Oncologic Fidelity of Minimally Invasive Surgery to Resect Neoadjuvant-Treated Wilms Tumors.

BACKGROUND: The Children's Oncology Group recommends upfront resection of Wilms tumor (WT), however, unique scenarios warrant neoadjuvant chemotherapy and delayed resection. We hypothesized that in the context of neoadjuvant chemotherapy, minimally invasive surgery (MIS) to resect WT achieves equivalent oncologic fidelity and better maintains therapy schedules. METHODS: A retrospective analysis of WT treated between 2010-2021 at a free-standing children's hospital was performed. Patient and disease specific characteristics were collected, and pre-resection tumor volumes (TV) were calculated. Impact of MIS or open resection on oncologic fidelity and time to resume chemotherapy was analyzed. RESULTS: For the study period, 62 patients were treated for 65 WT, and 14 patients (22.6%) received neoadjuvant chemotherapy to treat 17 WT (26.2%): 7 Stage I (all predisposition syndromes), 2 stage III, 7 stage IV, and 1 stage V (bilateral). MIS was utilized to resect 6 WT from 5 patients. For partial nephrectomy, pre-resection TV was 0.38 ml if MIS and 10.38 ml if open (P = .025). For radical nephrectomy, pre-resection TV was 31.58 ml if MIS and 175.00 ml if open (P = .101). No significant differences between surgical approach were detected regarding pathologic variables or survival. Epidural use was significantly greater with open procedures (P = .001). Length of stay was 2.00 days after MIS compared to 6.00 for open resection (P = .004). Time to resume chemotherapy was 7.00 days after MIS versus 27.00 for open (P = .004). CONCLUSION: After neoadjuvant chemotherapy for WT, MIS partial and radical nephrectomies achieved equivalent oncologic fidelity, reduced epidural use and post-operative stays, and better maintained adjuvant therapy timelines when compared to open resections.

Comparing 30-day outcomes between early versus delayed repair of anorectal malformations with perineal or rectovestibular fistulas: An analysis of the ACS NSQIP-Pediatric database.

BACKGROUND: Anorectal malformations (ARMs) have a wide spectrum of presentation ranging from mild defects with perineal fistulas to more severe defects requiring complex management. A primary repair of ARMs with perineal or rectovestibular fistulas has been shown to have good outcomes. However, the timing of the reconstruction is still debated. The aim of this study is to investigate the safety of early versus delayed repair. METHODS: This study was performed using data from the National Surgical Quality Improvement Program-Pediatric (NSQIP-P) from 2012 to 2017. Patients who underwent repair of anorectal malformation with perineal or vestibular fistula were included in the study. Patients with associated diagnosis for Hirschsprung disease, cloaca, rectal prolapse or stenosis, bladder exstrophy, and tracheoesophageal fistula were excluded. 30-day postoperative outcomes included wound and nonwound complications, readmissions, and reoperations. Outcomes were compared by early (≤7 days of age) versus delayed repair (6 weeks to 8 months). RESULTS: A total of 291 patients were included, with 66 in the early and 231 in the delayed group. Patients in the early group were more likely to be male (68.2% vs 31.8%; p < 0.01) and have cardiac risk factors (71.2% vs 49.4%, p < 0.01). The mean operative time was significantly shorter in the early group (90.1 vs 129.6 min; p < 0.01). 30-day complications were not statistically significant between the two groups (p = 0.76). After multivariate analysis, timing of repair did not affect 30-day complications (p = 0.15). CONCLUSION: Our study shows that early repair of low anorectal malformations with a perineal or vestibular fistula appears to be associated with no increase in risk of postoperative complications as compared to delayed repair. At present, the decision remains dependent on the surgeon's experience and judgment. LEVEL OF EVIDENCE: Level III. Retrospective comparative study.

The impact of post-operative opioid guidelines on prescribing behaviors in the pediatric population.

BACKGROUND: Opioid misuse continues to be a major source of morbidity and mortality in the US, in both the adult and pediatric populations. Post-operative opioid prescriptions are often the first exposure children have to opioids and increases their risk of chronic use. There is significant variation in the number of opioids following identical procedures and measures have been taken within the adult population to limit this. However, specific post-operative opioid prescription guidelines are not present in the pediatric population. METHODS: Seven common pediatric surgery procedures were selected for inclusion. The recommended number of opioid doses following each procedure was determined by a multi-disciplinary expert panel. All surgery residents were sent an initial survey to determine the number of opioids they would prescribe for each procedure. They were then shown the guidelines and the survey repeated to determine changes in response. RESULTS: 35 and 27 general surgery residents took part in and pre- and post-educational surveys respectively. In all procedures, there was a decrease in the mean number of post-operative opioids prescribed. In addition, there was an increase in the number of residents who prescribed within the guidelines and a decrease in the number who overprescribed post-operative opioids. CONCLUSION: Pediatric postoperative opioid prescribing guidelines derived from expert opinion increase resident compliance with appropriate dosing; this has the potential to decrease the classic problem of general surgery residents accustomed to treating adults overprescribing opioids to children. These results are promising, and we aim to expand on this work and incorporate these guidelines into our clinical practice. LEVEL OF EVIDENCE: III/IV.

