Outcomes in children after intestinal transplant

Paediatric intestinal pseudo-obstruction: a scoping review

Paediatric intestinal pseudo-obstruction (PIPO) encompasses a group of rare disorders in which patients present with the clinical features of bowel obstruction in the absence of mechanical occlusion. The management of PIPO presents a challenge as evidence remains limited on available medical and surgical therapy. Parenteral nutrition is often the mainstay of therapy. Long-term therapy may culminate in life-threatening complications including intestinal failure-related liver disease, central line thrombosis and sepsis. Intestinal transplantation remains the only definitive cure in PIPO but is a complex and resource-limited solution associated with its own morbidity and mortality. We conducted a scoping review to present a contemporary summary of the epidemiology, aetiology, pathophysiology, diagnosis, management and complications of PIPO.Conclusion: PIPO represents a rare disorder that is difficult to diagnose and challenging to treat, with significant morbitity and mortality. The only known cure is intestinal transplantation. What is Known: • Paediatric intestinal pseudo-obstruction is a rare, heterogeneous disorder that confers a high rate of morbidity and mortality • Complications of paediatric intestinal pseudo-obstruction include chronic pain, small intestine bacterial overgrowth and malrotation. Other complications can occur related to its management, such as line infections with parenteral nutrition or cardiac side effects of prokinetic medications What is New: • Progress in medical and surgical therapy in recent years has led to improved patient outcomes • Enteral autonomy has been reported in most patients at as early as 1 month post-transplantation.

Mesenteric neovascularization during spring-mediated intestinal lengthening

BACKGROUND

Short gut syndrome, a condition characterized by inadequate absorption of nutrients owing to decreased bowel length, has minimal avenues for treatment. We have proposed spring-mediated distraction enterogenesis to lengthen bowel in porcine jejunum as a treatment for short gut. We aim to evaluate the extent of mesenteric neovascularization in segments of lengthened bowel via spring-mediated enterogenesis.

METHODS

Female juvenile Yucatan pigs underwent laparotomy and insertion of gelatin-encapsulated compressed nitinol springs, held in place with plication sutures, into the jejunum. At surgery and sacrifice, macroscopic mesenteric blood vessels were counted between the plication sites. Histologic samples of the mesentery were obtained to evaluate microscopic vasculature.

RESULTS

A statistically significant increase in macroscopic mesenteric blood vessels was seen after intestinal lengthening (before: 1.9 ± 0.7 vessels, after: 4.7 ± 1.2 vessels, p = 0.001). A statistical significance is also seen in the density of arterioles (control: 3.0 ± 3.0 vessels/mm, spring: 7.0 ± 9.0 vessels/mm, p = 0.01) and venules (control: 4.0 ± 3.0 vessels/mm, spring: 8.0 ± 8.0 vessels/mm, p = 0.003).

CONCLUSION

Intestinal segments lengthened by intraluminal springs demonstrated total greater number of macroscopic vessels and microscopic blood vessels per length of mesentery as compared to control. This suggests local changes within the mesentery to recruit blood supply to growing intestine.

LEVEL OF EVIDENCE

N/A TYPE OF STUDY: Treatment study.

Latest developments in chronic intestinal pseudo-obstruction

Chronic intestinal pseudo-obstruction (CIPO) is a type of intestinal dysfunction presenting as symptoms of intestinal obstruction but without actual mechanical obstruction. An extremely low incidence, non-specific clinical symptoms, strong heterogeneity, and no definitive cause in some patients make CIPO very difficult to diagnose correctly. Imaging and gastrointestinal manometry are commonly used. Most patients have progressive worsening of their symptoms and require intervention, and nutritional assessment and treatment are very important to determine the prognosis. With improvements in surgical techniques, small bowel transplantation is a feasible treatment option for patients with advanced CIPO; however, the long-term prognosis for CIPO patients remains unsatisfactory. Generally, the disease is rare and difficult to diagnose, which leads to clinicians’ lack of understanding of the disease and results in a high rate of misdiagnosis. This review describes the characteristics of CIPO and the latest developments in diagnosis and treatment, in detail. The goal of our review is to improve clinicians' understanding of CIPO so that the disease is identified quickly and accurately, and treated as early as possible to improve patients’ quality of life.

Biomechanical Force Prediction for Lengthening of Small Intestine during Distraction Enterogenesis

Distraction enterogenesis has been extensively studied as a potential treatment for short bowel syndrome, which is the most common form of intestinal failure. Different strategies including parenteral nutrition and surgical lengthening to manage patients with short bowel syndrome are associated with high complication rates. More recently, self-expanding springs have been used to lengthen the small intestine using an intraluminal axial mechanical force, where this biomechanical force stimulates the growth and elongation of the small intestine. Differences in physical characteristics of patients with short bowel syndrome would require a different mechanical force—this is crucial in order to achieve an efficient and safe lengthening outcome. In this study, we aimed to predict the required mechanical force for each potential intestinal size. Based on our previous experimental observations and computational findings, we integrated our experimental measurements of patient biometrics along with mechanical characterization of the soft tissue into our numerical simulations to develop a series of computational models. These computational models can predict the required mechanical force for any potential patient where this can be advantageous in predicting an individual’s tissue response to spring-mediated distraction enterogenesis and can be used toward a safe delivery of the mechanical force.

STEP improves long-term survival for pediatric short bowel syndrome patients: A Markov decision analysis

INTRODUCTION

Increasingly, for pediatric patients with short bowel syndrome (SBS), intestinal lengthening procedures such as serial transverse enteroplasty (STEP) are being offered with the hope of improving patients' chances for achieving enteral autonomy. However, it remains unclear to what extent STEP reduces the long-term need for intestinal transplant or improves survival.

