Plexiglas (polymethylmethacrylate) implantation: technique, pre-clinical and clinical experience

Bulking agents in gastrointestinal endoscopy: present applications and future advances

PURPOSE OF REVIEW

Bulking agents are inert materials injected into an organ to affect the physical properties of the organ for a therapeutic purpose. Various agents have been developed to aid in the treatment of diseases like gastroesophageal reflux disease (GERD), fecal incontinence, obesity, malignancy, hemostasis, and tissue dissection. Here, we review the state of the art in bulking agents in gastrointestinal endoscopy, past failures, current limitations, and where we see the field heading in the future.

RECENT FINDINGS

Though bulking agents have been trialed for various different gastrointestinal diseases, there are currently limited uses in gastrointestinal endoscopy. Though various agents have been trialed for GERD, numerous complications and adverse events have limited its current use. However, for the treatment of fecal incontinence endoscopic bulking agent therapy is a reasonable option. Though in early stages of exploration, bulking agent therapy for enteric protection from radiotherapy may be a promising tool to improve treatment of pancreatic cancer. Bulking agents for tissue dissection have substantially improved lifting agents and complex polyp removal. Bulking agent therapy has not really been explored for endoscopic bariatric therapy or hemostasis but may be a fruitful area for exploration in the future.

SUMMARY

Bulking agent therapy has been trialed for various gastrointestinal diseases with mixed success. There is currently a therapeutic roll in the endoscopic management of fecal incontinence and tissue dissection. A future role in the treatment of GERD, obesity, malignancy, and hemostasis seem feasible.

Endoscopic lower esophageal sphincter bulking for the treatment of GERD: safety evaluation of injectable polymethylmethacrylate microspheres in miniature swine

BACKGROUND

Endoscopic therapy for GERD is an appealing, minimally invasive alternative to medical treatment and surgery. Various materials have been tested to augment the lower esophageal sphincter (LES), with limited success. To our knowledge, safety and migration of polymethylmethacrylate (PMMA) microspheres has never been evaluated.

OBJECTIVE

To assess the safety, migration, inflammatory reaction, and durability of PMMA injected into the LES of miniature swine to create a reflux barrier.

DESIGN

Animal study.

SETTING

Approved animal research facilities.

INTERVENTION

Injection of the LES of miniature swine with PMMA. Histopathology of the injected site at certain intervals and postnecropsy microsphere counts of various organs.

MAIN OUTCOME MEASUREMENTS

Minimal inflammatory reaction at the injection site, persistent bulking effect of the material, and no migration of microspheres.

RESULTS

Injection of LES with PMMA caused a mild inflammatory reaction. The bulking effect of the injected material was persistent. Migration of microspheres was eliminated with the use of larger-sized microspheres.

LIMITATIONS

Animal model.

CONCLUSION

Our phase I study documented that 40-microm polymethylmethacrylate microspheres are biocompatible and that PMMA microspheres are resistant to degradation when injected submucosally into the wall of the esophagus. The detection of 40-microm PMMA microspheres in local lymph nodes, liver, and lungs of some animals in the phase I study clearly documented transport of PMMA away from the injection site. This finding was eliminated by increasing the size of microspheres to 125 microm. The potential therapeutic effects of these larger microspheres for humans with GERD remains to be evaluated.

Murine Muscle Precursor Cells Survived and Integrated in a Cryoinjured Gastroesophageal Junction

BACKGROUND

Mini-invasive techniques for gastroesophageal reflux disease (GERD), such as endoscopic injections of inert materials, have been introduced in recent years. However, results are still preliminary. Cell injection has emerged as an alternative strategy in both vesicoureteral reflux and incontinence. Here we report, for the first time, the injection of muscle precursor cells (MPCs) in the gastroesophageal junction (GEJ).

MATERIALS AND METHODS

MPCs were derived from expanded satellite cells isolated from skeletal muscle fibers of green fluorescent protein (GFP) positive mice. Via laparotomy, GFP-negative mice were subjected to cryoinjury of GEJ followed by injection of MPCs (experimental animals), bone marrow derived cells, or saline (controls).

