Evaluation of 0.6% sodium alginate as a submucosal injection material in endoscopic submucosal dissection for early gastric cancer

Polysaccharides as submucosal injection materials (SIMs) in endoscopic resection: A comprehensive review

Submucosal injection materials (SIMs) play a vital role in the endoscopic treatment of benign and early malignant gastrointestinal lesions by effectively elevating lesions while significantly reducing the risks of thermal injury and bleeding. However, the traditional use of normal saline (NS) presents challenges due to its rapid absorption, which necessitates frequent reapplications and complicates procedural efficiency. Therefore, there is a pressing need for ideal SIMs that are cost-effective, readily available, and suitable for personalized therapy, while also demonstrating excellent biocompatibility and physicochemical stability. Recent advancements have highlighted the potential of polysaccharide-based natural polymers, such as sodium hyaluronate, cellulose, starch derivatives, chitosan, and sodium alginate, due to their superior biocompatibility and biodegradability. These polysaccharides have exhibited enhanced operational characteristics and therapeutic efficacy in animal and clinical studies. Nevertheless, ongoing research must address several challenges, including optimizing cost-effectiveness, improving mechanical strength and bioactivity, and mitigating intraoperative and postoperative complications. This review systematically examines the progress of polysaccharide-based natural polymers in SIMs, evaluates their current status and challenges in both research and clinical applications, and proposes future directions to enhance their utilization in gastrointestinal endoscopic therapy.

Konjac glucomannan/sodium alginate/ε-poly-l-lysine hydrogel promotes esophageal and colonic wound healing

Endoscopic submucosal dissection (ESD) is widely used to treat gastrointestinal mucosal and submucosal lesions. However, it may cause bleeding, perforation, and stricture. Although these complications can be avoided by introducing materials such as polyglycolic acid and carboxymethyl cellulose sheets, such approaches are expensive and time-consuming. Herein, we report a hydrogel prepared by combining a colloidal solution composed of konjac glucomannan (KGM) and sodium alginate (SA) and a fixative solution containing ε-poly-l-lysine (ε-PLL) and calcium chloride. The two solutions were mixed on the wound surface to form the KGM/SA/ε-PLL hydrogel through hydrogen bonds, coordination bonds, and electrostatic attraction. The effectiveness and convenience of applying the KGM/SA/ε-PLL hydrogel to promote wound healing in the esophagus and colon were assessed in vitro and in vivo. We found that the hydrogel stimulated epithelial proliferation, reduced inflammation, promoted recapillarization, and inhibited fibrosis in the esophagus and colon. Therefore, the KGM/SA/ε-PLL hydrogel is an effective and convenient agent that can promote post-ESD wound healing and is recommended for ulcer bed protection in daily clinical practice.

Innovative submucosal injection solution for endoscopic resection with phosphorylated pullulan: a preclinical study

BACKGROUND AND AIMS

A submucosal injection solution is used to assist in endoscopic surgery. The high viscosity of current solutions makes them difficult to inject. In the present study, we developed an extremely low-viscosity, easy-to-use submucosal injection solution using phosphorylated pullulan (PPL).

METHODS

The PPL solutions were prepared at different concentrations, and their viscosities were measured. The mucosal elevation capacity was evaluated using excised porcine stomachs. Controls included 0.4% sodium hyaluronate (SH), 0.6% sodium alginate (SA), and saline. To evaluate the practicality, the catheter injectability of 0.7% PPL was measured, and EMR and endoscopic submucosal dissection (ESD) were performed using the stomach and colorectum of live pigs. As controls, 0.4% SH and saline were used.

RESULTS

The PPL solutions were of extremely low viscosity compared to the solutions of 0.4% SH and 0.6% SA. Nevertheless, the mucosal elevation capacity of PPL solutions for up to 0.7% concentration was similar to that of 0.4% SH, and 0.7% PPL was less resistant to catheter infusion than 0.4% SH and 0.6% SA. In live pig experiments with endoscopic mucosal resection and ESD, snaring after submucosal injection of 0.7% PPL was easier than with 0.4% SH, ESD with 0.7% PPL produced less bubble formation than with 0.4% SH, and the procedure time tended to be shorter with 0.7% PPL than with 0.4% SH because of the shorter injection time.

CONCLUSIONS

The PPL solution is an innovative and easy-to-use submucosal injection solution.