METHODS

Based on existing literature, a decision analytic Markov state transition model was created to simulate the life of 1,000 pediatric SBS patients. Two simulations were modeled: 1) No STEP: patients were listed for transplant once medical management failed and 2) STEP: patients underwent STEP therapy and subsequent transplant listing if enteral autonomy was not achieved. Sensitivity analysis of small bowel length and anatomy was completed. Base case patients were defined as neonates with a small bowel length of 30cm.

RESULTS

For base case patients with an ostomy and a NEC SBS etiology, STEP was associated with increased rates of enteral autonomy after 10 years for patients with an ICV (53.9% [STEP] vs. 51.1% [No STEP]) and without an ICV (43.4% [STEP] vs. 36.3% [No STEP]). Transplantation rates were also reduced following STEP therapy for both ICV (17.5% [STEP] vs. 18.2% [No STEP]) and non-ICV patients (20.2% [STEP] vs. 22.1% [No STEP]). 10-year survival was the highest in the (+) STEP and (+) ICV group (85.4%) and lowest in the (-) STEP and (-) ICV group (83.3%).

CONCLUSIONS

For SBS patients, according to our model, STEP increases rates of enteral autonomy, reduces need for intestinal transplantation, and improves long-term survival.

TYPE OF STUDY

Economic/Decision Analysis or Modeling Studies LEVEL OF EVIDENCE: Level III.

Pediatric Intestinal Pseudo-obstruction in the Era of Genetic Sequencing

PURPOSE OF REVIEW

The purpose of this review is to discuss current knowledge on pediatric intestinal pseudo-obstruction. We will also review new mutations that have been identified through advancement in genetic testing, allowing for a better understanding of the underlying mechanisms of intestinal dysmotility and potential etiologies.

RECENT FINDINGS

With the advancements in genetic testing, new mutations have been identified in the diagnosis of megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIHS), a disorder leading to pediatric pseudo-obstruction. MYLK, LMOD1, MYL9, and MYH11 encode for various proteins within smooth muscle cells; abnormalities within these proteins lead to abnormal intestinal smooth muscle contractions. Chronic intestinal pseudo-obstruction (CIPO) is defined by symptoms of bowel obstruction in the absence of a lumen-occluding lesion. CIPO is a heterogeneous group of disorders caused by abnormalities in the enteric neurons, intestinal smooth muscle, and/or the interstitial cells of Cajal (ICC). Symptoms can be non-specific and etiologies include both primary and secondary causes of CIPO that contribute to the delay in recognizing this condition and making the correct diagnosis. Chronic intestinal pseudo-obstruction has been recognized in both adults and children with fundamental differences in the etiology, symptom onset, clinical features and natural history of this disorder. For this reason, it has been considered a separate entity referred to as pediatric intestinal pseudo-obstruction (PIPO).

Variable management strategies for NEC totalis: a national survey

BACKGROUND/OBJECTIVES

Necrotizing enterocolitis (NEC) is a serious disease linked to prematurity. A variant, NEC totalis, is associated with nearly 100% mortality. There is wide variation in counseling practices for NEC totalis. Our objectives are to determine what treatment options, if any, are offered to families, and which factors influence these decisions.

METHODS

An anonymous survey was distributed to members of the AAP Sections on Neonatal-Perinatal Medicine and Pediatric Surgery. Data were analyzed utilizing chi-square tests and Spearman correlations, where applicable.

RESULTS

In the setting of NEC totalis, 90% of the 378 respondents viewed offering life-sustaining interventions (LSI) as ethically permissible and 87% felt that transfer to another center willing to provide LSI should be considered; however, only 43% reported offering LSI to families.

CONCLUSIONS

Management of NEC totalis remains challenging and significant practice variability persists. Most respondents do not offer ongoing medical/surgical management, despite believing it is an ethically permissible option.

Double plication for spring-mediated intestinal lengthening of a defunctionalized Roux limb

BACKGROUND

Spring-mediated distraction enterogenesis has been shown to increase the length of an intestinal segment. The goal of this study is to use suture plication to confine a spring within an intestinal segment while maintaining luminal patency to the rest of the intestine.

METHODS

Juvenile mini-Yucatan pigs underwent placement of nitinol springs within a defunctionalized Roux limb of jejunum. A 20 French catheter was passed temporarily, and sutures were used to plicate the intestinal wall around the catheter at both ends of the encapsulated spring. Uncompressed springs placed in plicated segments and springs placed in nonplicated segments served as controls. The intestine was examined approximately 3 weeks after spring placement.

RESULTS

In the absence of plication, springs passed through the intestine within a week. Double plication allowed the spring to stay within the Roux limb for 3 weeks. Compared to uncompressed springs that showed no change in the length of plicated segments, compressed springs caused a significant 1.7-fold increase in the length of plicated segments.

CONCLUSIONS

Intestinal plication is an effective method to confine endoluminal springs. The confined springs could lengthen intestine that maintains luminal patency. This approach may be useful to lengthen intestine in patients with short bowel syndrome.

LEVEL OF EVIDENCE

Level I Experimental Study.

Nutritional Interventions in Chronic Intestinal Pseudoobstruction

Although chronic intestinal pseudo-obstruction (CIPO) is a rare disorder, it presents a wide spectrum of severity that ranges from abdominal bloating to severe gastrointestinal dysfunction. In the worst cases, patients may become dependent upon artificial nutrition via parenteral nutrition or choose to have an intestinal transplant. However, whatever the severity, a patient's quality of life can be seriously compromised. This article defines the disorder and discusses the spectrum of disease and challenges to providing adequate nutrition to help improve a patient's quality of life.