Development of Intestinal Scaffolds that Mimic Native Mammalian Intestinal Tissue.

IMPACT STATEMENT: This study is significant because it demonstrates an attempt to design a scaffold specifically for small intestine using a novel fabrication method, resulting in an architecture that resembles intestinal villi. In addition, we use the versatile polymer poly(glycerol sebacate) (PGS) for artificial intestine, which has tunable mechanical and degradation properties that can be harnessed for further fine-tuning of scaffold design. Moreover, the utilization of PGS allows for future development of growth factor and drug delivery from the scaffolds to promote artificial intestine formation.

Cognitive impairments induced by necrotizing enterocolitis can be prevented by inhibiting microglial activation in mouse brain.

Necrotizing enterocolitis (NEC) is a severe gastrointestinal disease of the premature infant. One of the most important long-term complications observed in children who survive NEC early in life is the development of profound neurological impairments. However, the pathways leading to NEC-associated neurological impairments remain unknown, thus limiting the development of prevention strategies. We have recently shown that NEC development is dependent on the expression of the lipopolysaccharide receptor Toll-like receptor 4 (TLR4) on the intestinal epithelium, whose activation by bacteria in the newborn gut leads to mucosal inflammation. Here, we hypothesized that damage-induced production of TLR4 endogenous ligands in the intestine might lead to activation of microglial cells in the brain and promote cognitive impairments. We identified a gut-brain signaling axis in an NEC mouse model in which activation of intestinal TLR4 signaling led to release of high-mobility group box 1 in the intestine that, in turn, promoted microglial activation in the brain and neurological dysfunction. We further demonstrated that an orally administered dendrimer-based nanotherapeutic approach to targeting activated microglia could prevent NEC-associated neurological dysfunction in neonatal mice. These findings shed light on the molecular pathways leading to the development of NEC-associated brain injury, provide a rationale for early removal of diseased intestine in NEC, and indicate the potential of targeted therapies that protect the developing brain in the treatment of NEC in early childhood.

The Development of Newborn Porcine Models for Evaluation of Tissue-Engineered Small Intestine.

Short bowel syndrome (SBS) is a major cause of morbidity and mortality in the pediatric population, for which treatment options are limited. To develop novel approaches for the treatment of SBS, we now focus on the development of a tissue-engineered intestine (also known as an "artificial intestine"), in which intestinal stem cells are cultured onto an absorbable bioscaffold, followed by implantation into the host. To enhance the translational potential of these preclinical studies, we have developed three clinically relevant models in neonatal piglets, which approximate the size of the human infant and were evaluated after implantation and establishment of intestinal continuity over the long term. The models included (1) a staged, multioperation approach; (2) a single operation with a de-functionalized loop of small intestine; and (3) a single operation with an intestinal bypass. The first model had complications related to multiple operations in a short time period, including surgical site infections and wound hernias. The second model avoided wound complications, but was associated with high ostomy output, local skin breakdown, and systemic dehydration with associated electrolyte imbalances. The third model was the most effective, although resulted in stoma prolapse. In summary, we have now developed and evaluated three operative methods for the long-term evaluation of the artificial intestine in the piglet, and conclude that a single operation with a de-functionalized loop of small intestine may be an optimal approach for evaluation over the long term.

Tissue engineering for the treatment of short bowel syndrome in children.

Short bowel syndrome is a major cause of morbidity and mortality in children. Despite decades of experience in the management of short bowel syndrome, current therapy is primarily supportive. Definitive treatment often requires intestinal transplantation, which is associated with significant morbidity and mortality. In order to develop novel approaches to the treatment of short bowel syndrome, we and others have focused on the development of an artificial intestine, by placing intestinal stem cells on a bioscaffold that has an absorptive surface resembling native intestine, and taking advantage of neovascularization to develop a blood supply. This review will explore recent advances in biomaterials, vascularization, and progress toward development of a functional epithelium and mesenchymal niche, highlighting both success and ongoing challenges in the field.