Feasibility and safety of 0.6% sodium alginate in endoscopic submucosal dissection for colorectal neoplastic lesion: A pilot study

Objectives

The usefulness of 0.6% sodium alginate (SA) as a submucosal (SM) injection solution for endoscopic SM dissection (ESD) has gained attention over the past few years. However, using ESD for colorectal neoplastic lesions is not explicitly researched as yet. Thus, we conducted this study to determine the feasibility and safety of 0.6% SA solution for colorectal ESD.

Methods

In this single-center, retrospective pilot study, a total of 100 cases treated with ESD using 0.6% SA as a SM injection solution for colorectal neoplasia at our institute were retrospectively reviewed to clarify the clinical feasibility and safety of 0.6% SA. The primary endpoint was to evaluate the complication rate, and the secondary endpoint was to determine the procedure time and the amount of solution used.

Results

Intraoperative perforation was observed in 1 case (1.0%), 2 cases (2.0%) presented with postprocedural hemorrhage, and no lethal adverse events were observed. The median ESD procedure times were 39.5 min (10-150), and the amount of solution used was less than 20 mL in 67 cases (67.0%). En-bloc resection could be achieved in 97 cases (97.0%). Although six cases underwent subsequent surgery due to the deep SM invasion (>1000 μm), there were no cases with nodal involvement, confirmed through histopathological evaluation.

Conclusions

Our findings indicate that 0.6% SA can potentially ensure safe and secure ESD for colorectal neoplasia.

Efficacy and safety of a submucosal injection solution of sodium alginate for endoscopic resection in a porcine model

Endoscopic resection techniques require the use of submucosal injection. Normal saline and sodium hyaluronate solutions are mainly used for this purpose, but an ideal solution has not yet been developed. The aim of this study was to assess a new solution, MC-003-a novel submucosal injection solution developed with sodium alginate as the main ingredient. Normal saline, a commercial sodium hyaluronate solution (Endo-Ease), and MC-003 were examined. A total of 18 gastric submucosal cushions were created in the stomachs of six pigs. The height of mucosal elevation was measured sequentially using endoscopic sonography. After euthanizing the animals either 2 h or 5 days after the procedure, pathologic examination was performed for each injection site. Although not statistically significant over the entire study period, MC-003 showed a superior result to normal saline and an equivalent result to Endo-Ease in the submucosal cushion height and its rate of decrease. There were no adverse outcomes after injection of the three solutions and there was no pathologically identified detrimental change in the resected specimens. MC-003 creates a sufficient submucosal fluid cushion without apparent tissue damage. It can be considered as an effective submucosal injection material.

Development of a hybrid hydrogel for submucosal injection in endoscopic resection of gastrointestinal neoplasm: From laboratory to clinical trial

Background and study aims Submucosal injection solution is essential for successful endoscopic resection of the early gastrointestinal tumor. We evaluated a new endoscopic hydrogel for submucosal injection and its clinical feasibility. Patients and methods A hydrogel (AceGel) containing 0.4% sodium alginate and 2% calcium lactate was developed for ex vivo and animal studies. Subsequently, a prospective, single-arm study was conducted to assess its feasibility and safety in humans. Patients with gastrointestinal neoplasms undergoing endoscopic resection were enrolled. All patients underwent endoscopic surveillance after 4 weeks and outpatient follow-up at week 6. Afterward, they received endoscopic follow-up according to the medical routine. Results In the ex vivo experiments, the submucosal elevation height of AceGel was equivalent to sodium hyaluronate and superior to saline or glycerol. Animal studies showed that the excised wounds healed well without surrounding tissue damage. Twelve patients participated in the clinical trial, including three, two, and seven patients with esophageal, gastric, and colonic lesions, respectively. The mean neoplasm size and submucosal injection volumes were 24.0±8.6 mm and 22.8±19.9 mL, respectively. All patients had adequate wound healing on 4-week surveillance endoscopy, and none had serious adverse events during 6-week follow-up. Moreover, endoscopic follow-up showed complete wound healing after 6 to 46 months without local mucosal inflammation in all patients. Conclusions AceGel is good for endoscopic submucosal injection and demonstrated its usefulness in durable mucosal elevation for endoscopic therapy in preclinical tests. This clinical trial shows its safety and feasibility in all participating patients.

Novel endoscopic management of gastroenterological anastomosis leakage by injecting gel-forming solutions: an experimental animal study

BACKGROUND

Anastomotic leakage (AL) after gastrointestinal surgery remains a challenging complication that requires surgical or non-surgical treatment. Although various therapeutic endoscopic techniques are available, no definitive interventions exist. We developed a therapeutic endoscopic submucosal injection method using novel gel-forming mixed solutions to close AL and evaluated the elasticity of the developed hydrogel. The safety and efficacy of the injection method were explored in porcine AL models.