Chronic Intestinal Pseudo-obstruction

Chronic intestinal pseudo-obstruction (CIP) is defined by either continuous or intermittent symptoms of bowel obstruction in the absence of fixed lumen excluding lesion. CIP includes a heterogeneous group of disorders which result either from diseases affecting the enteric neurons and smooth muscle lining or those involving the autonomic innervation of the bowel. Symptoms associated with CIP are nonspecific, which can sometimes contribute to the delay in recognizing the condition and making the correct diagnosis. The diagnostic workup should include imaging and manometry studies and, occasionally, full-thickness bowel biopsies for histopathological examination may be required. Multidisciplinary team approach for the management of these patients is recommended, and the team members should include a gastroenterologist, surgeon, chronic pain specialist, clinical nutritionist, and a psychologist. The treatment goals should include optimizing the nutritional status and preventing or delaying the development of intestinal failure. The majority of the patients require enteral or parenteral nutrition support, and chronic pain is a common and distressing symptom. Small bowel transplantation may be required if patients develop liver complications due to parenteral nutrition, have difficult central line access, or have poor quality of life and worsening pain despite aggressive medical management.

Current treatment paradigms in pediatric short bowel syndrome

Pediatric short bowel syndrome (SBS) is a serious condition which occurs in children with congenital or acquired reduction in length of the small intestine. SBS results in excessive fluid loss, nutrient malabsorption, electrolyte abnormalities, increased susceptibility to infections, parenteral nutrition associated complications and affects weight gain and growth. In children, SBS is debilitating and uniformly fatal without treatment. The primary goal of treatment is to restore enteral autonomy and reduce long-term dependence on parenteral support by increasing the absorptive potential of the remnant intestine. In this review, the medical and surgical management of SBS including pharmacologic agents, parenteral nutrition, dietary strategies, surgical lengthening procedures, and small bowel transplant will be discussed.

Anesthesia for Intestinal Transplantation

The diagnosis of irreversible intestinal failure confers significant morbidity, mortality, and decreased quality of life. Patients with irreversible intestinal failure may be treated with intestinal transplantation. Intestinal transplantation may include intestine only, liver-intestine, or other visceral elements. Intestinal transplantation candidates present with systemic manifestations of intestinal failure requiring multidisciplinary evaluation at an intestinal transplantation center. Central access may be difficult in intestinal transplantation candidates. Intestinal transplantation is a complex operation with potential for hemodynamic and metabolic instability. Patient and graft survival are improving, but graft failure remains the most common postoperative complication.

Intestinal Transplant in Children

The past decade has seen major advances in the field of transplantation; it is the treatment of choice for many with intestinal failure. One-year mortality from pediatric intestinal transplantation has significantly declined, from 30% to 10% to 15% nationally, mainly due to a multidisciplinary approach in transplant centers. Pediatric age carries special considerations along the spectrum of care that continue to cause challenges but also offers growth opportunities. Pediatric intestinal transplantation indications and timing are changing as a result of new developments in diagnostic and treatment tools. This article reviews updates on pediatric intestinal transplantation and highlights future directions.

Chronic intestinal pseudo-obstruction in children and adults: diagnosis and therapeutic options

BACKGROUND

Chronic intestinal pseudo-obstruction (CIPO) represents the most severe form of gastrointestinal dysmotility with debilitating and potentially lethal consequences. Symptoms can be non-specific, and result in this condition being diagnosed incorrectly or too late with consequences for morbidity and even mortality.

PURPOSE

The present article aims to provide pediatric and adult gastroenterologists with an up to date review about clinical features, diagnosis and therapeutic options for CIPO. Although pediatric and adult CIPO share many clinical aspects distinctive features can be identified. There is no single diagnostic test or pathognomonic finding of CIPO, thus a stepwise approach including radiology, endoscopy, laboratory, manometry, and histopathology should be considered in the diagnostic work-up. Treatment of patients with CIPO is challenging and requires a multidisciplinary effort with participation of appropriately experienced gastroenterologists, pathologists, dieticians, surgeons, psychologists, and other subspecialists based on the presence of comorbidities. Current treatment options invariably involve surgery and specialized nutritional support, especially in children. Medical therapies are mainly aimed to avoid complications such as sepsis or intestinal bacterial overgrowth and, where possible, restore intestinal propulsion. More efficacious therapeutic options are eagerly awaited for such difficult patients.

Vaccinations, response, and controls before and after intestinal transplantation in children

Vaccination is an effective strategy to decrease infections in transplant recipients. Children after intestinal transplantation carry a high risk of infection due to increased immunosuppression. In a series of 22 children after intestinal transplantation, we studied the vaccination schedules and the antibodies against vaccine-preventable diseases before transplantation, and at one and five yr after transplantation. We reviewed whether the vaccination schedules were complete, and we analysed the factors that may influence serological immunity and the incidence of disease in patients with deficient immunity. All patients completed the recommended vaccination schedules for DTaP-IPV and HBV. After transplantation, the negative antibodies against vaccine-preventable diseases were mostly related to an antirejection therapy: for DTaP-IPV: four of four patients with no antibody had been treated for rejection, for HBV: two of five, HAV: three of four, MMR: three of seven, and VZV: three of four. A post-transplantation varicella infection was followed by acute rejection, with probability for a relationship between both events. We observed 50% of varicella cases in unvaccinated children, highlighting the importance of pretransplant vaccination. Waning immunogenicity mediated by antibodies against vaccine-preventable disease after transplantation indicated a need for boosters. The recommendations should be regularly enforced, as the reliance on routine immunizations schedules is not adequate in immunocompromised patients.

