Magnets in the GI tract

Magnetic Living Hydrogels for Intestinal Localization, Retention, and Diagnosis

Natural microbial sensing circuits can be rewired into new gene networks to build living sensors that detect and respond to disease-associated biomolecules. However, synthetic living sensors, once ingested, are cleared from the gastrointestinal (GI) tract within 48 hours; retaining devices in the intestinal lumen is prone to intestinal blockage or device migration. To localize synthetic microbes and safely extend their residence in the GI tract for health monitoring and sustained drug release, an ingestible magnetic hydrogel carrier is developed to transport diagnostic microbes to specific intestinal sites. The magnetic living hydrogel is localized and retained by attaching a magnet to the abdominal skin, resisting the peristaltic waves in the intestine. The device retention is validated in a human intestinal phantom and an in vivo rodent model, showing that the ingestible hydrogel maintains the integrated living bacteria for up to seven days, which allows the detection of heme for GI bleeding in the harsh environment of the gut. The retention of microelectronics is also demonstrated by incorporating a temperature sensor into the magnetic hydrogel carrier.

Spatial Control of Probiotic Bacteria in the Gastrointestinal Tract Assisted by Magnetic Particles

Engineered probiotics have the potential to diagnose and treat a variety of gastrointestinal (GI) diseases. However, these exogenous bacterial agents have limited ability to effectively colonize specific regions of the GI tract due to a lack of external control over their localization and persistence. Magnetic fields are well suited to providing such control, since they freely penetrate biological tissues. However, they are difficult to apply with sufficient strength to directly manipulate magnetically labeled cells in deep tissue such as the GI tract. Here, it is demonstrated that a composite biomagnetic material consisting of microscale magnetic particles and probiotic bacteria, when orally administered and combined with an externally applied magnetic field, enables the trapping and retention of probiotic bacteria within the GI tract of mice. This technology improves the ability of these probiotic agents to accumulate at specific locations and stably colonize without antibiotic treatment. By enhancing the ability of GI-targeted probiotics to be at the right place at the right time, cellular localization assisted by magnetic particles (CLAMP) adds external physical control to an important emerging class of microbial theranostics.

A New Active Locomotion Capsule Endoscopy under Magnetic Control and Automated Reading Program

Capsule endoscopy (CE) is the first-line diagnostic modality for detecting small bowel lesions. CE is non-invasive and does not require sedation, but its movements cannot be controlled, it requires a long time for interpretation, and it has lower image quality compared to wired endoscopy. With the rapid advancement of technology, several methods to solve these problems have been developed. This article describes the ongoing developments regarding external CE locomotion using magnetic force, artificial intelligence-based interpretation, and image-enhancing technologies with the CE system.

Safety and efficacy of magnetic anchoring electrode-assisted irreversible electroporation for gastric tissue ablation

BACKGROUND

Irreversible electroporation (IRE) is an emerging tissue ablation technique, which is safe for sites where thermal-basis techniques are not suitable. The aim of this study is to evaluate the safety and efficacy of magnetic anchoring electrode (MAE)-assisted IRE for normal gastric tissue ablation in a rabbit model.

METHODS

IRE (500 V, 100 μs, 99 pulses, 1 Hz) of the gastric wall was performed in 24 adult New Zealand rabbits with a novel catheter-mounted MAE with fluoroscopy and a surgical approach. Procedure time, procedure-related bleeding, perforation, and other complications were recorded. Animals were sacrificed at 30 min, 1 day, 3 days, 7 days, 14 days, and 28 days post-IRE. The stomach was removed en bloc, and the diameter of each lesion was measured. Histopathological analyses by Hematoxylin-Eosin (H&E), masson trichrome, alpha-smooth muscle action (α-SMA), and terminal-deoxynucleotidyl transferase mediated nick end labeling (TUNEL) were performed.

RESULTS

Gastric tissue ablation with MAE-assisted IRE was successfully performed without any interruption. No perforation or bleeding was observed during IRE or throughout the follow-up period. A demarcated hemorrhage was found in the ablated area upon gross examination. H&E staining showed complete cell death with inflammatory infiltration, edema, and hemorrhaging. TUNEL presented diffuse positive cells in the ablated area. The tissue scaffold was well preserved without damage as indicated by Masson trichrome staining. Ulceration was observed starting from 3 days post-IRE. The mucosal layer was gradually recovered and regenerated within 14-28 days. No other complication was observed post-IRE.