Retinoic Acid Improves Incidence and Severity of Necrotizing Enterocolitis by Lymphocyte Balance Restitution and Repopulation of LGR5+ Intestinal Stem Cells.

Necrotizing enterocolitis (NEC) is the most devastating gastrointestinal disease of the premature infant. We have recently shown that NEC development occurs after an increase in proinflammatory CD4Th17 (Th17) cells and reduced anti-inflammatory forkhead box P3 regulatory T cells (Tregs) to the premature small intestine of mice and humans, which can be experimentally reversed in mice by administration of all-trans retinoic acid (ATRA). We have also shown that NEC is characterized by apoptosis of Lgr5-positive intestinal stem cells (ISCs-Lgr5 cells) within the crypts of Lieberkühn, which are subsequently essential for intestinal homeostasis. We now hypothesize that the normal lymphocyte balance within the lamina propria of the intestine can be achieved via administration of ATRA which restores mucosal integrity by preventing the loss of ISCs. Using both in vivo and in vitro strategies, we now demonstrate that Th17 recruitment and Treg depletion lead to increased apoptosis within ISC niches, significantly impairing proliferative capacity and mucosal healing. ATRA exerted its protective effects by preventing T cell imbalance, ultimately leading to the protection of the ISC pool preventing the development of NEC in mice. These findings raise the exciting possibility that dietary manipulations could prevent and treat NEC by modulating lymphocyte balance and the ISC pool within the newborn small intestine.

The human milk oligosaccharide 2'-fucosyllactose attenuates the severity of experimental necrotising enterocolitis by enhancing mesenteric perfusion in the neonatal intestine.

Necrotising enterocolitis (NEC) is a common disease in premature infants characterised by intestinal ischaemia and necrosis. The only effective preventative strategy against NEC is the administration of breast milk, although the protective mechanisms remain unknown. We hypothesise that an abundant human milk oligosaccharide (HMO) in breast milk, 2'-fucosyllactose (2'FL), protects against NEC by enhancing intestinal mucosal blood flow, and we sought to determine the mechanisms underlying this protection. Administration of HMO-2'FL protected against NEC in neonatal wild-type mice, resulted in a decrease in pro-inflammatory markers and preserved the small intestinal mucosal architecture. These protective effects occurred via restoration of intestinal perfusion through up-regulation of the vasodilatory molecule endothelial nitric oxide synthase (eNOS), as administration of HMO-2'FL to eNOS-deficient mice or to mice that received eNOS inhibitors did not protect against NEC, and by 16S analysis HMO-2'FL affected the microbiota of the neonatal mouse gut, although these changes do not seem to be the primary mechanism of protection. Induction of eNOS by HMO-2'FL was also observed in cultured endothelial cells, providing a link between eNOS and HMO in the endothelium. These data demonstrate that HMO-2'FL protects against NEC in part through maintaining mesenteric perfusion via increased eNOS expression, and suggest that the 2'FL found in human milk may be mediating some of the protective benefits of breast milk in the clinical setting against NEC.

Pulmonary Epithelial TLR4 Activation Leads to Lung Injury in Neonatal Necrotizing Enterocolitis.

We seek to define the mechanisms leading to the development of lung disease in the setting of neonatal necrotizing enterocolitis (NEC), a life-threatening gastrointestinal disease of premature infants characterized by the sudden onset of intestinal necrosis. NEC development in mice requires activation of the LPS receptor TLR4 on the intestinal epithelium, through its effects on modulating epithelial injury and repair. Although NEC-associated lung injury is more severe than the lung injury that occurs in premature infants without NEC, the mechanisms leading to its development remain unknown. In this study, we now show that TLR4 expression in the lung gradually increases during postnatal development, and that mice and humans with NEC-associated lung inflammation express higher levels of pulmonary TLR4 than do age-matched controls. NEC in wild-type newborn mice resulted in significant pulmonary injury that was prevented by deletion of TLR4 from the pulmonary epithelium, indicating a role for pulmonary TLR4 in lung injury development. Mechanistically, intestinal epithelial TLR4 activation induced high-mobility group box 1 release from the intestine, which activated pulmonary epithelial TLR4, leading to the induction of the neutrophil recruiting CXCL5 and the influx of proinflammatory neutrophils to the lung. Strikingly, the aerosolized administration of a novel carbohydrate TLR4 inhibitor prevented CXCL5 upregulation and blocked NEC-induced lung injury in mice. These findings illustrate the critical role of pulmonary TLR4 in the development of NEC-associated lung injury, and they suggest that inhibition of this innate immune receptor in the neonatal lung may prevent this devastating complication of NEC.