Polyurethane scaffolds seeded with autologous cells can regenerate long esophageal gaps: An esophageal atresia treatment model

Biomimetic tubular materials: from native tissues to a unifying view of new vascular, tracheal, gastrointestinal, oesophageal, and urinary grafts

Repairing tubular tissues-the trachea, the esophagus, urinary and gastrointestinal tracts, and the circulatory system-from trauma or severe pathologies that require resection, calls for new, more effective graft materials. Currently, the relatively narrow family of materials available for these applications relies on synthetic polymers that fail to reproduce the biological and physical cues found in native tissues. Mimicking the structure and the composition of native tubular tissues to elaborate functional grafts is expected to outperform the materials currently in use, but remains one of the most challenging goals in the field of biomaterials. Despite their apparent diversity, tubular tissues share extensive compositional and structural features. Here, we assess the current state of the art through a dual layer model, reducing each tissue to an inner epithelial layer and an outer muscular layer. Based on this model, we examine the current strategies developed to mimic each layer and we underline how each fabrication method stands in providing a biomimetic material for future clinical translation. The analysis provided here, addressed to materials chemists, biomaterials engineers and clinical staff alike, sets new guidelines to foster the elaboration of new biomimetic materials for effective tubular tissue repair.

Circumferential Esophageal Reconstruction Using a Tissue-engineered Decellularized Tunica Vaginalis Graft in a Rabbit Model

BACKGROUND

Pediatric surgeons have faced esophageal reconstruction challenges for decades owing to a variety of congenital and acquired conditions. This work aimed to introduce a reproducible and efficient approach for creating tissue-engineered esophageal tissue using bone marrow mesenchymal stem cells (BMSCs) cultured in preconditioned mediums seeded on a sheep decellularized tunica vaginalis (DTV) scaffold for partial reconstruction of a rabbit's esophagus.

METHODS

DTV was performed using SDS and Triton X-100 solutions. The decellularized grafts were employed alone (DTV group) or after recellularization with BMSCs cultured for 10 days in preconditioned mediums (RTV group) for reconstructing a 3 cm segmental defect in the cervical esophagus of rabbits (n = 20) after the decellularization process was confirmed. Rabbits were observed for one month, after which they were euthanized, and the reconstructed esophagi were harvested for histological analysis.

RESULTS

Six rabbits in the DTV group and eight rabbits in the RTV group survived until the end of the one-month study period. Despite histological examination demonstrating that both grafts completely repaired the esophageal defect, the RTV graft demonstrated a histological structure similar to that of the normal esophagus. The reconstructed esophagi in the RTV group revealed the arrangement of the different layers of the esophageal wall with the formation of newly formed blood vessels and Schwann-like cells.

CONCLUSION

DTV xenograft is a novel scaffold that promotes cell adhesion and differentiation and might be effectively utilized for regenerating esophageal tissue, paving the way for future clinical trials in pediatric patients.

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.

Building gut from scratch - progress and update of intestinal tissue engineering

Short bowel syndrome (SBS), a condition defined by insufficient absorptive intestinal epithelium, is a rare disease, with an estimated prevalence up to 0.4 in 10,000 people. However, it has substantial morbidity and mortality for affected patients. The mainstay of treatment in SBS is supportive, in the form of intravenous parenteral nutrition, with the aim of achieving intestinal autonomy. The lack of a definitive curative therapy has led to attempts to harness innate developmental and regenerative mechanisms to engineer neo-intestine as an alternative approach to addressing this unmet clinical need. Exciting advances have been made in the field of intestinal tissue engineering (ITE) over the past decade, making a review in this field timely. In this Review, we discuss the latest advances in the components required to engineer intestinal grafts and summarize the progress of ITE. We also explore some key factors to consider and challenges to overcome when transitioning tissue-engineered intestine towards clinical translation, and provide the future outlook of ITE in therapeutic applications and beyond.