CONCLUSIONS

MAE-assisted IRE is safe and effective for normal gastric tissue ablation and the gastric wall recovered in 14-28 days post-IRE.

Surgical Endoscopy Versus Endoscopic Surgery for Obesity

BACKGROUND

Obesity treatment options are of great interest worldwide with major developments in the past 20 years. From general surgery to natural orifice transluminal endoscopic surgery intervention nowadays, obesity surgical therapies have surely developed and are now offering a variety of possibilities.

AREAS OF UNCERTAINTY

Although surgery is the only proven approach for weight loss, a joint decision between the physician and patient is required before proceeding to such a procedure. With a lot of options available, the treatment should be individualized because the benefits of surgical intervention must be weighed against the surgical risks.

DATA SOURCES

Medline search to locate full-text articles and abstracts with obvious conclusions by using the keywords: obesity, surgical endoscopy, gastric bypass, bariatric surgery, and endoscopic surgery, alone and in various combinations. Additional relevant publications were also searched using the reference lists of the identified articles as a starting point.

RESULTS

Laparoscopic Roux-en-Y gastric bypass still is the most effective, less invasive, bariatric surgical intervention, although there are various complications encountered, such as postoperative hemorrhage (1.9%-4.4%), internal hernias, anastomotic strictures (2.9%-23%), marginal ulcerations (1%-16%), fistulas (1.5%-6%), weight gain, and nutritional deficiencies. However, the absence of parietal incisions, less pain, decreased risk of infection, and short hospital stay make room for endoscopic surgery as a possible valid option for obesity for both the doctors' and the patients' perspective.

CONCLUSIONS

The current tendency is to promote surgical treatment of obesity to a status of less invasive scars therefore promoting minimally invasive surgical techniques.

Magnetic Surgical Instruments for Robotic Abdominal Surgery

This review looks at the implementation of magnetic-based approaches in surgical instruments for abdominal surgeries. As abdominal surgical techniques advance toward minimizing surgical trauma, surgical instruments are enhanced to support such an objective through the exploration of magnetic-based systems. With this design approach, surgical devices are given the capabilities to be fully inserted intraabdominally to achieve access to all abdominal quadrants, without the conventional rigid link connection with the external unit. The variety of intraabdominal surgical devices are anchored, guided, and actuated by external units, with power and torque transmitted across the abdominal wall through magnetic linkage. This addresses many constraints encountered by conventional laparoscopic tools, such as loss of triangulation, fulcrum effect, and loss/lack of dexterity for surgical tasks. Design requirements of clinical considerations to aid the successful development of magnetic surgical instruments, are also discussed.

Emerging Issues and Future Developments in Capsule Endoscopy

Capsule endoscopy (CE) has transformed from a research venture into a widely used clinical tool and the primary means for diagnosing small bowel pathology. These orally administered capsules traverse passively through the gastrointestinal tract via peristalsis and are used in the esophagus, stomach, small bowel, and colon. The primary focus of CE research in recent years has been enabling active CE manipulation and extension of the technology to therapeutic functionality; thus, widening the scope of the procedure. This review outlines clinical standards of the technology as well as recent advances in CE research. Clinical capsule applications are discussed with respect to each portion of the gastrointestinal tract. Promising research efforts are presented with an emphasis on enabling active capsule locomotion. The presented studies suggest, in particular, that the most viable solution for active capsule manipulation is actuation of a capsule via exterior permanent magnet held by a robot. Developing capsule procedures adhering to current healthcare standards, such as enabling a tool channel or irrigation in a therapeutic device, is a vital phase in the adaptation of CE in the clinical setting.

A pilot trial of ambulatory monitoring of gastric motility using a modified magnetic capsule endoscope

The magnetic capsule endoscope has been modified to be fixed inside the stomach and to monitor the gastric motility. This pilot trial was designed to investigate the feasibility of the magnetic capsule endoscope for monitoring gastric motility. The magnetic capsule endoscope was swallowed by the healthy volunteer and maneuvered by the external magnet on his abdomen surface inside the stomach. The magnetic capsule endoscope transmitted image of gastric peristalsis. This simple trial suggested that the real-time ambulatory monitoring of gastric motility should be feasible by using the magnetic capsule endoscope.