METHODS

We developed a novel gel-forming solution, and the formed gel lasted approximately one week within the gastrointestinal wall. An indentation test evaluated the elasticity of the novel hydrogel. After the confirmation of AL on porcine anterior gastric walls, sodium alginate was endoscopically injected into the submucosal layer around the leakage site circularly, followed by a calcium lactate/chitosan-based solution. After that, the outcomes data were collected, and histopathological effectiveness was evaluated.

RESULTS

The increased sodium alginate elasticity with the addition of calcium lactate/chitosan-based solution facilitated long-lasting gel formation. Four pigs with AL underwent this intervention consecutively. Each endoscopic injection was completed in less than 5 min. No significant complications were observed for 3 weeks after the intervention. All AL sites were macroscopically healed. Histopathologic findings at 3 weeks showed that the wall defect was filled with collagen fibers that had grown around the site of the muscle layer tear. No tissue necrosis was observed.

CONCLUSION

This preclinical study demonstrated that the therapeutic injection method for gastroenterological AL using gel-forming solutions could be an alternative endoscopic treatment, especially in patients with severe conditions or comorbidities. The optimal target of this treatment is small size and early AL without poor blood flow or intense hypertrophic scar lesions.

Traversing the diverse avenues of exopolysaccharides-based nanocarriers in the management of cancer

Exopolysaccharides are unique polymers generated by living organisms such as algae, fungi and bacteria to protect them from environmental factors. After a fermentative process, these polymers are extracted from the medium culture. Exopolysaccharides have been explored for their anti-viral, anti-bacterial, anti-tumor, and immunomodulatory effects. Specifically, they have acquired massive attention in novel drug delivery strategies owing to their indispensable properties like biocompatibility, biodegradability, and lack of irritation. Exopolysaccharides such as dextran, alginate, hyaluronic acid, pullulan, xanthan gum, gellan gum, levan, curdlan, cellulose, chitosan, mauran, and schizophyllan exhibited excellent drug carrier properties. Specific exopolysaccharides, such as levan, chitosan, and curdlan, have demonstrated significant antitumor activity. Moreover, chitosan, hyaluronic acid and pullulan can be employed as targeting ligands decorated on nanoplatforms for effective active tumor targeting. This review shields light on the classification, unique characteristics, antitumor activities and nanocarrier properties of exopolysaccharides. In addition, in vitro human cell line experiments and preclinical studies associated with exopolysaccharide-based nanocarriers have also been highlighted.

Injectable shear-thinning sodium alginate hydrogels with sustained submucosal lift for endoscopic submucosal dissection

Endoscopic submucosal dissection (ESD) is one of the most effective approaches for the minimally invasive treatment of early gastrointestinal cancers. Submucosal injections help safely and successfully remove lesions during ESD by elevating the mucosa and separating the submucosal muscle layer. Herein, we report dynamic injectable sodium alginate hydrogels (ISAHs) with shear-thinning for ESD surgery, which were easily fabricated by the sulfhydryl group of GSH-modified sodium alginate (SA-GSH) reacting with the aldehyde group of oxidized sodium alginate (OSA) at room temperature. ISAHs have advantageous self-healing abilities and antioxidant activity. Additionally, according to an in vitro test on porcine colorectal submucosal lifting, the submucosal elevation heights created by ISAHs were 13 % -18 % greater than those created by commercial ESD solutions (0.4 w/v% sodium hyaluronate). These properties and biocompatibility were confirmed in vitro and in vivo experiments. ISAHs will hopefully become a novel submucosal injectable hydrogel to assist ESD surgery.

Foundations of gastrointestinal-based drug delivery and future developments

Gastrointestinal-based drug delivery is considered the preferred mode of drug administration owing to its convenience for patients, which improves adherence. However, unique characteristics of the gastrointestinal tract (such as the digestive environment and constraints on transport across the gastrointestinal mucosa) limit the absorption of drugs. As a result, many medications, in particular biologics, still exist only or predominantly in injectable form. In this Review, we examine the fundamentals of gastrointestinal drug delivery to inform clinicians and pharmaceutical scientists. We discuss general principles, including the challenges that need to be overcome for successful drug formulation, and describe the unique features to consider for each gastrointestinal compartment when designing drug formulations for topical and systemic applications. We then discuss emerging technologies that seek to address remaining obstacles to successful gastrointestinal-based drug delivery.