Decellularization of porcine esophageal tissue at three diameters and the bioscaffold modification with EETs-ECM gel

Damaged complex modular organs repair is a current clinical challenge in which one of the primary goals is to keep their biological response. An interesting case of study it is the porcine esophagus since it is a tubular muscular tissue selected as raw material for tissue engineering. The design of esophageal constructs can draw on properties of the processed homologous extracellular matrix (ECM). In this work, we report the decellularization of multilayered esophagus tissue from 1-, 21- and 45-days old piglets through the combination of reversible alkaline swelling and detergent perfusion. The bioscaffolds were characterized in terms of their residual composition and tensile mechanical properties. The biological response to esophageal submucosal derived bioscaffolds modified with ECM gel containing epoxyeicosatrienoic acids (EETs) was then evaluated. Results suggest that the composition (laminin, fibronectin, and sulphated glycosaminoglycans/sGAG) depends on the donor age: a better efficiency of the decellularization process combined with a higher retention of sGAG and fibronectin is observed in piglet esophageal scaffolds. The heterogeneity of this esophageal ECM is maintained, which implied the preservation of anisotropic tensile properties. Coating of bioscaffolds with ECM gel is suitable for carrying esophageal epithelial cells and EETs. Bioactivity of EETs-ECM gel modified esophageal submucosal bioscaffolds is observed to promote neovascularization and antiinflammatory after rabbit full-thickness esophageal defect replacement.

Esophageal regeneration following surgical implantation of a tissue engineered esophageal implant in a pediatric model

Diseases of the esophagus, damage of the esophagus due to injury or congenital defects during fetal esophageal development, i.e., esophageal atresia (EA), typically require surgical intervention to restore esophageal continuity. The development of tissue engineered tubular structures would improve the treatment options for these conditions by providing an alternative that is organ sparing and can be manufactured to fit the exact dimensions of the defect. An autologous tissue engineered Cellspan Esophageal Implant^TM (CEI) was surgically implanted into piglets that underwent surgical resection of the esophagus. Multiple survival time points, post-implantation, were analyzed histologically to understand the tissue architecture and time course of the regeneration process. In addition, we investigated CT imaging as an “in-life” monitoring protocol to assess tissue regeneration. We also utilized a clinically relevant animal management paradigm that was essential for long term survival. Following implantation, CT imaging revealed early tissue deposition and the formation of a contiguous tissue conduit. Endoscopic evaluation at multiple time points revealed complete epithelialization of the lumenal surface by day 90. Histologic evaluation at several necropsy time points, post-implantation, determined the time course of tissue regeneration and demonstrated that the tissue continues to remodel over the course of a 1-year survival time period, resulting in the development of esophageal structural features, including the mucosal epithelium, muscularis mucosae, lamina propria, as well as smooth muscle proliferation/migration initiating the formation of a laminated adventitia. Long term survival (1 year) demonstrated restoration of oral nutrition, normal animal growth and the overall safety of this treatment regimen.

Regenerative medicine for childhood gastrointestinal diseases

Several paediatric gastrointestinal diseases result in life-shortening organ failure. For many of these conditions, current therapeutic options are suboptimal and may not offer a cure. Regenerative medicine is an inter-disciplinary field involving biologists, engineers, and clinicians that aims to produce cell and tissue-based therapies to overcome organ failure. Exciting advances in stem cell biology, materials science, and bioengineering bring engineered gastrointestinal cell and tissue therapies to the verge of clinical trial. In this review, we summarise the requirements for bioengineered therapies, the possible sources of the various cellular and non-cellular components, and the progress towards clinical translation of oesophageal and intestinal tissue engineering to date.