Production of tissue-engineered intestine from expanded enteroids

BACKGROUND

Short bowel syndrome is a life-threatening condition with few solutions. Tissue-engineered intestine (TEI) is a potential treatment, but donor intestine is a limiting factor. Expanded epithelial surrogates termed enteroids may serve as a potential donor source.

MATERIALS AND METHODS

To produce TEI from enteroids, crypts were harvested from mice and enteroid cultures established. Enteroids were seeded onto polymer scaffolds using Matrigel or culture medium and implanted in immunosuppressed mice for 4 wk. Histology was analyzed using Periodic acid-Schiff staining and immunofluorescence. Neomucosa was quantified using ImageJ software. To determine whether TEI could be produced from enteroids established from small intestinal biopsies, 2 × 2-mm pieces of jejunum were processed for enteroid culture, enteroids were expanded and seeded onto scaffolds, and scaffolds implanted for 4 wk.

RESULTS

Enteroids in Matrigel produced TEI in 15 of 15 scaffolds, whereas enteroids in medium produced TEI in 9 of 15 scaffolds. Use of Matrigel led to more neomucosal surface area compared to media (10,520 ± 2905 μm versus 450 ± 127 μm, P < 0.05). Histologic examination confirmed the presence of crypts and blunted villi, normal intestinal epithelial lineages, intestinal subepithelial myofibroblasts, and smooth muscle cells. Crypts obtained from biopsies produced an average of 192 ± 71 enteroids. A single passage produced 685 ± 58 enteroids, which was adequate for scaffold seeding. TEI was produced in 8 of 9 scaffolds seeded with expanded enteroids.

CONCLUSIONS

Enteroids can be obtained from minimal starting material, expanded ex vivo, and implanted to produce TEI. This method shows promise as a solution to the limited donor intestine available for TEI production in patients with short bowel syndrome.

Development of Chitosan Scaffolds with Enhanced Mechanical Properties for Intestinal Tissue Engineering Applications

Massive resections of segments of the gastrointestinal (GI) tract lead to intestinal discontinuity. Functional tubular replacements are needed. Different scaffolds were designed for intestinal tissue engineering application. However, none of the studies have evaluated the mechanical properties of the scaffolds. We have previously shown the biocompatibility of chitosan as a natural material in intestinal tissue engineering. Our scaffolds demonstrated weak mechanical properties. In this study, we enhanced the mechanical strength of the scaffolds with the use of chitosan fibers. Chitosan fibers were circumferentially-aligned around the tubular chitosan scaffolds either from the luminal side or from the outer side or both. Tensile strength, tensile strain, and Young’s modulus were significantly increased in the scaffolds with fibers when compared with scaffolds without fibers. Burst pressure was also increased. The biocompatibility of the scaffolds was maintained as demonstrated by the adhesion of smooth muscle cells around the different kinds of scaffolds. The chitosan scaffolds with fibers provided a better candidate for intestinal tissue engineering. The novelty of this study was in the design of the fibers in a specific alignment and their incorporation within the scaffolds.

Impact of Intestinal Rehabilitation Program and Its Innovative Therapies on the Outcome of Intestinal Transplant Candidates

OBJECTIVES

The outcome of children with intestinal failure has improved during the past decade following the introduction of novel therapies by dedicated intestinal rehabilitation programs (IRP). The aim of the present study was to assess the impact of IRP on the outcome of intestinal transplant (IT) candidates and the transplant waiting list.

METHODS

A retrospective cohort study of children assessed for IT (n = 84) during a 10-year period. Comparisons were made among the following 3 time periods: before the establishment of our center's IRP (1999-2002; n = 33), early IRP (2003-2005; n = 18), and late IRP (2006-2009; n = 33). The following endpoints were used: patient outcome following IT assessment (not listed, listed and removed from the list, received transplant, died while on the list), patient characteristics at IT assessment, and patient status at the end of the study.

RESULTS

The late-IRP era was associated with an increase in patients who were not listed (42% vs 28% at other periods, P = NS) and patients who were removed from the IT waiting list because of clinical improvement (P < 0.0005), and a decrease in those who died before transplant (15% vs >60% at other periods, P < 0.0005). The cause of death shifted from traditional causes such as liver failure or sepsis to other comorbid conditions (P < 0.005). Improved liver function at listing was also observed during late IRP (P < 0.005).

CONCLUSIONS

Treatment by IRP, coupled with recent advances in the medical management of intestinal failure, is associated with improved survival and outcome of patients waiting for IT, and may lead to overall reduction in the number of IT in the future.

Successful implantation of an engineered tubular neuromuscular tissue composed of human cells and chitosan scaffold

BACKGROUND

There is an urgent need for gut lengthening secondary to massive resections of the gastrointestinal tract. In this study, we propose to evaluate the remodeling, vascularization, and functionality of a chitosan-based, tubular neuromuscular tissue on subcutaneous implantation in the back of athymic rats.

METHODS

Aligned innervated smooth muscle sheets were bioengineered with the use of human smooth muscle and neural progenitor cells. The innervated sheets were wrapped around tubular chitosan scaffolds. The engineered tubular neuromuscular tissue was implanted subcutaneously in the back of athymic rats. The implant was harvested after 14 days and assessed for morphology, vascularization, and functionality.

