Submucosal injection solutions for endoscopic mucosal resection and endoscopic submucosal dissection of gastrointestinal neoplasms

Hydrogels in Endoscopic Submucosal Dissection for Gastrointestinal Cancers

Endoscopic Submucosal Dissection (ESD) has emerged as a pivotal technique for the minimally invasive treatment of early gastrointestinal cancers, offering benefits such as reduced trauma, lower complication rates, and cost-effectiveness. Despite its advantages, the selection of optimal biomaterials for submucosal injection poses significant challenges. Current materials used in clinical settings often suffer from rapid diffusion, requiring multiple injections and potentially causing localized inflammation. These issues underscore the importance of identifying more effective submucosal injection materials to minimize postoperative complications and enhance patient outcomes. Recent advancements have highlighted the potential of hydrogels in this context, favored for their ability to maintain mucosal elevation longer and support wound healing. This review comprehensively examines the development and application of hydrogels in ESD, focusing on their physicochemical properties, biocompatibility, and the clinical implications of their use. These issues discuss various formulations of hydrogels, their mechanisms of action, and comparative analyses with traditional materials. Furthermore, the review explores ongoing innovations and future perspectives in hydrogel research, aiming to catalyze further advancements in ESD techniques. STATEMENT OF SIGNIFICANCE: This review critically examines hydrogel technologies in endoscopic submucosal dissection for gastrointestinal cancers, highlighting their role in improving procedural outcomes and patient recovery. It explores hydrogels' ability to enhance mucosal elevation, reduce complications, and accelerate healing, offering insights into their transformative potential in medical treatments. The findings emphasize the development of innovative materials that could significantly advance clinical practices in gastrointestinal cancer management.

Easily Injectable, Organic Solvent-Free Self-Assembled Hydrogel Platform for Endoscope Mediated Gastrointestinal Polypectomy

Endoscopic submucosal dissection (ESD) and endoscopic mucosal resection (ESR) are used to eliminate tiny, flat lesions in the gastrointestinal tract (GIT). A substantial submucosal cushion is required for effective dissection. Commonly used saline and hypertonic dextrose injections disperse quickly and do not offer significant elevation, whereas polymers such as gelatin and alginate are challenging to inject. In this study, a novel amphiphilic polyglycerol stearate-based hydrogel (PGSH) platform is demonstrated which could be administered via an endoscopic catheter to help create a stable submucosal elevation. PGSH is easy to inject across different needle gauges, shear-thinning, and forms a long-lasting submucosal cushion during ESD. This hydrogel can encapsulate hydrophilic drugs such as streptomycin, allowing controlled enzymatic and nonenzymatic release. Ex-vivo experiments on goat's GIT demonstrate that PGSH is smoothly injectable without clogging the catheter's needle, achieving the necessary submucosal elevation. Furthermore, ex-vivo blood studies demonstrate immediate clotting behavior while maintaining hemocompatibility. In-vivo, investigations in mice show that the hydrogel forms a biocompatible cushion of suitable height with a nontoxic organ profile that does not overexpress inflammatory cytokines. ESD studies in the porcine model suggest that PGSH has the potential to significantly improve treatment outcomes in the early endoscopic removal of gastrointestinal polyps.

Feasibility of a novel self-assembling submucosal injection peptide solution for endoscopic mucosal resection of colorectal lesions: A multicenter study

Objectives

Although a novel submucosal injection material consisting of a fully synthetic, self-assembling peptide solution, PuraLift, has recently become commercially available in Japan, there are a few reports regarding the usefulness of this solution. The aim of this study was to investigate the feasibility of PuraLift for conventional endoscopic mucosal resection (EMR) in clinical practice.

Methods

This multicenter retrospective study was conducted at the endoscopy units of five institutions from January 2023 to May 2023. Consecutive patients who underwent EMR with PuraLift for 5-20-mm colorectal lesions were included in the introduction of this solution at each institute. The primary endpoint was the "effective resection" rate, defined as pathological complete resection, with "effective injection" defined as requiring no more than one additional injection due to adequate maintenance of mucosal lifting during EMR.

