Vibrating gastric stimulators – the next big obesity treatment?

Credit: yana_vinnikova / Shutterstock

According to a 2023 GlobalData report, the obesity market will grow significantly over the next few years, reaching sales of $37.1 billion in 2031. Glucagon-like peptide-1 receptor agonist (GLP-1RA) therapies currently dominate the treatment space but concerns are rising over their side effects. Invasive procedures such as bariatric surgery are also on the decline due to requiring long-term lifestyle changes.

A team of scientists from the Department of Medical Engineering at the Massachusetts Institute of Technology (MIT), the Gastroenterology, Hepatology, and Endoscopy Department at Brigham and Women’s Hospital, and Harvard University, are devising a new vibratory stimulation technique which activates gastric stretch receptors.

“We have developed a new luminal stimulation technique to activate specifically gastric stretch receptors and elicit a vagal afferent response similar to mechanical distension,” says Dr Shriya Srinivasan, assistant professor of bioengineering at Harvard University. The outcome is VIBE - an oral capsule housing a tiny vibrating motor which stimulates the nucleus of the solitary tract (NTS) in the stomach, creating a sensation of being full similar to that experienced after eating a large meal. 

The Vibrating Ingestible BioElectronic Stimulator (VIBES) consists of a DC offset motor, a 1.55 volt, 80 mAh silver oxide battery, a central body, and a gelatinous membrane which dissolves in the stomach on contact with gastric juices. This system is encapsulated in a pill with the same dimensions as a size 000 capsule: 26.14 mm long, 9.97 mm in diameter and a volume of 1.37 millilitres.

When VIBES reaches the stomach, it encounters the gastric lining and activates upon exposure to gastric juices. The vibrations stimulate intraganglionic laminar endings (IGLEs) in the celiac plexus, signalling distension to the NTS. This interaction with the hunger circuitry generates the illusion of feeling full. Consequently, a signal is sent to the brain to release hormones, such as serotonin, which help digest food, induce satiety, and prompt the cessation of eating. 

The team of researchers have evaluated the vibrating capsule on a porcine model using Yorkshire pigs aged between 4 and 6 months and weighing 50 to 80 kg. “Given the need for anatomical dimensions similar to those of humans in order to accommodate the physical shape of the VIBES pill, we opted for a porcine model,” explains Giovanni Traverso, associate professor of mechanical engineering at MIT and a gastroenterologist at Brigham Women’s Hospital.

To gauge the impact of the capsules on appetite and food consumption, the research team devised an experiment involving four pigs, fed a total of 108 meals. A comparison was made between the amount consumed by each pig over a two-week period either with or without the vibrating capsule. The vibrating capsule was activated 30 minutes before each meal during the treatment phase. The findings, published in Science Advances, revealed a noticeable reduction in food intake, with the treated pigs consuming on average 40% less than their untreated counterparts. The research team also investigated the effect of the vibrating capsules on weight gain, observing a slower rate of weight gain in the treated pigs compared to the untreated ones. “Compared to the untreated controls, the rate of weight gain among subjects treated with VIBES was significantly lower, with P <0,05,” says Prof. Traverso, emphasising the statistical significance of the findings.

In this proof-of-concept study, the research team delved deeper into the effects of vibrating capsules on fasting porcine models, focusing specifically on the hormones which regulate digestion, satiety, and appetite. Six pigs were administered the capsules, while another six were given a placebo. Analysis of blood samples revealed a significant decrease in the hunger hormone ghrelin among the treated animals compared to the untreated group, indicating a noticeable reduction in appetite conducive to weight loss. Moreover, the safety profile of the vibrating capsules was thoroughly assessed in the treated pigs, revealing no adverse effects. No negative impacts on motility were observed in the treated animals, and no signs of distress or obstruction were recorded. Furthermore, endoscopy examinations and histology analysis revealed no abnormalities, irritation or inflammation following administration of VIBES.

These results suggest that the VIBES pill could be an effective method for reducing food intake and the rate of weight gain without causing any undesirable side effects. “Following further safety validations, clinical translation could facilitate a paradigm shift in potential treatment options for conditions such as obesity, polyphagia, and Prader-Willi syndrome where late onset of satiety leads to excessive eating and subsequent metabolic, cardiac, and endocrine comorbidities,” says Srinivasan.

Future research efforts will focus on developing miniaturised VIBES devices suitable for smaller animal models, including studies on canine models with stomach size more akin to humans. Shedding light on the passage of VIBES through the small intestine and its impact on nutrient absorption, microbiome dynamics, cytokine modulation, and overall gastrointestinal function will be a key focus of future investigations. Additionally, exploring mechanisms for external control over the activation or deactivation of the pill could enhance both safety and convenience.