RESULTS

Gross examination of the implants showed healthy color with no signs of inflammation. The implanted tissue became vascularized as demonstrated by gross and histologic analysis. Chitosan supported the luminal patency of the tissue. The innervated muscle remodeled around the tubular chitosan scaffold. Smooth muscle maintained its circumferential alignment and contractile phenotype. The functionality of the implant was characterized further by the use of real-time force generation. A cholinergic response was demonstrated by robust contraction in response to acetylcholine. Vasoactive intestinal peptide-, and electrical field stimulation-caused relaxation. In the presence of neurotoxin tetrodotoxin, the magnitude of acetylcholine-induced contraction and vasoactive intestinal peptide-induced relaxation was attenuated whereas electrical field stimulation-induced relaxation was completely abolished, indicating neuronal contribution to the response.

CONCLUSION

Our results indicated the successful subcutaneous implantation of engineered tubular neuromuscular tissues. The tissues became vascularized and maintained their myogenic and neurogenic phenotype and function, which provides potential therapeutic prospects for providing implantable replacement GI segments for treating GI motility disorders.

Development of an endoluminal intestinal lengthening device using a geometric intestinal attachment approach

BACKGROUND

Distraction enterogenesis may provide a novel therapy for short bowel syndrome. Previously described methods have relied on isolated intestinal segments or transmural fixation because of ineffective endoluminal attachment. We hypothesized that a novel approach of geometric coupling between a tapering device and the mesenteric curvature would allow trans-stomal distraction enterogenesis.

METHODS

A catheter device was designed with tapering stiffness, consisting of a stiff catheter with a taper to a flexible latex tip to prevent perforation. Yorkshire pigs underwent creation of a jejunal Roux limb with device placed via jejunostomy. Intestinal attachment was achieved without a substantial decrease in bowel perfusion as measured by laser Doppler. An external clamp was secured at the stoma to provide external fixation of the device. The catheter was advanced 1 cm/day for either 7 or 14 days before explant.

RESULTS

After 7 days, the distracted segment achieved a mean ± SD increase in length of 37 ± 6% versus fed, nondistracted bowel, corresponding to an absolute gain of 10.6 ± 1.7 cm (1.5 cm/day). After 14 days, the Roux limb achieved an 80 ± 2% increase in length versus fed control bowel, corresponding to an absolute gain of 16.8 ± 3.0 cm (1.2 cm/day). No perforation or stoma-related complication occurred.

CONCLUSION

We describe a novel catheter device with tapering stiffness allowing for endoluminal distraction enterogenesis via geometric coupling. This approach may allow development of clinically applicable technology for the treatment of patients with short bowel syndrome.

Advancement in the clinical management of intestinal pseudo-obstruction

Intestinal pseudo-obstruction is more commonly known in its chronic form (CIPO), a cluster of rare diseases characterized by gastrointestinal muscle and nerve impairment, so severe to result in a markedly compromised peristalsis mimicking an intestinal occlusion. The management of CIPO requires the cooperation of a group of specialists: the disease has to be confirmed by a number of tests to avoid mistakes in the differential diagnosis. The treatment should be aimed at relieving symptoms arising from gut dysmotility (ideally using prokinetic agents), controlling abdominal pain (possibly with non-opioid antinociceptive drugs) and optimizing nutritional support. Furthermore, a thorough diagnostic work-up is mandatory to avoid unnecessary (potentially harmful) surgery and to select patients with clear indication to intestinal or multivisceral transplantation.

Transforming growth factor-beta 3 alters intestinal smooth muscle function: implications for gastroschisis-related intestinal dysfunction

BACKGROUND

Gastroschisis (GS) is a congenital abdominal wall defect that results in the development of GS-related intestinal dysfunction (GRID). Transforming growth factor-β, a pro-inflammatory cytokine, has been shown to cause organ dysfunction through alterations in vascular and airway smooth muscle. The purpose of this study was to evaluate the effects of TGF-β3 on intestinal smooth muscle function and contractile gene expression.

METHODS

Archived human intestinal tissue was analyzed using immunohistochemistry and RT-PCR for TGF-β isoforms and markers of smooth muscle gene and micro-RNA contractile phenotype. Intestinal motility was measured in neonatal rats ± TGF-β3 (0.2 and 1 mg/kg). Human intestinal smooth muscle cells (hiSMCs) were incubated with fetal bovine serum ± 100 ng/ml of TGF-β 3 isoforms for 6, 24 and 72 h. The effects of TGF-β3 on motility, hiSMC contractility and hiSMC contractile phenotype gene and micro-RNA expression were measured using transit, collagen gel contraction assay and RT-PCR analysis. Data are expressed as mean ± SEM, ANOVA (n = 6-7/group).

RESULTS

GS infants had increased immunostaining of TGF-β3 and elevated levels of micro-RNA 143 & 145 in the intestinal smooth muscle. Rats had significantly decreased intestinal transit when exposed to TGF-β3 in a dose-dependent manner compared with Sham animals. TGF-β3 significantly increased hiSMC gel contraction and contractile protein gene and micro-RNA expression.

CONCLUSION

TGF-β3 contributed to intestinal dysfunction at the organ level, increased contraction at the cellular level and elevated contractile gene expression at the molecular level. A hyper-contractile response may play a role in the persistent intestinal dysfunction seen in GRID.

A novel double-balloon catheter device for fully endoluminal intestinal lengthening

OBJECTIVE

Distraction enterogenesis may provide a novel therapy for short bowel syndrome (SBS). Previously described methods have relied upon isolated intestinal segments or transmural fixation. Our objective was to develop a novel, fully endoluminal device, permitting placement and removal through an enteral stoma or orifice.