RESULTS

Immunofluorescence analyses of experimental GEJs demonstrated coexpression of GFP and desmin in grafted cells. GFP+ muscle neofibers were evident at 4 wk after injection. Coexpression of GFP and smooth muscle actin was also observed at 2 wk.

CONCLUSIONS

Satellite cells could be easily harvested, expanded in culture, and used as injectable substance in the GEJ. These results could be the background for the development of a new injection technique for GERD treatment, which might combine bulging and functional actions.

Endoluminal and transluminal surgery: current status and future possibilities

The field of minimally invasive surgery has seen tremendous growth since the first laparoscopic cholecystectomy was performed in 1987. The key question is not how successful these techniques are currently, but rather where may they lead in the future? New technologies promise to usher in an era of even less invasive procedures. The terms being coined in the literature include "incisionless," "endoluminal," "transluminal," and "natural orifice" transluminal endoscopic surgery. These techniques certainly have the potential to become the next wave of minimally invasive procedures. A recent editorial in Surgical Endoscopy by Macfadyen and Cuschieri highlighted the ongoing developments in endoscopic surgery and stressed the critical importance of surgeons being involved in future applications and permutations of these techniques [1]. There are early signs of such involvement. The work of numerous investigators in the field was presented recently at the 2005 Digestive Disease Week. The American Society for Gastrointestinal Endoscopy and the Society of American Gastrointestinal and Endoscopic Surgeons (SAGES), in collaboration with the American College of Surgeons, recently organized a postgraduate course in endoluminal therapy at the spring 2005 meeting held in Hollywood, Florida. The course is being offered again at the 2006 SAGES annual meeting. Similar courses are being offered at other regional and national meetings. This review attempts to highlight some of the available and evolving endoluminal therapies reviewed at that forum, including techniques for the management of gastroesophageal reflux disease, endoscopic mucosal resection, endoluminal bariatric surgery, transanal endoscopic microsurgery, and transgastric endoscopic surgery, as well as new technologies and possible future directions in luminal access surgery.

Endoscopic Therapies For Gastroesophageal Reflux Disease

Gastroesophageal reflux disease (GERD) is a chronic condition affect-ing over 7% of the US population. The primary objective of therapy is symptom relief, with secondary goals to heal esophagitis, prevent reflux-related complications, and maintain remission. There are several new endoscopic therapies (ETs) for treatment of GERD, generating considerable interest. An outpatient procedure, performed without an incision and general anesthesia, is attractive to patients and these therapies are being rapidly introduced, despite lack of long-term follow-up and randomized trials. In this article, the authors review endoscopic procedures, including technical aspects, mechanisms of action, safety, efficacy, and tolerability. Patient selection and relevant human studies are reviewed to clarify advantages and disadvantages of ET compared with conventional procedures.

Endoscopic treatment modalities for gastroesophageal reflux disease

A debate has been going for decades between surgeons and gastroenterologists about the treatment of choice for gastroesophageal reflux disease (GERD). The lower esophageal sphincter (LES) has been historically far from the reach of gastroenterologists, who adopted the symptomatic treatment as their approach to reflux disease through reduction of gastric acid. As for surgeons, reaching the LES was only possible by invading the thoracic or abdominal cavity. Although their approach was later refined to become "minimally" invasive, it was still deemed too invasive by others to allow it to be the "gold standard." Simple logic should lead one to think about the "natural route" as the easiest way to reach the LES. This concept has opened the door for the new era of GERD treatment through "endoscopic modality." Seven different techniques are currently being used to treat patients with GERD. We review the mechanism of action, potential side effects, efficacy, durability, and results from the most recent or largest experience of each. This review shows that endoscopic treatment has definitely earned its place as a viable option for GERD treatment in selected patients. With the available data from clinical trials, it is not possible to determine the best modality available, and the endoscopic treatment of choice is to be determined with further studies.