Effectiveness of sodium alginate as a submucosal injection material for endoscopic mucosal resection in animal

Easily injectable gelatin-nonanal hydrogel for endoscopic resectioning of gastrointestinal polyps

The use of submucosal injection is crucial for satisfactory submucosal elevation in the early resection of flat polyps originating from the gastrointestinal tract (GIT). Injectable hydrogels derived from natural polypeptides are attractive candidates due to their excellent biocompatibility and easy gelation properties. However, most of the reported hydrogels are not the class of catheter delivery materials due to quick gelation, high inherent viscosity, and injection clogging. This study presents a novel injectable shear-thinning hydrogel platform of small molecules (nonanal) modified gelatin polymer, which offers a promising submucosal injection for effective removal of polyps from GIT. Physicochemical characterizations of hydrogel demonstrate the suitable features as an effective submucosal injection, including shear thinning property, self-assembly, methylene blue dye encapsulation, flow behavior, stability, syringeability (18 G, 21 G, and 24 G needles) and fibrous morphology. Ex vivo investigations of developed submucosal formulation on goat intestines demonstrate the enhanced visibility of cushions and the ability to produce stable, long-lasting cushions of about 8.07 mm up to ∼60 min of submucosal injection. The rapid blood clotting behavior of hydrogel was observed in about 120 s without compromising hemocompatibility with the hemolysis of about 3.77 % only. In vitro biocompatibility of the hydrogel was also verified using the HepG2 and nHDF cells. In vivo study depicts desirable biocompatibility, a non-toxic organ profile, and optimal cushion height in mice models. Studies established the foundation of novel submucosal fluid to improve the therapeutic outcomes of early resection for gastrointestinal polyps.

Efficacy and safety of MC-003 solution for endoscopic mucosal or submucosal resection: a prospective, multicenter, randomized, triple-blinded, parallel-group, phase III study

BACKGROUND AND AIMS

The safety and efficacy of solutions for submucosal injection are critical for endoscopic resection of gastric adenomas or early gastric cancers. Although several injectable solutions have been introduced for endoscopic resection, they have some limitations. We aimed to compare the efficacy of the new sodium alginate-based solution MC-003 with that of normal saline (NS; 0.9% sodium chloride).

METHODS

In this randomized, triple-blind study, 70 patients were initially enrolled for EMR or endoscopic submucosal dissection (ESD). The main outcomes included the need for additional injections, completion of en bloc resection, and occurrence of adverse events.

RESULTS

Each group ultimately included 34 patients. Complete en bloc resections were achieved in all patients (P = 1.000). The MC-003 group had more peri-neoplasm tissue fibrosis (P = .056) and needed fewer additional injections for lesions >15 mm (P = .037), located in the distal portion of the stomach (P = .007), and during ESD procedures (P = .001). The adverse event rate was comparable in both groups.

CONCLUSIONS

MC-003 outperformed NS in reducing the need for additional injections during en bloc resection, particularly in larger lesions located in the distal portion of the stomach (where most lesions were found) during ESD procedures, without increasing the incidence of serious adverse events. MC-003 is a promising submucosal injectable solution in real-world clinical settings.

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.

Easily-injectable shear-thinning hydrogel provides long-lasting submucosal barrier for gastrointestinal endoscopic surgery

Submucosal injection material has shown protective effect against gastrointestinal injury during endoscopic surgery in clinic. However, the protective ability of existing submucosal injection material is strictly limited by their difficult injectability and short barrier time. Herein, we report a shear-thinning gellan gum hydrogel that simultaneously has easy injectability and long-lasting barrier function, together with good hemostatic property and biocompatibility. Shear-thinning property endows our gellan gum hydrogel with excellent endoscopic injection performance, and the injection pressure of our gellan gum hydrogel is much lower than that of the small molecule solution (50 wt% dextrose) when injected through the endoscopic needle. More importantly, our gellan gum hydrogel shows much stronger barrier retention ability than normal saline and sodium hyaluronate solution in the ex vivo and in vivo models. Furthermore, our epinephrine-containing gellan gum hydrogel has a satisfactory hemostatic effect in the mucosal lesion resection model of pig. These results indicate an appealing application prospect for gellan gum hydrogel utilizing as a submucosal injection material in endoscopic surgery.

