A number of types of surgical treatment are available to facilitate weight loss in obese people and reduce their incidence of associated health problems, especially diabetes. For those who are willing to undergo surgery, gastric bypass (Roux-en-Y) has long been the most common option. Bypass surgery does tend to yield the best results in terms of overall weight loss, but it still has some drawbacks. Like any major surgery, the procedure entails some risks.
Recently, however, researchers at the Massachusetts General Hospital (MGH) Weight Center and Gastrointestinal Unit have developed and tested a new way of treating obesity through “incisionless bariatric surgery.” A new medical device—called an endoluminal (i.e., intra-intestinal) sleeve (ELS)—which can be inserted endoscopically, mimics the effects of gastric bypass by sealing off the upper portion of the small intestine with an impermeable lining that prevents the intestine from sensing and absorbing the nutrients in food so that it passes through to the lower intestinal tract relatively undigested.
The MGH team reported on the first controlled tests of this device in an article in Obesity: “An Endoluminal Sleeve Induces Substantial Weight Loss and Normalizes Glucose Homeostasis in Rats with Diet-Induced Obesity,” authors Vincent Aguirre, Nicholas Stylopoulos, Ronit Grinbaum and Lee M. Kaplan, Obesity 16: 2585-2592
The Rat Model
The MGH team worked with two groups of rats. One group had been raised using a high-fat diet, so that they were obese and had mild diabetes. The second group had been brought up on a low-fat diet and remained lean; these rats had been genetically bred to gain weight quickly. In each group, the researchers implanted into half of the rats a flexible, 10-centimeter long endoluminal sleeve that was attached at the outlet of the stomach and lined the duodenum and upper jejunum.
During the 16-weeks following implantation, the overweight rats that had received the endoluminal sleeve (ELS) consumed 30 percent fewer calories than the overweight control group. After seven weeks, they weighed 20 percent less than the controls, and they maintained that loss for the duration of the study. Their diabetes indicators—fasting blood glucose, insulin, and oral glucose tolerance—all fell to normal levels. The formerly obese rats had achieved significant weight loss and their diabetes had disappeared.
In the second test group, all the lean rats were put on a high-fat diet. Almost all gained weight, but the rats with the ELS implant ate and gained significantly less weight (12% less) than the control group. These results indicated that the endoluminal sleeve could prevent as well as treat obesity.
Implications for human subjects
Implications For Human Subjects
The researchers postulate that the ELS may alter the activation or levels of certain hormones in the intestines—such as insulin—leading to metabolic changes that enable subjects to lose weight and eliminate diabetic symptoms.
"A key finding of this study is that the device induced a decrease in food intake as part of its effect and does not act by reducing absorption of nutrients," according to team member Dr. Lee Kaplan, an associate professor at Harvard Medical School and director of the MGH Weight Center, who led the study. "Like gastric bypass, it appears to change the way that neural and endocrine signals stimulated by nutrients act on their target organ.”
"[T]he human version of this device may be an effective treatment for obesity and diabetes…The next step will be to complete large-scale controlled trials of this procedure in human patients,” adds Kaplan. Because the sleeve is implanted endoscopically, the procedure is far less invasive and risky than surgical weight loss approaches.
The MGH study was supported by grants from the NIH and GI Dynamics, a medical device company that has developed a version of the endoluminal sleeve for human patients called the EndoBarrier Gastrointestinal Liner.