An extracellular matrix scaffold for esophageal stricture prevention after circumferential EMR

The Extracellular Matrix: Its Composition, Function, Remodeling, and Role in Tumorigenesis

The extracellular matrix (ECM) is a ubiquitous member of the body and is key to the maintenance of tissue and organ integrity. Initially thought to be a bystander in many cellular processes, the extracellular matrix has been shown to have diverse components that regulate and activate many cellular processes and ultimately influence cell phenotype. Importantly, the ECM's composition, architecture, and stiffness/elasticity influence cellular phenotypes. Under normal conditions and during development, the synthesized ECM constantly undergoes degradation and remodeling processes via the action of matrix proteases that maintain tissue homeostasis. In many pathological conditions including fibrosis and cancer, ECM synthesis, remodeling, and degradation is dysregulated, causing its integrity to be altered. Both physical and chemical cues from the ECM are sensed via receptors including integrins and play key roles in driving cellular proliferation and differentiation and in the progression of various diseases such as cancers. Advances in 'omics' technologies have seen an increase in studies focusing on bidirectional cell-matrix interactions, and here, we highlight the emerging knowledge on the role played by the ECM during normal development and in pathological conditions. This review summarizes current ECM-targeted therapies that can modify ECM tumors to overcome drug resistance and better cancer treatment.

Endoscopic Submucosal Dissection for Esophageal Cancer: Current and Future

Endoscopic submucosal dissection (ESD) has been widely used to treat superficial esophageal cancer. The advantages of esophageal ESD include a high en bloc resection rate and accurate pathological diagnosis. It enables local resection of the primary tumor and accurate identification of the risk factors for lymph node metastasis, including depth, vascular invasion, and types of invasion. Even in cases with clinical T1b-SM cancer, ESD and additional treatment can achieve radical cure, depending on the risk of lymph node metastasis. Esophageal ESD will be increasingly vital in minimally invasive and effective esophageal cancer treatment. This article describes the current status and prospects of esophageal ESD.

Tissue Engineering for Gastrointestinal and Genitourinary Tracts

The gastrointestinal and genitourinary tracts share several similarities. Primarily, these tissues are composed of hollow structures lined by an epithelium through which materials need to flow with the help of peristalsis brought by muscle contraction. In the case of the gastrointestinal tract, solid or liquid food must circulate to be digested and absorbed and the waste products eliminated. In the case of the urinary tract, the urine produced by the kidneys must flow to the bladder, where it is stored until its elimination from the body. Finally, in the case of the vagina, it must allow the evacuation of blood during menstruation, accommodate the male sexual organ during coitus, and is the natural way to birth a child. The present review describes the anatomy, pathologies, and treatments of such organs, emphasizing tissue engineering strategies.

A Comparative Assessment of the Diagnosis of Swallowing Impairment and Gastroesophageal Reflux in Canines and Humans

Swallowing impairment is a highly prevalent and clinically significant problem affecting people and dogs. There are myriad causes of swallowing impairment of which gastroesophageal reflux is the most common in both species. Similarities in anatomy and physiology between humans and canines results in analogous swallowing disorders including cricopharyngeus muscle achalasia, esophageal achalasia, hiatal herniation, and gastroesophageal reflux with secondary esophagitis and esophageal dysmotility. Accordingly, the diagnostic approach to human and canine patients with swallowing impairment is similar. Diagnostic procedures such as swallowing fluoroscopy, high-resolution manometry, pH/impedance monitoring, and endolumenal functional luminal imaging probe can be performed in both species; however, nasofacial conformation, increased esophageal length, and the difficulty of completing several of these procedures in awake dogs are inherent challenges that need to be considered. Human patients can convey their symptoms and respond to verbal cues, whereas veterinarians must rely on clinical histories narrated by pet owners followed by comprehensive physical examination and observation of the animal eating different food consistencies and drinking water. Dogs may also be unwilling to drink or eat in the hospital setting and may be resistant to physical restraint during diagnostic procedures. Despite the species differences and diagnostic challenges, dogs are a natural animal model for many oropharyngeal and esophageal disorders affecting people, which presents a tremendous opportunity for shared learnings. This manuscript reviews the comparative aspects of esophageal anatomy and physiology between humans and canines, summarizes the diagnostic assessment of swallowing impairment in both species, and discusses future considerations for collaborative medicine and translational research.

Phase II Trial Evaluating Esophageal Anastomotic Reinforcement with a Biologic, Degradable, Extracellular Matrix after Total Gastrectomy and Esophagectomy

BACKGROUND

A biologic, degradable extracellular matrix (ECM) has been shown to support esophageal tissue remodeling, which could reduce the risk of anastomotic leak following total gastrectomy and esophagectomy. We evaluated the safety and efficacy of reinforcing the anastomosis with ECM in reducing anastomotic leak as compared to a matched cohort.

STUDY DESIGN

In this single-center, nonrandomized phase II trial, gastric or esophageal adenocarcinoma patients undergoing total gastrectomy or esophagectomy were recruited from November 2013 through December 2018. ECM was surgically wrapped circumferentially around the anastomosis. Anastomotic leak was assessed clinically and by contrast study and defined as clinically significant if requiring invasive treatment (grade 3 or higher). Anastomotic stenosis, other adverse events, symptoms, and dysphagia score were collected by standardized forms at regular follow-up visits at approximately postoperative days (POD) 21 and 90. Patients receiving ECM were compared to a cohort matched for surgery type and age.

RESULTS

ECM placement was not feasible in 9 of 75 patients (12%), resulting in 66 patients receiving ECM. Total gastrectomy was performed in 50 patients (76%) and esophagectomy in 16 (24%). Clinically significant anastomotic leak was diagnosed in 6 of 66 patients (9.1%) (3/50 [6.0%] after gastrectomy, 3/16 [18.8%] after esophagectomy); this rate did not differ from that in the matched cohort (p = 0.57). Stenosis requiring invasive treatment occurred in 8 patients (12.5%), and 10 patients (15.6%) reported not being able to eat a normal diet at POD 90. No adverse events related to ECM were reported.

CONCLUSIONS

Esophageal anastomotic reinforcement after total gastrectomy or esophagectomy with a biologic, degradable ECM was mostly feasible and safe, but was not associated with a statistically significant decrease in anastomotic leak.

Advances in the application of regenerative medicine in prevention of post-endoscopic submucosal dissection for esophageal stenosis

Endoscopic submucosal dissection (ESD) is a curative treatment for superficial esophageal cancer with distinct advantages. However, esophageal stenosis after ESD remains a tough problem, especially after large circumferential proportion of esophageal mucosa is removed, which limits the wide use of ESD, especially in circumferential lesions. In this scenario, preventive procedures are highly recommended against post-ESD esophageal stenosis. However, the efficacy and safety of traditional prophylactic methods (steroids, metal and biodegradable stents, balloon dilation, radial incision, etc.) are not satisfactory and novel strategies need to be developed. Regenerative medicine has been showing enormous potential in the reconstruction of organs including the esophagus. In this review, we aimed to describe the current status of regenerative medicine in prevention of post-ESD esophageal stenosis. Cell injection, cell sheet transplantation, and extracellular matrix implantation have been proved effective. However, numerous obstacles still exist and further studies are necessary.