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Submucosal injection materials are widely used in endoscopic surgery to protect against gastrointestinal injury.

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Gellan gum hydrogel with shear-thinning character is a novel submucosal injection material.

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Gellan gum hydrogel simultaneously has easy injectability and long-lasting barrier performance in vivo.

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Epinephrine-containing gellan gum hydrogel has a satisfactory hemostatic effect.

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.

Injectable Thermogel Generated by the "Block Blend" Strategy as a Biomaterial for Endoscopic Submucosal Dissection

Endoscopic submucosal dissection is an established method for the removal of early cancers and large lesions from the gastrointestinal tract but is faced with the risk of perforation. To decrease this risk, a submucosal fluid cushion (SFC) is needed clinically by submucosal injection of saline and so on to lift and separate the lesion from the muscular layer. Some materials have been tried as the SFC so far with disadvantages. Here, we proposed a thermogel generated by the "block blend" strategy as an SFC. This system was composed of two amphiphilic block copolymers in water, so it was called a "block blend". We synthesized two non-thermogellable copolymers poly(d,l-lactide-co-glycolide)-b-poly(ethylene glycol)-b-poly(d,l-lactide-co-glycolide) and blended them in water to achieve a sol-gel transition upon heating in both pure water and physiological saline. We explored the internal structure of the resultant thermogel with transmission electron microscopy, three-dimensional light scattering, ¹³C NMR, fluorescence resonance energy transfer, and rheological measurements, which indicated a percolated micelle network. The biosafety of the synthesized copolymer was preliminarily confirmed in vitro. The main necessary functions as an SFC, namely, injectability of a sol and the maintained mucosal elevation as a gel after injection, were verified ex vivo. This study has revealed the internal structure of the block blend thermogel and illustrated its potential application as a biomaterial. This work might be stimulating for investigations and applications of intelligent materials with both injectability and thermogellability of tunable phase-transition temperatures.

Viscosity and degradation controlled injectable hydrogel for esophageal endoscopic submucosal dissection

Endoscopic submucosal dissection (ESD) is a common procedure to treat early and precancerous gastrointestinal lesions. Via submucosal injection, a liquid cushion is created to lift and separate the lesion and malignant part from the muscular layer where the formed indispensable space is convenient for endoscopic incision. Saline is a most common submucosal injection liquid, but the formed liquid pad lasts only a short time, and thus repeated injections increase the potential risk of adverse events. Hydrogels with high osmotic pressure and high viscosity are used as an alternate; however, with some drawbacks such as tissue damage, excessive injection resistance, and high cost. Here, we reported a nature derived hydrogel of gelatin-oxidized alginate (G-OALG). Based on the rheological analysis and compare to commercial endoscopic mucosal resection (EMR) solution (0.25% hyaluronic acid, HA), a designed G-OALG hydrogel of desired concentration and composition showed higher performances in controllable gelation and injectability, higher viscosity and more stable structures. The G-OALG gel also showed lower propulsion resistance than 0.25% HA in the injection force assessment under standard endoscopic instruments, which eased the surgical operation. In addition, the G-OALG hydrogel showed good in vivo degradability biocompatibility. By comparing the results acquired via ESD to normal saline, the G-OALG shows great histocompatibility and excellent endoscopic injectability, and enables create a longer-lasting submucosal cushion. All the features have been confirmed in the living both pig and rat models. The G-OALG could be a promising submucosal injection agent for esophageal ESD.

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Injectable gel with controlled viscosity.

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Injectable gel with controlled degradation.

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Making esophageal submucosal liquid cushion.

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Potential treatment for early esophageal cancer.

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Big animal in-situ imaging.

