A Novel Intragastric Satiety-Inducing Device to Inhibit Weight Gain in Juvenile Pigs: a Pilot Study

Repeated photodynamic therapy using a chlorin e6-embedded device to prolong the therapeutic effects on obesity

OBJECTIVE

This study aimed to investigate the efficacy and safety of repeated photodynamic therapy (PDT) with a chlorin e6 (Ce6)-embedded intragastric satiety-inducing device (ISD) to maintain therapeutic effects of obesity in a juvenile pig.

METHODS

The Ce6-embedded ISD was fabricated with a dipping method. Twelve pigs were divided into four groups of three and were administered control, single, biweekly, or weekly PDT, respectively. The therapeutic effects were assessed by comparing the results of phototoxicity, endoscopy, fluoroscopy, hormone and weight changes, and histological examination.

RESULTS

The percentage of total body weight gain was significantly suppressed in PDT-treated pigs compared with control pigs (all p < 0.001). This suppression persisted in the repeated PDT groups, but percentage of total body weight gain gradually increased when PDT was stopped. Ghrelin levels in the PDT-treated groups were significantly lower and leptin levels were significantly higher than those in the control group (all p < 0.05). Inflammatory cell infiltration, collagen, TUNEL, and anti-ghrelin-positive deposition in the weekly group were significantly higher than those in the control, single, and biweekly groups (all p < 0.01).

CONCLUSIONS

Repeated and periodic PDT was technically feasible and safe and successfully maintained the therapeutic effects against obesity while eliminating the indwelling time and reducing ISD-related complications in pigs.

Photoactive intragastric satiety-inducing device using polymeric photosensitizers for minimally invasive weight loss treatment

An intragastric satiety-inducing device (ISD) located in the stomach induce satiety and fullness in the absence of food by continuously pressing on the distal esophagus and cardia of the stomach. To improve the therapeutic function of ISD, Chlorin e6 (Ce6) was embedded in a disk portion of ISD, generating reactive oxygen species and stimulating endocrine cells under the laser irradiation. Since Ce6 has remarkable light efficiency but poor solubility in various solvents, it is essential to use a polymeric photosensitizer and optimize a suitable coating solution composition. Methoxy polyethylene glycol-Ce6 was uniformly coated and the spontaneous release amount of the Ce6 from the device could be reduced, which induced photo-responsive cell death and reduced ghrelin levels in vitro. In mini pigs operated single therapy (PDT or ISD) or combination therapy (Photoreactive ISD), there were differences in body weight (control: 28% vs. Photoreactive ISD: 4%, P < 0.001), ghrelin (control: 4% vs. Photoreactive ISD: 35%, P < 0.001), and leptin levels (control: 8% vs. Photoreactive PDT: 35%, P < 0.001) at 4 weeks.

Photodynamic Methylene Blue-Embedded Intragastric Satiety-Inducing Device to Treat Obesity

Bariatric surgery is the most effective treatment for weight recidivism, and endoscopic bariatric treatment has been developed for a similar effect without anatomical modification. An intragastric satiety-inducing device (ISD) is a minimally invasive approach to induce satiety by continuously pressing the stomach and stimulating ghrelin-producing cells. To enhance the therapeutic effects of ISD, photodynamic therapy (PDT) can be combined by generating singlet oxygen under laser irradiation. Methylene blue (MB), as a photosensitizer (PS), was coated on the ISD surface for singlet oxygen production to stimulate or destroy cells. Ghrelin-producing cells effectively inhibited ghrelin secretion and induced gastrointestinal satiety signals compared with the MB-uncoated device via PDT. Herein, MB-embedded ISDs were developed, and their photoresponsive abilities were demonstrated in the device itself and in vitro. PDT with an MB-embedded ISD was successfully performed in a porcine model, which had 2-fold reduced body weight gain (12% in PDT vs 24% in control) and 2-fold reduced ghrelin levels (21.2 pg/mL in PDT vs 45.1 pg/mL in control) at the first week postprocedure. The simple and unique operation extends the point of view in PDT and is expected to be a novel endoscopic bariatric therapy.

Endoscopic Procedures for Weight Loss

PURPOSE OF REVIEW

To provide updated evidence on the endoscopic procedures for weight loss and to bring personal insights on the future of endobariatrics.

RECENT FINDINGS

Intragastric balloons promote significant improvement in histologic and radiologic aspects of non-alcoholic steatohepatitis; the endoscopic sleeve gastroplasty is effective up to 5 years and seems particularly beneficial to patients with BMI≤40kg/m²; distal POSE is a promising technique but still lacks adequate clinical data; aspiration therapy triggers remarkable weight loss, but data on weight trends after removal of the device are still lacking; the satiety-inducing device, the sleeveballoon, the gastric mucosal devitalization, and the endoscopic magnetic partial jejunal diversion are promising procedures still under study and refinements. Several therapeutic options are necessary during obesity's natural history. Therefore, endobariatrics should act in harmony with lifestyle interventions, diet modification, psychological treatment, pharmacotherapy, and bariatric surgery seeking the best outcome in the long term.