Comparison of sodium alginate-based and sodium hyaluronate-based submucosal injection materials based on rheological analysis

As a viscous high-performance submucosal injection material (SIM) used in endoscopic submucosal dissection (ESD), sodium alginate-based SIM (SA-SIM) was recently introduced as high-performance SIM equivalent to sodium hyaluronate-based SIM (HA-SIM) in Japan. However, a comprehensive, detailed comparison of SA and HA is yet to be performed. In this study, we precisely measured the viscoelastic properties, submucosal elevation height (SEH), and injection pressure (IP). Furthermore, we compared the outcomes of ESD using an ex vivo ESD model. There was no significant difference in SEHs between HA-SIM and SA-SIM at all post-injection times, and the IP of the SA-SIM injection was significantly higher than that of the HA-SIM injection in all conditions (P < 0.0001). The viscosity at high shear rates of SA-SIM was higher than that of HA-SIM; this result was consistent with SEH/IP measurement results. No significant difference was observed in ESD procedure time and total volume of injected SIM between HA-SIM and SA-SIM (18.1 ± 6.7 and 17.8 ± 6.0 min, P = 0.8987; 13.3 ± 5.3 and 11.6 ± 5.9 ml, P = 0.4658, respectively). Although SA-SIM was slightly more difficult to inject than HA-SIM, there was no significant difference in performance between the materials. Thus, this basic study demonstrated that SA-SIM can be used for endoscopic treatment as well as HA-SIM, and supported previous clinical research data.

Cellulose nanofiber dispersion as a new submucosal injection material for endoscopic treatment: preliminary experimental study

Background and aims  Although various solutions have been tested for submucosal injections during endoscopic treatment, the ideal solution has not been established. We investigated the suitability of a cellulose nanofiber (CNF) dispersion with high viscosity and thixotropy as a potential submucosal injection material for endoscopic treatment. Methods  We evaluated the catheter injectability and mucosa-elevating capacity of CNF dispersion compared with sodium hyaluronate (SH) solution, which has been reported to be a promising submucosal injection solution. The catheter injectability of CNF dispersion was examined under conditions equivalent to those used clinically in endoscopic treatment. The mucosa-elevating capacity of CNF dispersion was examined in porcine stomachs. Results  There was no significant difference between the catheter injectability of 0.4 % CNF dispersion and 0.4 % SH solutions; however, 0.4 % CNF dispersion maintained significantly higher and longer elevation of the submucosal layer than 0.4 % SH solution. A clear separation of the mucosal layer from the underlying muscle layer was achieved by injecting 0.4 % CNF dispersion. Conclusion  This preliminary study suggests that CNF dispersion could be an ideal submucosal injection material for endoscopic treatment because of its unique high thixotropy index.

Hydrogels Based Drug Delivery Synthesis, Characterization and Administration

Hydrogels represent 3D polymeric networks specially designed for various medical applications. Due to their porous structure, they are able to swollen and to entrap large amounts of therapeutic agents and other molecules. In addition, their biocompatibility and biodegradability properties, together with a controlled release profile, make hydrogels a potential drug delivery system. In vivo studies have demonstrated their effectiveness as curing platforms for various diseases and affections. In addition, the results of the clinical trials are very encouraging and promising for the use of hydrogels as future target therapy strategies.

Efficacy and safety of 0.6% sodium alginate solution in endoscopic submucosal dissection for esophageal and gastric neoplastic lesion: A randomized controlled study

OBJECTIVES

Sodium alginate (SA) solution has characteristic viscoelasticity. We aimed to determine efficacy and safety of 0.6% SA for submucosal injection during endoscopic submucosal dissection (ESD) in patients with localized neoplastic lesion in the esophageal and gastric mucosa.

METHODS

We conducted a randomized controlled study at six major hospitals in Japan including 130 patients with endoscopically localized neoplastic lesion in the esophageal and gastric mucosa and eligible for ESD. Patients were randomly assigned to SA or 0.4% sodium hyaluronate (SH) group (control); ESD was performed using a submucosal injection of SA/SH. As a primary outcome measure, non-inferiority of SA against SH was investigated using en bloc complete resection in ESD and formation and maintenance of mucosal elevation upon injection as an efficacy index. Adverse events during the study were evaluated as safety outcome measures. This study was registered with Pharmaceuticals and Medical Devices Agency (clinical trial no. 28-277/2016-18; clinical trial identification no. KP2013-009_C001).