Evaluation of Eleview® Bioadhesive Properties and Cushion-Forming Ability

Submucosal injection is generally required for both endoscopic-mucosal resection (EMR) and submucosal dissection (ESD). SIC-8000 (Eleview®) is a new liquid composition in the form of a microemulsion for submucosal injection, approved by the Food and Drug Administration (FDA) 510(k) and Conformité Européene (CE) marked, containing a biocompatible polymer as a cushioning agent. The aim of this study was to evaluate Eleview®’s performance in terms of bioadhesive properties and cushion-forming ability. The bioadhesion was evaluated by measuring the interaction between Eleview® and the extracellular matrix (the main component of the submucosal layer) using the texture analyzer. To better comprehend the mechanism of action of Eleview® after submucosal injection, force of detachment and adhesion work were measured for the following formulations: Eleview®, Eleview® without poloxamer (functional polymer), poloxamer solution alone, normal saline, and MucoUp® (competing product on the Japanese market). The results obtained show the interaction between Eleview® and the extracellular matrix, highlighting the stronger bioadhesive properties of Eleview® compared with Eleview® without poloxamer, poloxamer solution alone, as well as normal saline and MucoUp®. The ability of Eleview® to form a consistent and long-lasting cushion in situ, once injected into the submucosal layer, was tested ex vivo on a porcine stomach. The results obtained show a better permanence in situ for the product compared with normal saline injection and to MucoUp® (t-test, p < 0.05).

A New Ex Vivo Model for the Evaluation of Endoscopic Submucosal Injection Material Performance

Increasing the performance of submucosal injection materials (SIMs) is important for endoscopic therapy of early gastrointestinal cancer. It is essential to establish an ex vivo model that can evaluate SIM performance accurately, for developing high-performance SIMs. In our previous study, we developed a new ex vivo model that can be used to evaluate the performance of various SIMs in detail by applying constant tension to the specimen's ends. We also confirmed that the proposed new ex vivo model allows accurate submucosal elevation height (SEH) measurement under uniform conditions and detailed comparisons of the performances of various types of SIMs. Here, we describe the new ex vivo model and explain the detailed setup methodology of this model. Since all parts of the new model were easy to obtain, the setup of the new model could be completed quickly. SEH of various SIMs could be measured more accurately by using the new model. The critical factor that determines SIM performance can be identified using the new model. SIM development speed will drastically increase after the factor has been identified.

Identification of the critical viscoelastic factor in the performance of submucosal injection materials

High-performance submucosal injection materials (SIMs) contribute to the success of endoscopic therapy for early-stage gastrointestinal neoplasms. This study aimed to identify the most important factor (viscoelastic parameter) that determines SIM performance and the ease of injection. To determine the ideal viscoelastic parameters of SIMs, submucosal elevation heights (SEHs) and the ease of submucosal injection [characterized by injection pressures (IPs)] were evaluated using a newly developed ex vivo model, in which a constant tension was applied to the studied specimen. The strongest positive correlation was observed between the loss modulus determined at an oscillation frequency of 0.1 rad/s and SEH (correlation coefficient > 0.9) and between the loss modulus at 10 rad/s and IP (correlation coefficient > 0.9). SIMs with high loss moduli (0.1 rad/s) also contributed to maintenance of the submucosal elevation. Moreover, the SEHs of pseudoplastic fluid SIMs (whose loss moduli increased slightly with increasing angular frequency) were greater than those of Newtonian fluid SIMs (whose loss modulus increased drastically with increasing angular frequency). In this study, the ideal viscoelastic SIM parameters were clarified. The loss modulus (0.1 rad/s) was the most important viscoelastic factor affecting SIM performance. Additionally, the development of pseudoplastic fluid SIMs may lead to the creation of next-generation SIMs, with a performance superior to that of sodium hyaluronate, which is currently used widely in endoscopic treatments.

