Tissue-engineered Esophagus Research Articles

Ultrastructural changes in esophageal tissue undergoing stretch tests with possible impact on tissue engineering and long gap esophageal repairs performed under tension

Esophageal biomechanical studies are being performed to understand structural changes resulting from stretches during repair of esophageal atresias as well as to obtain biomechanical values for tissue-engineered esophagus. The present study offers insights into ultrastructural changes after stretching of the ovine esophagus using uniaxial stretch tests. In vitro uniaxial stretching was performed on esophagi (n = 16) obtained from the abattoir within 4–6 h of 1-month-old lambs. Esophagi were divided into 4 groups (4 esophagi/group): control, Group1 (G1), Group2 (G2), Group3 (G3) stretched to 20%, 30% and 40% of their original length respectively. Force and lengthening were measured with 5 cycles performed on every specimen. Transmission electron microscopic (TEM) studies were performed on the 4 groups. During observational TEM study of the control group there were no significant differences in muscle cell structure or extracellular matrix. In all stretched groups varying degrees of alterations were identified. The degree of damage correlated linearly with the increasing level of stretch. Distance between the cells showed significant difference between the groups (control (μ = 0.41 μm, SD = 0.26), G1 (μ = 1.36 μm, SD = 1.21), G2 (μ = 2.8 μm, SD = 1.83), and G3 (μ = 3.01 μm, SD = 2.06). The diameter of the cells (control μ = 19.87 μm, SD = 3.81; G1 μ = 20.38 μm, SD = 4.45; G2 μ = 21.7 μm, SD = 6.58; G3 μ = 24.48 μm, SD = 6.69) and the distance between myofibrils (control μ = 0.23 μm, SD = 0.08; G1 μ = 0.27 μm, SD = 0.08; G2 μ = 0.4 μm, SD = 0.15; G3 μ = 0.61 μm, SD = 0.2) were significantly different as well ( p < 0.05 was considered to be significant). Esophageal stretching > 30% alters the regular intracellular and extracellular structure of the esophageal muscle and leads to disruption of intra- and extracellular bonds. These findings could provide valuable insights into alterations in the microscopic structure of the esophagus in esophageal atresias repaired under tension as well as the basis for mechanical characterization for tissue engineering of the esophagus.

Assessment of Esophageal Reconstruction via Bioreactor Cultivation of a Synthetic Scaffold in a Canine Model.

Using tissue-engineered materials for esophageal reconstruction is a technically challenging task in animals that requires bioreactor training to enhance cellular reactivity. There have been many attempts at esophageal tissue engineering, but the success rate has been limited due to difficulty in initial epithelialization in the special environment of peristalsis. The purpose of this study was to evaluate the potential of an artificial esophagus that can enhance the regeneration of esophageal mucosa and muscle through the optimal combination of a double-layered polymeric scaffold and a custom-designed mesenchymal stem cell-based bioreactor system in a canine model. We fabricated a novel double-layered scaffold as a tissue-engineered esophagus using an electrospinning technique. Prior to transplantation, human-derived mesenchymal stem cells were seeded into the lumen of the scaffold, and bioreactor cultivation was performed to enhance cellular reactivity. After 3 days of cultivation using the bioreactor system, tissue-engineered artificial esophagus was transplanted into a partial esophageal defect (5×3 cm-long resection) in a canine model. Scanning electron microscopy (SEM) showed that the electrospun fibers in a tubular scaffold were randomly and circumferentially located toward the inner and outer surfaces. Complete recovery of the esophageal mucosa was confirmed by endoscopic analysis and SEM. Esophagogastroduodenoscopy and computed tomography also showed that there were no signs of leakage or stricture and that there was a normal lumen with complete epithelialization. Significant regeneration of the mucosal layer was observed by keratin-5 immunostaining. Alpha-smooth muscle actin immunostaining showed significantly greater esophageal muscle regeneration at 12 months than at 6 months. Custom-designed bioreactor cultured electrospun polyurethane scaffolds can be a promising approach for esophageal tissue engineering.