Effects of Different Anesthetic and Analgesic Methods on Cellular Immune Function and Stress Hormone Levels in Patients Undergoing Esophageal Cancer Surgery

The change of perioperative immune function in patients with esophageal cancer is mainly caused by the joint action of surgical trauma and anesthesia. In our study, we aimed to investigate the effects of different anesthetic methods on the changes of T lymphocyte subsets and cytokines in peripheral blood of patients with esophageal cancer surgery. 50 patients with esophageal cancer were divided into the study group and the control group. Among them, the patients in the control group chose intravenous anesthesia and received self-controlled intravenous analgesia after surgery. Patients in the study group chose thoracic epidural anesthesia combined with general anesthesia, undergoing self-controlled epidural analgesia after surgery; serum interleukin-2 (IL-2) and soluble interleukin-2 receptor (sIL-2R) were measured by ELISA. Serum stress hormones GH and sIL-8 were measured by radioimmunoassay. Both groups of patients achieved significant postoperative analgesia, but the VAS score in the study group at the T2-T4 time point was lower than that in the control group. The serum GH concentration in the study group increased at T1 and reached its highest peak at T2, then decreased. The serum IL-8 concentration of the two groups showed a downward trend from T1 to T4. Thoracic epidural anesthesia combined with general anesthesia for postoperative epidural analgesia can relieve the degree of cellular immunosuppression during and after surgery. Moreover, the thoracic epidural block combined with general anesthesia for esophageal cancer surgery and epidural analgesia after surgery for patients are anesthetic and analgesic methods with clinically significant effects. Our research results have a positive effect on the promotion of postoperative rehabilitation in patients with malignant cell tumors.

Recent Advances of Biomedical Materials for Prevention of Post-ESD Esophageal Stricture

Esophageal stricture commonly occurs in patients that have suffered from endoscopic submucosal dissection (ESD), and it makes swallowing difficult for patients, significantly reducing their life qualities. So far, the prevention strategies applied in clinical practice for post-ESD esophageal stricture usually bring various inevitable complications, which drastically counteract their effectiveness. Nowadays, with the widespread investigation and application of biomedical materials, lots of novel approaches have been devised in terms of the prevention of esophageal stricture. Biomedical polymers and biomedical-derived materials are the most used biomedical materials to prevent esophageal stricture after ESD. Both of biomedical polymers and biomedical-derived materials possess great physicochemical properties such as biocompatibility and biodegradability. Moreover, some biomedical polymers can be used as scaffolds to promote cell growth, and biomedical-derived materials have biological functions similar to natural organisms, so they are important in tissue engineering. In this review, we have summarized the current approaches for preventing esophageal stricture and put emphasis on the discussion of the roles biomedical polymers and biomedical-derived materials acted in esophageal stricture prevention. Meanwhile, we proposed several potential methods that may be highly rational and feasible in esophageal stricture prevention based on other researches associated with biomedical materials. This review is expected to offer a significant inspiration from biomedical materials to explore more effective, safer, and more economical strategies to manage post-ESD esophageal stricture.

Esophageal defect repair by artificial scaffolds: a systematic review of experimental studies and proportional meta-analysis

BACKGROUND

The traditional technique of gastrointestinal reconstruction of the esophagus after esophagectomy presents plenty of complications. Hence, tissue engineering has been introduced as an effective artificial alternative with potentially fewer complications. Three types of esophageal scaffolds have been used in experimental studies so far. The aim of our meta-analysis is to present the postoperative outcomes after esophageal replacement with artificial scaffolds and the investigation of possible factors that affect these outcomes.

METHODS

The present proportional meta-analysis was designed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses and A MeaSurement Tool to Assess systematic Reviews guidelines. We searched Medline, Scopus, Clinicaltrials.gov, EMBASE, Cochrane Central Register of Controlled Trials CENTRAL, and Google Scholar databases from inception until February 2020.

RESULTS

Overall, 32 studies were included that recruited 587 animals. The pooled morbidity after esophageal scaffold implantation was 53.4% (95% CI = 36.6-70.0%). The pooled survival interval was 111.1 days (95% CI = 65.5-156.8 days). Graft stenosis (46%), postoperative dysphagia (15%), and anastomotic leak (12%) were the most common complications after esophageal scaffold implantation. Animals that underwent an implantation of an artificial scaffold in the thoracic part of their esophagus presented higher survival rates than animals that underwent scaffold implantation in the cervical or abdominal part of their esophagus (P < 0.001 and P = 0.011, respectively).

CONCLUSION

Tissue engineering seems to offer an effective alternative for the repair of esophageal defects in animal models. Nevertheless, issues like graft stenosis and lack of motility of the esophageal scaffolds need to be addressed in future experimental studies before scaffolds can be tested in human trials.

Human Bronchial Epithelial Cell Growth on Homologous Versus Heterologous Tissue Extracellular Matrix

BACKGROUND

Extracellular matrix (ECM) bioscaffolds produced by decellularization of source tissue have been effectively used for numerous clinical applications. However, decellularized tracheal constructs have been unsuccessful due to the immediate requirement of a functional airway epithelium on surgical implantation. ECM can be solubilized to form hydrogels that have been shown to support growth of many different cell types. The purpose of the present study is to compare the ability of airway epithelial cells to attach, form a confluent monolayer, and differentiate on homologous (trachea) and heterologous (urinary bladder) ECM substrates for potential application in full tracheal replacement.

MATERIALS AND METHODS

Porcine tracheas and urinary bladders were decellularized. Human bronchial epithelial cells (HBECs) were cultured under differentiation conditions on acellular tracheal ECM and urinary bladder matrix (UBM) bioscaffolds and hydrogels and were assessed by histology and immunolabeling for markers of ciliation, goblet cell formation, and basement membrane deposition.

RESULTS

Both trachea and urinary bladder tissues were successfully decellularized. HBEC formed a confluent layer on both trachea and UBM scaffolds and on hydrogels created from these bioscaffolds. Cells grown on tracheal and UBM hydrogels, but not on bioscaffolds, showed positive-acetylated tubulin staining and the presence of mucus-producing goblet cells. Collagen IV immunolabeling showed basement membrane deposition by these cells on the surface of the hydrogels.

CONCLUSIONS

ECM hydrogels supported growth and differentiation of HBEC better than decellularized ECM bioscaffolds and show potential utility as substrates for promotion of a mature respiratory epithelium for regenerative medicine applications in the trachea.

