Ernica Clinical Consensus Statements on Total Colonic and Intestinal Aganglionosis

BACKGROUND

Hirschsprung disease is a congenital intestinal motility disorder characterized by an absence of enteric ganglion cells. Total colonic aganglionosis and near total or total intestinal aganglionosis, defined as absence of ganglion cells in the entire colon and with variable length of small bowel involved, are life-threatening conditions which affect less than 10 % of all patients with Hirschsprung disease. The aim of this project was to develop clinical consensus statements within ERNICA, the European Reference Network for rare congenital digestive diseases, on four major topics: Surgical treatment of total colonic aganglionosis, surgical treatment of total intestinal aganglionosis, management of poor bowel function in total colonic and/or intestinal aganglionosis and long-term management in total colonic and or intestinal aganglionosis.

METHODS

A multidisciplinary panel of representatives from ERNICA centers was invited to participate. Literature was searched, using specified search terms, in Medline (ALL), Embase and Google Scholar. Abstracts were screened and full text publications were selected. The panel was divided in four groups that extracted data from the full text publications and suggested draft statements for each of the major topics. A modified Delphi process was used to refine and agree on the statements.

RESULTS

The consensus statement was conducted by a multidisciplinary panel of 24 participants from 10 European countries, 45 statements reached consensus after 3 Delphi-rounds. The availability of high-quality clinical evidence was limited, and most statements were based on expert opinion. Another 25 statements did not reach consensus.

CONCLUSIONS

Total colonic and total intestinal aganglionosis are rare variants of Hirschsprung disease, with very limited availability of high-quality clinical evidence. This consensus statement provides statements on the surgical treatment, management of poor bowel function and long-term management for these rare patients. The expert panel agreed that patients benefit from multidisciplinary and personalized care, preferably in an expert center.

TYPE OF STUDY

Clinical consensus statement.

LEVEL OF EVIDENCE

3a.

European Pediatric Surgeons' Association Survey on Timing of Inguinal Hernia Repair in Premature Infants

AIM

 This article evaluates the practice patterns of European Pediatric Surgeons' Association (EUPSA) members regarding the timing of inguinal hernia (IH) repair in premature infants.

METHODS

 Online survey containing 29 questions distributed to EUPSA members during January 2023.

RESULTS

 A total of 180 responds were received. Overall, IH repair prior to discharge was favored by 60% of respondents when there was a history of incarceration and 56% when there was not. In the case of very/extremely premature infants (< 32 weeks) with no history of incarceration, fewer (43%) respondents postpone the surgery until after discharge. The majority of respondents cited the risk of incarceration as the reason for advocating surgery prior to discharge, whereas a reduced risk of apnea was the most cited reason for respondents who prefer delayed surgery. Open approach under general anesthesia was favored by 54% of respondents, with 27% of them preferring open approach with spinal anesthesia. Laparoscopic surgery for premature infants is used in 11% while 7% of them preferred in all premature infants including extremely/very premature ones. Contralateral side evaluation was never done by 40% of respondents and 29% only performed it only during laparoscopic repair. The majority of respondents (77%) indicated that they have an overnight stay policy for premature infants < 45 weeks of gestation.

CONCLUSION

 There is variation in the practice patterns of pediatric surgeons in the treatment of IH in premature infants. Due to the concern for the high risk of incarceration, IH repair before discharge was the most prevalent practice. Lower risk of postoperative apnea was cited as the most common reason for delaying surgery. Randomized studies are required to establish the optimal timing for IH repair in premature infants.

Financial and relational impact of having a boy with posterior urethral valves

Introduction

Childhood chronic diseases affect family functioning and well-being. The aim of this study was to measure the impact of caring for a child with PUV, and the factors that most impact the burden of care.

Patients and method

We gave a questionnaire on the familial impact of having a child with posterior urethral valves to all parents of a child included in the CIRCUP trial from 2015 onwards. The questionnaire included questions about the parents' demographics, health, professional, financial and marital status and how these evolved since the child's birth as well as the "impact on family scale" (IOFS), which gives a total score ranging from 15 (no impact) to 60 (maximum impact). We then analyzed both the results of the specific demographic questions as well as the factors which influenced the IOFS score.