Results

In total, 110 lesions in 70 patients were treated by conventional EMR using PuraLift. En-bloc resection was performed for 109 (99%) lesions, and complete resection was performed for 102 (93%) lesions. More than 95% of the lesions were neoplastic. Additional injections were required in only two lesions. Both were single additional injections, and the median overall injection volume was 1.5 mL. Therefore, the effective injection rate was 93% (95% confidence interval, 86%-96%). No adverse events occurred during the study period.

Conclusions

Although direct comparison with other materials is required, PuraLift seems feasible as an injection material for EMR.

Novel submucosal injection material comprising fully synthetic and self-assembling peptide solution in endoscopic submucosal dissection: A pilot study

Endoscopic submucosal dissection (ESD) requires an injection solution to create a submucosal cushion for safe endoscopic resection. This study evaluated the safety and feasibility of a new injection solution (PuraLift) in ESD for early-stage gastrointestinal tumors. This prospective, single-arm, single-center pilot study included 11 patients with gastrointestinal neoplasms of the stomach (n = 5) or colorectum (n = 6) who underwent ESD. All patients underwent outpatient follow-up at week 4 to confirm presence or absence of adverse events (AEs). All underwent protocol treatment and post-treatment follow-up. None of the AEs were judged to have a cause-and-effect relationship with the study. Questionnaires to the operators who performed the protocol treatment and assistants who performed submucosal injections were evaluated in comparison with saline, and maintenance of mucosal lifting was long, comparable, and short (9/2/0). En bloc and R0 resections were achieved in all patients without intraprocedural AEs. Median size of the specimens was 40 mm (range, 20-70). Median excision time was 52 minutes (range, 22-130). Median volume of PuraLift was 32 mL (range, 22-130). No postoperative bleeding or delayed perforation was observed in any patient. The novel injectable material, PuraLift, can potentially ensure safe and feasible ESD.

Injectable Hyaluronic Acid-Based Hydrogels for Rapid Endoscopic Submucosal Dissection

Endoscopic submucosal dissection (ESD) is a widely used procedure for the treatment of early and precancerous gastrointestinal lesions and has become the standard treatment. In this procedure, the commonly used materials have a short retention time and a limited lifting capacity, which will prolong the duration of the ESD procedure. Furthermore, these liquids tend to diffuse after ESD surgery, failing to adequately protect the wound. Therefore, we designed and developed injectable hydrogels based on hyaluronic acid. A series of oxidized hyaluronic acid (OHA) and hydrazide hyaluronic acid (AHA) were synthesized, and 16 kinds of injectable hydrogels were fabricated to investigate the effects of molecular structures on the properties of the hydrogels. Among these, the O1A3 hydrogel exhibited a suitable injection performance, gelation time, and mechanical properties, along with good blood and cell compatibility in vitro. Subsequently, in a porcine model of the ESD procedure, the results demonstrated that the O1A3 hydrogel exhibited a good retention time and lifting performance while also significantly reducing the operation time from 1-2 h to ∼10 min. Furthermore, the adhesive property of the O1A3 hydrogel on small bleeding spots and wounds could be observed, which was beneficial in protecting the wound from the complex environment of the gastrointestinal tract. The present work of injectable hyaluronic acid-based hydrogels could be promising to improve the efficiency of ESD surgery.

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.

Hypertonic solution as an optimal submucosal injection solution for endoscopic resection of gastrointestinal mucosal lesions: Systematic review and network meta-analysis

OBJECTIVES

Based on different physicochemical properties, common submucosal injection solutions could be classified into three categories: normal saline solution (NS), hypertonic solution (HS), and viscous solution (VS). We compared the efficacy and safety of various categories of solutions in this network meta-analysis of randomized controlled trials (RCTs) to identify the optimal submucosal injection fluid.

METHODS

PubMed, Embase, Web of Science, and the Cochrane Library were searched for RCTs that compared the efficacy and safety of NS, HS, and VS during endoscopic resection for gastrointestinal (GI) mucosal lesions. Pairwise and network analyses were conducted to determine the ranking of different fluids.

