Ventral body wall closure: Mechanistic insights from mouse models and translation to human pathology.

The ventral body wall (VBW) that encloses the thoracic and abdominal cavities arises by extensive cell movements and morphogenetic changes during embryonic development. These morphogenetic processes include embryonic folding generating the primary body wall; the initial ventral cover of the embryo, followed by directed mesodermal cell migrations, contributing to the secondary body wall. Clinical anomalies in VBW development affect approximately 1 in 3000 live births. However, the cell interactions and critical cellular behaviors that control VBW development remain little understood. Here, we describe the embryonic origins of the VBW, the cellular and morphogenetic processes, and key genes, that are essential for VBW development. We also provide a clinical overview of VBW anomalies, together with environmental and genetic influences, and discuss the insight gained from over 70 mouse models that exhibit VBW defects, and their relevance, with respect to human pathology. In doing so we propose a phenotypic framework for researchers in the field which takes into account the clinical picture. We also highlight cases where there is a current paucity of mouse models for particular clinical defects and key gaps in knowledge about embryonic VBW development that need to be addressed to further understand mechanisms of human VBW pathologies.

Managing giant omphalocele: A systematic review of surgical techniques and outcomes.

AIM: We analysed closure techniques in the treatment of giant omphalocele. A challenging pathology where there lacks consensus. METHODS: Cochrane, MEDLINE and EMBASE were searched between 1 January 1992 and 31 December 2022 using terms and variations: omphalocele, exomphalos, giant, closure and outcome. Papers were selected using Preferred Reporting Items for Systematic review and Meta-Analyses 2020 criteria. Data collected included demographics, timing and technique of surgical repair, morbidity and mortality. RESULTS: We identified 342 papers; 34 met inclusion criteria with a total 356 neonates. Initial non-operative management was described in 26 papers (14 dressings, eight silo, four serial sac-ligation). Operative techniques by paper were as follows: Early closure: nine primary suture closure without patch, two primary closure with patch and four mixed methods. Delayed closure: five simple, four-component separation technique, four tissue expanders, one Botox/pneumoperitoneum and two with patch. Median number of procedures was two (1-6) in the early group versus three (1-4) in the delayed. The most favourable was early primary closure with biological patch. The most unfavourable was delayed closure with patch. Cumulative reported mortality remained high, mostly due to non-surgical causes. CONCLUSION: Definitions of giant omphalocele in the literature were heterogeneous with a variety of management approaches described.

Matrix Metalloproteinase-7 and Osteopontin Serum Levels as Biomarkers for Biliary Atresia.

OBJECTIVES: Matrix metallopeptidase-7 (MMP-7) and osteopontin (OPN) are important components in the pathophysiology of fibrosis in biliary atresia (BA). There has been much recent interest in MMP-7 serum level in the diagnosis of BA. We aimed to assess the diagnostic accuracy and prognostic value of both MMP-7 and OPN in a Western BA study. METHODS: Diagnostic value was assessed by comparison of serum MMP-7 and OPN levels in infants with BA and age-matched cholestatic controls. Prognostic value was assessed through subsequent clearance of jaundice (COJ) and need for liver transplantation (LT). RESULTS: Serum was assessed from 32 BA and 27 controls. Median MMP-7 was higher in BA (96.4 vs 35 ng/mL; P < 0.0001) with an optimal cut-off value of 69 ng/mL. Sensitivity and specificity was 68% and 93%, respectively [negative predictive value (NPV) = 71%]. Similarly, median OPN was higher in BA (1952 vs 1457 ng/mL; P = 0.0001) and an optimal cut-off of 1611 ng/mL. Sensitivity and specificity was 84% and 78%, respectively (NPV = 81%). MMP-7 level correlated positively with Ishak liver fibrosis score (r = 0.27, P = 0.04). Neither MMP-7 (70 vs 100 ng/mL; P = 0.2) nor OPN (1969 vs 1939 ng/mL; P = 0.3) were predictive of COJ, or need for LT (99 vs 79 ng/mL; P = 0.7, and 1981 vs 1899 ng/mL; P = 0.2), respectively. CONCLUSIONS: MMP-7 and OPN may have contributory value in the diagnosis of BA, but remain far of the "gold standard" role. Much more prospective data are required and collaborative multi-center initiatives should be the next logical steps.

Intestinal Bowel Lengthening within the First 6 Months of Life: Institutional Experience and Review of the Literature.