Development of a new ex vivo model for evaluation of endoscopic submucosal injection materials performance

BACKGROUND AND AIMS

Development of high-performance submucosal injection materials (SIMs) contribute to the advancement of endoscopic therapy for early-stage gastrointestinal neoplasms. This study aimed to develop a new ex vivo model that mimics the human gastrointestinal tract to evaluate the performance (the height and duration of the submucosal elevation) of various SIMs in detail.

METHODS

A new ex vivo model that applies a constant tension to the tested specimen (the porcine gastric specimen) was developed. SIMs were injected into the submucosa at the center or edge of the tested specimen, and submucosal elevation heights (SEHs) were measured over time.

RESULTS

The average value and standard deviation of SEH determined using the conventional model (the tested specimen was fixed with pins) were higher than those obtained using the new model, which showed that the new model could precisely measure the SEH of a given SIM. In addition, the performance (SEH) of SIMs decreased with increasing tension applied to the specimen, suggesting that the performance of SIMs deteriorates with the over-expansion of the gastrointestinal tract. The submucosal elevation formed at the specimen edge disappeared faster than that formed at the specimen's center.

CONCLUSIONS

The proposed new ex vivo model allows accurate SEH measurement under uniform conditions and detailed comparison of the performances of various types of SIMs and can contribute to the development of high-performance materials.

Gastric endoscopic submucosal dissection using sodium carboxymethylcellulose as a new injection substance

AIM

To investigate the feasibility of endoscopic submucosal dissection (ESD) using sodium carboxymethylcellulose (SCMC) for gastric cancer.

METHODS

During October 2011 through April 2013, 98 lesions from 98 patients who underwent ESD using SCMC (ESD-SCMC) for early gastric cancer were enrolled in this study.　Two endoscopists, who had each performed fewer than 30 ESD procedures (less-experienced ESD physicians), performed ESD-SCMC under the supervision of two experts.　The primary outcome was the en bloc resection rate.　Secondary outcomes included the complete resection rate, the procedural time, the bleeding rate after SCMC injection, and complications.　Patient characteristics, time necessary for hemostasis after SCMC injection, rate of treatment completion by less-experienced ESD physicians alone, and the effects of SCMC during ESD and on resected specimens were also evaluated.

RESULTS

The en bloc resection rate was 100%.　Among these resections, 87.8% of the cases were completed by a less-experienced ESD physician alone.　The complete resection rate was 98.0%.　The mean total procedural time was 75.4 min.　The mean incidence of intraoperative bleeding following SCMC local injection was 1.7 times.　No bleeding was observed after SCMC injection in 29.6% of cases (29/98).　Five complications occurred: one case of microperforation (1.0%) and four cases of postoperative bleeding (4.0%).　SCMC remained in the submucosa.　The submucosa was readily manipulated when the deep submucosa was dissected, even after placing the specimen on a slide.

CONCLUSION

ESD-SCMC is feasible for the resection of early gastric cancer.

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.

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

BACKGROUND AND AIM

We have focused on sodium alginate (SA) solution as a potential submucosal injection material for endoscopic submucosal dissection (ESD). A previous SA solution had high viscosity and problems such as difficult handling. After its properties were adjusted, SA solution was examined in vitro and its clinical safety was evaluated.

METHODS

With 0.4% sodium hyaluronate (SH) solution as a control, catheter injectability and mucosa-elevating capacity of 0.3-0.8% SA solutions were evaluated. Next, 0.6% SA solution was used for ESD in 10 patients with early gastric cancer in a prospective clinical study.

RESULTS

Compared with 0.4% SH solution, 0.6% SA solution exhibited no significant difference in catheter injectability but significant superiority in mucosa-elevating capacity. In the clinical study, no adverse events were observed in any patient.

CONCLUSION

The safety of 0.6% SA solution as a submucosal injection material was confirmed and it is suggested that its efficacy should be investigated in a larger number of cases.

Alginate hydrogel as a potential alternative to hyaluronic acid as submucosal injection material

BACKGROUND

Sodium alginate is currently used in medical products, including drugs and cosmetic materials. It can also be used as a submucosal injection material due to its excellent water retention ability. Alginate with a high water retention ability is called alginate hydrogel (AH). The aim of this study was to investigate the usefulness of AH as a submucosal injection material.