RESULTS

Thirteen RCTs were included in the final analysis with 1637 patients (1639 lesions). HS outperformed NS in rates of en bloc (pooled relative risk [RR] 1.50; 95% confidence interval [CI] 1.10-1.90), overall bleeding (pooled odds ratio [OR] 0.33; 95% CI 0.10-0.88; lesions >10 mm OR 4.65 × 10-2; 95% CI 1.10 × 10-3-0.46), and intraoperative bleeding (lesions >10 mm OR 7.10 × 10-6; 95% CI 4.30 × 10-18-0.26). HS showed the highest probability of ranking first in each outcome except for the volume of injection. Although VS was superior to NS in rates of en bloc, overall, and intraoperative bleeding in the lesions >10 mm subgroup, and required less fluid in pooled analysis, it ranked last in cost of submucosal injection solution.

CONCLUSIONS

Both HS and VS were superior to NS in comparisons of efficacy and safety. Considering the better performance and potentially low cost, HS might be an optimal choice during gastrointestinal endoscopic resection, especially for colorectal endoscopic mucosal resection.

Nanodrugs systems for therapy and diagnosis of esophageal cancer

With the increasing incidence of esophageal cancer, its diagnosis and treatment have become one of the key issues in medical research today. However, the current diagnostic and treatment methods face many unresolved issues, such as low accuracy of early diagnosis, painful treatment process for patients, and high recurrence rate after recovery. Therefore, new methods for the diagnosis and treatment of esophageal cancer need to be further explored, and the rapid development of nanomaterials has brought new ideas for solving this problem. Nanomaterials used as drugs or drug delivery systems possess several advantages, such as high drug capacity, adjustably specific targeting capability, and stable structure, which endow nanomaterials great application potential in cancer therapy. However, even though the nanomaterials have been widely used in cancer therapy, there are still few reviews on their application in esophageal cancer, and systematical overview and analysis are deficient. Herein, we overviewed the application of nanodrug systems in therapy and diagnosis of esophageal cancer and summarized some representative case of their application in diagnosis, chemotherapy, targeted drug, radiotherapy, immunity, surgery and new therapeutic method of esophageal cancer. In addition, the nanomaterials used for therapy of esophageal cancer complications, esophageal stenosis or obstruction and oesophagitis, are also listed here. Finally, the challenge and the future of nanomaterials used in cancer therapy were discussed.

Design and validation of performance-oriented injectable chitosan thermosensitive hydrogels for endoscopic submucosal dissection

Endoscopic submucosal dissection (ESD) is a challenging procedure. The use of biomaterials to improve the operator's convenience (operating affinity) has received little attention. We prepared two thermosensitive hydrogels, lactobionic acid-modified chitosan/chitosan/β-glycerophosphate thermosensitive hydrogel (hydrogel 1) and its lyophilized powders (hydrogel 2), characterized their physicochemical properties and evaluated their performance in ESD experiments on large animals, by comparing with the commonly used normal saline (NS) and glycerin fructose (GF). These hydrogels showed good low-temperature fluidity; their viscosities at 4 °C were 92.2 mPa.s and 26.9 mPa.s, respectively. The hydrogels provided significantly better viscoelastic properties than NS and GF. The relaxation moduli of hydrogels were higher than those of NS and GF when the strains were 1 %, 5 %, and 10 %. The hydrogels can be maintained for seven days, even at pH 1, after which they degrade entirely. In pig model experiments, we performed submucosal injection and ESD procedures in the stomach and esophagus. The cushion height produced by the hydrogels was higher than those of NS and GF 30 min after injection. The ESD operation time for hydrogels was significantly shorter. Postoperative wound observation and histological analysis showed that the hydrogels promoted wound healing. The two hydrogels differed in fluidity, viscoelasticity, and other properties, which makes it possible to select the hydrogels according to the size and location of the lesion during ESD operation, and hydrogel 2 may be more suitable for use in lengthier procedures. In general, the hydrogels showed good performance, facilitated the intraoperative operation of ESD, shorten the operation time and promoted wound healing, which is of great significance for reducing the complications and reducing the threshold of ESD operation and further promoting the popularity of ESD.

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.