Background: Management of short bowel syndrome in children has been surrounded by much debate with timing of the lengthening procedure still controversial. Early bowel lengthening procedure (EBLP) has been defined as any bowel lengthening procedure performed before 6 months of age. The purpose of this paper is to report the institutional experience in EBLP and to review the literature on this subject to identify common indications. Methods: An institutional retrospective analysis of all the intestinal lengthening procedures was performed. Furthermore, an Ovid/Embase search regarding children who underwent bowel lengthening in the past 38 years was conducted. Primary diagnosis, age at procedure, type of procedure, indication, and outcome were analyzed. Results: Ten EBLP were performed in Manchester from 2006 to 2017. Median age at surgery was 121 days (102-140), preoperative small bowel (SB) length was 30 cm (20-49) while postoperative SB length was 54 cm (40-70), with a median increased bowel length of 80%. Ninety-seven papers were reviewed, with more than 399 lengthening procedures performed. Twenty-nine papers matched criteria with more than 60 EBLP were observed of which 10 were performed in a single center from 2006 to 2017. EBLP was performed due to SB atresia, to excessive bowel dilatation or failure to enteral feeds, at a median age of 60 days (1-90). Serial transverse enteroplasty was the most frequent procedure used lengthening the bowel from 40 cm (29-62.5) to 63 cm (49-85), with a median increased bowel length of 57%. Conclusions: This study confirms that no clear consensus on indication or timing to perform early SB lengthening is reported. According to the gathered data, EBLP should be considered, only in cases of actual necessity after review of qualified intestinal failure center.

TNAP limits TGF-ß-dependent cardiac and skeletal muscle fibrosis by inactivating the SMAD2/3 transcription factors.

Fibrosis is associated with almost all forms of chronic cardiac and skeletal muscle diseases. The accumulation of extracellular matrix impairs the contractility of muscle cells contributing to organ failure. Transforming growth factor ß (TGF-ß) plays a pivotal role in fibrosis, activating pro-fibrotic gene programmes via phosphorylation of SMAD2/3 transcription factors. However, the mechanisms that control de-phosphorylation of SMAD2 and SMAD3 (SMAD2/3) have remained poorly characterized. Here, we show that tissue non-specific alkaline phosphatase (TNAP, also known as ALPL) is highly upregulated in hypertrophic hearts and in dystrophic skeletal muscles, and that the abrogation of TGF-ß signalling in TNAP-positive cells reduces vascular and interstitial fibrosis. We show that TNAP colocalizes and interacts with SMAD2. The TNAP inhibitor MLS-0038949 increases SMAD2/3 phosphorylation, while TNAP overexpression reduces SMAD2/3 phosphorylation and the expression of downstream fibrotic genes. Overall our data demonstrate that TNAP negatively regulates TGF-ß signalling and likely represents a mechanism to limit fibrosis.

Transgelin-expressing myofibroblasts orchestrate ventral midline closure through TGFß signalling.

Ventral body wall (VBW) defects are among the most common congenital malformations, yet their embryonic origin and underlying molecular mechanisms remain poorly characterised. Transforming growth factor beta (TGFß) signalling is essential for VBW closure, but the responding cells are not known. Here, we identify in mouse a population of migratory myofibroblasts at the leading edge of the closing VBW that express the actin-binding protein transgelin (TAGLN) and TGFß receptor (TGFßR). These cells respond to a temporally regulated TGFß2 gradient originating from the epithelium of the primary body wall. Targeted elimination of TGFßR2 in TAGLN+ cells impairs midline closure and prevents the correct subsequent patterning of the musculature and skeletal components. Remarkably, deletion of Tgfbr2 in myogenic or chondrogenic progenitor cells does not manifest in midline defects. Our results indicate a pivotal significance of VBW myofibroblasts in orchestrating ventral midline closure by mediating the response to the TGFß gradient. Altogether, our data enable us to distinguish highly regulated epithelial-mesenchymal signalling and successive cellular migration events in VBW closure that explain early morphological changes underlying the development of congenital VBW defects.

Distinct Cellular Mechanisms Underlie Smooth Muscle Turnover in Vascular Development and Repair.

RATIONALE: Vascular smooth muscle turnover has important implications for blood vessel repair and for the development of cardiovascular diseases, yet lack of specific transgenic animal models has prevented it's in vivo analysis. OBJECTIVE: The objective of this study was to characterize the dynamics and mechanisms of vascular smooth muscle turnover from the earliest stages of embryonic development to arterial repair in the adult. METHODS AND RESULTS: We show that CD146 is transiently expressed in vascular smooth muscle development. By using CRISPR-Cas9 genome editing and in vitro smooth muscle differentiation assay, we demonstrate that CD146 regulates the balance between proliferation and differentiation. We developed a triple-transgenic mouse model to map the fate of NG2+CD146+ immature smooth muscle cells. A series of pulse-chase experiments revealed that the origin of aortic vascular smooth muscle cells can be traced back to progenitor cells that reside in the wall of the dorsal aorta of the embryo at E10.5. A distinct population of CD146+ smooth muscle progenitor cells emerges during embryonic development and is maintained postnatally at arterial branch sites. To characterize the contribution of different cell types to arterial repair, we used 2 injury models. In limited wire-induced injury response, existing smooth muscle cells are the primary contributors to neointima formation. In contrast, microanastomosis leads to early smooth muscle death and subsequent colonization of the vascular wall by proliferative adventitial cells that contribute to the repair. CONCLUSIONS: Extensive proliferation of immature smooth muscle cells in the primitive embryonic dorsal aorta establishes the long-lived lineages of smooth muscle cells that make up the wall of the adult aorta. A discrete population of smooth muscle cells forms in the embryo and is postnatally sustained at arterial branch sites. In response to arterial injuries, existing smooth muscle cells give rise to neointima, but on extensive damage, they are replaced by adventitial cells.