Results

We retrieved answers for 38/51 families (74.5% response rate). The average IOFS score was 23.7 (15-51). We observed that the child's creatinine level had an effect on the IOFS score (p = 0.02), as did the parent's gender (p = 0.008), health status (p = 0.015), being limited in activity since the birth of the child (p = 0.020), being penalized in one's job (p = 0.009), being supported in one's job (p = 0.002), and decreased income (p = 0.004). Out of 38 mother/father binomials, 8/33 (24.2%) declared that they were no longer in the same relationship afterwards.

Conclusion

In conclusion, having a boy with PUV significantly impacts families. The risk of parental separation and decrease in revenue is significant. Strategies aiming to decrease these factors should be put in place as soon as possible.

Comparison of single-use flexible ureteroscopes with a reusable ureteroscope for the management of paediatric urolithiasis

INTRODUCTION

To compare the efficacy, side effects, and cost-effectiveness between a single-use digital flexible ureteroscope and a reusable flexible ureteroscope in the treatment of paediatric renal stones.

METHODS

This analytic, case-control, monocentric study included all patients undergoing flexible ureterosopies for stone treatment. Between April 2016 and February 2019, a reusable (Flex-X^C®, Karl Storz) flexible ureteroscope was used (control group), whereas a single-use (Uscope®, PUSEN Medical©) flexible ureteroscope was used in all procedures from March 2019 to April 2021. Clinical and procedural outcomes, operative times, complication rates, hospital stay, and costs per procedure were evaluated.

RESULTS

Forty-three cases using a reusable flexible ureteroscope and thirty-nine using a single-use flexible ureteroscope were included in the study. Demographic patient characteristics, stone burden, location and composition, preoperative presence of a double-J stent, procedural outcomes, mean length of postoperative hospital stay, and complications (4.6% versus 5%, p = 0.81) were comparable between the two groups. Median operative duration for stone removal was 93 min (20-170) with reusable versus 81 min (55-107) with the single-use scope (p = 0.18). Scope failure occurred four times with the reusable scope and in no case with the single-use. The total cost per procedure associated with the use of single-use scopes (798 Euros) was lower than a reusable scope (1483.23 Euros).

DISCUSSION

Single-use flexible ureteroscopes were created to bypass the problems incurred when reusable scopes were damaged and therefore not available for use in surgical procedures. Single-use flexible ureteroscopes are always immediately available and ready to be used, even in urgent cases, as they typically do not require maintenance or sterilization. Compared with their reusable counterparts, single-use flexible ureteroscopes have similar digital performance (270°), image quality and we found no difference in the success and complication rates. Cost analysis of a reusable flexible ureteroscope must consider the purchase price, maintenance and repair costs, and decontamination costs (including handling, detergent, bacterial culture, transportation, and storage costs). In contrast, only purchase price is included in cost analysis for single-use flexible ureteroscopes. Our study suggests that single-use flexible ureteroscopes may be associated with lower costs per procedure than their reusable counterparts.

CONCLUSION

Single-use flexible ureteroscopes are an interesting alternative to their reusable counterparts, particularly in terms of material resource management. Cost analyses conducted using a low volume of cases representative of a paediatric urology division favour the use of single-use ureteroscopes.

European Pediatric Surgeons' Association Survey on the Use of Splenic Embolization in Blunt Splenic Trauma in Children

INTRODUCTION

 This article assesses (1) access to splenic embolization (SE), (2) indications for SE, and (3) post-embolization management in high-grade splenic trauma in children.

MATERIALS AND METHODS

 An online questionnaire was sent in 2021 to all members of European Pediatric Surgeons' Association.

RESULTS

 There were a total of 157 responses (50 countries, 83% academic hospitals). Among them, 68% have access to SE (SE) and 32% do not (nSE). For a hemodynamic stable patient with high-grade isolated splenic trauma without contrast extravasation (CE) on computed tomography (CT) scan, 99% SE and 95% nSE respondents use nonoperative management (NOM). In cases with CE, NOM decreases to 50% (p = 0.01) and 51% (p = 0.007) in SE and nSE centers, respectively. SE respondents report a significant reduction of NOM in stable patients with an associated spine injury requiring urgent surgery in prone position, both without and with CE (90 and 28%, respectively). For these respondents, in stable patients the association of a femur fracture only tends to decrease the NOM, both without and with CE (93 and 39%, respectively). There was no significant difference in NOM in group nSE with associated injuries with or without CE. After proximal SE with preserved spleen vascularization on ultrasound Doppler, 44% respondents prescribe antibiotics and/or immunizations.