Tissue-engineered esophagus: recellular esophageal extracellular matrix based on perfusion-decellularized technique and mesenchymal stem cells

Perfusion-decellularization was an interesting technique to generate a natural extracellular matrix (ECM) with the complete three-dimensional anatomical structure and vascular system. In this study, the esophageal ECM (E-ECM) scaffold was successfully constructed by perfusion-decellularized technique through the vascular system for the first time. And the physicochemical and biological properties of the E-ECM scaffolds were evaluated. The bone marrow mesenchymal stem cells (BMSCs) were induced to differentiate into myocytes in vitro. E-ECM scaffolds reseeded with myocytes were implanted into the greater omenta to obtain recellular esophageal ECM (RE-ECM), a tissue-engineered esophagus. The results showed that the cells of the esophagi were completely and uniformly removed after perfusion. E-ECM scaffolds retained the original four-layer organizational structure and vascular system with excellent biocompatibility. And the E-ECM scaffolds had no significant difference in mechanical properties comparing with fresh esophagi, p > 0.05. Immunocytochemistry showed positive expression of α-sarcomeric actin, suggesting that BMSCs had successfully differentiated into myocytes. Most importantly, we found that in the RE-ECM muscularis, the myocytes regenerated linearly and continuously and migrated to the deep, and the tissue vascularization was obvious. The cell survival rates at 1 week and 2 weeks were 98.5 ± 3.0% and 96.4 ± 4.6%, respectively. It was demonstrated that myocytes maintained the ability for proliferation and differentiation for at least 2 weeks, and the cell activity was satisfactory in the RE-ECM. It follows that the tissue-engineered esophagus based on perfusion-decellularized technique and mesenchymal stem cells has great potential in esophageal repair. It is proposed as a promising alternative for reconstruction of esophageal defects in the future.

Esophagus stretch tests: Biomechanics for tissue engineering and possible implications on the outcome of esophageal atresia repairs performed under excessive tension.

Esophageal biomechanical studies are important to understand structural changes resulting from stretches during repair of esophageal atresias as well as to obtain values to compare with the biomechanics of tissue-engineered esophagus in the future. This study aimed to investigate light microscopic changes after uniaxial stretching of the ovine esophagus. In vitro uniaxial stretching was performed on esophagi (n = 20) of 1-month-old lambs within 4-6h post-mortem. Esophagi were divided into 5 groups: control and stretched (1.1, 1.2, 1.3 and 1.4). Force and lengthening were measured with 5 cycles performed on every specimen using a PBS organ bath at 37°C. Histological studies were performed on the 5 groups. Low forces of ~ 2N (N) were sufficient for a 1.2-1.25 stretch in the 1st cycle, whereas a three times higher force (~ 6N) was needed for a stretch of 1.3. In the 2nd to 5th cycle, the tissue weakened and a force of ~ 3N was sufficient for a stretch of 1.3. Histologically, in the 1.3-1.4 stretch groups, rupture of muscle fibers and capillaries were observed, respectively. Changes in mucosa and collagen fibers could not be observed. These results offer norm values from the native esophagus to compare with the biomechanics of future tissue-engineered esophagus. Esophageal stretching > 1.3 leads to tears in muscle fibers and to rupture of capillaries. These findings can explain the decrease in microcirculation and scarring in mobilized tissue and possibly offer clues to impaired motility in esophagus atresias repaired under excessive tension.

In Vitro Regeneration of Decellularized Pig Esophagus Using Human Amniotic Stem Cells.

Decellularization of esophagus was studied using three different protocols. The sodium deoxycholate/DNase-I (SDC/DNase-I) method was the most successful as evidenced by histology and DNA quantification of the acellular scaffolds. Acellular scaffolds were further analyzed and compared with native tissue by histology, quantitative analysis of DNA, and extracellular matrix (ECM) proteins. Histologically, the SDC/DNase-I protocol effectively produced scaffold with preserved structural architecture similar to native tissue architecture devoid of any cell nucleus. ECM proteins, such as collagen, elastin, and glycosaminoglycans were present even after detergent-enzymatic decellularization. Immunohistochemical analysis of acellular scaffold showed weak expression of Gal 1, 3 Gal epitope compared with native tissue. For performing recellularization, human amnion-derived mesenchymal stem cells (MSCs) and epithelial cells were seeded onto acellular esophagus in a perfusion–rotation bioreactor. In recellularized esophagus, immunohistochemistry showed infiltration of MSCs from adventitia into the muscularis externa and differentiation of MSCs into the smooth muscle actin and few endothelial cells (CD31). Our study demonstrates successful preparation and characterization of a decellularized esophagus with reduced load of Gal 1, 3 Gal epitope with preserved architecture and ECM proteins similar to native tissue. Upon subsequent recellularization, xenogeneic acellular esophagus also supported stem cell growth and partial differentiation of stem cells. Hence, the current study offers the hope for preparing a tissue-engineered esophagus in vitro which can be transplanted further into pigs for further in vivo evaluation.

