when the animals were fasted.

The researchers then tested the effects of this stimulation on the animals’ appetite. They found that when the pill was activated for about 20 minutes, before the animals were given food, they consumed on average 40 percent less than when the pill was not activated. The animals also gained weight more slowly during the periods they were treated with the vibrating pill.

“Behavior change is profound and requires the use of the endogenous system rather than any exogenous therapeutics. We have the potential to overcome some of the challenges and costs associated with biologic drug delivery by modulating the enteric nervous system,” explains Traverso.

The current version of the pill is designed to vibrate for about 30 minutes after arriving in the stomach, but researchers plan to explore adapting it to stay in the stomach for longer periods, where it could be turned on and off. wirelessly according to your needs. In animal studies, the pills passed through the digestive tract in four or five days.

The study also found that the animals showed no signs of obstruction, perforation or other negative impacts while the pill was in their digestive tract.

An alternative approach

This type of pill could offer an alternative to current approaches to treating obesity, researchers say. Nonmedical interventions such as diet and exercise don’t always work, and many of the existing medical interventions are quite invasive. These include gastric bypass surgery, as well as gastric balloons, which are no longer widely used in the United States due to safety concerns.

Medications such as GLP-1 agonists can also help with weight loss, but most of them require injection and are unaffordable for many people. According to Srinivasan, MIT capsules could be manufactured at a cost that would make them accessible to people who don’t have access to more expensive treatment options.

“For many populations, some of the most effective therapies for obesity are very expensive. At scale, our device could be manufactured quite cost-effectively,” she says. “I would like to see how this would transform care and therapy for people working in global health settings who may not have access to some of the more sophisticated or expensive options available today.”

The researchers now plan to explore ways to scale up manufacturing of the capsules, which could enable human clinical trials. Such studies would be important to learn more about the safety of the devices, as well as to determine the best time to swallow the capsule before a meal and how often it should be administered.

Other authors of the paper include Amro Alshareef, Alexandria Hwang, Ceara Byrne, Johannes Kuosmann, Keiko Ishida, Joshua Jenkins, Sabrina Liu, Wiam Abdalla Mohammed Madani, Alison Hayward and Niora Fabian.

This story is republished courtesy of MIT News (web.mit.edu/newsoffice/), a popular site that covers news about MIT research, innovation and education.