CONCLUSION

 Two-thirds of respondents have access to SE. For SE respondents, SE is used even in stable patients when CE showed on initial CT scan and its use increased with the concomitant need for spinal surgery. There is currently a variation in the use of SE and antibiotics/immunizations following SE.

European Pediatric Surgeons' Association Survey on the Management of Primary Spontaneous Pneumothorax in Children

AIM

 To evaluate the practice patterns of the European Pediatric Surgeons' Association (EUPSA) members regarding the management of primary spontaneous pneumothorax (PSP) in children.

METHODS

 An online survey was distributed to all members of EUPSA.

RESULTS

 In total, 131 members from 44 countries participated in the survey. Interventional approach (78%) is the most common choice of treatment in the first episode, and most commonly, chest tube insertion (71%) is performed. In the case of a respiratory stable patient, 60% of the responders insert chest tubes if the pneumothorax is more than 2 cm. While 49% of surgeons prefer surgical intervention in the second episode, 42% still prefer chest tube insertion. Main indications for surgical treatment were the presence of bullae more than 2 cm (77%), and recurrent pneumothorax (76%). Eighty-four percent of surgeons prefer thoracoscopy and perform excision of bullae with safe margins (91%). To prevent recurrences, 54% of surgeons perform surgical pleurodesis with pleural abrasion (55%) and partial pleurectomy (22%). The responders who perform thoracoscopy use more surgical pleurodesis and prefer shorter chest tube duration than the surgeons performing open surgery (p < 0.05).

CONCLUSION

 Most of the responders prefer chest tube insertion in the management of first episode of PSP and perform surgical treatment in the second episode in case of underlying bullae more than 2 cm and recurrent pneumothorax. The surgeons performing thoracoscopy use more surgical pleurodesis and prefer shorter chest tube duration than the responders performing open surgery. The development of evidence-based guidelines may help standardize care and improve outcomes in children with PSP.

Partial splenectomy in children undergoing liver transplantation or venous shunt for severe hypersplenism: A case control comparative study

BACKGROUND AND AIM

Hypersplenism is a consequence of portal hypertension and splenomegaly secondary to cirrhosis or portal cavernoma in children. In order to avoid persistent hypersplenism and splenomegaly after liver transplantation (LT) or venous shunt (VS), partial splenectomy (PS) may represent a relevant therapeutic option. The aim of this retrospective study was to evaluate the results of PS performed in children presenting hypersplenism.

METHODS

The following end-points were evaluated: (1) reversion of hypersplenism and its durability over time, (2) postoperative outcome, (3) courses of spleen size and volume and (4) comparison to a control group in which PS was not performed.

RESULTS

Between 1996 and 2020, 16 children underwent PS associated with LT (8 cases) for cirrhosis or VS (8 cases) for portal cavernoma. From Day 0 to 1 month, mean platelet and white blood cell counts (WBC) dramatically improved from 48 ± 19 at day 0 to 176 ± 70 × 10⁹/L (P < 0.0001) and from 2469 ± 853 to 7198 ± 3982/L (P = 0.001) respectively. PS allowed significant reduction of splenic length and volume from 176 ± 33 to 112 ± 24 cm (P < 0.0001) and from 1228 ± 464 to 450 ± 297 cm³ (P = 0.0003) respectively. After a mean follow-up of 92.6 ± 84.7 months (range: 4.1-210.7), 14 patients are alive with normal platelet and WBC counts and persistent spleen size reduction. Compared to control group, PS was associated with a significant platelet count rise from baseline to one year.

CONCLUSIONS

PS appears to be effective for treatment of hypersplenism and splenomegaly in combination with LT or VS without compromising outcome.