Surgical and Endoscopic Intervention for Chronic Pancreatitis in Children: The Kings College Hospital Experience.

Paediatric chronic pancreatitis (CP) is a rare and debilitating pathology that often requires invasive diagnostics and therapeutic interventions either to address a primary cause such as a pancreaticobiliary malunion or to deal with secondary complications such as chronic pain. Endoscopic retrograde cholangiopancreatography (ERCP) and endoscopic ultrasound (EUS) are two endoscopic modalities that have an established diagnostic role in paediatric CP, and their therapeutic utilisation is increasing in popularity. Surgical decompression of the obstructed and dilated pancreatic duct plays a role in alleviating pancreatic duct hypertension, a common association in CP. Surgery equally has a role in certain anatomical abnormalities of the pancreaticobiliary draining system, or occasionally in some CP complications such as drainage of a symptomatic pancreatic pseudocyst.

Standardising the elusive diagnosis of NEC in the premature infant - A practical score.

OBJECTIVE: The perceived risk of necrotising enterocolitis (NEC) can result in overtreatment of the otherwise adapting preterm neonate. We aim to develop an assessment tool to aid the decision making in the management of preterm neonates at risk of NEC. METHOD: An evidence-based assessment tool was designed bringing together clinical, laboratory and radiological signs commonly associated with NEC. A numerical score was awarded for each sign, with those more specific to NEC being graded higher. A multi-centre validation was conducted of the proposed assessment tool over three tertiary neonatal units. RESULTS: A total of 125 patients were included, 53 (42.4 %) with a final diagnosis of NEC and 72 (57.6 %) with an alternative diagnosis. The NEC group had a significantly higher total score compared to the non-NEC group; 15(2-28) vs. 4(1-9) (p ≤ 0.0001). In ROC analysis, using a cut-off of eight, the assessment tool gave a sensitivity of 92.3 % and a specificity of 90.4 % for identifying NEC compared to an alternative diagnosis. CONCLUSION: This comprehensive scoring system encourages a full assessment of the infant before deciding on withholding feeds, starting antibiotics, and transferring to a surgical centre. It is a safe objective measure to support a diagnosis of NEC in the presence of certain clinical signs.

Cardiac-associated biliary atresia (CABA): a prognostic subgroup.

OBJECTIVES: To describe the range of concurrent cardiac malformations in biliary atresia (BA) while providing a functional framework of risk. METHODS: Demographic and variables were collected from a prospectively maintained single-centre database. Infants were grouped according to a cardiac functional framework (A=acyanotic, B=cyanotic and C=insignificant shunt). Primary outcome was set as clearance of jaundice (bilirubin ≤20 µmol/L) following Kasai portoenterostomy (KPE). Native liver survival and overall actuarial survival were compared with a date-matched control infant with BA (n=77). P value <0.05 was regarded as significant. RESULTS: 524 infants with histologically confirmed BA were treated between January 1999 and December 2018, 37 (7%) had a concurrent cardiac anomaly (A: n=23 (62%), B: n=10 (27%), C: n=4 (11%)). Infants with biliary atresia splenic malformation (BASM) or cat-eye syndrome (CES) contributed over half of the cases (21/37; 57%).Overall, 20 (54%) infants cleared jaundice (vs 50/77 (65%) controls; p=0.2), but with higher mortality compared with the non-cardiac controls (15/37 (40%) vs 3/77 (4%); HR 15.5 (95% CI 5.5 to 43.4); p<0.00001). Infants requiring cardiac intervention in the first year of life (n=15) were more likely to clear jaundice (6/7 vs 2/8; p=0.04) and had a trend towards higher survival (6/7 vs 3/8; p=0.1) when KPE followed cardiac surgery. Yet, the type of cardiac pathology did not impact clearance of jaundice or mortality. CONCLUSION: We propose the term cardiac-associated biliary atresia (CABA) as a high-risk group. We believe that restorative cardiac surgery should precede KPE wherever possible to improve outcome.