Progress of esophageal stricture prevention after endoscopic submucosal dissection by regenerative medicine and tissue engineering

Endoscopic submucosal dissection (ESD) has been widely accepted as an effective treatment for early esophageal cancer. However, post-ESD esophageal stricture remains a thorny issue. We herein review many strategies for preventing post-ESD esophageal stricture, as well as discuss their strengths and weaknesses. These strategies include pharmacological prophylaxis, esophageal stent and tissue engineering and regenerative medicine treatment. In this review, we summarize these studies and discuss the underlying progress and future directions of tissue engineering and regenerative medicine treatment.

Efficacy of oral steroid gel in preventing esophageal stricture after extensive endoscopic submucosal dissection: a randomized controlled trial

BACKGROUND AND AIMS

Esophageal stricture is a distressing issue for patients with early esophageal cancer following extensive endoscopic submucosal dissection (ESD), and the current steroid-based approaches are unsatisfactory for stricture prophylaxis. We evaluated the efficacy of oral hydrocortisone sodium succinate and aluminum phosphate gel (OHA) for stricture prophylaxis after extensive ESD.

METHODS

Patients undergoing > 3/4 circumferential ESD were randomized to either the endoscopic loco-regional triamcinolone acetonide injection (ETI) plus oral prednisone group or the OHA group. The primary endpoint was incidence of esophageal stricture, and the secondary endpoints included adverse events (AEs) and endoscopic balloon dilations (EBDs).

RESULTS

The incidence of esophageal stricture in OHA group (per-protocol analysis, 9.4%, 3/32; intention-to-treat analysis, 12.1%, 4/33) was significantly less than that of control group (per-protocol analysis, 35.5%, 11/31, P = 0.013; intention-to-treat analysis, 39.4%, 13/33, P = 0.011). Two sessions of EBD were necessary to release all strictures in the OHA group, while the similar EBDs (median 2, range 1-4) for 11 of the control. Operation-related AEs included infection (control vs. OHA group = 9.7% vs. 31.3%, P = 0.034), operation-related hypokalemia (19.4% vs. 31.3%, P = 0.278), perforation (3.2% vs. 3.1%), post-ESD hemorrhage (6.5% vs. 0%), and cardiac arrhythmia (0% vs. 6.3%). Steroid-related AEs included steroid-related hypokalemia (16.1% vs. 25%) and bone fracture (3.2% vs. 0%). Multivariate logistic regression analysis demonstrated that OHA was an independent protective factor for stricture (OR 0.079; 95%CI 0.011, 0.544; P = 0.01) and mucosal defect > 11/12 circumference was an independent risk factor (OR 49.91; 95%CI 6.7, 371.83; P < 0.001).

CONCLUSIONS

OHA showed significantly better efficacy in preventing esophageal stricture after > 3/4 circumferential ESD compared to ETI plus oral prednisone.

Prevention of Stricture after Endoscopic Submucosal Dissection for Superficial Esophageal Cancer: A Review of the Literature

Endoscopic resection has been the standard treatment for intramucosal esophageal cancers (ECs) because of the low risk of lymph node metastases in the lesions. In recent years, endoscopic submucosal dissection (ESD), which can resect large ECs, has been performed. However, the risk of esophageal stricture after ESD is high when the mucosal defect caused by the treatment exceeds 3/4 of the circumference of the lumen. Despite the subsequent high risk of luminal stricture, ESD has been performed even in cases of circumferential EC. In such cases, it is necessary to take measures to prevent stricture. Therefore, in this review, we aimed to clarify the current status of stricture prevention methods after esophageal ESD based on previous literature. Although various prophylactic methods have been reported to have stricture-preventing effects, steroid injection therapy and oral steroid administration are mainstream. However, in cases of circumferential EC, both steroid injection therapy and oral steroid administration cannot effectively prevent luminal stricture. To solve this issue, clinical applications, such as tissue shielding methods with polyglycolic acid sheet, autologous oral mucosal epithelial sheet transplantation, and stent placement, have been developed. However, effective prophylaxis of post-ESD mucosal defects of the esophagus is still unclear. Therefore, further studies in this research field are needed.

Regenerative medicine for the upper gastrointestinal tract

The main surgical strategy for gastrointestinal tract malignancy is en bloc resection, which consists of not only resection of the involved organs but also simultaneous resection of the surrounding or adjacent mesenteries that contain lymph vessels and nodes. After resection of the diseased organs, the defect of the gastrointestinal conduit is replaced with organs located downstream, such as the stomach and jejunum. However, esophageal and gastric reconstruction using these natural substitutes is associated with a diminished quality of life due to the loss of the reserve function, damage to the antireflux barrier, and dumping syndrome. Thus, replacement of the deficit after resection with the patient's own regenerated tissue to compensate for the lost function and tissue using regenerative medicine will be an ideal treatment. Many researchers have been trying to construct artificial organs through tissue engineering techniques; however, none have yet succeeded in growing a whole organ because of the complicated functions these organs perform, such as the processing and absorption of nutrients. While exciting results have been reported with regard to tissue engineering techniques concerning the upper gastrointestinal tract, such as the esophagus and stomach, most of these achievements have been observed in animal models, and few successful approaches in the clinical setting have been reported for the replacement of mucosal defects. We review the recent progress in regenerative medicine in relation to the upper gastrointestinal tract, such as the esophagus and stomach. We also focus on the functional capacity of regenerated tissue and its role as a culture system to recapitulate the mechanisms underlying infectious disease. With the emergence of technology such as the fabrication of decellularized constructs, organoids and cell sheet medicine, collaboration between gastrointestinal surgery and regenerative medicine is expected to help establish novel therapeutic modalities in the future.

Advances in the Prevention and Treatment of Esophageal Stricture after Endoscopic Submucosal Dissection of Early Esophageal Cancer

Endoscopic submucosal dissection (ESD) has become the main treatment for early esophageal cancer. While treating the disease, ESD may also cause postoperative esophageal stricture, which is a global issue that needs resolution. Various methods have been applied to resolve the problem, such as mechanical dilatation, glucocorticoids, anti-scarring drugs, and regenerative medicine; however, no standard treatment regimen exists. This article describes and evaluates the strengths and limitations of new and promising potential strategies for the treatment and prevention of esophageal strictures.

Extracellular Matrix-Based Biomaterials and Their Influence Upon Cell Behavior

Biologic scaffold materials composed of allogeneic or xenogeneic extracellular matrix (ECM) are commonly used for the repair and remodeling of injured tissue. The clinical outcomes associated with implantation of ECM-based materials range from unacceptable to excellent. The variable clinical results are largely due to differences in the preparation of the material, including characteristics of the source tissue, the method and efficacy of decellularization, and post-decellularization processing steps. The mechanisms by which ECM scaffolds promote constructive tissue remodeling include mechanical support, degradation and release of bioactive molecules, recruitment and differentiation of endogenous stem/progenitor cells, and modulation of the immune response toward an anti-inflammatory phenotype. The methods of ECM preparation and the impact of these methods on the quality of the final product are described herein. Examples of favorable cellular responses of immune and stem cells associated with constructive tissue remodeling of ECM bioscaffolds are described.