Preliminary experience in endoscopic section of posterior urethral valves using the Holmium: YAG laser

INTRODUCTION

Refinements in endoscopic instrumentation, the widespread popularization of endourology and the minimal invasiveness of endoscopic approaches have led to evolving interest in expanding applications for their use and now include incision of posterior urethral valves (PUV). We aimed to report our paediatric experience of PUV incision with Holmium:YAG laser updating of the endoscopic technique, how we set parameters for the laser energy and provide some tips and tricks to increase the likelihood of completing treatment.

METHODS

A monocentric, prospective, continuous series of boys with PUV were treated endoscopically using a Holmium: YAG laser (1.2 J, 20 Hz, 800 μs). Feasibility was evaluated using operative time in minutes, spontaneous normal micturition after bladder catheter removal, and the duration of bladder catheterization in days in the absence of satisfactory micturition. Peri-operative complications were recorded. A VCUG was performed at 6 weeks postoperatively to exclude residual valves.

RESULTS

Since September 2018, 18 children with PUV were included. The median age at the time of endoscopic laser incision was 12 days (1 day-5 years). The median operative duration was 28 min (17-35). The urinary catheter was systematically removed on the first postoperative day. There were no intraoperative or anaesthesia-related complications. More specifically, no urethral injuries and no bleeding were recorded. No incomplete VUP incision was found on follow-up VCUG, and no endoscopic revision was necessary thus far, with a median follow-up of 44 months (6 months-60 months).

DISCUSSION

The use of the Holmium: YAG laser introduces new perspectives in the treatment of PUV. Its mechanism of action is considered a photothermic effect with a vapourization effect. The laser energy released by the Holmium: YAG source has a short tissue penetration distance and is strongly absorbed in an aqueous environment and therefore limits thermal tissue damage and favours early tissue re-epithelialization, reducing the risk of urethral stricture and decreasing postoperative oedema. The use of the laser in "incision" mode is the setting that most solicits the capacities of the laser (high energy, high frequency, and long pulse). The use of laser energy has the advantage of allowing tissue vapourization while ensuring maximal haemostasis and the possibility of introducing the laser fibre through the working channels of small, 6-Fr paediatric endoscopes.

CONCLUSION

In our experience, endoscopic PUV incision using the Holmium: YAG laser appears to be a safe and efficient technique.

Altered epithelial barrier functions in the colon of patients with spina bifida

Our objectives were to better characterize the colorectal function of patients with Spina Bifida (SB). Patients with SB and healthy volunteers (HVs) completed prospectively a standardized questionnaire, clinical evaluation, rectal barostat, colonoscopy with biopsies and faecal collection. The data from 36 adults with SB (age: 38.8 [34.1-47.2]) were compared with those of 16 HVs (age: 39.0 [31.0-46.5]). Compared to HVs, rectal compliance was lower in patients with SB (p = 0.01), whereas rectal tone was higher (p = 0.0015). Ex vivo paracellular permeability was increased in patients with SB (p = 0.0008) and inversely correlated with rectal compliance (r = - 0.563, p = 0.002). The expression of key tight junction proteins and inflammatory markers was comparable between SB and HVs, except for an increase in Claudin-1 immunoreactivity (p = 0.04) in SB compared to HVs. TGFβ1 and GDNF mRNAs were expressed at higher levels in patients with SB (p = 0.02 and p = 0.008). The levels of acetate, propionate and butyrate in faecal samples were reduced (p = 0.04, p = 0.01, and p = 0.02, respectively). Our findings provide evidence that anorectal and epithelial functions are altered in patients with SB. The alterations in these key functions might represent new therapeutic targets, in particular using microbiota-derived approaches.Clinical Trials: NCT02440984 and NCT03054415.

Lessons from a large nationwide cohort of 350 children with ovarian mature teratoma: A study in favor of ovarian-sparing surgery

BACKGROUND

Ovarian mature teratoma (OMT) is a common ovarian tumor found in the pediatric population. In 10%-20% of cases, OMT occurs as multiple synchronous or metachronous lesions on ipsi- or contralateral ovaries. Ovarian-sparing surgery (OSS) is recommended to preserve fertility, but total oophorectomy (TO) is still performed.