First-in-Human Segmental Esophageal Reconstruction Using a Bioengineered Mesenchymal Stromal Cell-Seeded Implant

Introduction

Resection and reconstruction of the esophagus remains fraught with morbidity and mortality. Recently, data from a porcine reconstruction model revealed that segmental esophageal reconstruction using an autologous mesenchymal stromal cell-seeded polyurethane graft (Cellspan esophageal implant [CEI]) can facilitate esophageal regrowth and regeneration. To this end, a patient requiring a full circumferential esophageal segmental reconstruction after a complex multiorgan tumor resection was approved for an investigational treatment under the Food and Drug Administration Expanded Access Use (Investigational New Drug 17402).

Methods

Autologous adipose-derived mesenchymal stromal cells (Ad-MSCs) were isolated from the Emergency Investigational New Drug patient approximately 4 weeks before surgery from an adipose tissue biopsy specimen. The Ad-MSCs were grown and expanded under current Good Manufacturing Practice manufacturing conditions. The cells were then seeded onto a polyurethane fiber mesh scaffold (Cellspan scaffold) and cultured in a custom bioreactor to manufacture the final CEI graft. The cell-seeded scaffold was then shipped to the surgical site for surgical implantation. After removal of a tumor mass and a full circumferential 4 cm segment of the esophagus that was invaded by the tumor, the CEI was implanted by suturing the tubular CEI graft to both ends of the remaining native esophagus using end-to-end anastomosis.

Results

In this case report, we found that a clinical-grade, tissue-engineered esophageal graft can be used for segmental esophageal reconstruction in a human patient. This report reveals that the graft supports regeneration of the esophageal conduit. Histologic analysis of the tissue postmortem, 7.5 months after the implantation procedure, revealed complete luminal epithelialization and partial esophageal tissue regeneration.

Conclusions

Autologous Ad-MSC seeded onto a tubular CEI tissue-engineered graft stimulates tissue regeneration following implantation after a full circumferential esophageal resection.

Circumferential esophageal replacement by a decellularized esophageal matrix in a porcine model

BACKGROUND

Tissue engineering is an attractive alternative to conventional esophageal replacement techniques using intra-abdominal organs which are associated with a substantial morbidity. The objective was to evaluate the feasibility of esophageal replacement by an allogenic decellularized esophagus in a porcine model. Secondary objectives were to evaluate the benefit of decellularized esophagus recellularization with autologous bone marrow mesenchymal stromal cells and omental maturation of the decellularized esophagus.

METHODS

Eighteen pigs divided into 4 experimental groups according to mesenchymal stromal cells recellularization and omental maturation underwent a 5-cm long circumferential replacement of the thoracic esophagus. Turbo green florescent protein labelling was used for in vivo mesenchymal stromal cells tracking. The graft area was covered by a stent for 3 months. Clinical and histologic outcomes were analyzed over a 6-month period.

RESULTS

The median follow-up was 112 days [5; 205]. Two animals died during the first postoperative month, 2 experienced an anastomotic leakage, 13 experienced a graft area stenosis following stent migration of which 3 were sacrificed as initially planned after successful endoscopic treatment. The stent could be removed in 2 animals: the graft area showed a continuous mucosa without stenosis. After 3 months, the graft area showed a tissue specific regeneration with a mature epithelium and muscular cells. Clinical and histologic results were similar across experimental groups.

CONCLUSION

Circumferential esophageal replacement by a decellularized esophagus was feasible and allowed tissue remodeling toward an esophageal phenotype. We could not demonstrate any benefit provided by the omental maturation of the decellularized esophagus nor its recellularization with mesenchymal stromal cells.

A new method of primary engineering of esophagus using orthotopic in-body tissue architecture

PURPOSE

Tissue engineering of esophagus is required for management of long-gap esophageal atresia (LGEA). Collagenous connective tissue membranes fabricated by in-body tissue architecture (iBTA), called biosheets, can repair esophageal defects and generate tissues similar to native esophagus. However, iBTA requires second-stage surgery because of heterotopic preparation of biosheets. Our aim was to develop orthotopic iBTA for primary engineering of the esophagus by interposing a tubular mold to the esophageal defect.