METHODS

A flexible device was designed consisting of two latex balloons mounted on coaxial catheters. The inner catheter allowed longitudinal force transmission from an external spring. Yorkshire pigs underwent jejunal Roux limb creation with device placement via jejunostomy. Balloons were inflated to 52 mmHg without significant reduction in bowel perfusion as measured by laser Doppler. The device was explanted after 7 days.

RESULTS

Distracted bowel achieved an increase in length of 26.1 ± 6.1 % vs nondistracted fed bowel. As the device resided in unfed bowel, a 66.7 ± 14.5% increase vs unfed bowel was noted. These corresponded to a gain of 6.3 ± 2.3 cm (0.9 ± 0.3 cm/day) and 12.9 ± 7.6 cm (1.8 ± 1.1 cm/day), respectively. Attachment sites demonstrated occasional epithelial sloughing with no balloon-associated perforation.

CONCLUSION

A novel double-balloon catheter device allows for fully endoluminal distraction enterogenesis. This approach may allow development of clinically applicable technology for the treatment of patients with SBS.

Counselling variation among physicians regarding intestinal transplant for short bowel syndrome

BACKGROUND

Intestinal transplant in infants with severe short bowel syndrome (SBS) is an emerging therapy, yet without sufficient long-term data or established guidelines, resulting in possible variation in practice.

OBJECTIVES

To assess current attitudes and counselling practices among physicians regarding intestinal transplant in infants with SBS, and to determine whether counselling and management vary between subspecialists or centres.

METHODS

A national sample of practicing paediatric surgeons and neonatologists was surveyed via the American Academy of Paediatrics listserves. Results were analysed by physician subspecialty and again by presence or absence of intestinal transplant at respondent's centre.

RESULTS

The survey was completed by 433 respondents, consisting of 363 neonatologists and 70 paediatric surgeons. Fifty-seven respondents (13.2%) practiced at a centre that performed intestinal transplants in children. The vast majority of respondents (91% for preterm, 95% for term neonates) felt that maintaining a neonate with SBS on total parenteral nutrition for intestinal transplant was ethically optional (neither impermissible nor obligatory), and that parents should be given an informed choice whether to pursue that option. However, only 33% indicated they often/always offer intestinal transplant as a treatment option to families in this situation.

CONCLUSIONS

There is a marked disparity between individual physicians' beliefs regarding the acceptability of intestinal transplant for severe SBS and their reported practice. Wide variability exists among physicians with respect to their knowledge, beliefs and practice regarding severe SBS, raising concerns about transparency and justice. Survival data prior to transplant, currently unavailable, are essential to rational decision making and informed parental permission.

Function of mechanically lengthened jejunum after restoration into continuity

PURPOSE

Distraction enterogenesis is a potential treatment for patients with short bowel syndrome. We previously demonstrated successful lengthening of jejunum using a degradable spring device in rats. Absorptive function of the lengthened jejunum after restoration into intestinal continuity needs to be determined.

METHODS

Encapsulated polycaprolactone springs were placed into isolated jejunal segments in rats for four weeks. Lengthened segments of jejunum were subsequently restored into intestinal continuity. Absorption studies were performed by placing a mixture of a non-absorbable substrate and glucose into the lumen of the restored jejunum.

RESULTS

Restored jejunal segments demonstrated visible peristalsis at specimen retrieval. Compared to normal jejunal controls, restored segments demonstrated equal water absorption and greater glucose absorption. Restored segments had thicker smooth muscle, increased villus height, increased crypt depth, and decreased sucrase activity compared to normal jejunum. The density of enteric ganglia increased after restoration to near normal levels in the submucosa and to normal levels in the myenteric plexus.

CONCLUSION

Jejunum lengthened with a degradable device demonstrates peristaltic and enzymatic activity as well as glucose and water absorption after restoration into intestinal continuity. Our findings further demonstrate the therapeutic potential of a degradable device.

A novel biodegradable device for intestinal lengthening

PURPOSE

Previous studies demonstrated successful mechanical lengthening of rat jejunum using an encapsulated Nitinol spring device over a stabilizing guidewire. We sought to improve the applicability of intestinal lengthening by creating a biodegradable device.

METHODS

Using properties of the Nitinol spring device, polycaprolactone (PCL) springs with similar outer diameter and spring constant were created. After in vitro testing in dry and hydrated environments, they were used to lengthen 1-cm isolated segments of rat jejunum in vivo. Retrieved segments were analyzed histologically.

RESULTS

Optimal PCL spring devices had an average spring constant 1.8 ± 0.4 N/m, pitch 1.55 ± 0.85 mm, and band width 0.825 ± 0.016 mm. In vitro testing demonstrated stable spring constants. Jejunal segments were lengthened from 1.0 cm to 2.7 ± 0.4 cm without needing a stabilizing guidewire. Histology demonstrated increased smooth muscle thickness and fewer ganglia compared to controls. Lengthened jejunum was successfully restored into intestinal continuity and demonstrated peristalsis under fluoroscopy.

CONCLUSIONS

A novel biodegradable spring device was successfully created and used to mechanically lengthen intestinal segments. Use of a biodegradable device may obviate the need for retrieval after lengthening. This improves device applicability and may be useful for the treatment of short bowel syndrome.

Clinical practice guidelines--Nursing management for pediatric patients with small bowel or multivisceral transplant

PURPOSE

Small bowel or multivisceral transplant is a relatively new treatment for irreversible intestinal damage, and no published practice guidelines exist. The purpose of this article is to report evidence regarding the best plan of care to achieve adequate nutrition and appropriate development for children.