DESIGN

This study reviews the clinical data of patients with OMT, and analyzes risk factors for second events. A national retrospective review of girls under 18 years of age with OMTs was performed. Data on clinical features, imaging, laboratory studies, surgical reports, second events and their management were retrieved.

RESULTS

Overall, 350 children were included. Eighteen patients (5%) presented with a synchronous bilateral form at diagnosis. Surgery was performed by laparotomy (85%) and laparoscopy (15%). OSS and TO were performed in 59% and 41% of cases, respectively. Perioperative tumor rupture occurred in 23 cases, independently of the surgical approach. Twenty-nine second events occurred (8.3%) in a median time of 30.5 months from diagnosis (ipsilateral: eight cases including one malignant tumor; contralateral: 18 cases; both ovaries: three cases). A large palpable mass, bilateral forms, at diagnosis and perioperative rupture had a statistical impact on the risk of second event, whereas the type of surgery or approach did not.

CONCLUSION

This study is a plea in favor of OSS as the first-choice treatment of OMT when possible. Close follow-up during the first 5 years is mandatory considering the risk of 8.3% of second events, especially in cases with risk factors.

European Pediatric Surgeon' Association Survey on the Management of Short-Bowel Syndrome

INTRODUCTION

 The aim of this study was to assess the management of short-bowel syndrome (SBS) at the time of primary surgery, and the strategies used to facilitate enteral autonomy depending on the institutional expertise.

MATERIALS AND METHODS

 An online questionnaire was sent in 2019 to members of The European Pediatric Surgeons' Association.

RESULTS

 Among the 65 responding members (26 countries, 85% from university hospitals), 57% manage less than three new patients with SBS per year (group A), and 43% at least three patients (group B). The cut-off of three patients treated yearly used in our study was defined after statistical analysis of different cut-offs. A multidisciplinary intestinal rehabilitation program is significantly more frequent in group B than in group A (85 and 53%, respectively; p = 0.009). Considering the primary surgical management of multiple intestinal atresia and congenital ultra-short bowel with jejunal atresia, primary surgical strategies to optimize bowel length are more often used in group B than group A (p = 0.09 and p = 0.04, respectively). A minimum of one intestinal lengthening procedure every 2 to 3 years is significantly more frequent in group B than group A (95 and 45%, respectively; p = 0.0013). Among the strategies used to promote intestinal adaptation, group B (35%) uses significantly more often glucagon-like peptide 2 analogs than group A (10%) (p = 0.02).

CONCLUSION

 Based on our survey, a minimum number of SBS patients treated yearly is required to manage this challenging disease according to up-to-date medical and surgical strategies. However, whatever their level of expertise is in managing SBS, most of pediatric surgeons are involved in the primary surgery. Medical education programs about SBS should be more largely available to pediatric surgeons.

Analysis of enteric nervous system and intestinal epithelial barrier to predict complications in Hirschsprung's disease

In Hirschsprung’s disease (HSCR), postoperative course remains unpredictable. Our aim was to define predictive factors of the main postoperative complications: obstructive symptoms (OS) and Hirschsprung-associated enterocolitis (HAEC). In this prospective multicentre cohort study, samples of resected bowel were collected at time of surgery in 18 neonates with short-segment HSCR in tertiary care hospitals. OS and HAEC were noted during postoperative follow-up. We assessed the enteric nervous system and the intestinal epithelial barrier (IEB) in ganglionic segments by combining immunohistochemical, proteomic and transcriptomic approaches, with functional ex vivo analysis of motility and para/transcellular permeability. Ten HSCR patients presented postoperative complications (median follow-up 23.5 months): 6 OS, 4 HAEC (2 with OS), 2 diarrhoea (without OS/HAEC). Immunohistochemical analysis showed a significant 41% and 60% decrease in median number of nNOS-IR myenteric neurons per ganglion in HSCR with OS as compared to HSCR with HAEC/diarrhoea (without OS) and HSCR without complications (p = 0.0095; p = 0.002, respectively). Paracellular and transcellular permeability was significantly increased in HSCR with HAEC as compared to HSCR with OS/diarrhoea without HAEC (p = 0.016; p = 0.009) and HSCR without complications (p = 0.029; p = 0.017). This pilot study supports the hypothesis that modulating neuronal phenotype and enhancing IEB permeability may treat or prevent postoperative complications in HSCR.