RESULTS

Efficacy rate of submucosal injection during ESD was 91.7% (55/60) and 88.7% (55/62) in the SA and SH groups, respectively, demonstrating non-inferiority of SA against SH. Adverse events for which a causal relationship with submucosal injection solution could not be eliminated were noted in 8.2% (5/61) and 4.7% (3/64) in the SA and SH groups, respectively, but symptoms disappeared without treatment/after drug administration in both groups.

CONCLUSIONS

In Japan, 0.4% SH is the only commercially approved formulation for submucosal injection during ESD. The study results may expand submucosal injection solution options in clinical practice.

Endoscopic submucosal dissection with a novel high viscosity injection solution (LiftUp) in an ex vivo model: a prospective randomized study

Introduction  Endoscopic submucosal dissection (ESD) is increasingly being used in the western world. Submucosal injectates are an essential tool for the ESD procedure. In this study, we evaluated a novel copolymer injectate (LiftUp, Ovesco, Tübingen Germany) in an established ESD model (EASIE-R) in comparison to existing submucosal injectables. Materials and methods  We conducted a prospective, randomized ex vivo study performing ESD with three injectates: LiftUp, hydroxyethyl starch (HAES 6 %) and normal saline solution (NaCl 0.9 %). A total of 60 artificial lesions, each 3 × 3 cm in size, were resected in an ex vivo porcine model, utilizing one of the three studied injectates (n = 20 ESDs per injectate). Study parameters were: en bloc resection rate, perforation rate, lifting property, time of injection, injectate volume, general ESD procedure time, and overall procedure time. Results  All 60 lesions were successfully resected using the standard ESD technique. LiftUp had no procedure related perforations, one perforation occurred in the HAES group, and two perforations in the NaCl group ( P  > 0.05). Furthermore, adequate lifting was achieved in 16/20 (80 %) using LiftUp, 6/20 (30 %) in the HAES group and 6/20 (30 %) in the NaCl group ( P  < 0.0002). En bloc resection was achieved in 19 (95 %) with LiftUp, in 20 (100 %) with HAES, and in 16 (80 %) with NaCl. General ESD procedure time and overall procedure time were not different among the three groups. Conclusion  LiftUp appears to be a safe alternative to established fluids for ESD. It had a significantly improved lifting effect and required significantly less injected volume compared to well-established lifting solutions.

Preclinical evaluation of a novel thermally sensitive co-polymer (LiftUp) for endoscopic resection

Introduction: Endoscopic resection techniques can successfully resect large lesions either in "en bloc" fashion or in "piece-meal" technique by using a submucosal injection solution. The aim of this study was to evaluate the safety of a novel injectable, containing thermally sensitive co-polymer from ethylenoxide and propylenoxide (LiftUp) used as submucosal injection solution.Material and methods: We conducted an in vivo animal trial in the porcine model to evaluate the LiftUp gel in a preclinical setting and to study the effectiveness of mucosal lifting and the safety of the new injectable. In seven animals a total of 63 injections and endoscopic resections were carried out in different anatomical locations (esophagus, stomach and rectum). The resection sites were controlled endoscopically one and four weeks after resection and a histopathological evaluation of the resection sites was performed after four weeks.Results: The application of LiftUp was safe and there were no negative effects on wound healing after injection and resection. A major procedural complication rate (defined as perforation and major haemorrhage) of 3.2% was registered, which undercuts the anticipated mean complication rate of 4-8%. Furthermore, there was no necessity of reinjection after the initial submucosal injection in 90.5% and no procedural complications in 98.8%. The histopathological examination of the tissue samples indicated normal wound healing with granulation tissue and epithelialisation.Conclusion: The use of LiftUp as submucosal injection solution was feasible for different endoscopic resection techniques, with high and long-lasting elevation and fewer procedural adverse events than expected at trial planning. The new injectable is a practical advancement over the current state-of-the-art of submucosal injection and could fasten up the resection procedure and make endoscopic 'en bloc' resection safer.

