The impact of the recipient intestinal site on the differentiation of transplanted enteric neural crest cells

PURPOSE

It has long been established that the failure of enteric neural crest cells (ENCCs) to colonize the entire gut results in aganglionosis at the distal colon in Hirschsprung disease (HD). However, it is still unclear how the intestinal microenvironment of the distal aganglionic gut differs from that of the proximal ganglionic gut in HD versus normal gut. We have recently succeeded in transplanting ENCC into aganglionic gut in endothelin receptor B (Ednrb) knockout (KO) mice. to advance the development of cell therapy for HD, it is essential to determine if the transplanted ENCCs differentiate normally in aganglionic gut. Therefore, we designed this study to investigate the impact of the environment of the recipient intestinal tract, at various sites of aganglionic gut, on the differentiation of transplanted ENCCs.

METHODS

ENCCs were isolated from Sox10 Venus transgenic (Tg) mouse gut on embryonic day 18.5 (E18.5) and neurospheres (NS) were generated. Then, NS were transplanted into aganglionic KO and wildtype (WT) gut that had been transected just distal to the ENCC wavefront (KO-wf: n = 6, WT: n = 7), and into distal KO gut transected at a site equivalent to that of the WT (KO-d: n = 6) on E12.5. ENCC differentiation was evaluated using whole-mount immunohistochemistry with Tuj-1 (neuronal marker) and GFAP (glial marker) antibodies.

RESULTS

The transplanted ENCCs migrated to form the myenteric and submucosal plexus in all groups. The ratio of the area of Tuj-1-positive cells/GFAP-positive cells in migrated cells in the recipient gut was found to be significantly lower in KO-d compared to KO-wf and WT, while there was no significant difference between KO-wf and WT groups. This suggests that neuronal/glial differentiation was decreased in KO-d compared to that in KO-wf and WT groups.

CONCLUSION

Our study highlights the differences in ENCC differentiation depending on the site of transplantation. To further develop cell therapy for HD, it is important to consider the impact of the recipient intestinal environment on transplanted ENCCs.

A novel mouse model of intestinal neuronal dysplasia: visualization of the enteric nervous system

PURPOSE

Intestinal neuronal dysplasia (IND) is a congenital anomaly affecting gastrointestinal neural innervation, but the pathogenesis remains unclear. The homozygous Ncx/Hox11L.1 knockout (Ncx-/-) mice exhibit megacolon and enteric ganglia anomalies, resembling IND phenotypes. Sox10-Venus transgenic mouse were used to visualize enteric neural crest cells in real time. This study aims to establish a novel mouse model of Sox10-Venus+/Ncx-/- mouse to study the pathogenesis of IND.

METHODS

Sox10-Venus+/Ncx-/- (Ncx-/-) (n = 8) mice and Sox10-Venus+/Ncx+/+ controls (control) (n = 8) were euthanized at 4-5 weeks old, and excised intestines were examined with fluorescence microscopy. Immunohistochemistry was performed on tissue sections with neural marker Tuj1.

RESULTS

Ncx-/- mice exhibited dilated cecum and small intestine. Body weight of Ncx-/- mice was lower with higher ratio of small intestine length relative to body weight. The neural network (Sox10-Venus) was observed along the intestine wall in Ncx-/- and control mice without staining. Ectopic and increased expression of Tuj1 was observed in both small intestine and proximal colon of Ncx-/- mice.

CONCLUSION

This study has established a reliable animal model that exhibits characteristics similar to patients with IND. This novel mouse model can allow the easy visualization of ENS in a time- and cost-effective way to study the pathogenesis of IND.

Increased enteric neural crest cell differentiation after transplantation into aganglionic mouse gut

PURPOSE

In recent years, many studies have made considerable progress in the development of stem cell-based therapies for Hirschsprung's disease (HD). However, the question of whether enteric neural crest-derived cells (ENCCs) that are transplanted into the aganglionic gut can migrate, proliferate, and differentiate in a normal manner remains unanswered. Thus, we designed this study to compare the behavior of ENCCs transplanted into the aganglionic gut of endothelin receptor B knockout (Ednrb-KO) mice versus wild-type (WT) mice.