Esophageal extracellular matrix hydrogel mitigates metaplastic change in a dog model of Barrett's esophagus

Chronic inflammatory gastric reflux alters the esophageal microenvironment and induces metaplastic transformation of the epithelium, a precancerous condition termed Barrett's esophagus (BE). The microenvironmental niche, which includes the extracellular matrix (ECM), substantially influences cell phenotype. ECM harvested from normal porcine esophageal mucosa (eECM) was formulated as a mucoadhesive hydrogel, and shown to largely retain basement membrane and matrix-cell adhesion proteins. Dogs with BE were treated orally with eECM hydrogel and omeprazole (n = 6) or omeprazole alone (n = 2) for 30 days. eECM treatment resolved esophagitis, reverted metaplasia to a normal, squamous epithelium in four of six animals, and downregulated the pro-inflammatory tumor necrosis factor-α+ cell infiltrate compared to control animals. The metaplastic tissue in control animals (n = 2) did not regress. The results suggest that in vivo alteration of the microenvironment with a site-appropriate, mucoadhesive ECM hydrogel can mitigate the inflammatory and metaplastic response in a dog model of BE.

Urinary Bladder Matrix Scaffolds Promote Pericardium Repair in a Porcine Model

Pericardium closure after cardiac surgery is recommended to prevent postoperative adhesions to the sternum. Synthetic materials have been used as substitutes, with limited results because of impaired remodeling and fibrotic tissue formation. Urinary bladder matrix (UBM) scaffolds promote constructive remodeling that more closely resemble the native tissue. The aim of the study is to evaluate the host response to UBM scaffolds in a porcine model of partial pericardial resection. Twelve Landrace pigs were subjected to a median sternotomy. A 5 × 7 cm pericardial defect was created and then closed with a 5 × 7 cm multilayer UBM patch (UBM group) or left as an open defect (control group). Animals were survived for 8 wk. End points included gross morphology, biomechanical testing, histology with semiquantitative score, and cardiac function. The UBM group showed mild adhesions, whereas the control group showed fibrosis at the repair site, with robust adhesions and injury to the coronary bed. Load at failure (gr) and stiffness (gr/mm) were lower in the UBM group compared with the native pericardium (199.9 ± 59.2 versus 405.3 ± 99.89 g, P = 0.0536 and 44.23 ± 15.01 versus 146.5 ± 24.38 g/mm, P = 0.0025, respectively). In the UBM group, the histology resembled native pericardial tissue, with neovascularization, neofibroblasts, and little inflammatory signs. In contrast, control group showed fibrotic tissue with mononuclear infiltrates and a lack of organized collagen fibers validated with a histologic score. Both groups had normal ultrasonography results without cardiac motility disorders. In this setting, UBM scaffolds showed appropriate features for pericardial repair, restoring tissue properties that could help reduce postsurgical adhesions and prevent its associated complications.

Underwater-adhesive microparticle dressing composed of hydrophobically-modified Alaska pollock gelatin for gastrointestinal tract wound healing

Despite the success of minimally-invasive endoscopic submucosal dissection (ESD) for the treatment of early gastrointestinal cancer, additional symptoms after ESD, including contracture, perforation, bleeding, and esophageal stricture remain. Conventional wound dressings were ineffective in preventing stricture because of poor stability of underwater-adhesives on living tissues. Here, we present a microparticle-based wound dressing with underwater adhesive stability for the treatment of gastrointestinal tract wound healing after ESD. Monodisperse microparticles composed of hydrophobically-modified Alaska pollock gelatin were prepared by self-assembly of gelatin in water-ethanol mixed solvents and thermal crosslinking. Hydrophobic modification of gelatin with aliphatic aldehydes increased adhesion strength to gastric and esophageal submucosal tissues through hydrophobic interaction with living tissues and cohesion force. Optimal hydrophobic modification drastically improved underwater stability of microparticles compared to that of non-modified gelatin and formed a thick, integrated hydrogel layer on tissues. Histological observation of rat skin wound healing models showed that hydrophobically-modified gelatin microparticles decreased the expression levels of α-smooth muscle actin in the dermis layer and could suppress fibrosis and inflammation after ESD. The microparticle wound dressing with high underwater-adhesive stability has enormous therapeutic potential to promote wound healing in the gastrointestinal tract and prevent additional symptoms after ESD. STATEMENT OF SIGNIFICANCE: The goal of this study was to develop wound dressing with strong tissue-adhesive property to living tissues for promoting wound healing after ESD treatment. Monodisperse microparticles composed of hydrophobically-modified Alaska pollock gelatin were prepared by self-assembly of gelatin in water-ethanol mixed solvents and thermal crosslinking. Hydrophobic modification of gelatin with aliphatic aldehydes enhanced adhesion strength to gastric and esophageal submucosal tissues through hydrophobic interaction with living tissues and cohesion force. Optimal hydrophobic modification drastically improved underwater stability of microparticles. The in vivo studies were performed to evaluate the ability of this colloidal wound dressing to suppress fibrosis. This new biomaterial has enormous potential to promote wound healing after ESD.

Extracellular Matrix Degradation Products Downregulate Neoplastic Esophageal Cell Phenotype

IMPACT STATEMENT

Extracellular matrix (ECM) biomaterials were used to treat esophageal cancer patients after cancer resection and promoted regrowth of normal mucosa without recurrence of cancer. The present study investigates the mechanisms by which these materials were successful to prevent the cancerous phenotype. ECM downregulated neoplastic esophageal cell function (proliferation, metabolism), but normal esophageal epithelial cells were unaffected in vitro, and suggests a molecular basis (downregulation of PI3K-Akt, cell cycle) for the promising clinical results. The therapeutic effect appeared to be enhanced using homologous esophageal ECM. This study suggests that ECM can be further investigated to treat cancer patients after resection or in combination with targeted therapy.

Multifunctional Hydrophobized Microparticles for Accelerated Wound Healing after Endoscopic Submucosal Dissection

Endoscopic submucosal dissection (ESD) provides strong therapeutic benefits for early gastrointestinal cancer as a minimally invasive treatment. However, there is currently no reliable treatment to prevent scar contracture resulting from ESD which may lead to cicatricial stricture. Herein, a multifunctional colloidal wound dressing to promote tissue regeneration after ESD is demonstrated. This sprayable wound dressing, composed of hydrophobized microparticles, exhibits the multifunctionality necessary for wound healing including tissue adhesiveness, blood coagulation, re-epithelialization, angiogenesis, and controlled inflammation based on hydrophobic interaction with biological systems. An in vivo feasibility study using swine gastric ESD models reveals that this colloidal wound dressing suppresses fibrosis and accelerates wound healing. Multifunctional colloidal and sprayable wound dressings have an enormous therapeutic potential for use in a wide range of biomedical applications including accelerated wound healing after ESD, prevention of perforation, and the treatment of inflammatory diseases.