METHODS

To investigate the optimal viscosity of AH as a submucosal injection material, we observed the changes in submucosal height from the initial submucosal height in the stomachs of six miniature pigs for each injection material tested (0.3 % AH, 0.5 % hyaluronic acid, glycerol). All submucosal heights were compared serially over time (3, 5, 10, 20, and 30 min). Both immediate and 1-week delayed tissue reactions were investigated endoscopically in the same living pigs. Histological analyses were performed after the animals had been sacrificed.

RESULTS

In a preliminary study, we determined that 0.3 % sodium alginate mixed with BaCl2 (400 μl) was the optimal viscosity of AH as an injection material. Our comparison of submucosal height changes over time showed that there was a significant decrease in submucosal height just 3 min following the injection of hyaluronic acid and glycerol, but that following the injection of AH a significant decrease in submucosal height was observed only after 10 min (p < 0.05). The histological analyses revealed that there were mild capillary dilations with congestion and mild fibrotic changes with some lymphocytic infiltration at the AH injection site.

CONCLUSION

Alginate hydrogel demonstrated long-lasting maintenance of submucosal elevation, safety, and cost-effectiveness in a pig model, which makes it a potential alternative to hyaluronic acid.

A pilot animal and clinical study of autologous blood solution compared with normal saline for use as an endoscopic submucosal cushion

Normal saline is the most popular agent used during endoscopic submucosal injection. However, endoscopists have never identified an optimal submucosal injection solution, which is not only safe and cost-effective but has a unique lifting ability with endoscopic submucosal cushion and causes less tissue damage. This study aimed to evaluate the effectiveness and microscopic characteristics of a blood solution, including whole blood and plasma solution, as a submucosal cushioning agent, compared with normal saline. Endoscopic submucosal dissection (ESD) procedures in pig stomachs were performed by injecting plasma solution (n=4) and normal saline (n=4). A total of 38 patients with gastrointestinal neoplasms underwent endoscopic musocal resection (EMR) procedures. Of 38 EMRs, 7 used whole blood injection, and 31 of 38 acting as the control group used normal saline. A tissue damage scoring system was developed based on injection-induced hydrops and tears for the evaluation of tissue damage. In animal experiments, the lifting time of the injection with normal saline in the pig colon was shorter than that of the group with plasma solution (18.25±5.44 min vs. 6.5±2.38 min, P=0.007). In animal experiments with ESD procedures in the stomach, the hydrops in the normal saline injection group were more extensive than those in the group with plasma (P=0.011). The degree of tearing in the group with normal saline was observed to be less than that in the group with plasma (P=0.008). In patients with EMR, using the histological scoring method, it was determined that the degree of hydrops in the group with normal saline injection was more extensive than that in the group with whole blood (P<0.001). The effective submucosal tearing in the group with normal saline was less than that in the group with blood (P<0.001). The blood solution, including whole blood and plasma solution, as a novel submucosal injection agent, may outperform normal saline with a unique lifting ability, less pronounced tissue damage and marked effective submucosal blunt dissection.

Injectable drug-eluting elastomeric polymer: a novel submucosal injection material

BACKGROUND

Biodegradable hydrogels can deliver therapeutic payloads with great potentials in EMR and endoscopic submucosal dissection (ESD) to yield improvements in efficacy and foster mucosal regeneration.

OBJECTIVE

To assess the efficacy of an injectable drug-eluting elastomeric polymer (iDEEP) as a submucosal injection material.

DESIGN

Comparative study of 3 different solutions by using material characterization tests and ex vivo and in vivo porcine models.

SETTING

Academic hospital.

INTERVENTIONS

Thirty gastric submucosal cushions were achieved with saline solution (0.9%), sodium hyaluronate (0.4%), and iDEEP (n = 10) in ex vivo porcine stomachs. Four porcine gastric submucosal cushions were then created in vivo by using iDEEP.