A colonoscopic overtube system that creates a 'therapeutic zone' and permits retraction facilitates endoscopic submucosal dissection, was associated with fewer deep bowel wall injuries and instrument exchanges, and required less lifting solution vs classic endoscopic submucosal dissection in an ex vivo bovine model

INTRODUCTION

Endoscopic submucosal dissection (ESD) is the 'gold standard' for large flat polyps; nevertheless, the rate of adoption in the USA is low. In ESD, the polyp is 'surgically' detached with a needle knife after a submucosal lift; gravity and the dissection cap are used for retraction. ESD would be easier if active retraction were possible. In an ex vivo bovine colon model, this study assessed an overtube system (Boston Scientific ORISE Tissue Retraction System, TRS) that permits retraction and creates 'an operative field' for removal of rectal/sigmoid lesions.

METHOD

Classic ESD (C-ESD) was compared to TRS-facilitated ESD (TRS-ESD). Cleaned/preserved bovine large bowel was used, and two 2-cm 'lesions'/colon were branded onto the mucosal surface 25 and 35 cm from the anus. Submucosal saline lifts were made using a thin catheter and a standard needle knife. We tracked case length, number of instrument exchanges (to refresh lift), the volume of lift solution, the fullness of resection, and deep muscle injuries.

RESULTS

Fifty ESDs were carried out in 25 colons (25 C-ESD, 25 TRS-ESD). Complete resections were noted in all cases. The TRS method required fewer instrument exchanges (median 5) vs C-ESD (median 9, p < 0.0001) and less lift solution (median 39 ml) than the C-ESD cases (median 55 ml, p = 0.0003). TRS-ESD was associated with fewer deep muscle injuries (median 2) than C-ESD (median 3, p = 0.0191). Finally, the TRS group's median case length (34.5 min) was shorter than that of C-ESD (41 min, p = 0.0543).

CONCLUSION

The TRS system provides retraction and facilitates ESD regarding the number of lift injections, the volume of lift solution needed, and avoidance of muscle injuries. Of note, there is an apparent TRS learning curve, and the device mandates a distal-to-proximal approach and initial 360 degree mucosal incision. Further study is warranted.

Application of Hemocoagulase Bothrops Atrox in the submucosal injection for endoscopic submucosal dissection: a preliminary trial

OBJECTIVE

This study aimed to evaluate the efficacy and safety of using Hemocoagulase Bothrops Atrox in the submucosal injection solution for endoscopic submucosal dissection (ESD).

METHODS

A total of 120 patients with superficial neoplastic lesions of the esophagus, stomach, and colon receiving ESD were randomly divided into two groups: The epinephrine group used epinephrine-containing submucosal fluid cushion for ESD, while the hemocoagulase group used Hemocoagulase Bothrops Atrox-containing submucosal fluid cushion for ESD. The preoperative, intraoperative, and postoperative clinical parameters and postoperative adverse events of the two groups were recorded, and comparative analysis within and between groups was performed.

RESULTS

There was no significant difference in the demographic and clinical characteristics between the hemocoagulase and epinephrine group (all P > 0.05). ESD surgery was completed in all patients. The hemocoagulase group had significantly shorter surgery time (P = 0.003) and less number of intraoperative bleeding (P = 0.010) than the epinephrine group. However, there was no significant difference in the incidences of postoperative delayed hemorrhage, and adverse events between the two groups (all P > 0.05). Multivariate linear regression demonstrated that the epinephrine group had significantly more number of intraoperative bleeding (B: 0.98, 95% confidence interval: 0.04-1.93) as compared with the hemocoagulase group.

CONCLUSION

Compared with epinephrine, using Hemocoagulase Bothrops Atrox in the submucosal injection for ESD surgery can significantly reduce the number of intraoperative bleeding, shorten the operation time, and did not elevate the incidence of adverse events.

The feasibility of a fully synthetic and self-assembled peptide solution as submucosal injection material: a preliminary animal study

BACKGROUND AND AIM

An injection solution is required to create a submucosal cushion (SMC) for safe endoscopic resection procedures. The aim of this preliminary animal study was to clarify the safety and efficacy of a novel fully synthetic and self-assembled peptide (FSSP) solution as a submucosal injection material (SMIM).