Strategies to prevent stricture after esophageal endoscopic submucosal dissection

Endoscopic submucosal dissection (ESD) has been widely applied as a less invasive and more effective method for treating early esophageal cancers such as squamous cell carcinoma and dysplasia of Barrett's esophagus. However, post-ESD esophageal stricture often occurs if patients suffer circumferential mucosal defects of more than three-quarters of the circumference of the esophagus, which makes it difficult for patients to swallow and greatly reduces their quality of life. Moreover, there is currently no standard method to treat post-ESD esophageal stricture, even though it is extraordinarily important to prevent its formation. In recent years, several strategies to prevent esophageal stricture have emerged. These strategies can be classified into pharmacological, mechanical, tissue engineering, and other novel strategies, with each strategy having its own strengths and weaknesses. Although the pharmacological prophylaxis and mechanical strategies are relatively mature, they still have their drawbacks like high time-consumption, the occurrence of re-stricture, and significant side effects. Tissue engineering strategies and other novel strategies have shown promising preliminary results, but more clinical trials are needed. In this review, we discuss these strategies, with a particular focus on tissue engineering strategies and other novel strategies. It is hoped that this discussion will aid in finding more effective and safer strategies to prevent esophageal stricture.

Porcine bladder extracellular matrix in paediatric pilonidal wound care: healing and patient experience evaluation

OBJECTIVE

Pilonidal disease (PD) with inflammation and abscess formation occurs frequently in adolescents. The management of pilonidal disease, time to wound healing, and patient satisfaction, however remains variable despite advances in wound care methods. Porcine bladder extracellular matrix (PBEM) facilitates site-specific tissue deposition/re-growth for the management of a variety of wounds. The aim was to describe the use and outcomes of PBEM in PD at a single centre.

METHOD

A retrospective chart review of adolescent patients who underwent treatment of pilonidal disease with PBEM between 2012 and 2016 at a single institution, was undertaken. Patient demographics and clinical characteristics were collected and compared with historical controls and literature regarding traditional wound therapies.

RESULTS

We reviewed 52 pilonidal disease wounds on 41 patients. Of these 36 were treated with PBEM. The average age was 16 years old at the time of operation with 39% male. Furthermore, 85% were being treated for recurrent pilonidal disease. Follow-up was available by chart review for 89% of patients with documented complete wound healing in 78% of patients treated with PBEM at an average of two months. Subjective reports included majority positive experience with PBEM dressing, minimal pain and overall high levels of patient satisfaction. There were three patients in which pilonidal disease recurred within two years of initial treatment and underwent repeat treatment with PBEM. There was one patient who transitioned to wet-to-dry saline dressings because of difficulty keeping the PBEM dressing intact.

CONCLUSION

Advances in wound care technology include materials such as PBEM to promote site-specific tissue deposition. Follow-up phone calls and a prospective study to compare alternative wound care with porcine PBEM in the management of pilonidal disease is underway to better quantify time to wound healing and patient satisfaction.

Comparison of two porcine benign esophageal stricture models using radiofrequency ablation and endoscopic submucosal tunnel dissection

BACKGROUND/AIMS

Large-animal benign esophageal stricture (BES) models are needed for the development of new endoscopic therapies and related devices. This study was undertaken to develop and compare swine BES models produced by radiofrequency ablation (RFA) or endoscopic submucosal tunnel dissection (ESTD).

MATERIALS AND METHODS

RFA and ESTD were each performed on three pigs. Follow-up endoscopy and esophagography were performed immediately after the procedures and then 2, 3, and 4 weeks later. Four weeks after the procedures, all animals were sacrificed, and gross and histologic examinations were performed.

RESULTS

BES was successfully achieved in both the RFA and ESTD groups, and all animals survived without any serious adverse events during the 4-week follow-up period. Mean procedural times were 9.3 min for RFA and 89.3 min for ESTD. ESTD caused long segment strictures whose average length was 4.5 cm, whereas RFA produced short strictures whose average length was 1.4 cm. BES began to form 2 weeks after both procedures. Degrees of strictures were similar at 3 and 4 weeks in the ESTD group; however, it started deteriorating over time in the RFA group. Histologic examinations showed that ESTD caused inflammation and fibrosis in the submucosal layer, whereas RFA induced extensive inflammation in the submucosal and muscularis propria layers.

CONCLUSION

BES was successfully achieved using RFA or ESTD in swine without serious complications. The methods have different characteristics; therefore, researchers should choose the method more appropriate for their purposes.

Comparison of in vivo remodeling of urinary bladder matrix and acellular dermal matrix in an ovine model

Aim: Biologically derived surgical graft materials come from a variety of sources with varying mechanical properties. This study aimed to evaluate the host response and mechanical performance of two extracellular matrix devices in a large animal preclinical model. Materials & methods: Bilateral defects were created in the fascia lata of sheep and repaired with either an acellular dermal matrix (ADM) or urinary bladder matrix (UBM). After 1 or 3 months, the repair site was explanted for histological and mechanical analysis. Results & conclusion: Despite pre-implantation mechanical differences, both UBM and ADM demonstrated similar mechanical performance at 3 months. However, UBM was completely remodeled into site-appropriate tissue by 3 months, while ADM showed limited tissue incorporation.

Autologous Flap Transfer for Esophageal Stricture Prevention After Endoscopic Submucosal Dissection in a Porcine Model

BACKGROUND

Esophageal stricture caused by endoscopic submucosal dissection for a mucosal defect that covers more than three quarters of the circumference of the esophagus has a high incidence. To date, no method for preventing such strictures has been widely recognized as effective in clinical practice.

AIMS

We examined whether esophageal stricture caused by circumferential endoscopic submucosal dissection could be prevented by autologous flap transfer.

METHODS

Six pigs (N = 6) underwent circumferential esophageal endoscopic submucosal dissection under general anesthesia. For animals in the flap group (N = 3), an autologous flap was constructed and then placed at the resection site and secured with metal clips. Animals in the control group (N = 3) underwent endoscopic submucosal dissection only. Endoscopy was performed 3 weeks postoperative to evaluate the effects of flap transfer.

RESULTS

Animals in the flap group gained more weight than animals in the control group. At 3 weeks postoperative, animals in the flap group developed clinically slight stricture; in these animals, an endoscope could be passed through the stricture with slight resistance. In contrast, in the control group, significant stricture was observed, and the stricture was difficult to cross with an endoscope.

CONCLUSION

Autologous flap transfer after circumferential esophageal endoscopic submucosal dissection is a novel approach that remarkably decreases the degree of esophageal stricture that arises.