MAIN OUTCOME MEASUREMENTS

Maximum injection pressure, rebamipide release rate, submucosal elevation duration, and assessment of in vivo efficacy by en bloc resection.

RESULTS

No significant difference in injection pressures between iDEEP (28.9 ± 0.3 psi) and sodium hyaluronate (29.5 ± 0.4 psi, P > .05) was observed. iDEEP gels displayed a controlled release of rebamipide up to 2 weeks in vitro. The elevation height of iDEEP (5.7 ± 0.5 mm) was higher than that of saline solution (2.8 ± 0.2 mm, P < .01) and sodium hyaluronate (4.2 ± 0.2 mm, P < .05). All EMR procedures were successfully performed after injection of iDEEP, and a large gel cushion was noted after the resection procedure.

LIMITATIONS

Benchtop, ex vivo, and nonsurvival pig study.

CONCLUSIONS

A novel injection solution was evaluated for endoscopic resection. These results suggest that iDEEP may provide a significant step toward the realization of an ideal EMR and endoscopic submucosal dissection injection material.

Sodium alginate as an ideal submucosal injection material for endoscopic submucosal resection: preliminary experimental and clinical study

BACKGROUND

Sodium alginate is used clinically in the treatment of peptic ulcer disease. Because of its viscosity, sodium alginate could possibly become a new submucosal injection material for use in endoscopic resection.

OBJECTIVE

We evaluated the feasibility of endoscopic submucosal dissection (ESD) using sodium alginate.

SETTING AND INTERVENTIONS

The lesion-lifting properties of sodium alginate were examined in porcine stomachs and were compared with those of normal saline solution and sodium hyaluronate solution. After confirming the proper concentration of sodium alginate, ESD using sodium alginate was performed in 11 patients with gastric mucosal cancer or adenoma.

MAIN OUTCOME MEASUREMENT

The lesion-lifting properties of sodium alginate and clinical outcomes were assessed.

RESULTS

The thickness of the submucosal elevation created by 3% sodium alginate in porcine stomach was equivalent to that of sodium hyaluronate. ESD using sodium alginate was completed successfully in all patients without adverse effects except in 1 patient in whom transient shrinkage of the gastric wall disappeared spontaneously after approximately 30 minutes. The mean tumor size was 15.3 mm. En bloc resection and a negative resection margin were obtained in all. Histopathologic examination revealed that all tumors were confined to the mucosal layer except for 1 that was confined to the submucosal layer without lymphovascular invasion, and there were no adverse effects such as tissue damage. No patient required additional treatment, and none showed recurrence during a median follow-up period of 28 months.

LIMITATIONS

Small sample size.

CONCLUSION

This preliminary study suggests that sodium alginate might be a novel, safe submucosal injection material for use in endoscopic resection. Further investigation of the properties of sodium alginate is warranted.

Electrical characteristics of various submucosal injection fluids for endoscopic mucosal resection

Submucosal fluid injection, prerequisite to endoscopic mucosal resection, necessitates detailed evaluation for proper selection. We aimed to compare height of gastric tissues after submucosal injection, and to verify electrical implications of injectants. Porcine stomach pieces were cut out, and eight solutions were used: normal saline, 0.5% sodium hyaluronate (SH), 0.25% SH, hydroxypropyl methylcellulose, 10% glycerin, fibrinogen, 1% sodium alginate (SA), and 2.5% SA. Elevated heights were measured after submucosal injection of the eight fluids, and electrical impedance was measured for fluids plus a reference solution (0.01 N KCl) with a potentiostat electroimpedance spectrometry and an insulation-tipped knife. Resistivity was calculated thereafter. Normal saline and 10% glycerin solution showed greater height diminution. Resistivity were in the range of 80-110 Omega cm, except for 309.7 Omega cm for fibrinogen. Higher resistivity may improve performance of electrosurgery, probably by strengthening impedance and heat dissipation. Further studies are required to back up this basic experiment for clinical application.