METHODS

ENCCs were isolated from the fetal guts of Sox10 transgenic mice, in which ENCCs were labeled with an enhanced green fluorescent protein, Venus, on an embryonic day 18.5 (E18.5). Neurospheres were generated and transplanted into the aganglionic region of either Ednrb-KO mice gut, or WT mice gut that had not yet been colonized, on E12.5. Time-lapse imaging of the transplanted ENCCs was performed after 24, 48, and 72 h of culture. Neuronal differentiation was evaluated using whole-mount immunohistochemistry.

RESULTS

Sox10-positive ENCCs were seen to successfully migrate into the myenteric region of the aganglionic gut following transplantation in both the Ednrb-KO and WT mice. The ratio of Tuj1-positive/Sox10-positive cells was significantly increased after 72 h of culture compared to 24 h in the Ednrb-KO mice, which suggests that the transplanted ENCCs differentiated over time. In addition, at the 72 h timepoint, neuronal differentiation of transplanted ENCC in the aganglionic gut of Ednrb-KO mice was significantly increased compared to that of WT mice.

CONCLUSIONS

The results of our study demonstrated that transplanted ENCCs migrated into the myenteric region of the aganglionic recipient gut in mice. The increased neuronal differentiation of transplanted ENCC in Endrb-KO mice gut suggests that the microenvironment of this region affects ENCC behavior following transplantation. Further research to explore the characteristics of this microenvironment will improve the potential of developing cell therapy to treat HD patients.

Differentiation of enteric neural crest cells transplanted from SOX10-Venus mouse embryonic stem cells into the gut of the endothelin receptor B null mouse model

PURPOSE

Failure of enteric neural crest-derived cells (ENCCs) to correctly colonize the embryonic gut results in Hirschsprung's disease (HD). Embryonic stem cells (ESCs) have the potential to differentiate into all tissue-specific cells and lineages, including ENCCs. We investigated the cellular differentiation of ESCs from Sox10-Venus ⁺ mice into both control and endothelin receptor-B knockout (Ednrb KO) mouse gut to assess each region.

METHODS

We established ESCs from Sox10-Venus ⁺ mice. These cells were cultured for 2 days, then selected and co-cultured with either a dissociated control or Sox10-Venus ^- Ednrb KO mouse gut (both small intestine and colon) on embryonic day (E) 13.5. Four days later, cells were immunolabeled for Tuj1 and visualized using confocal microscopy.

RESULTS

Confocal microscopy revealed that transplanted Sox10-Venu ⁺ cells from ESCs migrated extensively within the host gut. Moreover, Tuj1-positive neurites were detected in the transplanted ESCs. Tuj1 expression was significantly decreased in aganglionic HD colon compared to controls (p < 0.05) and the HD small intestine (p < 0.05).

CONCLUSIONS

This study demonstrated that an appropriate host environment is crucial for normal and complete colonization of the gut. Further investigations are required to confirm whether modifying this environment can improve the results of this model.

Assessment of laparoscopic inguinal hernia repair using the classification for single port laparoscopy in adolescents and young adults

BACKGROUND

Inguinal hernia repair is one of the most common operations performed worldwide. No consensus currently exists regarding the most appropriate operation for inguinal hernia in adolescent and young adult (AYA) patients. This study aimed to evaluate the outcomes in AYA patients undergoing high ligation or mesh repair under laparoscopy by examining the location and size of the hernia orifice defect.

METHODS

We retrospectively reviewed all patients aged 15 to 40 years old who underwent laparoscopic hernia repair. Under single port laparoscopy, we classified the anatomic location (lateral, medial, or femoral) and size of the hernia orifice according to the classification by the European Hernia Society (EHS). A laparoscopic percutaneous extraperitoneal closure (LPEC) was performed on the patients with a lateral hernia with a hernia orifice defect size of ≤1.5 cm (L1). Transabdominal preperitoneal (TAPP) repair was performed on the patients with a lateral hernia with a hernia orifice defect size of >1.5 cm (L2 or 3).

RESULTS

Overall, 40 patients underwent the mentioned surgical procedures. We performed LPEC on 22 patients, and TAPP on 18 patients. There were no intraoperative or postoperative complications and recurrences.

CONCLUSIONS

This is the first report that evaluated the outcomes of AYA patients who underwent high ligation or mesh repair under laparoscopy by examining the location and size of the hernia orifice defect. Our data indicated that LPEC were effective and safe for AYA patients with small hernia orifice defect.

Do Parameatal Urethral Cysts in Children Need Surgical Excision?