Extracellular Matrix Membrane Induces Cementoblastic/Osteogenic Properties of Human Periodontal Ligament Stem Cells

Objective: Periodontitis affects nearly 90% of adults over the age of 70, resulting to periodontal tissue infection, destruction, and ultimately tooth loss. Guided tissue regeneration (GTR) is a method widely used to treat severe periodontal disease, and involves placement of an occlusive barrier to facilitate regeneration of the damaged area by periodontal ligament stem cells (PDLSCs). In this study, we evaluate natural extracellular matrix (ECM) as a scaffold material to provide a suitable microenvironment to support the proliferation, differentiation, and tissue-regenerating properties of PDLSCs. Design: The viability, proliferation, apoptosis, and migration of PDLSCs cultured on ECM membrane, that was isolated from porcine urinary bladders, were compared with those cultured on type I collagen membrane, a commonly used scaffold in GTR. To evaluate the effects of ECM vs. type I collagen on the tissue-regenerating properties of PDLSCs, the bio-attachment and cementoblastic/osteogenic differentiation of PDLSCs were evaluated. Results: Incubation of PDLSCs with ECM resulted in increased viability, proliferation, and reduced apoptosis, compared with type I collagen treated PDLSCs. Co-culture with ECM membrane also increased the migration and bio-attachment of PDLSCs. Incubation of PDLSCs with ECM membrane increased expression of the cementoblastic/osteogenic differentiation markers BSP, RUNX2, ALP, OPN, OCN, and periostin. Conclusion: ECM membrane enhances the proliferation and regenerative properties of PDLSCs, indicating that ECM membrane can serve as a suitable scaffold in the application of GTR to treat periodontal disease.

Retrorectus repair of incisional ventral hernia with urinary bladder matrix reinforcement in a long-term porcine model

Aim: Not all biologically derived materials elicit the same host response when used for reinforcement of ventral hernia repairs. This study aimed to evaluate the remodeling characteristics of the abdominal wall following reinforcement with urinary bladder matrix (UBM) in a large animal preclinical model of ventral hernia repair. Materials & methods: Midline defects in 36 Yucatan minipigs were reinforced with UBM-derived surgical devices using a classic Rives–Stoppa–Wantz approach, and compared with primary repair controls. After 3 or 8 months, the abdominal wall was explanted for histological and mechanical analysis. Results & conclusion: All UBM-derived surgical devices were completely resorbed within 8 months and facilitated deposition of vascularized, biomechanically functional connective tissue in the retrorectus plane, with no evidence of hernia formation.

Scarring vs. functional healing: Matrix-based strategies to regulate tissue repair

All vertebrates possess mechanisms to restore damaged tissues with outcomes ranging from regeneration to scarring. Unfortunately, the mammalian response to tissue injury most often culminates in scar formation. Accounting for nearly 45% of deaths in the developed world, fibrosis is a process that stands diametrically opposed to functional tissue regeneration. Strategies to improve wound healing outcomes therefore require methods to limit fibrosis. Wound healing is guided by precise spatiotemporal deposition and remodelling of the extracellular matrix (ECM). The ECM, comprising the non-cellular component of tissues, is a signalling depot that is differentially regulated in scarring and regenerative healing. This Review focuses on the importance of the native matrix components during mammalian wound healing alongside a comparison to scar-free healing and then presents an overview of matrix-based strategies that attempt to exploit the role of the ECM to improve wound healing outcomes.

Progress on the Prevention of Esophageal Stricture after Endoscopic Submucosal Dissection

Endoscopic submucosal dissection (ESD) has been widely accepted as an effective, minimally invasive treatment for superficial esophageal cancers. However, esophageal stricture often occurs in patients with large mucosal defects after ESD. In this review, we discuss various approaches recently researched to prevent esophageal strictures after ESD. These approaches can be classified as pharmacological treatments, esophageal stent treatments, and tissue engineering approaches. Most of the preventive approaches still have their limitations and require further research. With the improvement of current therapies, ESD can be more widely utilized as a minimally invasive treatment with minimal complications.

Regenerative medicine for the esophagus

Advances in tissue engineering techniques have made it possible to use human cells as biological material. This has enabled pharmacological studies to be conducted to investigate drug effects and toxicity, to clarify the mechanisms underlying diseases, and to elucidate how they compensate for impaired organ function. Many researchers have tried to construct artificial organs using these techniques, but none has succeeded in growing a whole organ. Unlike other digestive organs with complicated functions, such as the processing and absorption of nutrients, the esophagus has the relatively simple function of transporting content, which can be replicated easily by a substitute. In regenerative medicine, various combinations of materials have been applied, including scaffolding, cell sources, and bioreactors. Exciting results of tissue engineering techniques for the esophagus have been reported. In animal models, replacing full-thickness and full-circumferential defects remains challenging because of stenosis and leakage after implantation. Although many reports have manipulated various scaffolds, most have emphasized the importance of both epithelial and mesenchymal cells for the prevention of stenosis. However, the results of repair of partial full-thickness defects and mucosal defects have been promising. Two successful approaches for the replacement of mucosal defects in a clinical setting have been reported, although in contrast to the many animal models, there are few pilot studies in humans. We review the recent results and evaluate the future of regenerative medicine for the esophagus.

Acellular dermal matrix for esophageal stricture prevention after endoscopic submucosal dissection in a porcine model

BACKGROUND AND AIMS

Endoscopic submucosal dissection (ESD) is considered an effective treatment for early esophageal cancer and precancerous lesions. Esophageal stenosis is closely associated with quasi-circumferential ESD. We examined whether post-ESD esophageal stricture can be prevented by grafting an acellular dermal matrix (ADM) membrane.

METHODS

Fourteen Bama miniature pigs were randomly divided into an ADM group (n = 7) and a control group (n = 7). Semicircumferential ESD was performed at the distal esophagus in all animals, and in the ADM group an ADM patch graft was placed at the resection site and secured innovatively with metal clips. Animals in the control group underwent ESD only. Endoscopy was performed at 3 days, 1 week, 2 weeks, and 4 weeks post-ESD, and fluoroscopy was performed at 4 weeks for assessment of the degree of stenosis, after which the remodeled esophageal tissues were excised for histologic analysis.

RESULTS

No animals in the ADM group developed clinically significant esophageal stenosis, whereas 42.8% (3/7) in the control group did. The degree of stenosis was severe in the control group (39.8% vs 17.2%, respectively; P = .01). Animals in the ADM group had less feeding difficulty and lost less weight (-.9 kg vs -4.1 kg, respectively; P = .007). Histologically, complete mucosal epithelium, slight local inflammation, and organized collagenous fibers were observed in the ADM group.

CONCLUSIONS

ADM patch graft appears, after short-term observation, to be a potentially useful new treatment strategy for prevention of esophageal stricture after ESD. A metal clip fixation technique is effective for endoscopic graft attachment.