Application of MESNA in endoscopic submucosal dissection for esophageal diseases

With the development of digestive endoscopy, early esophageal carcinoma, esophageal leiomyoma, achalasia, and mediastinal lesions, which were previously treated by thoracoscopy or thoracotomy, may be treated by digestive endoscopy. Endoscopic submucosal dissection (ESD) can achieve en bloc resection of large gastrointestinal mucosal and submucosal lesions and has become the first-line treatment for early esophageal cancer and precancerous lesions without lymph node metastasis. Submucosal tunnel endoscopy has expanded endoscopic indications by establishing a submucosal tunnel, and it has been applied in esophageal lesions originating from the muscularis propia and even mediastinal tumors. An ideal submucosal fluid infusion may shorten dissection time during ESD or submucosal tunnel endoscopy. Selecting appropriate submucosal injection is one of the important factors for ESD success. Submucosal injections of sodium-2-mercaptoethanesulfonate can soften tissues and facilitate endoscopic submucosal dissection and is worthy of clinical promotion.

Rebamipide solution: a novel submucosal injection material to promote healing speed and healing quality of ulcers induced by endoscopic submucosal dissection

BACKGROUND AND AIMS

Rebamipide is administered perorally to protect the gastric mucosa. We assessed the efficacy and safety of a novel rebamipide solution as a submucosal injection material for endoscopic submucosal dissection (ESD) using an in vivo porcine model.

METHODS

An endoscopist blinded to the test agents performed ESDs of hypothetical 30 mm lesions using a 2% rebamipide solution at 2 sites (rebamipide group) and a saline solution at 2 other sites (control group) in the stomachs of 8 pigs. The technical outcomes were compared between the 2 groups. The gastric ulcer stages were evaluated by endoscopy once weekly for 4 weeks after the ESD to determine the healing score (1-6). The pigs were killed at 1 week (n = 2), 2 weeks (n = 2), and 4 weeks (n = 4) after the ESD for pathologic evaluation of ESD-induced ulcers and scarring.

RESULTS

There were no significant differences in any of the technical outcomes between the 2 groups, and no adverse events related to the ESD in any of the animals. The healing score was significantly higher in the rebamipide group than in the control group at 2 weeks (P = .027), 3 weeks (P = .034), and 4 weeks (P = .012). In the histopathologic assessment, fibrosis was significantly less extensive in the rebamipide group than in the control group at 2 weeks (P = .02) and 4 weeks (P = .04).

CONCLUSIONS

The rebamipide solution appeared to promote both the speed and quality of healing of ESD-induced ulcers by suppressing fibrosis.

Thermo-sensitive isopentane aerification for mucosal lift during endoscopic resection in animal models (with video)

BACKGROUND AND AIMS

Mucosal lift is critical for successful endoscopic treatment. Normal saline (NS) solution is widely used as the submucosal filler, but its short persistency restricts clinical endoscopic submucosal dissection (ESD). In this study, thermo-sensitive isopentane was introduced for submucosal injection. With a boiling point at 27.8°C, liquid isopentane can be easily applied, and gasification inflation can provide great support for submucosal lifting at body temperature. The feasibility and efficiency of isopentane were evaluated in this study.

METHODS

Porcine stomachs were used for in vitro evaluation. A 37°C water bath was used to mimic body temperature. Compared with NS, isopentane was studied for its lifting performance, including injection dosage, persistence of lifting strength, and efficacy for assisting submucosal dissection. The changes in submucosal tissue were also compared. For in vivo evaluation, rats were used to further compare the differences between isopentane and NS, including lifting efficacy, pathologic effect, and safety.

RESULTS

Compared with NS, the maximum lifting height was achieved with less isopentane (2% NS volume). Longer persistency and faster operation for submucosal dissection were also recorded for isopentane during the in vitro study. Aerification resulted in vacuolization of submucosal connective tissue, which facilitates EMR and postoperative recovery. The same results were confirmed in the rat model. With the same dosage, isopentane produced better mucosal elevation and larger range than NS. According to the histologic examination, no tissue injury was observed with isopentane application.

CONCLUSIONS

As a submucosal injection agent, the feasibility, efficacy, and safety of isopentane has been demonstrated. Thermo-sensitive aerification may be a promising approach to facilitate ESD.

Efficacy and safety of a combination of hyaluronic acid, chondroitin sulfate, and poloxamer 407 as a submucosal injection solution for endoscopic resection: pilot study on a swine model

BACKGROUND AND AIMS

 Endoscopic resection techniques require use of submucosal injection. The aim of this study was to assess a new solution that combines hyaluronic acid, chondroitin sulfate, and poloxamer 407 for submucosal injection.

METHODS

 A total of 48 gastric submucosal cushions were created in fresh porcine stomachs using gelafundin (n = 16) or the new solution diluted at 50 % (n = 16), or 80 % (n = 16). The duration of mucosal elevation was measured. In an in vivo model, 10 gastric submucosal cushions were created by injecting 2 mL of the new solution at 80 % and the animal was euthanized 30 minutes after the last injection.