Semaphorin 3A controls enteric neuron connectivity and is inversely associated with synapsin 1 expression in Hirschsprung disease

Most of the gut functions are controlled by the enteric nervous system (ENS), a complex network of enteric neurons located throughout the wall of the gastrointestinal tract. The formation of ENS connectivity during the perinatal period critically underlies the establishment of gastrointestinal motility, but the factors involved in this maturation process remain poorly characterized. Here, we examined the role of Semaphorin 3A (Sema3A) on ENS maturation and its potential implication in Hirschsprung disease (HSCR), a developmental disorder of the ENS with impaired colonic motility. We found that Sema3A and its receptor Neuropilin 1 (NRP1) are expressed in the rat gut during the early postnatal period. At the cellular level, NRP1 is expressed by enteric neurons, where it is particularly enriched at growth areas of developing axons. Treatment of primary ENS cultures and gut explants with Sema3A restricts axon elongation and synapse formation. Comparison of the ganglionic colon of HSCR patients to the colon of patients with anorectal malformation shows reduced expression of the synaptic molecule synapsin 1 in HSCR, which is inversely correlated with Sema3A expression. Our study identifies Sema3A as a critical regulator of ENS connectivity and provides a link between altered ENS connectivity and HSCR.

A collagen VI-dependent pathogenic mechanism for Hirschsprung's disease

Hirschsprung's disease (HSCR) is a severe congenital anomaly of the enteric nervous system (ENS) characterized by functional intestinal obstruction due to a lack of intrinsic innervation in the distal bowel. Distal innervation deficiency results from incomplete colonization of the bowel by enteric neural crest cells (eNCCs), the ENS precursors. Here, we report the generation of a mouse model for HSCR--named Holstein--that contains an untargeted transgenic insertion upstream of the collagen-6α4 (Col6a4) gene. This insertion induces eNCC-specific upregulation of Col6a4 expression that increases total collagen VI protein levels in the extracellular matrix (ECM) surrounding both the developing and the postnatal ENS. Increased collagen VI levels during development mainly result in slower migration of eNCCs. This appears to be due to the fact that collagen VI is a poor substratum for supporting eNCC migration and can even interfere with the migration-promoting effects of fibronectin. Importantly, for a majority of patients in a HSCR cohort, the myenteric ganglia from the ganglionated region are also specifically surrounded by abundant collagen VI microfibrils, an outcome accentuated by Down syndrome. Collectively, our data thus unveil a clinically relevant pathogenic mechanism for HSCR that involves cell-autonomous changes in ECM composition surrounding eNCCs. Moreover, as COL6A1 and COL6A2 are on human Chr.21q, this mechanism is highly relevant to the predisposition of patients with Down syndrome to HSCR.

Secondary plastic closure of gastroschisis is associated with a lower incidence of mechanical ventilation

INTRODUCTION

Nonsurgical closure after primary silo placement, secondary plastic closure (SPC), has been used as an alternative to secondary surgical closure (SSC) in gastroschisis. The benefits described were closure without formal surgical procedure, cosmetic aspect, and minimization of intra-abdominal pressures. This study compared requirements for mechanical ventilation and general anesthesia, nutritional care, and outcomes between SPC and SSC.

PATIENTS AND METHODS

We included patients with primary staged-silo reduction with a 1-year minimum follow-up. SPC was performed at bedside with sedation using a nonadherent dressing. SSC was performed in operating room under general anesthesia using standard surgical techniques.

RESULTS

This retrospective study included 64 patients, 23 SPC and 41 SSC. The characteristics of the two groups were comparable. Mechanical ventilation was used for 15 SPC and 41 SSC (p=0.0001) with a comparable median duration (5.5 and 6.0 days, not significant [NS]). General anesthesia was required for 9 SPC and 41 SSC (p<0.0001). Complications included one SPC and six SSC with necrotizing enterocolitis, zero SPC and four SSC with intestinal atresia, two SPC and four SSC with small bowel obstruction, zero SPC and one SSC with abdominal compartment syndrome resulting in a short bowel syndrome (NS). Median duration of parenteral nutrition (30 and 27 days), time to first feeds (14 and 14 days), time at or above minimal enteral feeding (22 and 17 days), time to full feeds (31 and 28 days), length of stay (LOS) in neonatal intensive care unit (24 and 23.5 days) and overall hospital LOS (37 and 36 days) were not statistically different between SPC and SSC patients without complications, respectively. These data were comparable for SPC and SSC patients with complications. Five SPC and six SSC developed an umbilical hernia (NS); two patients in each group required a surgical repair (NS).