SIS/aligned fibre scaffold designed to meet layered oesophageal tissue complexity and properties

With donor organs not readily available, the need for a tissue-engineered oesophagus remains high, particularly for congenital childhood conditions such as atresia. Previous attempts have not been successful, and challenges remain. Small intestine submucosa (SIS) is an acellular matrix material with good biological properties; however, as is common with these types of materials, they demonstrate poor mechanical properties. In this work, electrospinning was performed to mechanically reinforce tubular SIS with polylactic-co-glycolic acid (PLGA) nanofibres. It was hypothesised that if attachment could be achieved between the two materials, then this would (i) improve the SIS mechanical properties, (ii) facilitate smooth muscle cell alignment to support directional growth of muscle cells and (iii) allow for the delivery of bioactive molecules (VEGF in this instance).Through a relatively simple multistage process, adhesion between the layers was achieved without chemically altering the SIS. It was also found that altering mandrel rotation speed affected the alignment of the PLGA nanofibres. SIS-PLGA scaffolds performed mechanically better than SIS alone; yield stress improvement was 200% and 400% along the longitudinal and circumferential directions, respectively. Smooth muscle cells cultured on the aligned fibres showed resultant unidirectional alignment. In vivo the SIS-PLGA scaffolds demonstrated limited foreign body reaction judged by the type and proportion of immune cells present and lack of fibrous encapsulation. The scaffolds remained intact at 4 weeks in vivo, and good cellular infiltration was observed. The incorporation of VEGF within SIS-PLGA scaffolds increased the blood vessel density of the surrounding tissues, highlighting the possible stimulation of endothelialisation by angiogenic factor delivery. Overall, the designed SIS-PLGA-VEGF hybrid scaffolds might be used as a potential matrix platform for oesophageal tissue engineering. In addition to this, achieving improved attachment between layers of acellular matrix materials and electrospun fibre layers offers the potential utility in other applications. Statement of SignificanceBecause of its multi-layered nature and complex structure, the oesophagus tissue poses several challenges for successful clinical grafting. Therefore, it is promising to utilise tissue engineering strategies to mimic and form structural compartments for its recovery. In this context, we investigated the use of tubular small intestine submucosa (SIS) reinforced with polylactic-co-glycolic acid (PLGA) nanofibres by using electrospinning and also, amongst other parameters, the integrity of the bilayered structure created. This was carried out to facilitate smooth muscle cell alignment, support directional growth of muscle cells and allow the delivery of bioactive molecules (VEGF in this study). We evaluated this approach by using in vitro and in vivo models to determine the efficacy of this new system.

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 14days. 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.

DOZ047.101: Preclinical studies of tissue engineering for long-gap esophageal atresia in pigs. A systematic literature review

Abstract Introduction Current approaches for esophageal substitution in long-gap esophageal atresia (LGEA) are associated with complications that impact quality of life. Tissue-engineered (TE) esophagus appears as a promise to overcome these issues. The pig has been used as large-animal model to test TE esophagus before its clinical application. Different approaches have been reported. This study aims at conducting a systematic review of TE approaches for complete esophageal defects in pigs. Materials and Methods This work was registered in PROSPERO (ID 127838). A systematic literature review was performed following SYRCLE’s guidelines, using the CAMARADES-NC3Rs platform (SyRF). PubMed and OpenGrey databases were reviewed identifying articles on complete esophagus defects in pigs restored by TE. The analyses of bias and 3Rs were based on the ARRIVE guidelines. Results In the period 2009–2018, 14 articles were identified using pigs as a model for a TE approach in complete esophageal defects. Animal age/weight/sex, size/localization of the defect, TE strategy, follow-up, and outcomes greatly differ among different studies. Few studies report strategies to improve 3Rs and internal validation. Discussion Further studies in LGEA preclinical models should be performed in an attempt to create a defect in the intrathoracic esophagus. Methodological design may help to avoid bias and define strategies related to the 3Rs. TE approaches with best results include the use of different cell populations seeded in scaffolds that are maturated in bioreactors before their implantation. The next questions to be addressed are developing techniques to avoid stent migration and promoting regeneration of the enteric nervous system.