RESULTS

 Submucosal cushions with the new solution at 80 % and 50 % concentration lasted longer than with gelafundin (23.13 ± 15.57, 13.1 ± 6.6, 3.94 ± 1.53 minutes, respectively; P  = 0.000). In the in vivo study, no damage or necrosis was observed in the mucosa or muscularis propria.

CONCLUSION

 The combination of hyaluronic acid, chondroitin sulfate, and poloxamer 407 produces a long-lasting submucosal cushion and does not seem to induce acute damage in the tissue making it suitable for submucosal injection.

Future Development of Endoscopic Accessories for Endoscopic Submucosal Dissection

Endoscopic submucosal dissection (ESD) has recently been accepted as a standard treatment for patients with early gastric cancer (EGC), without lymph node metastases. Given the rise in the number of ESDs being performed, new endoscopic accessories are being developed and existing accessories modified to facilitate the execution of ESD and reduce complication rates. This paper examines the history underlying the development of these new endoscopic accessories and indicates future directions for the development of these accessories.

Updated evidence on endoscopic resection of early gastric cancer from Japan

BACKGROUND

Endoscopic resection for early gastric cancer (EGC) plays a central role in the treatment of EGC in Japan. However, there is still room for improvement, and it is necessary to summarize the recently obtained knowledge from Japan for further improvement.

METHODS

We conducted a PubMed search to select relevant articles in the 5 years until September 18, 2016, using the keywords "gastric cancer" and "endoscopic treatment," "endoscopic submucosal dissection," "endoscopic mucosal resection," or "polypectomy" and filtering article types as "clinical study" or "clinical trial."

RESULTS

Among the 329 articles selected automatically from the keywords "polypectomy" (1 article), "endoscopic mucosal resection" (29 articles), "endoscopic submucosal dissection" (77 articles), and "endoscopic treatment" (222 articles) in combination with "gastric cancer," 32 relevant articles from Japanese investigators were chosen. Seven articles were categorized into "equipment," 4 into "preparation and sedation," 17 into "complications and their prevention," and 4 into "therapeutic outcomes." Among them, CO₂ insufflation, propofol sedation, and how to prevent post-endoscopic submucosal dissection (ESD) ulcer bleeding and achieve post-ESD ulcer healing were intensively investigated. Long-term outcomes of endoscopic mucosal resection and ESD were also reported as favorable outcomes.

CONCLUSIONS

Endoscopic resection for EGC is still developing toward an ideal form, pursuing a more reliable, safer, and faster minimally invasive treatment.

Endoscopic submucosal dissection of gastric tumors: A systematic review and meta-analysis

AIM: To systematically review the medical literature in order to evaluate the safety and efficacy of gastric endoscopic submucosal dissection (ESD).

METHODS: We performed a comprehensive literature search of MEDLINE, Ovid, CINAHL, and Cochrane for studies reporting on the clinical efficacy and safety profile of gastric ESD.

RESULTS: Twenty-nine thousand five hundred and six tumors in 27155 patients (31% female) who underwent gastric ESD between 1999 and 2014 were included in this study. R0 resection rate was 90% (95%CI: 87%-92%) with significant between-study heterogeneity (P < 0.001) which was partly explained by difference in region (P = 0.02) and sample size (P = 0.04). Endoscopic en bloc and curative resection rates were 94% (95%CI: 93%-96%) and 86% (95%CI: 83%-89%) respectively. The rate of immediate and delayed perforation rates were 2.7% (95%CI: 2.1%-3.3%) and 0.39% (95%CI: 0.06%-2.4%) respectively while rates of immediate and delayed major bleeding were 2.9% (95%CI: 1.3-6.6) and 3.6% (95%CI: 3.1%-4.3%). After an average follow-up of about 30 mo post-operative, the rate of tumor recurrence was 0.02% (95%CI: 0.001-1.4) among those with R0 resection and 7.7% (95%CI: 3.6%-16%) among those without R0 resection. Overall, irrespective of the resection status, recurrence rate was 0.75% (95%CI: 0.42%-1.3%).

CONCLUSION: Our meta-analysis, the largest and most comprehensive assessment of gastric ESD till date, showed that gastric ESD is safe and effective for gastric tumors and warrants consideration as first line therapy when an expert operator is available.