Extracellular Matrix Bioscaffolds for Building Gastrointestinal Tissue

Regenerative medicine is a rapidly advancing field that uses principles of tissue engineering, developmental biology, stem cell biology, immunology, and bioengineering to reconstruct diseased or damaged tissues. Biologic scaffolds composed of extracellular matrix have shown great promise as an inductive substrate to facilitate the constructive remodeling of gastrointestinal (GI) tissue damaged by neoplasia, inflammatory bowel disease, and congenital or acquired defects. The present review summarizes the preparation and use of extracellular matrix scaffolds for bioengineering of the GI tract, identifies significant advances made in regenerative medicine for the reconstruction of functional GI tissue, and describes an emerging therapeutic approach.

Novel use of porcine extracellular matrix in recurrent stricture following repair of tracheoesophageal fistula

Anastomotic stricture is a common complication following repair of esophageal atresia (EA). Many factors are thought to contribute to stricture formation and a variety of management techniques have been developed. In this case report, we describe the treatment of a recurrent anastomotic stricture following repair of long-gap esophageal atresia. Porcine bladder extracellular matrix (ECM) was mounted on a stent and delivered endoscopically to the site of recurrent stricture. An appropriate positioning was confirmed using direct endoscopic visualization and intra-operative fluoroscopy. The patient recovered well with persistent radiographic and functional improvements in previous stricture.

The extracellular matrix of the gastrointestinal tract: a regenerative medicine platform

The synthesis and secretion of components that constitute the extracellular matrix (ECM) by resident cell types occur at the earliest stages of embryonic development, and continue throughout life in both healthy and diseased physiological states. The ECM consists of a complex mixture of insoluble and soluble functional components that are arranged in a tissue-specific 3D ultrastructure, and it regulates numerous biological processes, including angiogenesis, innervation and stem cell differentiation. Owing to its composition and influence on embryonic development, as well as cellular and organ homeostasis, the ECM is an ideal therapeutic substrate for the repair of damaged or diseased tissues. Biologic scaffold materials that are composed of ECM have been used in various surgical and tissue-engineering applications. The gastrointestinal (GI) tract presents distinct challenges, such as diverse pH conditions and the requirement for motility and nutrient absorption. Despite these challenges, the use of homologous and heterologous ECM bioscaffolds for the focal or segmental reconstruction and regeneration of GI tissue has shown promise in early preclinical and clinical studies. This Review discusses the importance of tissue-specific ECM bioscaffolds and highlights the major advances that have been made in regenerative medicine strategies for the reconstruction of functional GI tissues.

The Role of Tumor Microenvironment in Chemoresistance: To Survive, Keep Your Enemies Closer

Chemoresistance is a leading cause of morbidity and mortality in cancer and it continues to be a challenge in cancer treatment. Chemoresistance is influenced by genetic and epigenetic alterations which affect drug uptake, metabolism and export of drugs at the cellular levels. While most research has focused on tumor cell autonomous mechanisms of chemoresistance, the tumor microenvironment has emerged as a key player in the development of chemoresistance and in malignant progression, thereby influencing the development of novel therapies in clinical oncology. It is not surprising that the study of the tumor microenvironment is now considered to be as important as the study of tumor cells. Recent advances in technological and analytical methods, especially ‘omics’ technologies, has made it possible to identify specific targets in tumor cells and within the tumor microenvironment to eradicate cancer. Tumors need constant support from previously ‘unsupportive’ microenvironments. Novel therapeutic strategies that inhibit such microenvironmental support to tumor cells would reduce chemoresistance and tumor relapse. Such strategies can target stromal cells, proteins released by stromal cells and non-cellular components such as the extracellular matrix (ECM) within the tumor microenvironment. Novel in vitro tumor biology models that recapitulate the in vivo tumor microenvironment such as multicellular tumor spheroids, biomimetic scaffolds and tumor organoids are being developed and are increasing our understanding of cancer cell-microenvironment interactions. This review offers an analysis of recent developments on the role of the tumor microenvironment in the development of chemoresistance and the strategies to overcome microenvironment-mediated chemoresistance. We propose a systematic analysis of the relationship between tumor cells and their respective tumor microenvironments and our data show that, to survive, cancer cells interact closely with tumor microenvironment components such as mesenchymal stem cells and the extracellular matrix.

The impact of flexible endoscopy in esophageal surgery

Achalasia and Treatment of esophageal Adenocarcinoma are commonly associated to surgical resection. Newer technologies in interventional endoscopy gave way to a substantial paradigm shift in the management of these conditions. In the case of achalasia, endoscopic myotomy is rapidly displacing Heller's myotomy as the gold standard in many centers. Early stage neoplasia in Barrett's esophagus (BE) comprising high-grade dysplasia (HGD), intramucosal and, in some cases, submucosal carcinoma is now being treated without the need of esophagectomy. This review presents a summary of the most relevant endoscopic techniques for both achalasia and esophageal cancer. Endoscopic advances in diagnostic and therapeutic arenas allow for minimally invasive therapies and organ preservation in most settings of achalasia and early stage neoplasia of the esophagus provided that the clinical setting and physician's expertise are prepared for this approach.

ADSC-sheet Transplantation to Prevent Stricture after Extended Esophageal Endoscopic Submucosal Dissection

In past years, the cell-sheet construct has spurred wide interest in regenerative medicine, especially for reconstructive surgery procedures. The development of diversified technologies combining adipose tissue-derived stromal cells (ADSCs) with various biomaterials has led to the construction of numerous types of tissue-engineered substitutes, such as bone, cartilage, and adipose tissues from rodent, porcine, or human ADSCs. Extended esophageal endoscopic submucosal dissection (ESD) is responsible for esophageal stricture formation. Stricture prevention remains challenging, with no efficient treatments available. Previous studies reported the effectiveness of mucosal cell-sheet transplantation in a canine model and in humans. ADSCs are attributed anti-inflammatory properties, local immune modulating effects, neovascularization induction, and differentiation abilities into mesenchymal and non-mesenchymal lineages. This original study describes the endoscopic transplantation of an ADSC tissue-engineered construct to prevent esophageal stricture in a swine model. The ADSC construct was composed of two allogenic ADSC sheets layered upon each other on a paper support membrane. The ADSCs were labeled with the PKH67 fluorophore to allow probe-based confocal laser endomicroscopy (pCLE) monitoring. On the day of transplantation, a 5-cm and hemi-circumferential ESD known to induce esophageal stricture was performed. Animals were immediately endoscopically transplanted with 4 ADSC constructs. The complete adhesion of the ADSC constructs was obtained after 10 min of gentle application. Animals were sacrificed on day 28. All animals were successfully transplanted. Transplantation was confirmed on day 3 with a positive pCLE evaluation. Compared to transplanted animals, control animals developed severe strictures, with major fibrotic tissue development, more frequent alimentary trouble, and reduced weight gain. In our model, the transplantation of allogenic ADSCs, organized in double cell sheets, after extended ESD was successful and strongly associated with a lower esophageal stricture rate.