METHOD

The cervical esophagus of six rats was transected. An acrylic tube (internal diameter 2.6 mm, length 7.0 mm) was inserted and fixed between the ends of the upper and lower esophagus, and a 3 mm-long esophageal defect was created. Four weeks later, the rats were sacrificed for histological analysis.

RESULTS

Postoperatively the rats could intake liquid food. After four weeks, the esophageal defects were filled with regenerated tissues. Histologically the new esophageal walls stained positive for collagen type I. The inner surfaces were covered with stratified squamous epithelium that expressed pan-cytokeratin. In only one of six rats, regeneration of muscular-like tissue was suggested by positive immunohistochemical staining for desmin.

CONCLUSION

Orthotopic iBTA can regenerate a substitute esophagus with esophageal epithelium and collagenous wall. This technique may be a novel treatment for esophageal atresia with gaps of various lengths including LGEA.

Tissue Engineering Opportunities for Vaginal Replacement in a Pediatric Population

Treatment for children born with vaginal agenesis remains difficult, without a clear gold standard for tissue replacement. An autologous-engineered vaginal replacement would significantly improve quality of life for people born with this condition. The aim of this study was to critically review literature on the current state of tissue engineering for vaginal reconstruction in a pediatric population. An electronic literature search was conducted using PubMed for articles describing pediatric vaginal tissue engineering from January 2003 to December 2020. Nine studies met inclusion criteria and were reviewed. The model, methods, cell type and source, scaffold type, and time of analysis and evaluation were compared. Three studies used in vitro and six used an in vivo design. Of the six in vivo studies, one was able to investigate autologous vaginal epithelial cells in human clinical trials. This review discusses the current knowledge and progress of vaginal tissue engineered replacements that can potentially be used as a basis for both future preclinical animal and clinical human studies. Impact statement The current methods of treatment for congenital vaginal anomalies leave room for improvement. The state of tissue engineering may provide a method to improve the surgical interventions provided for these patients, in hopes of providing increased vaginal functionally and quality of life.

A narrative review of esophageal tissue engineering and replacement: where are we?

Long-gap esophageal defects, whether congenital or acquired, are very difficult to manage. Any significant surgical peri-esophageal dissection that is performed to allow for potential stretching of two ends of a defect interrupts the esophageal blood supply and leads to complications such as leak and stricture, even in the youngest, healthiest patients. The term “congenital” applied to these defects refers mainly to long-gap esophageal atresia (LGA). Causes of acquired long-segment esophageal disruption include recurrent leaks and fistulae after primary repair, refractory GERD, caustic ingestions, cancer, and strictures. 5,000–10,000 patients per year in the US require esophageal replacement. Gastric, colonic, and jejunal pull-up surgeries are fraught with high rates of both short and long term complications thus creating a space for a better option. Since the 1970’s many groups around the world have been unsuccessfully attempting esophageal replacement with tissue-engineered grafts in various animal models. But, recent advances in these models are now combining novel technologic advances in materials bioscience, stem-cell therapies, and transplantation and are showing increasing promise to human translational application. Transplantation has been heretofore unsuccessful, but given modern improvements in transplant microsurgery and immunosuppressive medications, pioneering trials in animal models are being undertaken now. These rapidly evolving medical innovations will be reviewed here.

A Continuous Suture Anastomosis Outperforms a Simple Interrupted Suture Anastomosis in Esophageal Elongation

INTRODUCTION

 Long-gap esophageal atresia represents a distinct entity among the esophageal atresia spectrum. In many patients, achieving a reasonable anastomosis depends on some millimeters of tissue. We aimed to determine what effect the suturing technique would have on esophageal ex vivo elongation as it may determine the strength of a primary anastomosis.

MATERIALS AND METHODS

 In an analysis of porcine esophagi from animals for slaughter (100-120 days old with a weight of 100-120 kg), we determined esophageal length gain of simple continuous and simple interrupted suture anastomoses subjected to linear traction until linear breaking strength was reached. Statistical power of 80% was ensured based on an a priori power analysis using five specimens per group in a separate exploratory experiment.