DESIGN AND METHODS

An integrative review was conducted with 54 articles related to management of this transplant population. A nine-member nursing team integrated the findings.

PRACTICE IMPLICATIONS

This resulting guideline represents the best research and best practices on which to base staff education and competency validations to manage this medically fragile patient population.

Distraction-induced intestinal growth: the role of mechanotransduction mechanisms in a mouse model of short bowel syndrome

Novel strategies are needed to address the problem of patients with short bowel syndrome. We previously demonstrated a three-fold lengthening of pig bowel after 2 weeks of applied distractive forces, but we have not elucidated the mechanisms facilitating this growth. We used a mouse model of distraction-induced enterogenesis. High molecular weight polyethylene glycol (PEG) osmotically stretched an isolated small bowel segment (PEG-stretch). Significant increases in villus height and crypt depth and in intestinal epithelial cell length and numbers suggested epithelial remodeling in addition to proliferation during enterogenesis. LC-MS/MS analysis showed a two-fold upregulation of α-actinin-1 and -4. We also demonstrated that p-focal adhesion kinase (FAK), FAK, α-actinin, and Rac1 were significantly upregulated and that F-actin was relocalized in PEG-stretch versus controls. Blockade of the phosphotidyl inositol 3' kinase pathway failed to influence the increase in proliferation or decline in apoptosis after stretch, suggesting alternative signaling pathways are used, including MEK and P38MAPK, which were both upregulated during enterogenesis. Our data suggests that several known mechanotransduction pathways drive distraction-induced enterogenesis.

Management of short bowel syndrome in infancy

Short bowel syndrome (SBS) is a reduction in functioning bowel length which is most often a result of surgical resection. Risk factors in the neonatal period include necrotising enterocolitis, small bowel atresia and gastroschisis. With increasing survival of preterm infants there is an increase in incidence. Management is dependent on the use of parenteral nutrition to maintain fluid and electrolyte homeostasis and promote growth and development with the longer term aim being to promote intestinal adaptation to achieve partial or complete enteral autonomy. In this review we discuss the incidence, aetiology, pathophysiology, medical and surgical treatments and outcome.

Tissue engineering: a promising therapeutic approach to necrotizing enterocolitis

Tissue engineering is a promising potential candidate for treating intestinal failure resulting from necrotizing enterocolitis. This requires the acquisition, preparation and implantation of autologous organoid units. This may be affected by the complexities of periods of storage of viable donor tissue and delayed implantation. This chapter addresses the development, methodology, and application of tissue-engineered intestine in the experimental and clinical setting. Tissue engineering has the potential of avoiding the inherent toxicities of intestinal transplantation and prolonged immunosuppression.

Glucagon-like peptide 2 increases efficacy of distraction enterogenesis

BACKGROUND

Application of distractive forces to small bowel induces intestinal growth, or enterogenesis. This emerging area of research may provide treatment for short bowel syndrome. Glucagon-like peptide 2(GLP-2) has also been reported to induce small bowel growth after bowel resection. We hypothesized that exogenous GLP-2 will result in enhanced distraction-induced enterogenesis.

METHODS

Distraction-induced model was performed in 10-wk-old C57BL/6 mice using osmotic forces with high molecular weight polyethylene glycol (PEG)-stretch. Four groups were studied: Control group (PEG-/GLP-2-); PEG-stretch (PEG+/GLP-2-); GLP-2 control (PEG-/GLP-2+); and GLP-2 stretch (PEG+/GLP-2+). GLP-2 was given via subcutaneous osmotic pump over the 5 d of experiment. Morphology was measured by histomicrography. Epithelial cell (EC) proliferation was measured with proliferating cell nuclear antigen immunofluorescent staining. Total intestinal growth and blood vessel volume was assessed with Micro computed tomography volumetry. Vascular endothelial growth factor, fibroblast growth factor 1 and 2, and platelet-derived growth factor were measured by reverse-transcriptase polymerase chain reaction.

RESULTS

EC proliferation increased significantly in all groups compared with controls, but was greatest in the GLP-2 stretch group. Diameter and length significantly increased in the PEG-stretch and GLP-2 stretch groups. Moreover, there was statistically greater diameter, crypt depth and EC proliferation in the GLP-2 stretch versus PEG-stretch groups. GLP-2 stretch vessel volume was greater than all other groups and was significantly increased compared with controls. The relative expression of platelet-derived growth factor increased significantly in the PEG-stretch group versus the Control group.

CONCLUSIONS

GLP-2 had an additive effect on EC proliferation, tissue growth, histomorphology, and vascularization. We also demonstrated a unique action of GLP-2, the enhancement of intestinal vascularization. The combination of enterogenesis and GLP-2 may yield an improved approach to treat short bowel syndrome.

Tissue engineering the small intestine

Short bowel syndrome (SBS) results from the loss of a highly specialized organ, the small intestine. SBS and its current treatments are associated with high morbidity and mortality. Production of tissue-engineered small intestine (TESI) from the patient's own cells could restore normal intestinal function via autologous transplantation. Improved understanding of intestinal stem cells and their niche have been coupled with advances in tissue engineering techniques. Originally described by Vacanti et al of Massachusetts General Hospital, TESI has been produced by in vivo implantation of organoid units. Organoid units are multicellular clusters of epithelium and mesenchyme that may be harvested from native intestine. These clusters are loaded onto a scaffold and implanted into the host omentum. The scaffold provides physical support that permits angiogenesis and vasculogenesis of the developing tissue. After a period of 4 weeks, histologic analyses confirm the similarity of TESI to native intestine. TESI contains a differentiated epithelium, mesenchyme, blood vessels, muscle, and nerve components. To date, similar experiments have proved successful in rat, mouse, and pig models. Additional experiments have shown clinical improvement and rescue of SBS rats after implantation of TESI. In comparison with the group that underwent massive enterectomy alone, rats that had surgical anastomosis of TESI to their shortened intestine showed improvement in postoperative weight gain and serum B12 values. Recently, organoid units have been harvested from human intestinal samples and successfully grown into TESI by using an immunodeficient mouse host. Current TESI production yields approximately 3 times the number of cells initially implanted, but improvements in the scaffold and blood supply are being developed in efforts to increase TESI size. Exciting new techniques in stem cell biology and directed cellular differentiation may generate additional sources of autologous intestinal tissue for direct translation to human therapy.