CONCLUSION

Plastic closure of gastroschisis after primary silo reduction is simple, safe, reproducible, and associated with a significant lower incidence of mechanical ventilation. Nutritional management and length of hospital stay were similar to conventional surgical closure for patients. Plastic closure allows nonoperative management without general anesthesia at patient's bedside, in comparison with surgical closure that must be performed under general anesthesia in the operating room. Plastic closure does not appear to be associated with more umbilical hernias in this retrospective study.

Lentiviral vectors that express UGT1A1 in liver and contain miR-142 target sequences normalize hyperbilirubinemia in Gunn rats

BACKGROUND & AIMS

Crigler-Najjar type 1 (CN-I) is an inherited liver disease caused by an absence of bilirubin-uridine 5'-diphosphate-glucuronosyltransferase (UGT1A1) activity. It results in life-threatening levels of unconjugated bilirubin, and therapeutic options are limited. We used adult Gunn rats (an animal model of the disease) to evaluate the efficiency of lentiviral-based gene therapy to express UGT1A1 in liver.

METHODS

Gunn rats were given intraportal injections of VSVG-pseudotyped lentiviral vectors that encode UGT1A1 under the control of a liver-specific transthyretin promoter (mTTR.hUGT1A1); this vector does not contain target sequences for miR-142, a microRNA that is expressed specifically in hematopoietic cells. Rats were also injected with the vector mTTR.hUGT1A1.142T, which contains 4 copies of the miR-142 target sequences; its messenger RNA should be degraded in antigen-presenting cells. Bilirubinemia was monitored, and the presence of transduced hepatocytes was analyzed by quantitative polymerase chain reaction. Vector expression was tested in vitro in rat hematopoietic cells.

RESULTS

In Gunn rats, bilirubin levels normalized 2 weeks after administration of mTTR.hUGT1A1. However, hyperbilirubinemia resumed 8 weeks after vector administration, concomitant with the induction of an immune response. In contrast, in rats injected with mTTR-UGT1A1.142T, bilirubin levels normalized for up to 6 months and transduced cells were not eliminated.

CONCLUSIONS

Lentiviral vectors that express UGT1A1 reduce hyperbilirubinemia in immunocompetent Gunn rats for at least 6 months. The immune response against virally expressed UGT1A1 can be circumvented by inclusion of miR-142 target sequences, which reduce vector expression in antigen-presenting cells. This lentiviral-based gene therapy approach might be developed to treat patients with CN-I.

Transient increase in intrahepatic pressure mediates successful treatment of the Gunn rat with reduced doses of lentiviral vector

Lentiviral vectors can stably transduce hepatocytes and are promising tools for gene therapy of hepatic diseases. Although hepatocytes are accessible to blood-borne viral vectors through fenestrations of the hepatic endothelium, improved liver transduction after delivery of vectors to the blood stream is needed. As the normal endothelial fenestration and lentiviral vectors are similar in size (150 nm), we hypothesized that a transient increase in hepatic blood pressure may enhance in vivo gene transfer to hepatocytes. We designed a simple surgical procedure, by which the liver is temporarily excluded from blood flow. Lentiviral vectors were injected in a large volume to increase intrahepatic pressure. We demonstrated that in the Gunn rat, a model of Crigler-Najjar disease, the administration of low vector doses (corresponding to a multiplicity of infection of 0.2) by this procedure resulted in therapeutic correction of hyperbilirubinemia, without toxicity. The correction was sustained for 10 months (end of study). The same vector amounts yielded only partial correction after intraportal delivery. We believe that this new and clinically applicable strategy may broaden the range of genetic liver diseases accessible to gene therapy.