Tissue-Engineered Esophagus via Bioreactor Cultivation for Circumferential Esophageal Reconstruction.

The use of biomaterials for circumferential esophageal repair is technically challenging in a rat model, and an optimal scaffold implantation technique with nutritional support is essential. The purpose of this study was to investigate the effects of three-dimensional printed esophageal grafts and bioreactor cultivation on muscle regeneration and reepithelialization from circumferential esophageal defects in a rat model. Here, we designed an artificial esophagus that can enhance the regeneration of esophageal mucosa and muscle through the optimal combination of a two-layered tubular scaffold and mesenchymal stem cell-based bioreactor system. The graft was verified by the performance comparison with an omentum-cultured esophageal scaffold. We also applied a new surgical anastomosis technique and a thyroid gland flap over the implanted scaffold to improve graft survival. Although no regenerated mucosal layer was observed around the implants of the control group, histological examination of the regenerative esophagi along the scaffold revealed that the bioreactor system and omentum-cultured groups showed more than 80% of the mucosal regeneration without a fistula. The regenerated tissues showed that the integration of the esophageal scaffold and its native esophageal tissue was intact and were covered with layers of stratified squamous epithelium with several newly developed blood vessels. Therefore, this study describes a novel approach for circumferential esophageal reconstruction. Impact Statement In vivo functional esophageal reconstruction remains challenging due to anastomosis site leakage and necrosis of the implanted scaffold in a circumferential esophageal defect. Therefore, it is necessary to develop a tissue-engineered esophagus that enables regeneration of esophageal mucosa and muscle without leakage of the esophageal anastomosis. In this study, we proposed an intriguing strategy that combines a mesenchymal stem cell-seeded tubular scaffold with a bioreactor system for esophageal reconstruction and introduced a new surgical anastomosis technique with the thyroid gland flap over the implanted scaffold to improve graft survival. We believe that this system should be a powerful platform for circumferential replacement of the esophagus in a rat model.

Morphological evaluation of the quality of decellularized esophagus in rat

The main aim of our investigation was analysis and optimization of the existing protocols of esophagus decellularization in rats, identification of parameters affecting the quality of decellularization and intactness of the native properties of esophageal extracellular matrix (ECM). Materials and methods. We developed a modified decellularization protocol based on detergent-enzymatic method using sodium deoxycholate and DNAse. Results. Morphological evaluation of the obtained decellularized matrices demonstrated the absence of cells and cell elements while mechanical properties of ECM were preserved. Conclusion. The developed protocol of esophagus decellularization is a potential basis for obtaining of tissue-engineered esophagus scaffold constructions.

Editorial Expression of Concern: Experimental orthotopic transplantation of a tissue-engineered oesophagus in rats.

Editorial Expression of Concern: Experimental orthotopic transplantation of a tissue-engineered oesophagus in rats

Biomimetic and synthetic esophageal tissue engineering

Background/PurposeA tissue-engineered esophagus offers an alternative for the treatment of pediatric patients suffering from severe esophageal malformations, caustic injury, and cancer. Additionally, adult patients suffering from carcinoma or trauma would benefit. MethodsDonor rat esophageal tissue was physically and enzymatically digested to isolate epithelial and smooth muscle cells, which were cultured in epithelial cell medium or smooth muscle cell medium and characterized by immunofluorescence. Isolated cells were also seeded onto electrospun synthetic PLGA and PCL/PLGA scaffolds in a physiologic hollow organ bioreactor. After 2 weeks of in vitro culture, tissue-engineered constructs were orthotopically transplanted. ResultsIsolated cells were shown to give rise to epithelial, smooth muscle, and glial cell types. After 14 days in culture, scaffolds supported epithelial, smooth muscle and glial cell phenotypes. Transplanted constructs integrated into the host's native tissue and recipients of the engineered tissue demonstrated normal feeding habits. Characterization after 14 days of implantation revealed that all three cellular phenotypes were present in varying degrees in seeded and unseeded scaffolds. ConclusionsWe demonstrate that isolated cells from native esophagus can be cultured and seeded onto electrospun scaffolds to create esophageal constructs. These constructs have potential translatable application for tissue engineering of human esophageal tissue.