METHOD

To compare the submucosal-lifting properties, 0.3% FSSP, Eleview®, sodium hyaluronate acid solution (SHA) and normal saline (NS) were randomly injected using an injection needle into the submucosa of exposed stomach and colon in five living dogs in a blind fashion. The mean height, and volume of SMCs were measured using a digital caliper immediately and 10, 20, 30, and 40 min after injecting each solution. All resected specimens were examined histopathologically.

RESULTS

In both the colon and stomach, ANOVA for repeated measures showed the significant interaction between time and solution for the time-dependent change in the height. In the colon, FSSP created significantly higher SMC than NS 20 min after injection (p = .0015) and Eleview® and NS 40 min after injection (p = .0009 and p = .0002). Furthermore, FSSP and SHA tended to maintain height and volume when compared to the other two solutions. In the stomach, FSSP and SHA tended to maintain height and volume when compared to the other two solutions. There were no significant differences between the histopathological finding and the injecting solutions used.

CONCLUSION

FSSP seems to be useful as a SMIM for endoscopic resection especially in the colon. Further studies are needed prior to clinical use of FSSP.

A Novel One-Step Knife Approach Can Reduce the Submucosal Injection Time of Endoscopic Submucosal Dissection: A Single-Blinded Randomized Multicenter Clinical Trials

BACKGROUND/AIMS

: Endoscopic submucosal dissection (ESD) is a curative treatment modality for early gastric neoplasms; however, ESD can be a time-consuming process. To overcome this pitfall, we developed the one-step knife (OSK) approach, which combines an endoscopic knife and injection needle on a single sheath. We aimed to evaluate whether this approach could reduce the ESD procedure time.

METHODS

This single-blinded randomized multicenter trial at four tertiary hospitals from June 2019 to June 2020 included patients aged 19 to 85 years undergoing ESD. Patients were randomly assigned to two groups (OSK or conventional knife [CK]). The injection time, total procedure time, resected specimen size, submucosal fluid amount, degree of device satisfaction, and adverse events were evaluated and compared between groups.

RESULTS

Fifty-one patients were analyzed (OSK: 25 patients and CK: 26 patients). No baseline differences were observed between groups, with the exception of a higher portion of males in the OSK group. The mean injection time was significantly reduced in the OSK group (39.0 seconds) compared to that in the CK group (87.5 seconds, p<0.001). A decrease of more than 10 minutes in the total procedure time (18.0 minutes vs 28.1 minutes, p=0.055) in the OSK group compared to the CK group was observed. Second-look esophagogastroduodenoscopy revealed two delayed bleeding cases in the OSK group that were easily controlled by endoscopic hemostasis.

CONCLUSIONS

OSK reduced the injection time and showed a decrease in total procedure time compared with the CK approach. OSK can be a feasible tool for ESD, especially in difficult cases.

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.

EMR/ESD: Techniques, Complications, and Evidence

PURPOSE OF REVIEW

To discuss endoscopic resection techniques of early gastrointestinal malignancy. The review will focus on the indications and outcomes of endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD).

RECENT FINDINGS

EMR is indicated for upper GI lesions less than 20 mm provided they can be easily lifted and have a low risk of submucosal invasion (SMI). ESD should be considered for esophageal and gastric lesions that are bulky, show intramucosal carcinoma, or have a risk of superficial submucosal invasion. With regard to colonic polyps, EMR is acceptable for the removal of large colonic polyps using a piecemeal technique. ESD can be reserved for rectal neuroendocrine tumors, fibrotic polyps, or polyps harboring early malignancy. In selected cases, particularly in lesions less than 2 cm in size, EMR can be safe and effective. For larger lesions or lesions with submucosal invasion, ESD is effective and curative. Choosing the best approach can be tailored for each patient depending on lesion size, pathology, and availability of local expertise.