OBJECTIVE

To examine pathophysiology of parameatal urethral cyst (PUC) with comparison between the surgical excision group and the spontaneous resolution group.

METHODS

We retrospectively reviewed all patients diagnosed with PUC and aged ≤15 years. Initially, all the patients received observation without any treatment. The indication of surgical excision was family preference. The patients were analyzed according to their sex, age, symptoms, clinical course, and pathological examination findings.

RESULTS

Among the 54 boys visited our hospital for PUC. The median age at presentation was 35 (IQR: 12-50) months, including 7 (13.0%) neonates cases. In total, 38 (70.4%) patients were underwent surgical excision, 12 (22.2%) had spontaneous resolution during observation, 1 (1.9%) had observation without resolution, and 3 (5.6%) were lost to follow-up. The median size of PUC at the first visit was significantly larger in the surgical excision group (5 mm median, IQR 3-5) than in the spontaneous resolution group (1.5 mm median, IQR 1-2.5) (P <.0001). In this study, PUC ≥5 mm in diameter did not have spontaneous resolution.

CONCLUSION

This is the largest study of PUC conducted at a single institute. This study indicated that 22% of PUCs had spontaneous resolution, and PUCs <5 mm had potential for spontaneous resolution. The results recommend an observation of at least 5.5 months for patients with asymptomatic PUC <5 mm. By contrast, we recommend the surgical excision for symptomatic PUC ≥5 mm according to the family preference.

In vitro investigation of the differentiation of enteric neural crest-derived cells following transplantation of aganglionic gut in a mouse model

PURPOSE

Cell therapy is a promising approach to treat enteric neuropathies such as Hirschsprung disease (HD). Recent studies have reported that enteric neurons derived from stem cells (ENCCs) can be grafted into the HD colon. Thus, we investigated the migration and generation of enteric neurospheres from SOX10-VENUS⁺ mice after transplantation into control or Ednrb KO mice, which are a model of HD.

METHODS

Single-cell suspensions were isolated from the fetal guts of SOX10-VENUS⁺ mice E13.5 and dissociated. These cells were cultured for 7 days under non-adherent conditions to generate neurospheres, which were co-cultured with dissociated control or SOX10-VENUS^- Ednrb KO mouse gut on E13.5. 4 days later, these cells were fixed and the expression of the neuronal marker, Tuj1, was evaluated.

RESULTS

Transplanted neurospheres had undergone abundant neuronal migration and differentiation of ENCCs in the control gut compared with the HD gut. The average length and intersections were significantly decreased in HD colon compared with controls (p < 0.05), and a similar pattern was observed in the HD small intestine (p < 0.05).

CONCLUSIONS

We demonstrated that transplanted ENCCs did not differentiate properly in HD gut. These results highlight the importance of the neuronal environment in the recipient gut for enteric nervous system development.

Forty-Year Experience Alleviating Postoperative Hirschsprung-Associated Enterocolitis by Complete Full-Thickness Posterior Rectal Cuff Excision. The Anorectal Line Eliminates Problematic Anastomoses

Introduction: A modified pull-through (PT) distinguished by complete full-thickness removal of the posterior rectal cuff, initially developed as an open procedure in 1980, has been performed with laparoscopic assistance since 1997. Postoperative bowel dysfunction improved when the anatomic landmark for PT surgery was revised from the dentate line (DL) to the anorectal (or Herrmann's) line (ARL) in 2007. A 40-year (1980-2019) review of 153 consecutive rectal/rectosigmoid type Hirschsprung's disease (HD) patients is presented. Methods: Data for postoperative bowel dysfunction and Hirschsprung-associated enterocolitis (HAEC) classified according to the American Pediatric Surgical Association (APSA) scale were obtained retrospectively. Results: PT was open (n = 43) and laparoscopic (n = 110). Dissection was DL (n = 57) and ARL (n = 96). Over 40 years, 5/153 patients (3.3%) had postoperative obstructive symptoms (POS), and 10/153 patients (6.5%) had 13 episodes of postoperative HAEC; APSA grades were: I (n = 4); II (n = 8); and III: (n = 1) presenting with explosive diarrhea (10/13; 76.9%), fever (10/13; 76.9%), abdominal distension (9/13; 69.2%), or bloody stools/shock (1/13 with grade III; 7.7%). The grade III case had histologically-proven transitional zone PT. Postoperative HAEC developed in 3/5 (60.0%) POS+ patients and 7/148 (4.7%) POS- patients (P = .002). Symptom duration and treatment were not correlated with APSA grades. Conclusions: Complete full-thickness posterior rectal cuff excision and using the ARL reduced postoperative HAEC significantly in this series. Despite being anatomically distinct, the DL is inadequate as a precise landmark for PT surgery because it lacks functional relevance. The APSA scale could benefit from timely review to improve its clinical and prognostic value.

