Update on Foregut Molecular Embryology and Role of Regenerative Medicine Therapies

Thoracoscopic Stage Internal Traction Repair Reduces Time to Achieve Esophageal Continuity in Long Gap Esophageal Atresia

OBJECTIVE

 Management of long gap esophageal atresia (LGOA) is controversial. This study aims at comparing the management of LGOA between two high-volume centers.

METHODS

 We included patients with LGOA (type A and B) between 2008 and 2022. Demographics, surgical methods, and outcomes were collected and compared.

RESULTS

 The study population involved 28 patients in center A and 24 patients in center B. A surgical approach was thoracoscopic in center A, only for one patient was open for final procedure. In center B, 3 patients were treated only thoracoscopically, 2 converted to open, and 19 as open surgery. In center A primary esophageal anastomosis concerned 1 case, two-staged esophageal lengthening using external traction 1 patient, and 26 were treated with the multistaged internal traction technique. In 24 patients a full anastomosis was achieved: in 23 patients only the internal traction technique was used, while 1 patient required open Collis-Nissen procedure as final management. In center B primary anastomosis was performed in 7 patients, delayed esophageal anastomosis in 8 patients, esophageal lengthening using external traction in 1 case, and 9 infants required esophageal replacement with gastric tube. Analyzed postoperative complications included: early mortality, 2/28 due to accompanied malformations (center A) and 0/24 (center B); anastomotic leakage, 4/26 (center A) treated conservatively-all patients had a contrast study-and 0/24 (center B), 1 case of pleural effusion, but no routine contrast study; recurrent strictures, 13/26 (center A) and 7/15 (center B); and need for fundoplication, 5/26 (center A) and 2/15 (center B). Age at esophageal continuity was as a median of 31 days in center A and 110 days in center B. Median time between initial procedure and esophageal anastomosis was 11 days in center A and 92 days in center B.

CONCLUSION

 Thoracoscopic internal traction technique reduces time to achieve esophageal continuity and the need for esophageal substitution while maintaining a similar early complication rate.

Regenerative medicine: current research and perspective in pediatric surgery

The field of regenerative medicine, encompassing several disciplines including stem cell biology and tissue engineering, continues to advance with the accumulating research on cell manipulation technologies, gene therapy and new materials. Recent progress in preclinical and clinical studies may transcend the boundaries of regenerative medicine from laboratory research towards clinical reality. However, for the ultimate goal to construct bioengineered transplantable organs, a number of issues still need to be addressed. In particular, engineering of elaborate tissues and organs requires a fine combination of different relevant aspects; not only the repopulation of multiple cell phenotypes in an appropriate distribution but also the adjustment of the host environmental factors such as vascularisation, innervation and immunomodulation. The aim of this review article is to provide an overview of the recent discoveries and development in stem cells and tissue engineering, which are inseparably interconnected. The current status of research on tissue stem cells and bioengineering, and the possibilities for application in specific organs relevant to paediatric surgery have been specifically focused and outlined.

Endoscopic interventional therapies for tracheoesophageal fistulas in children: A systematic review

Methods

An electronic literature search was performed using the keywords "tracheoesophageal fistula," "endoscopic," and "children" in the four major medical databases (Ovid, Embase, PubMed, and Web of Science) right from inception to September 2022. All English language articles describing the endoscopic interventional therapies of TEF in children were reviewed. Two independent researchers screened eligible articles at the title and abstract level. Full texts of potentially relevant articles were then screened again, and reference lists were screened manually to identify additional studies. Relevant data were extracted and analyzed. A synthesis of the relevant data was presented in descriptive form because of the heterogeneity of the included articles. The Chi-Squared test was used with a significance level of 5% (P < 0.05).

Results

Among the 1,167 retrieved papers, a total of 46 studies describing 170 TEF patients with an age range of 0.3-175 months were included, including 11 cases of acquired tracheoesophageal fistula, 144 cases of recurrent tracheoesophageal fistula, and 15 cases of congenital tracheoesophageal fistula (H-type TEF). A total of 119 out of 170 fistulas were successfully blocked via endoscopic techniques with an overall success rate of 70.0%, while 48 fistulas failed to close by endoscopic interventions, following which the procedure was converted to open surgery. No obviously severe intraoperative/postoperative complications occurred during the follow-up period, but only a mild esophageal stricture was noticed in six patients and grade II tracheal stenosis in one patient. Two patients died from causes unrelated to endoscopic procedures, with a mortality rate of approximately 1.2%. A comparative assessment of different endoscopic interventional techniques for TEF that detected endotracheal stenting was performed in six patients and one fistula was successfully blocked (16.7%). De-epithelialization alone was performed in 65 patients and the fistula healed in 47 of them (72.3%), with the mean number of successful treatments required being 2.3 times. Chemical sealant injection was administered in 33 patients and success was achieved in 21 (63.6%). The average requirement for endoscopic procedures was 1.5 times. De-epithelialization, in combination with chemical sealant injection, was performed in 62 patients, achieving the highest success rate of 77.4% (48 patients). Other treatment methods were performed in four patients and successfully treatment outcomes were reported in two of them (50.0%). The mean number of successful treatments required was four times, and a treatment was converted to surgery in one patient (25.0%). An assessment of different TEF types showed that 9 out of 15 congenital TEFs, 7 out of 11 acquired TEFs, and 103 out of 144 recurrent TEFs were successfully occluded. A comparison of the success rate across multiple groups showed a significant difference with a score of P < 0.05, while there was no significant difference in the success rate of different TEF-type groups (P > 0.05).