Efficacy and Safety of a Novel Submucosal Injection Solution for Resection of Gastrointestinal Lesions

Endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) are minimally invasive and efficient techniques for the removal of gastrointestinal (GI) mucosal polyps. In both techniques, submucosal injection solutions are necessary for complete effectiveness and safety during the intervention to be obtained. The main objective of this study was to evaluate the efficacy and safety of a new sterile submucosal injection solution for EMR/ESD used within a clinical protocol in patients with intestinal polyps. We carried out a prospective study between 2016 and 2017 with patients who attended the Endoscopy Consultation—Digestive Department of Primary Hospital. Patients were selected for EMR/ESD after the application of clinical protocols. Thirty-six patients were selected (≥ 66 years with comorbidities and risk factors). Lesions were located mainly in the colon. Our solution presented an intestinal lift ≥ 60 min in EMR/ESD and a high expansion of tissue, optimum viscosity, and subsequent complete resorption. The genes S100A9 and TP53 presented an expression increase in the distal regions. TP53 and PCNA were the only genes whose expression was increased in polyp specimens vs. the surrounding tissue at the mRNA level. In EMR/ESD, our solution presented a prolonged effect at the intestinal level during all times of the intervention. Thus, our solution seems be an effective and safe alternative in cases of flat lesions in both techniques.

Histopathological Findings Related to ORISE™ Injectable Submucosa Lifting Agent Used in the Endoscopic Mucosal Resection of Bowel Neoplasms: A Review of Three Cases

The use of nonsaline injectable lifting agents is now routine in the performance of endoscopic mucosal resection of bowel neoplasms (EMR). These agents are used to elevate the mucosa from the muscularis propria and permit more a complete resection of the lesion while mitigating risk of possible thermal injury to the bowel wall and thus preventing perforation. After injection, these new agents, which are replacing normal saline, often remain present in the tissues for some time following the procedure and may be identified in the resection specimens where they may mimic a number of other conditions such as mucin pools, lymphangiomas, granulomatous inflammation, and amyloid deposition. We describe the histological findings associated with the use of nonsaline injectable mucosal lifting agents. Awareness of these agents and their associated artefact may reduce misdiagnosis or the use of unnecessary ancillary studies and highlights the importance of proving relevant clinical information on submission of specimens for pathological examination.

Endoscopic submucosal dissection: an update on tools and accessories

Endoscopic submucosal dissection (ESD) is a minimally invasive therapeutic procedure to remove larger polyps or early non-metastatic lesions. It has long been used in Asia, but is now fast growing in popularity in the West. There are multiple challenges faced by ESD practitioners. While the practice of ESD in gastric lesions is relatively well established, the oesophagus with its narrow lumen and challenging workspace, and the colon with its tortuous course and folds are more challenging frontiers. The nature of performing a procedure endoscopically means that conventional methods offer no mechanism for providing counter-traction while performing dissection, impeding visibility and increasing the rate of complications. There are a multitude of tools available to those performing ESD for the different stages of the procedure. This article reviews the accessories currently used in regular ESD practice including the knives used to cut and dissect lesions, the cap and hood devices used to improve visibility and safety, injection fluids to lift the submucosal plane, haemostatic devices, generators, and finally, emerging traction apparatus. There is some evidence behind the use of these tools, however, ESD remains the domain of a small number of practitioners and the practice relies heavily on expert experience. Evolution of the ESD toolbox will make the procedure more accessible to more endoscopists, which in turn will drive the development of a more substantial evidence base to evaluate efficacy and safety of the multitude of tools.

Endoscopically Injectable Shear-Thinning Hydrogels Facilitating Polyp Removal

Submucosal elevation, the process of instilling material in the submucosal space for separation of the surface mucosa and deeper muscularis layer, is a significant aspect of the endoscopic mucosal resection of large lesions performed to facilitate lesion removal and maximize safety. Submucosal injection, when applied, has historically been performed with normal saline, though this is limited by its rapid dissipation; solutions ideally need to be easily injectable, biocompatible, and provide a long-lasting submucosal cushion with a desirable height. Here, reported is a new set of materials, endoscopically injectable shear-thinning hydrogels, meeting these requirements because of their biocompatible components and ability to form a solid hydrogel upon injection. These findings are supported by evaluation in a large animal model and ultimately demonstrate the potential of these shear-thinning hydrogels to serve as efficient submucosal injection fluids for cushion development. Given these unique characteristics, their broad application in mucosal resection techniques is anticipated.

