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

Abstract

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.

Localized Photodynamic Therapy Using a Chlorin e6-Embedded Silicone-Covered Self-Expandable Metallic Stent as a Palliative Treatment for Malignant Esophageal Strictures

“…Tissue damage induced by PDT occurs when the PS generates ROS after laser irradiation at a specific wavelength, which can in turn induce cellular apoptosis via oxidative stress. ,, TUNEL-stained tissues of the PDT-treated rat esophagus indicated that controlled ROS release led to localized tissue damage and induced apoptosis. − A single session of localized PDT using PS-embedded silicone covered devices demonstrated therapeutic effects for obesity, but the effects lasted for only 2 weeks. Damaged tissues gradually regenerated at 3–4 weeks after PDT. , Despite only a week of follow-up results in our study, therapeutic effects with apoptotic tissue changes were well maintained. The stent was placed after localized PDT to maintain the patency of the PDT-treated esophagus and prevent the possibility of esophageal stricture formation after the PDT procedure.…”

“…In this study, a Ce6-embedded silicone-covered SEMS was successfully fabricated based on the well-established Ce6-embedded silicone membrane to perform localized and endoluminal PDT. The Ce6-embedded silicone-covered SEMS demonstrated its significance in terms of improved PS bioavailability and better practicality for laser irradiation . This study demonstrated that the Ce6-embedded silicone-covered SEMS validates the optimized irradiation energy doses and PDT-induced tissue changes in an in vivo rat esophagus.…”

“…A dose-ranging study of PDT is complex due to the nature of the dynamic interactions between light, PS, and oxygen . The clinical efficacy of PDT depends on the dosimetry, total dose, irradiation time, and delivery method. , However, very few preclinical evaluations have investigated the irradiation energy-dose range of localized PDT with the PS-embedded silicone-covered SEMS. ,, …”

A Unique Chemo-photodynamic Antitumor Approach to Suppress Hypoxia via Ultrathin Graphitic Carbon Nitride Nanosheets Supported a Platinum(IV) Prodrug

“…In recent years, photodynamic therapy (PDT) has become a focal point of scientists by reason of the predominant advantages to overcome the resistance and side effects of multidrugs in conventional therapies. − Normally, PDT comprises three important essential factors in the treatment: an excitation light source, oxygen in tissues, and a photosensitizer (PS). In the presence of light excitation, the PS is capable of transferring the absorbed photon energy into an electron, which induces oxygen to generate reactive oxygen species (ROS) and ultimately triggers oxidative photodamage to kill tumor cells and damage tissue. , …”

“…In the presence of light excitation, the PS is capable of transferring the absorbed photon energy into an electron, which induces oxygen to generate reactive oxygen species (ROS) 5 and ultimately triggers oxidative photodamage to kill tumor cells and damage tissue. 6,7 Because PS is a core issue in PDT, tremendous effort has been made to find a fresh PS that possesses the virtue of high stability, high light conversion efficacy, and sensitivity to irradiation. 8 Lately, metal-free graphitic carbon nitride (g-C 3 N 4 ) with a band gap energy of approximately 2.71 eV has been considered as a promising PS.…”