Can Intraoperative Video Recordings Contribute to Improving Laparoscopic Percutaneous Extraperitoneal Closure in Children with Inguinal Hernia and Prevent Recurrence? A Pilot Study

Aim: We reviewed intraoperative video recordings (IVRs) of laparoscopic percutaneous extraperitoneal closure (LPEC) for inguinal hernia in children blindly to assess performance. Methods: IVRs of 183 LPEC performed between April 2013 and March 2016, graded by the operating surgeon as difficult (D; n = 8), straightforward (S; n = 96), or easy (E; n = 79), were scored by a panel of reviewers with advanced (group A; >400 LPEC cases; n = 5), intermediate (group I; 50-150 cases; n = 5), and basic (group B; <10 cases; n = 5) experience, according to suturing, dissection plane, vas/vessel dissection, bleeding, and peritoneal injury. They also allocated a recurrence risk rank (RRR; highest = 6; lowest = 1) for each IVR. Mean score variance for each IVR was also compared between reviewers. Results: There was one recurrence (R; 4-year-old male; level E). RRR were: 1, 2, and 2 for reviewers A, I, and B, respectively. Reviewer A scores for "suturing" and "bleeding," and reviewer I scores for "dissection plane" and "peritoneal injury" correlated significantly with RRR. No reviewer B scores correlated with RRR. Score variance between A and I and A and B for cases D1 and D2 were statistically significant. Conclusion: Advanced reviewers showed greatest variance, questioning the validity of whether experience alone improves surgical technique.

DPP4 inhibitor reinforces cell junction proteins in mouse model of short bowel syndrome

PURPOSE

Bacterial overgrowth commonly occurs and favors bacterial translocation in short bowel syndrome (SBS). Glucagon-like peptide-2 (GLP-2) is effective for treating SBS, but is rapidly inactivated by dipeptidyl peptidase IV (DPP4). DPP4 inhibitor (DPP4I) is known to be effective for treating SBS. Here, we investigated cell junction protein function following DPP4I administration in a mouse model of SBS.

METHODS

Mice were divided into four groups: naïve (n = 5), naïve + DPP4I (n = 6), control (n = 6), and DPP4I (n = 5). All control and DPP4I mice had 50% of their proximal small bowel resected. DPP4I or normal saline was administered orally twice daily from days 1-7 postoperatively. The functions of cell junction proteins were assessed by RT-PCR and immunohistochemistry. Body weights and blood glucose levels were recorded.

RESULTS

E-Cadherin was significantly higher in the DPP4I group than in the control group. E-Cadherin, occludin, and claudin-4 were significantly higher in the naïve group than in the control group. Positive staining for E-cadherin and occludin varied widely between the control and DPP4I groups.

CONCLUSION

Up-regulation of E-cadherin and occludin by DPP4I may be correlated with the anti-inflammatory action of DPP4I. Therefore, DPP4I may reduce bacterial translocation in SBS.

Animal Models of Hirschsprung's Disease: State of the Art in Translating Experimental Research to the Bedside

Hirschsprung's disease (HSCR) is caused by incomplete colonization of enteric neural crest-derived cell (ENCC) in the bowel, the failure of ENCCs to proliferate, differentiate, and migrate leads to an absence of enteric neurons in the distal colon, resulting in colonic motility dysfunction. Various animal models of HSCR have been important in the understanding of the anatomy and pathophysiology of the disease and in the discovery of genes involved in HSCR. Four types of HSCR animal models have been developed: teratogen-induced, surgically created, naturally occurring models, and knockout models. Mutations in several genes affect enteric nervous system (ENS) development and can have pleiotropic effects on this system. Furthermore, certain animal models are informative regarding how such molecules control the development and functional differentiation of the ENS. In this article, we summarize recent advances in this field and highlight opportunities for new discoveries.