Murine and human tissue-engineered esophagus form from sufficient stem/progenitor cells and do not require microdesigned biomaterials.

Tissue-engineered esophagus (TEE) may serve as a therapeutic replacement for absent foregut. Most prior esophagus studies have favored microdesigned biomaterials and yielded epithelial growth alone. None have generated human TEE with mesenchymal components. We hypothesized that sufficient progenitor cells might only require basic support for successful generation of murine and human TEE. Esophageal organoid units (EOUs) were isolated from murine or human esophagi and implanted on a polyglycolic acid/poly-l-lactic acid collagen-coated scaffold in adult allogeneic or immune-deficient mice. Alternatively, EOU were cultured for 10 days in vitro prior to implantation. TEE recapitulated all key components of native esophagus with an epithelium and subjacent muscularis. Differentiated suprabasal and proliferative basal layers of esophageal epithelium, muscle, and nerve were identified. Lineage tracing demonstrated that multiple EOU could contribute to the epithelium and mesenchyme of a single TEE. Cultured murine EOU grew as an expanding sphere of proliferative basal cells on a neuromuscular network that demonstrated spontaneous peristalsis in culture. Subsequently, cultured EOU generated TEE. TEE forms after transplantation of mouse and human organ-specific stem/progenitor cells in vivo on a relatively simple biodegradable scaffold. This is a first step toward future human therapies.

Isolation of esophageal stem cells with potential for therapy.

PurposeLong-gap esophageal atresia represents a significant challenge for pediatric surgeons and current surgical approaches are associated with significant morbidity. A tissue-engineered esophagus, comprising cells seeded onto a scaffold, represents a therapeutic alternative. In this study, we aimed to determine the optimal techniques for isolation and culture of mouse esophageal epithelial cells and to isolate CD34-positive esophageal epithelial stem cells from cadaveric mouse specimens.MethodsPrimary epithelial cells were isolated from mouse esophagi by enzymatic dissociation from the mucosal layer (Dispase, Trypsin/EDTA) using three different protocols. In protocol A, isolated mucosa was minced and incubated with trypsin once. In protocol B, intact mucosal sheets underwent two trypsin incubations yielding a single-cell suspension. In protocol C, intact mucosa explants were plated epithelial side down. Epithelial cells were cultured on collagen-coated wells.ResultsInitial findings showed that Protocol B gave the best results in terms of yield, viability, and least contamination with different cell types and microbes. Esophageal epithelial cells isolated using Protocol B were stained for CD34 and sorted using fluorescence-activated cell sorting (FACS). Of the total cells sorted, 8.3 % (2–11.3) [%median (range)] were CD34 positive.ConclusionsOur results demonstrate that mouse esophageal epithelial cells can be successfully isolated from fresh mouse esophagi using two consecutive trypsin incubations of intact mucosal sheets. Furthermore, the cells obtained using this method were successfully stained for CD34, a putative esophageal epithelial stem cell marker. Further research into the factors necessary for the successful proliferation of CD34 positive stem cell lines is needed to progress toward clinical application.

Sufficient Progenitor Cells Do Not Require Microdesigned Biomaterials to Generate Murine and Human Tissue-Engineered Esophagus

Sufficient Progenitor Cells Do Not Require Microdesigned Biomaterials to Generate Murine and Human Tissue-Engineered Esophagus

Oesophagus: tissue-engineered oesophagus successfully transplanted in rats.

Oesophagus: tissue-engineered oesophagus successfully transplanted in rats.

Experimental orthotopic transplantation of a tissue-engineered oesophagus in rats.

A tissue-engineered oesophageal scaffold could be very useful for the treatment of pediatric and adult patients with benign or malignant diseases such as carcinomas, trauma or congenital malformations. Here we decellularize rat oesophagi inside a perfusion bioreactor to create biocompatible biological rat scaffolds that mimic native architecture, resist mechanical stress and induce angiogenesis. Seeded allogeneic mesenchymal stromal cells spontaneously differentiate (proven by gene-, protein and functional evaluations) into epithelial- and muscle-like cells. The reseeded scaffolds are used to orthotopically replace the entire cervical oesophagus in immunocompetent rats. All animals survive the 14-day study period, with patent and functional grafts, and gain significantly more weight than sham-operated animals. Explanted grafts show regeneration of all the major cell and tissue components of the oesophagus including functional epithelium, muscle fibres, nerves and vasculature. We consider the presented tissue-engineered oesophageal scaffolds a significant step towards the clinical application of bioengineered oesophagi.