Using a double-channel gastroscope reduces procedural time in performing gastric endoscopic submucosal dissection

Objective:

Complications are important determining factors for safety of endoscopic submucosal dissection (ESD). ESD of large lesions is associated with increased procedural time. This study investigated whether double-channel gastroscope could be used to reduce procedural time in gastric antrum ESD.

Methods:

A retrospective cohort study of 46 patients with one gastric antrum lesion resected by ESD was conducted between January 2013 and December 2015. The diameter of a lesion was from 2cm to 4cm in 46 patients. EUS before ESD was used to evaluate the submucosal vascular structure and the location of lesion in gastric wall. Forty six lesions had ESD with either the ordinary gastroscope (OS group) (n=24) or the double-channel gastroscope (DC group) (n=22).

Results:

The mean procedural time was significantly lower in the DC group than in the OS group (49.1 minutes vs. 20.5 minutes, p=0.04). There were no significant differences in submucosal injection frequency, specimen size, en bloc resection rate and perforation rate between the two endoscopic groups. There was no recurrence in any case during the follow-up period.

Conclusions:

Our data suggest that ESD utilizing double-channel gastroscope may provide a better platform for quicker ESD with equal safety.

Safe and Efficient Colonic Endoscopic Submucosal Dissection Using an Injectable Hydrogel

Endoscopic submucosal dissection (ESD) has not yet been widely adopted in the treatment of early colonic cancers due to the greater technical difficulty involved, longer procedure time, and the increased risk of perforation. Adequate mucosal elevation by submucosal injection is crucial for en bloc resection and prevention of perforation during colonic ESD. This study is aimed to evaluate the efficacy of an injectable thermoreversible hydrogel as the colonic submucosal agent for the first time. Triblock copolymer poly(lactic acid-co-glycolic acid)-poly(ethylene glycol)-poly(lactic acid-co-glycolic acid) (PLGA-PEG-PLGA) was synthesized, and its concentrated aqueous solution was injected into the colonic submucosa of living minipig and spontaneously transformed into an in situ hydrogel with adequate mucosal elevation at body temperature. Such a mucosal lifting lasted for a longer time than that created by the control group, glycerol fructose. Colonic ESD was then performed with the administration of hydrogels at various polymer concentrations or glycerol fructose. All colonic lesions were successfully resected en bloc after one single injection of the hydrogel, and repeated injections were not needed. No evidence of major hemorrhage, perforation and tissue damage were observed. Considering the injection pressure, duration of mucosal elevation and efficacy of "autodissection", the hydrogel containing 15 wt % polymer was the optimized system for colonic ESD. Consequently, the thermoreversible hydrogel is an ideal submucosal fluid that provides a durable mucosal lifting and makes colonic ESD accessible to a large extent. In particular, the efficacy of "autodissection" after one single injection of the hydrogel simplifies significantly the procedures while minimizing the complications.

Solutions for submucosal injection in endoscopic resection: a systematic review and meta-analysis

BACKGROUND AND AIMS

Submucosal injection is standard practice in endoscopic mucosal resection of gastrointestinal lesions. Several solutions are used. Our aim was to systematically review their efficacy and safety.

PATIENTS AND METHODS

We performed a systematic review and meta-analysis using a random effects model of randomized controlled trials (RCTs) from MEDLINE. Studies in animal models were qualitatively assessed for efficacy and safety.

RESULTS

In total, 54 studies were qualitatively assessed. Eleven RCTs were analyzed, two of which were on endoscopic submucosal dissection (ESD). The quantitative synthesis included nine RCTs on endoscopic mucosal resection (EMR), comprising 792 subjects and 793 lesions. Mean lesion size was 20.9 mm (range 8.5 - 46 mm). A total of 209 lesions were randomized to sodium hyaluronate (SH) vs normal saline (NS), 72 to 50 % dextrose (D50) vs NS, 82 to D50 vs SH, 43 to succinylated gelatin, 25 to hydroxyethyl starch and 36 to fibrinogen. In total, 385 were randomized to NS as controls. NS and SH are the best studied solutions and seem to be equally effective in achieving complete resection (OR 1.09; 95 %CI 0.82, 1.45). No solution was proven to be superior in complete resection rate, post-polypectomy bleeding or coagulation syndrome/perforation incidence. Many solutions have been tested in animal studies and most seem more effective for mucosal elevation than NS.

CONCLUSIONS

There are several solutions in clinical use and many more under research, but most are poorly studied. SH seems to be clinically equivalent to NS. There are no significant differences in post-polypectomy complications. Larger RCTs are needed to determine any small differences that may exist between solutions.