Hirschsprung's disease in the laparoscopic transanal pull-through era: implications of age at surgery and technical aspects

AIM

Detailed implications of age at laparoscopic transanal pull-through (LTAPT) on postoperative bowel function (POBF) in Hirschsprung's disease (HD) are somewhat obscure because of a spectrum of factors.

METHODS

Age at surgery was used to categorize 106 consecutive postoperative HD cases treated by our modified LTAPT (JLTPAT) between 1997 and 2015; group A: < 3 months old (n = 31); group B: 3-11 months old (n = 44); group C: 1-3 years old (n = 19); and group D: ≥ 4 years old (n = 12). POBF was assessed by reviewing outpatient records 1, 3, 5, 7, and 10 years after JLTAPT prospectively and scoring each of 5 criteria on a scale of 0-2; best score = 10.

RESULTS

Only operative time was statistically longer in group D versus groups A, B, and C. Differences in gender ratios, blood loss, duration of follow-up, and POBF scores were not statistically significant. Mean POBF scores over time were: group A: 6.8, 7.6, 8.4, 8.6, and 8.4; group B: 7.1, 7.8, 8.3, 8.5, and 9.0; group C: 6.9, 7.9, 8.1, 8.3, and 8.6; group D: 7.0, 7.4, 8.2, 8.1, and 8.5, respectively.

CONCLUSION

Age at JLTAPT was not correlated with POBF in HD.

Increased expression of Semaphorin 3A in the endothelin receptor-B null mouse model of Hirschsprung disease

PURPOSE

Semaphorins are guidance cues for developing neurons, implicated in the determination of the migratory pathway of neural crest-derived neural precursors during enteric nervous system development. Recently, it has been reported that Semaphorin 3A (SEMA3A) expression is up-regulated in the aganglionic colon in Hirschsprung disease (HD) patients, suggesting that increased SEMA3A expression may be a risk factor for HD. Thus, the aim of our study was to determine the expression of SEMA3A using Sox10-Venus mice gut.

METHODS

We harvested the gut on postnatal day 2 (P2). SOX10-Venus+/EDNRB^-/- mice were compared with SOX10-Venus+/EDNRB^+/+ mice as controls. QRT-PCR was performed to determine gene expression of SEMA3A (n=8). Fluorescent immunohistochemistry was performed to assess protein distribution.

RESULTS

On P2, gene expression levels of SEMA3A were significantly increased in the HD group compared to controls in the proximal and distal colon (p<0.05). Laser scanning microscopy revealed SEMA3A expression was localized within the submucosa and muscle layer of the gut in both HD and controls. In HD, SEMA3A was highly expressed in the proximal and distal colon.

CONCLUSIONS

In the present study, we demonstrated that SEMA3A expression is increased in the EDNRB-/- HD model on P2, suggesting that SEMA3A may interfere with ENCC migration, resulting in an absence of enteric neurons.

Altered expression of laminin alpha1 in aganglionic colon of endothelin receptor-B null mouse model of Hirschsprung's disease

PURPOSE

Laminin, an extracellular matrix molecule, is essential for normal development of the nervous system. The alpha1 subunit of laminin-1 (LAMA1) has been reported to promote neurites and outgrowth and is expressed only during embryogenesis. Previously, we developed a Sox10 transgenic version of the Endothelin receptor-B (Ednrb) mouse to visualize Enteric neural crest-derived cell (ENCC)s with a green fluorescent protein, Venus. We designed this study to investigate the expression of LAMA1 using Sox10-VENUS mice gut.

METHODS

We harvested the gut on days 13.5 (E13.5) and 15.5 (E15.5) of gestation. Sox10-VENUS⁺/Ednrb ^-/- mice (n = 8) were compared with Sox10-VENUS⁺/Ednrb ^+/+ mice (n = 8) as controls. Gene expression of LAMA1 was analysed by real-time RT-PCR. Fluorescent immunohistochemistry was performed to assess protein distribution.

RESULTS

The relative mRNA expression levels of LAMA1 were significantly increased in HD in the proximal and distal colon on E15.5 compared to controls (p < 0.05), whereas there were no significant differences on E13.5. LAMA1 was expressed in the serosa, submucosa and basal lamina in the gut, and was markedly increased in the proximal and distal colon of HD on E15.5.

CONCLUSIONS

Altered LAMA1 expression in the aganglionic region may contribute to impaired ENCC migration, resulting in HD. These data could help in understanding the pathophysiologic interactions between LAMA1 and ENCC migration.