Glottic regeneration with a tissue-engineering technique, using acellular extracellular matrix scaffold in a canine model

Acellular extracellular matrix scaffold derived from porcine urinary bladder (UBM) is decellularized material that has shown success for constructive remodelling of various tissues and organs. The regenerative effects of UBM were reported for the tympanic membrane, oesophagus, trachea, larynx, pleura and pericardium in animal studies, with promising results. The aim of this study was to investigate the regenerative effects of UBM on hemilarynx, using a canine model. A left partial hemilaryngectomy was performed and the surgical defects were reconstructed by insertion of UBM scaffold. Although local infection was observed in one dog in 1 week after implantation of the scaffold, all dogs showed good re-epithelialization with minimum complication in 1 month. The effect of regeneration of the larynx was evaluated 6 months after the operation. The excised larynx experiments were performed to measure phonation threshold pressure (PTP), normalized mucosal wave amplitude (NMWA) and normalized glottal gap (NGG). The results of the measurements showed that PTP was normal or near normal in two cases and NMWA was within normal range in three cases, although there were individual variations. Histological examination was completed to evaluate structural changes in the scaffold with the appearance of the new cartilaginous structure. However, the regenerated vocal fold mucosa was mostly scarred. The UBM scaffold has shown to be biocompatible, biodegradable and useful for tissue regeneration of the hemilarynx, with possible restoration of function of the vocal fold. The vocal fold mucosa was scarred, which is the next challenge to be addressed. Copyright © 2014 John Wiley & Sons, Ltd.

Decellularized scaffolds in regenerative medicine

Allogeneic organ transplantation remains the ultimate solution for end-stage organ failure. Yet, the clinical application is limited by the shortage of donor organs and the need for lifelong immunosuppression, highlighting the importance of developing effective therapeutic strategies. In the field of regenerative medicine, various regenerative technologies have lately been developed using various biomaterials to address these limitations. Decellularized scaffolds, derived mainly from various non-autologous organs, have been proved a regenerative capability in vivo and in vitro and become an emerging treatment approach. However, this regenerative capability varies between scaffolds as a result of the diversity of anatomical structure and cellular composition of organs used for decellularization. Herein, recent advances in scaffolds based on organ regeneration in vivo and in vitro are highlighted along with aspects where further investigations and analyses are needed.

Topical hemostatic powder promotes reepithelialization and reduces scar formation after extensive esophageal mucosal resection

The development of techniques for endoscopic resection has provided new strategies for radical conservative treatment of superficial esophageal neoplasms, even those that are circumferential, such as Barrett's neoplasia. However, it is necessary to prevent the formation of scar tissue that can be responsible for esophageal strictures following circumferential resection. Preliminary data have suggested the possible efficacy of a hemostatic powder in the promotion of wound healing. The study aims to assess the effectiveness of Hemospray (Cook Medical) in a swine model of post-endoscopic esophageal stricture. Our prospective controlled study included 21 pigs. A 6-cm circumferential submucosal dissection of the esophagus (CESD) was performed in each pig. Group 1 (n = 11) only underwent CESD and Group 2 (n = 10) had repeated Hemospray applications after CESD. Clinical, endoscopic, and radiological monitoring were performed, blood levels of four inflammatory or pro-fibrotic cytokines were assessed, and histological analysis was performed. Median esophageal diameter was greater in the group treated with Hemospray (2 mm [1-3] vs. 3 mm [2-4], P = 0.01), and the rate of symptomatic esophageal stricture was 100% and 60% in Groups 1 and 2, respectively (P = 0.09). The thicknesses of esophageal fibrosis and inflammatory cell infiltrate were significantly lower in Group 2 than in Group 1 (P = 0.002 and 0.0003, respectively). The length of the neoepithelium was greater in Group 2 than in Group 1 (P = 0.0004). Transforming growth factor-β levels were significantly lower in Group 2 than in Group 1 (P = 0.01). The application of Hemospray after esophageal CESD reduces scar tissue formation and promotes reepithelialization, and therefore is a promising therapeutic approach in the prevention of post-endoscopic esophageal stricture.

In-vivo oesophageal regeneration in a human being by use of a non-biological scaffold and extracellular matrix

BACKGROUND

Tissue-engineered extracellular matrix populated with autologous pluripotent cells can result in de-novo organogenesis, but the technique is complex, not widely available, and has not yet been used to repair large oesophageal defects in human beings. We aimed to use readily available stents and extracellular matrix to regenerate the oesophagus in vivo in a human being to re-establish swallowing function.

METHODS

In a patient aged 24 years, we endoscopically placed a readily available, fully covered, self-expanding, metal stent (diameter 18 mm, length 120 mm) to bridge a 5 cm full-thickness oesophageal segment destroyed by a mediastinal abscess and leading to direct communication between the hypopharynx and the mediastinum. A commercially available extracellular matrix was used to cover the stent and was sprayed with autologous platelet-rich plasma adhesive gel. The sternocleidomastoid muscle was placed over the matrix. After 4 weeks, stent removal was needed due to stent migration, and was replaced with three stents telescopically aligned to improve anchoring. The stents were removed after 3·5 years and the oesophagus was assessed by endoscopy, biopsy, endoscopic ultrasonography, and high-resolution impedance manometry.

FINDINGS

After stent removal we saw full-thickness regeneration of the oesophagus with stratified squamous epithelium, a normal five-layer wall, and peristaltic motility with bolus transit. 4 years after stent removal, the patient was eating a normal diet and maintaining a steady weight.

INTERPRETATION

Maintenance of the structural morphology of the oesophagus with off-the-shelf non-biological scaffold and stimulation of regeneration with commercially available extracellular matrix led to de-novo structural and functional regeneration of the oesophagus.

FUNDING

None.

Prevention of Esophageal Strictures After Endoscopic Submucosal Dissection: A Promising Therapy Using Carboxymethyl Cellulose Sheets

BACKGROUND

Esophageal stricture is one of the serious adverse events following endoscopic submucosal dissection (ESD). However, optimum preventive techniques are still lacking.

AIMS

Our primary objective was to evaluate the incidence of post-ESD esophageal stricture with the application of carboxymethyl cellulose (CMC) sheets. Secondary objectives were to determine the number of sessions of endoscopic balloon dilatation (EBD) required to resolve post-ESD strictures and the incidence rate of peri-operative adverse events.

METHODS

This was a pilot, single-center, prospective study. Seven patients who had high risks of developing post-ESD esophageal stricture were enrolled into our study. CMC sheets were applied to the mucosal defects immediately after the completion of ESD. Patients were monitored and reviewed after ESD to detect any adverse events.

RESULTS

The incidence rate of post-operative stricture was 57 % (4/7 patients). Among patients who required EBD, the number of sessions performed was 2.8 ± 2.2. No serious post-operative adverse events were reported.

CONCLUSION

The use of CMC sheets appears to be a safe and effective prophylactic treatment for esophageal stricture following extensive ESD.