RESULTS

 The simple continuous suture anastomosis in 15 porcine esophagi (  = 4.47 cm, 95% confidence interval: 4.08-4.74 cm) outperformed the simple interrupted suture anastomosis in another 15 esophagi (  = 3.03 cm, 95% confidence interval: 2.59-3.43 cm) in length gain (Δ = 1.44 cm, 95% confidence interval: 0.87-2.01 cm, p < 0.0001).

CONCLUSION

 Simple continuous anastomoses achieved higher length gain compared with simple interrupted suture anastomoses. This effect warrants an experimental assessment in vivo to assess its potential merits for clinical applicability.

Pore geometry influences growth and cell adhesion of infrapatellar mesenchymal stem cells in biofabricated 3D thermoplastic scaffolds useful for cartilage tissue engineering

The most pressing need in cartilage tissue engineering (CTE) is the creation of a biomaterial capable to tailor the complex extracellular matrix of the tissue. Despite the standardized used of polycaprolactone (PCL) for osteochondral scaffolds, the pronounced stiffness mismatch between PCL scaffold and the tissue it replaces remarks the biomechanical incompatibility as main limitation. To overcome it, the present work was focused in the design and analysis of several geometries and pore sizes and how they affect cell adhesion and proliferation of infrapatellar fat pad-derived mesenchymal stem cells (IPFP-MSCs) loaded in biofabricated 3D thermoplastic scaffolds. A novel biomaterial for CTE, the 1,4-butanediol thermoplastic polyurethane (b-TPUe) together PCL were studied to compare their mechanical properties. Three different geometrical patterns were included: hexagonal (H), square (S), and, triangular (T); each one was printed with three different pore sizes (PS): 1, 1.5 and 2 mm. Results showed differences in cell adhesion, cell proliferation and mechanical properties depending on the geometry, porosity and type of biomaterial used. Finally, the microstructure of the two optimal geometries (T1.5 and T2) was deeply analyzed using multiaxial mechanical tests, with and without perimeters, μCT for microstructure analysis, DNA quantification and degradation assays. In conclusion, our results evidenced that IPFP-MSCs-loaded b-TPUe scaffolds had higher similarity with cartilage mechanics and T1.5 was the best adapted morphology for CTE.

3D printing of tissue engineering scaffolds: a focus on vascular regeneration

Tissue engineering is an emerging means for resolving the problems of tissue repair and organ replacement in regenerative medicine. Insufficient supply of nutrients and oxygen to cells in large-scale tissues has led to the demand to prepare blood vessels. Scaffold-based tissue engineering approaches are effective methods to form new blood vessel tissues. The demand for blood vessels prompts systematic research on fabrication strategies of vascular scaffolds for tissue engineering. Recent advances in 3D printing have facilitated fabrication of vascular scaffolds, contributing to broad prospects for tissue vascularization. This review presents state of the art on modeling methods, print materials and preparation processes for fabrication of vascular scaffolds, and discusses the advantages and application fields of each method. Specially, significance and importance of scaffold-based tissue engineering for vascular regeneration are emphasized. Print materials and preparation processes are discussed in detail. And a focus is placed on preparation processes based on 3D printing technologies and traditional manufacturing technologies including casting, electrospinning, and Lego-like construction. And related studies are exemplified. Transformation of vascular scaffolds to clinical application is discussed. Also, four trends of 3D printing of tissue engineering vascular scaffolds are presented, including machine learning, near-infrared photopolymerization, 4D printing, and combination of self-assembly and 3D printing-based methods.