Design of Nanocomposite Injectable Hydrogels for Minimally Invasive Surgery

Biocompatible hydrogels are materials that hold great promise in medicine and biology since the porous structure, the ability to entrap a large amount of water, and the tunability of their mechanical and tissue adhesive properties make them suitable for several applications, including wound healing, drug and cell delivery, cancer treatment, bioelectronics, and tissue regeneration. Among the possible developed systems, injectable hydrogels, owing to their properties, are optimal candidates for in vivo minimally invasive procedures. To be injectable, a hydrogel must be liquid before and during the injection, but it must quickly jellify after injection to form a soft, self-standing, solid material. The possibility to work with a liquid precursor encoding the functions that will be available after gelation allows the development of biocompatible materials that can be employed in surgery and, in particular, in noninvasive procedures. The underlying idea is to reach the target tissue by using just a needle, or by exploiting the natural body orifices, reducing surgery procedure time, induced pain, and risk of infections. Hydrogels with different properties can be obtained by changing the type of cross-linking, the cross-linking density or the molecular weight of the polymer, or by introducing pending functional groups. The introduction of a nanofiller in the hydrogel network allows for expanding the suite of the structural and functional properties and for better mimicking native tissues. In this Account, we discuss how to provide a hydrogel network with designed properties by playing with both the polymeric chains and the fillers. We present selected examples from the literature that show how to introduce stiffness, stretchability, adhesiveness, self-healing, anisotropy, antimicrobial activity, biodegradability, and conductivity in injectable hydrogels. We further describe how the chemical composition, the mechanical properties, and the microarchitecture of the hydrogel influence cell adhesion, proliferation, and differentiation. Examples of injectable hydrogels for innovative minimally invasive procedures are then discussed in detail; in particular, we showcase the use of hydrogels for tumor resection and as vascular chemoembolization agents. We further discuss how one can improve the rheological properties of injectable hydrogels to exploit them in osteochondral tissue engineering. The effect of the introduction of a conductive filler is then presented in relation to the development of electroactive scaffolds for cardiac-tissue engineering and neural and nerve repair. We believe that the rational design of biocompatible, injectable hybrid hydrogels with tunable properties will likely play a crucial role in reducing the invasiveness and improving the outcome of several clinical and surgical setups.

Solutions for submucosal injection: What to choose and how to do it

During the past decades, endoscopic resection techniques have gradually improved and gained more importance for the management of premalignant lesions and early cancers. These endoscopic resection techniques can be divided in 3 major groups: snare polipectomy, endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD). The use of submucosal injection is essential for the majority of EMR techniques and is an integral part of ESD, whereas during polipectomy it is not crucial in most cases except to prevent bleeding in large polyps and/or those with large stalks as an alternative to mechanical methods. Injection provides a lifting up effect of the lesion separating it from the muscular layer, thereby reducing thermal injury and the risk of perforation and bleeding while also facilitating en-bloc resection by improving technical feasibility. With this work, we aim to review the most common endoscopic resection techniques and the importance of submucosal injection in each one of them. For that, we present some of the most commonly used submucosal injection solutions, taking into account their advantages and disadvantages. We also discuss, based on current recommendations and our own experience, how and when to preform submucosal injection, depending on lesions features and endoscopic resection technique that´s being used, to assure complete resection and to prevent associated adverse events. Finally, we also present and discuss some new proposed submucosal injection solutions, endoscopic resection techniques and devices that may have a major impact on the future of therapeutic endoscopy.

Optimal injection solution for endoscopic submucosal dissection: A randomized controlled trial of Western solutions in a porcine model

BACKGROUND AND AIM

When carrying out endoscopic submucosal dissection (ESD), procedural safety increases with greater tissue elevation and efficiency increases with longer-lasting submucosal cushion. Fluids specifically developed for ESD in Asia are not commercially available in the West, leaving endoscopists to use a variety of injectable fluids off-label. To determine the optimal fluid available in the West, we compared commonly used fluids for Western ESD.