Conclusion

Endoscopic intervention is currently a preferred treatment modality for children with TEF because of its less-invasive nature, less complications, and high success rate. Among all interventional techniques, de-epithelialization, in combination with chemical sealant, has a higher success rate than other techniques. However, due to the limited number of cases reported for implementing many kinds of techniques, an ideal endoscopic interventional technique has yet to be devised, often necessitating more treatment applications and close follow-up.

Delayed primary anastomosis for repair of long-gap esophageal atresia: technique revisited

The operative management of patients born with long-gap esophageal atresia (LGEA) remains a major challenge for most pediatric surgeons, due to the rarity and complex nature of this malformation. In LGEA, the distance between the proximal and distal esophageal end is too wide, making a primary anastomosis often impossible. Still, every effort should be made to preserve the native esophagus as no other conduit can replace its function in transporting food from the oral cavity to the stomach satisfactorily. In 1981, Puri et al. observed that in newborns with LGEA spontaneous growth and hypertrophy of the two segments occur at a rate faster than overall somatic growth in the absence of any form of mechanical stretching, traction or bouginage. They further noted that maximal natural growth arises in the first 8-12 weeks of life, stimulated by the swallowing reflex and reflux of gastric contents into the lower esophageal pouch. Since then, creation of an initial gastrostomy and continuous suction of the upper esophageal pouch followed by delayed primary anastomosis at approximately 3 months of age has been widely accepted as the preferred treatment option in most LGEA cases, generally providing good functional results. The current article offers a comprehensive update on the various aspects and challenges of this technique including initial preoperative management and subsequent gap assessment, while also discussing potential postoperative complications and long-term outcome.

A case of esophageal atresia with the bronchial-like lower esophagus which originates from the left lower lobe bronchus

Background

Esophageal atresia with or without a trachea–esophageal fistula occurs due to the failure of separation or incomplete development of the foregut. Therefore, esophageal atresia is often associated with various forms of tracheobronchial anomalies. We report an extremely rare case of esophageal atresia.

Case presentation

A female infant was born at 37 weeks of gestation and weighed 2596 g. A diagnosis of esophageal atresia and total anomalous pulmonary vein return type III were confirmed. The infant had respiratory distress that required tracheal intubation and ventilatory support soon after birth. Temporary banding of the gastroesophageal junction and gastrostomy were performed on the second day of life. However, her respiratory condition deteriorated due to atelectasis of the left lung and compensatory hyperinflation of the right lung. Preoperative examinations showed the unilobe and atelectatic left lung. The trachea was trifurcated in three directions, and the branch that was expected to be the left main bronchus was blind-ended. The dorsal branch was cartilaginous and bifurcated into the left lower lobe bronchus and lower esophagus approximately 1 cm distal from the tracheal trifurcation. The cartilaginous tissue continued to the lower esophagus. The diagnosis of esophageal atresia with the lower esophagus which originated from the left lower lobe bronchus was made. Esophageal atresia repair was performed when the patient was 4 months of age. The esophagus was dissected distally to the bifurcation of the left lower lobe bronchus via right thoracotomy. The lower esophagus was bronchial-like in appearance, transitioning to the normal esophageal wall approximately 7 mm distal to the transected edge. The cartilage tissue was completely resected during surgery, and a primary end-to-end anastomosis of the esophagus was successfully performed. Histopathological findings revealed that the extracted specimen was surrounded by tracheal cartilage and that the inner surface was covered by stratified squamous epithelium that originated from the esophagus.

Conclusions

In cases of esophageal atresia with an atypical clinical presentation, there may be unique structural abnormalities of the foregut. We emphasize the importance of a preoperative surgical planning since an inadequate operation can lead to fatal complications.