Detergent enzymatic treatment for the development of a natural acellular matrix for oesophageal regeneration

Tissue engineering of the oesophagus has been proposed as a therapeutic alternative to organ transplantation. We previously demonstrated that a detergent enzymatic treatment (DET) is a valid method to obtain an acellular matrix with preservation of the native architecture. In this study, we aimed to develop a natural acellular matrix from pig oesophagus, as a valid framework for oesophageal replacement. Pig oesophagi (n=4) were decellularized with continuous luminal infusion of DET. To evaluate the efficiency of the decellularization, samples were assessed by histology and DNA quantification. Moreover, the ultra-structural characteristics of the acellular matrix were investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Decellularization of the oesophagus was achieved after three cycles of DET. Histological analysis showed the maintenance of tissue matrix architecture with absence of cellular elements, verified by measurement of DNA. SEM and TEM analysis confirmed preservation of the ultra-structural characteristics of the native tissue. Oesophageal acellular matrix can be successfully obtained by decellularization of pig oesophagus using a gentle DET via the oesophageal lumen. This decellularization method preserves the ultrastructure of the native tissue and could represent the basis for a tissue-engineered oesophagus.

Tissue engineered esophagus by mesenchymal stem cell seeding for esophageal repair in a canine model

PurposeAcellular porcine small intestinal submucosa (SIS) has been successfully used for esophagoplasty in dogs. However, this has not led to complete epithelialization and muscular regeneration. We undertook the present study to assess the effect of tissue-engineered esophagus generated by seeding bone marrow mesenchymal stem cells (BMSCs) onto an SIS scaffold (BMSCs-SIS) in a canine model. MethodsWe cultured, passaged, and measured autologous BMSCs and myoblasts with cell proliferation and immunohistochemical assays. We labeled the third passage of BMSCs with PKH-26, a fluorescent dye, before seeded it onto the SIS. We resected canine cervical esophagus to generate a defect 5 cm in length and 50% in circumference, which we repaired with BMSCs-SIS or SIS alone. ResultsFour weeks later, barium esophagram demonstrated that esophageal lumen surface of the patch graft was smoother in the BMSCs-SIS group compared with the SIS group. Histological examination suggested a strong similarity between BMSCs and esophageal myoblasts in terms of morphology and function. Although both BMSCs-SIS and SIS repaired the esophageal defects, we noted complete re-epithelialization with almost no inflammation only in the former group. By 12 wk after the surgery, we observed long bundles of skeletal muscles only in the BMSCs-SIS group, where the microvessel density was also much greater. ConclusionsBone marrow mesenchymal stem cells on an SIS scaffold can promote re-epithelialization, revascularization, and muscular regeneration. This approach may provide an attractive option for esophageal regeneration.

Tissue-engineering of the gastrointestinal tract

The purpose of this review is to describe recent advancements in tissue-engineering of the gastrointestinal system. For some patients, a congenital or acquired defect in the alimentary system results in digestive or nutritional deficiencies requiring intervention. Unfortunately, these treatments are associated with morbid complications. Advances in the growth of tissue-engineered esophagus, stomach, small intestine, colon and anus have been made in recent years. The progress reviewed here hopefully will someday benefit patients with gastrointestinal organ loss by providing a tissue replacement with morphology and function similar to native tissue. In native gastrointestinal tissue, epithelial homeostasis is governed largely by the interaction of the stem cell and its surrounding cellular niche. In particular, the small intestinal stem cell populations identified as the crypt base columnar cell (CBCC) and at cell position 4 (cp4) are responsible for mucosal maintenance and response to injury. This work influences efforts to generate bioengineered tissues for both in-vitro mucosal models and full-thickness in-vivo tissue-engineered esophagus, stomach, intestine and colon. Gastrointestinal organ loss is a challenge to manage. Current therapy can be life-saving, but is associated with morbid complications. Tissue-engineering will someday restore normal gastrointestinal function and eliminate the need for nutritional supplementation or transplant.