Evaluation of Bilayer Silk Fibroin Grafts for Tubular Esophagoplasty in a Porcine Defect Model

Surgical reconstruction of tubular esophageal defects with autologous gastrointestinal segments is the gold standard treatment to replace damaged or diseased esophageal tissues. Unfortunately, this approach is associated with adverse complications, including dysphagia, donor-site morbidity, and in some cases patient death. Bilayer silk fibroin (BLSF) scaffolds were investigated as alternative, acellular grafts for tubular esophagoplasty in a porcine defect model for 3 months of implantation. Adult Yucatan mini-swine (n = 5) were subjected to esophageal reconstruction with tubular BLSF grafts (2 cm in length) in combination with transient esophageal stenting for 2 months followed by a 1-month period, where the graft site was unstented. All animals receiving BLSF grafts survived and were capable of solid food consumption, however strictures were noted at graft regions in 60% of the experimental cohort between 2 and 3 months postop and required balloon dilation. In addition, fluoroscopic analysis showed peristaltic function in only 1/5 neotissues. Following swine harvest at 3 months, ex vivo tissue bath evaluations revealed that neoconduits exhibited contractile responses to carbachol, electric field stimulation, and KCl, whereas sodium nitroprusside and isoproterenol induced relaxation effects. Histological (Masson's Trichrome) and immunohistochemical analyses of regenerated tissue conduits showed a stratified, squamous epithelium expressing pan-cytokeratins buttressed by a vascularized lamina propria containing a smooth muscle-rich muscularis mucosa surrounded by a muscularis externa. Neuronal density, characterized by the presence of synaptophysin-positive boutons, was significantly lower in neotissues in comparison to nonsurgical controls. BLSF scaffolds represent a promising platform for the repair of tubular esophageal defects, however improvements in scaffold design are needed to reduce the rate of complications and improve the extent of constructive tissue remodeling. Impact statement The search for a superior "off-the-shelf" scaffold capable of repairing tubularesophageal defects as well as overcoming limitations associated with conventional autologous gastrointestinal segments remains elusive. The purpose of this study was to investigate the performance of an acellular, bilayer silk fibroin graft (BLSF) for tubular esophagoplasty in a porcine model. Our results demonstrated that BLSF scaffolds supported the formation of tubular neotissues with innervated, vascularized epithelial and muscular components capable of contractile and relaxation responses. BLSF scaffolds represent a promising platform for esophageal tissue engineering.

Tissue Engineered Esophageal Patch by Mesenchymal Stromal Cells: Optimization of Electrospun Patch Engineering

Aim of work was to locate a simple, reproducible protocol for uniform seeding and optimal cellularization of biodegradable patch minimizing the risk of structural damages of patch and its contamination in long-term culture. Two seeding procedures are exploited, namely static seeding procedures on biodegradable and biocompatible patches incubated as free floating (floating conditions) or supported by CellCrown^TM insert (fixed conditions) and engineered by porcine bone marrow MSCs (p-MSCs). Scaffold prototypes having specific structural features with regard to pore size, pore orientation, porosity, and pore distribution were produced using two different techniques, such as temperature-induced precipitation method and electrospinning technology. The investigation on different prototypes allowed achieving several implementations in terms of cell distribution uniformity, seeding efficiency, and cellularization timing. The cell seeding protocol in stating conditions demonstrated to be the most suitable method, as these conditions successfully improved the cellularization of polymeric patches. Furthermore, the investigation provided interesting information on patches’ stability in physiological simulating experimental conditions. Considering the in vitro results, it can be stated that the in vitro protocol proposed for patches cellularization is suitable to achieve homogeneous and complete cellularizations of patch. Moreover, the protocol turned out to be simple, repeatable, and reproducible.