Functional human gastrointestinal organoids can be engineered from three primary germ layers derived separately from pluripotent stem cells

Human organoid model systems lack important cell types that, in the embryo, are incorporated into organ tissues during development. We developed an organoid assembly approach starting with cells from the three primary germ layers-enteric neuroglial, mesenchymal, and epithelial precursors-that were derived separately from human pluripotent stem cells (PSCs). From these three cell types, we generated human antral and fundic gastric tissue containing differentiated glands surrounded by layers of smooth muscle containing functional enteric neurons that controlled contractions of the engineered antral tissue. Using this experimental system, we show that human enteric neural crest cells (ENCCs) promote mesenchyme development and glandular morphogenesis of antral stomach organoids. Moreover, ENCCs can act directly on the foregut to promote a posterior fate, resulting in organoids with a Brunner's gland phenotype. Thus, germ layer components that are derived separately from PSCs can be used for tissue engineering to generate complex human organoids.

Gastrointestinal duplication cysts: what a radiologist needs to know

Gastrointestinal tract duplication cysts are rare congenital malformations which can be diagnosed as early as the prenatal period but are frequently found in infancy or incidentally in adulthood. They can be seen throughout the alimentary tract with the most common involving the distal ileum and second most common the esophagus. Many duplication cysts are asymptomatic and thus discovered as an incidental imaging finding, though they can also be symptomatic with an array of clinical presentations dependent largely on their location. The vast majority of duplication cysts are benign; however, there are rare instances of malignant transformation reported. The aim of this review is to show how multimodality imaging can help in the diagnosis of duplication cysts at various anatomical locations. Duplication cyst can become symptomatic and in rare cases undergo malignant transformation; therefore, they are typically managed with surgical excision, particularly if found prenatally or during infancy. Given the diversity of anatomic locations, multiple differential diagnoses, and the need for surgical intervention, it is valuable to comprehend the role of multimodality imaging role in diagnosing duplication cysts.

Prioritizing and characterizing functionally relevant genes across human tissues

Knowledge of genes that are critical to a tissue's function remains difficult to ascertain and presents a major bottleneck toward a mechanistic understanding of genotype-phenotype links. Here, we present the first machine learning model-FUGUE-combining transcriptional and network features, to predict tissue-relevant genes across 30 human tissues. FUGUE achieves an average cross-validation auROC of 0.86 and auPRC of 0.50 (expected 0.09). In independent datasets, FUGUE accurately distinguishes tissue or cell type-specific genes, significantly outperforming the conventional metric based on tissue-specific expression alone. Comparison of tissue-relevant transcription factors across tissue recapitulate their developmental relationships. Interestingly, the tissue-relevant genes cluster on the genome within topologically associated domains and furthermore, are highly enriched for differentially expressed genes in the corresponding cancer type. We provide the prioritized gene lists in 30 human tissues and an open-source software to prioritize genes in a novel context given multi-sample transcriptomic data.

Tissue engineering of the gastroesophageal junction

The gastroesophageal junction has been of clinical interest for some time due to its important role in preventing reflux of caustic stomach contents upward into the esophagus. Failure of this role has been identified as a key driver in gastroesophageal reflux disease, cancer of the lower esophagus, and aspiration-induced lung complications. Due to the large population burden and significant morbidity and mortality related to reflux barrier dysfunction, there is a pressing need to develop tissue engineering solutions which can replace diseased junctions. While good progress has been made in engineering the bodies of the esophagus and stomach, little has been done for the junction between the two. In this review, we discuss pertinent topics which should be considered as tissue engineers begin to address this anatomical region. The embryological development and adult anatomy and histology are discussed to provide context about the native structures which must be replicated. The roles of smooth muscle structures in the esophagus and stomach, as well as the contribution of the diaphragm to normal anti-reflux function are then examined. Finally, engineering considerations including mechanics and current progress in the field of tissue engineering are presented.

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.

Multi-stage bioengineering of a layered oesophagus with in vitro expanded muscle and epithelial adult progenitors

A tissue engineered oesophagus could overcome limitations associated with oesophageal substitution. Combining decellularized scaffolds with patient-derived cells shows promise for regeneration of tissue defects. In this proof-of-principle study, a two-stage approach for generation of a bio-artificial oesophageal graft addresses some major challenges in organ engineering, namely: (i) development of multi-strata tubular structures, (ii) appropriate re-population/maturation of constructs before transplantation, (iii) cryopreservation of bio-engineered organs and (iv) in vivo pre-vascularization. The graft comprises decellularized rat oesophagus homogeneously re-populated with mesoangioblasts and fibroblasts for the muscle layer. The oesophageal muscle reaches organised maturation after dynamic culture in a bioreactor and functional integration with neural crest stem cells. Grafts are pre-vascularised in vivo in the omentum prior to mucosa reconstitution with expanded epithelial progenitors. Overall, our optimised two-stage approach produces a fully re-populated, structurally organized and pre-vascularized oesophageal substitute, which could become an alternative to current oesophageal substitutes.

Combining decellularised scaffolds with patient-derived cells holds promise for bioengineering of functional tissues. Here the authors develop a two-stage approach to engineer an oesophageal graft that retains the structural organisation of native oesophagus.