METHODS

All phases were carried out in an ex vivo porcine stomach model. Phase 1 compared tissue elevation and duration of submucosal cushions produced by various standard volumes of various injectable solutions used for ESD. The two best-performing solutions used off-label were tested head-to-head in ESD in Phase 2. Phase 3 compared the best solution from Phase 2 to Eleview^® , currently the only submucosal injection fluid approved in the USA. In Phases 2 and 3, five ESD were carried out with each solution. The solutions were randomized and the endoscopist blinded to the solution.

RESULTS

The best-performing solutions in Phase 1 were 0.4% hyaluronic acid, 6% hydroxyethyl starch (HES), and Eleview^® . Phase 2 compared 6% HES and hydroxypropyl methylcellulose (HPMC), showing that ESD with 6% HES was easier (P = 0.007), faster (P = 0.041) and required less injection volume (P = 0.003). In Phase 3, resection speed, ease of ESD and total volume per area resected were comparable between 6% HES and Eleview^® .

CONCLUSIONS

Of the submucosal injection fluids currently available in the West, Eleview^® and 6% HES are the best-performing solutions for ESD in a porcine model.

A feasibility study of a thermally sensitive elastin-like polypeptide for submucosal injection application in endoscopic resection in 3 animal models

BACKGROUND AND AIMS

Endoscopic submucosal dissection (ESD) can successfully resect large lesions en bloc by using a submucosal injection solution, but the cost of currently available submucosal injection solutions is not satisfactory. The authors' aim was to evaluate the feasibility and effectiveness of a thermally sensitive elastin-like polypeptide (ELP) used as submucosal injection solution in ESD.

METHODS

We conducted an ex vivo study to determine the optimal concentration of ELPs in rabbits, an in vivo study to evaluate the effectiveness of mucosal elevation in rats, and a large animal study to confirm the feasibility of preclinical application by using conventional clinical procedure in pigs.

RESULTS

ELP (500 μM) was proved to be the optimal injectable submucosal injection solution and elevated mucosa more efficiently than any control. The same concentration of ELP exhibited an equivalent effectiveness of mucosal elevation, the retention of the elevation, and minimal bleeding with sodium hyaluronate. The ESD procedure time with 500 μM ELP in a preclinical study with pigs was significantly shorter than with any other concentration of ELP and normal saline solution.

CONCLUSIONS

Use of ELP as submucosal injection solution was feasible, with higher and longer-lasting elevation and fewer adverse events.

[Aseptic process validation and stability study of an injectable preparation of fructose (5%)-glycerol (10%) as part of a hospital clinical research program on endoscopic curative treatment for early epithelial neoplastic lesions of the gastrointestinal tract]

INTRODUCTION

As part of a hospital clinical research program on endoscopic curative treatment for early epithelial neoplastic lesions of the gastrointestinal tract, a new hospital sterile and non-pyrogenic preparation of fructose (5%)-glycerol (10%) was realized. Under pharmaceutical legislation, the provision of this hospital preparation involves of aseptic process validation and achieve a stability study.

MATERIALS AND METHODS

After the aseptic process validation with Mediafill Test, the preparation was made under aseptic conditions associated with a sterilizing filtration according to the good practices preparation. Prepared flexible bags (100mL of solution) were stored for one year in a climatic chamber (25±2°C). To assess stability, the physicochemical controls (fructose concentration, glycerol concentration, hydroxy-methyl-5 furfural [5-HMF] concentration, sodium concentration, pH measure, osmolality and sub-visible particles count) and microbiological (bioburden, bacterial endotoxin and sterility) were performed at regular intervals for one year.

RESULTS

Neither significant decrease of fructose concentration, glycerol concentration and sodium concentration nor pH, 5-HMF, osmolality variations out of specifications were observed for one year. The sub-visible particles count, the bacterial endotoxin and sterility were in accordance with the European pharmacopoeia attesting limpidity, apyrogenicity and sterility of this injectable preparation.

DISCUSSION AND CONCLUSION

The hospital preparation was stable over one year at 25±2°C, ensuring safe administration in humans within the framework of this clinical research.