Mechanical stimuli enhance simultaneous differentiation into oesophageal cell lineages in a double-layered tubular scaffold

The tissue-engineered oesophagus serves as an alternative and promising therapeutic approach for long-gap oesophageal replacement. This study proposes an advanced in vitro culture platform focused on construction of the oesophagus by combining an electrospun double-layered tubular scaffold, stem cells, biochemical reagents, and biomechanical factors. Human mesenchymal stem cells were seeded onto the inner and outer surfaces of the scaffold. Mechanical stimuli were applied with a hollow organ bioreactor along with different biochemical reagents inside and outside of the scaffold. Electrospun fibres in a tubular scaffold were found to be randomly and circumferentially oriented for the inner and outer surfaces, respectively. Amongst the two types of mechanical stimuli, the intermittent shear flow that can simultaneously cause circumferential stretching due to hydrostatic pressure, and shear stress caused by flow on the inner surface, was found to be more effective for simultaneous differentiation into epithelial and muscle lineage than steady shear flow. Under these conditions, the expression of epithelial markers on the inner surface was significantly observed, although it was minimal on the outer surface. Muscle differentiation showed the opposite expression pattern. Meanwhile, the mechanical tests showed that the strength of the scaffold was improved after incubation for 14 days. We have developed a potential platform for tissue-engineered oesophagus construction. Specifically, simultaneous differentiation into epithelial and muscle lineages can be achieved by utilizing the double-layered scaffold and appropriate mechanical stimulation.

Oesophageal atresia

Oesophageal atresia (EA) is a congenital abnormality of the oesophagus that is caused by incomplete embryonic compartmentalization of the foregut. EA commonly occurs with a tracheo-oesophageal fistula (TEF). Associated birth defects or anomalies, such as VACTERL association, trisomy 18 or 21 and CHARGE syndrome, occur in the majority of patients born with EA. Although several studies have revealed signalling pathways and genes potentially involved in the development of EA, our understanding of the pathophysiology of EA lags behind the improvements in surgical and clinical care of patients born with this anomaly. EA is treated surgically to restore the oesophageal interruption and, if present, ligate and divide the TEF. Survival is now ~90% in those born with EA with severe associated anomalies and even higher in those born with EA alone. Despite these achievements, long-term gastrointestinal and respiratory complications and comorbidities in patients born with EA are common and lead to decreased quality of life. Oesophageal motility disorders are probably ubiquitous in patients after undergoing EA repair and often underlie these complications and comorbidities. The implementation of several new diagnostic and screening tools in clinical care, including high-resolution impedance manometry, pH-multichannel intraluminal impedance testing and disease-specific quality of life questionnaires now provide better insight into these problems and may contribute to better long-term outcomes in the future.

Biological properties of a bionic scaffold for esophageal tissue engineering research

Polyurethane is a good matrix material with wide application prospects in tissue engineering because of its adjustable and mechanical properties. A novel biodegradable crosslinked poly(ester urethane) (CPU) with flexible poly(caprolactone) (PCL) and hydrophilic poly(ethylene glycol) (PEG) components has been synthesized using a ferric iron catalyst in our laboratory. In the present study, to promote the interaction between the CPU material and cells, the material was superficially modified by silk fibroin (SF) grafting using an aminolysis and glutaraldehyde crosslinking method to achieve a biocompatible material, CPU-SF. Considering the esophageal-specific architecture, three types of scaffolds were fabricated. S1 was a CPU-SF channel (200 μm in diameter and 30 μm in depth with 30 μm of wall thickness) to support muscle regeneration; S2 was the decellularized matrix of the esophageal mucosa/submucosa obtained by enzyme treatment; and S3 was a combination of S1 and S2, aiming to promote esophageal regeneration with histological structure and function. The biological properties and functions of the materials and scaffolds were investigated by qualitative and quantitative analyses using scanning electron microscopy, immunofluorescence staining, cell adhesion and proliferation measurements, and western blotting technology. The results showed that esophageal smooth muscle cells (SMCs) and epithelial cells (ECs) were very well supported by the scaffolds. In particular, SMCs exhibited guided directional growth and ECs infiltrated the acellular mucosa with retained biological functions when co-cultured on the composite scaffold S3. These findings suggest that the composite bionic scaffold will be a good alternative for esophageal replacement.