A novel tetra-PEG based hydrogel for prevention of esophageal stricture after ESD in a porcine model

Advances in natural polysaccharide/protein-based bioadhesive formulations for the potential application in esophagus: A review

The esophagus is susceptible to various injuries or disorders, which can significantly impact quality of life and pose potentially life-threatening risks. The unique anatomical and physiological characteristics of the esophagus present challenges in achieving optimal bioavailability and efficacy during diagnosis and treatment. To address these challenges, polysaccharide- and protein-based bioadhesive formulations have been developed to adhere to esophageal tissue, thereby prolonging residence time and enhancing diagnostic accuracy and therapeutic outcomes. Natural polysaccharides and proteins have garnered attention in the medical field owing to their exceptional properties, including biocompatibility, bioavailability, biodegradability, and low toxicity. A substantial body of research has demonstrated the significant potential of polysaccharides and proteins in clinical applications for the esophagus. The objective of this review is to discuss the structural characteristics and biological activities of various polysaccharides, including chitosan, hyaluronic acid, alginate, cellulose, guar gum, gellan gum, and xanthan gum, as well as proteins such as gelatin and fibrin, and their utilization in esophageal bioadhesive formulations. The practical challenges and prospects associated with implementing polysaccharide and protein-based bioadhesives on the esophagus are also discussed.

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 theranostic hydrogels for targeted gastrointestinal cancer treatment

Gastrointestinal tumors are the main causes of death among the patients. These tumors are mainly diagnosed in the advanced stages and their response to therapy is unfavorable. In spite of the development of conventional therapeutics including surgery, chemotherapy, radiotherapy and immunotherapy, the treatment of these tumors is still challenging. As a result, the new therapeutics based on (nano)biotechnology have been introduced. Hydrogels are polymeric 3D networks capable of absorbing water to swell with favorable biocompatibility. In spite of application of hydrogels in the treatment of different human diseases, their wide application in cancer therapy has been improved because of their potential in drug and gene delivery, boosting chemotherapy and immunotherapy as well as development of vaccines. The current review focuses on the role of hydrogels in the treatment of gastrointestinal tumors. Hydrogels provide delivery of drugs (both natural or synthetic compounds and their co-delivery) along with gene delivery. Along with delivery, hydrogels stimulate phototherapy (photothermal and photodynamic therapy) in the suppression of these tumors. Besides, the ability of hydrogels for the induction of immune-related cells such as dendritic cells can boost cancer immunotherapy. For more specific cancer therapy, the stimuli-responsive types of hydrogels including thermo- and pH-sensitive hydrogels along with their self-healing ability have improved the site specific drug delivery. Moreover, hydrogels are promising for diagnosis, circulating tumor cell isolation and detection of biomarkers in the gastrointestinal tumors, highlighting their importance in clinic. Hence, hydrogels are diagnostic and therapeutic tools for the gastrointestimal tumors.

Strategies for Preventing Esophageal Stenosis After Endoscopic Submucosal Dissection and Progress in Stem Cell-Based Therapies

Endoscopic submucosal dissection (ESD) has been widely used in the early neoplasia of the esophagus. However, postoperative esophageal stenosis is a big problem, particularly when a large circumferential proportion of esophageal mucosa is resected. Currently, there are several methods available to prevent esophageal stenosis after ESD, including steroid administration, esophageal stent implantation, and endoscopic balloon dilation (EBD). However, the therapeutic effects of these are not yet satisfactory. Stem cell-based therapies has shown promising potential in reconstructing tissue structure and restoring tissue function. In this study, we discussed the current strategies for preventing esophageal stenosis after ESD and perspectives of stem cell-based therapies for the prevention of esophageal stenosis.

Optimizing a self-solidifying hydrogel as an endoscopically deliverable hydrogel coating system: a proof-of-concept study on porcine endoscopic submucosal dissection-induced ulcers

Endoscopic submucosal dissection (ESD) benefits patients in the early stages of cancer, but it poses various risks of complication. Strategies involving the application of clinically approved products to cover ulcers caused by ESD can reduce these complications, but the fixed nature of their properties limit the understanding of their effects on ulcer healing. This study was focused on Tetra–PEG gel, an innovative hydrogel with controllable physical properties made from a sulfhydryl–maleimide pair. The use of biocompatible polyethylene glycol (PEG) in Tetra–PEG gel may allow for its application as a biomaterial. The aims of our study were to identify the characteristics of a self-solidifying hydrogel for endoscopic application and to develop a new ulcer coating agent for post-ESD treatment. We developed a specialized double-lumen catheter and determined the optimal application conditions of the hydrogel. We examined the hydrodynamic properties of the gelling solutions and elucidated the pressure drop that occurred during device operation. Finally, by considering previous experimental results, we successfully applied the hydrogel to post-ESD ulcers in porcine stomachs. We believed that by further optimizing hydrogels with effectively controlled properties and by continuing to investigate them through animal experiments, we could expand our understanding of the relationships among material and ulcer healing properties and apply this knowledge to clinical applications.

Progress in the treatment and prevention of esophageal stenosis after endoscopic submucosal dissection

The primary treatment for early esophageal cancer and precancerous lesions is endoscopic submucosal dissection (ESD). However, this approach leads to a high incidence of postoperative esophageal stenosis, which can significantly impact a patient's quality of life. While various methods are available to prevent post-ESD esophageal stenosis, their effectiveness varies. Therefore, this study aims to provide an overview of the currently employed methods for preventing post-ESD esophageal stenosis in clinical practice in view of assisting clinical practitioners.

Bilayer wound dressing composed of asymmetric polycaprolactone membrane and chitosan-carrageenan hydrogel incorporating storax balsam

A comprehensive approach is needed to develop multifunctional wound dressing that is simple yet efficient. In this work, Liquidambar orientalis Mill. storax loaded hydroxyethyl chitosan (HECS)-carrageenan (kC) based hydrogel (HECS-kC) and polydopamine coated asymmetric polycaprolactone membrane (PCL-DOP) were used to develop a multifunctional and modular bilayer wound dressing. Asymmetric PCL-DOP membrane was prepared by non-solvent induced phase separation (NIPS) followed by polydopamine coating and demonstrated an excellent barrier against bacteria while allowing permeability for 5.45 ppm dissolved‑oxygen and 2130 g/m2 water vapor transmission in 24 h in addition to 805 kPa tensile strength. Storax loaded HECS-kC hydrogel, on the other hand, demonstrated a pH-responsive degradation and swelling to provide necessary conditions to facilitate wound healing. The hydrogels showed stretchability above 140 %, mild adhesive strength on sheep skin and PCL-DOP membrane, while the storax incorporation enhanced antibacterial and antioxidant activity. Furthermore, rat full-thickness skin defect model showed that the developed bilayer wound dressing could significantly facilitate wound healing compared to Tegaderm™ and control groups. This study shows that the bilayered wound dressing has the potential to be used as a simple and effective wound care system.