Adaptive functioning and its correlates after intestine and liver transplantation

In this cross-sectional study, we compared levels of adaptive functioning and examined potential correlates of adaptive functioning in 18 pediatric intestine (ITX) and 22 liver (LTX) recipients transplanted between June 2003 and March 2009. Family caregivers completed the ABAS-II scale and provided socio-demographic information regarding recipients' age at transplantation, gender, ethnicity, time since transplantation, and caregivers' role, ethnicity, education, and family income. Overall adaptive functioning and all three adaptive functioning subdomain scores were significantly lower in ITX patients compared with LTX patients (p ≤ 0.04) and compared with the general population normative mean (p ≤ 0.003). Significant correlates of adaptive functioning after abdominal transplant included type of transplant procedure (r = -0.4, p = 0.02), gender (r = 0.4, p = 0.01), and educational level of caregiver (r = 0.5, p = 0.003) and together explained 45% of the variance in overall adaptive functioning. Findings provide new information regarding everyday functioning outcomes of ITX patients, add to existing data regarding non-medical outcomes for LTX patients, and highlight the need for ongoing monitoring and intervention following transplantation to enhance outcomes.

Post-transplant critical care outcomes for pediatric multivisceral and intestinal transplant patients

This study reviews the post-operative management of pediatric intestinal transplant patients at a single center with reporting of standard PICU benchmarks for quality of care. It is a retrospective, descriptive, chart review describing our institution's experience between 2006 and 2010. Twenty patients were included. Median age at transplant was 1.6 yr. Median length of PICU stay was 12 days. Median ventilation time was two days. Median time for continuous sedation infusion was two days, with median continuous pain medication infusion of three days. All patients were placed on parental nutrition and started on enteral feedings between days 3 and 4. Forty percent of patients required hemodynamic support. Only 35% of patients required insulin therapy. Diuretics were frequently used in this patient population. There were no episodes of early rejection. The survival rate to PICU discharge was 95%. Our institution's experience over the past four yr has been very successful with a short duration of mechanical ventilation, limited use of pain and sedation drips, early initiation of enteral feedings, minimal hemodynamic support, and a low mortality rate to PICU discharge despite a preponderance of complex MVTx recipients.

Ethics of emerging technologies and their transition to accepted practice: intestinal transplant for short bowel syndrome

Parental counseling becomes complex when considering the use of emerging technologies, especially if it is unclear whether the level of evidence is sufficient to transform the proposed therapy into accepted practice. This paper addresses ethical issues underlying medical decision-making and counseling in the setting of emerging treatments, when long-term outcomes are still in the process of being fully validated. We argue that the ethical transition of emerging technologies, ideally from ethically impermissible to permissible, to obligatory, depends primarily on two factors: outcome data (or prognosis) and treatment feasibility. To illustrate these points, we will use intestinal transplant for short bowel syndrome (SBS) as a specific example. After reviewing the data, this paper will identify the ethical justifications for both comfort care only and intestinal transplant in patients with ultra SBS, and argue that both are ethically permissible, but neither is obligatory. The approach outlined will not only be valuable as ultra SBS outcomes data continue to change, but will also be applicable to other novel therapies as they emerge in perinatal medicine.

Neonatal short bowel syndrome as a model of intestinal failure: physiological background for enteral feeding

Intestinal failure (IF) is a well identified clinical condition, which is characterised by the reduction of functional gut capacity below the minimum needed for adequate digestion and absorption of nutrients for normal growth in children. Short bowel syndrome (SBS) is the leading cause of IF in neonates, infants and young children usually as a result of extensive intestinal resection during the neonatal period. Simultaneously maintaining optimal nutritional status and achieving intestinal adaptation is a clinical challenge in short bowel patients. Both growth and development of the child as well as gut adaptation should be considered synergistically as primary outcome parameters. Enteral nutrition (EN) can be introduced orally and/or by tube feeding (TF). Several controversies over nutritional treatment of children with SBS related intestinal failure remain. As reported from different centres around the world, most practices are more "experienced based" rather than "evidence based". This is partly due to the small number of patients with this condition. This review (based on a consensus) discusses the physiological principles and nutritional management, including the type of diet and route of delivery. Perspectives in optimizing intestinal adaptation and reducing the consequences of small intestinal bacterial overgrowth are also discussed.

Distraction-induced intestinal enterogenesis: preservation of intestinal function and lengthening after reimplantation into normal jejunum

BACKGROUND

Significant bowel lengthening can occur in an isolated intestinal segment with the use of linearly directed distractive forces, resulting in increased surface area and epithelial cell proliferation. We hypothesized that reimplantation of this lengthened intestine into normal jejunum would preserve this gain in intestinal length and function similar to normal jejunum.

METHODS

An intestinal lengthening device was inserted into isolated jejunal segments in pigs, and fully expanded over 8 days. Lengthened segments were then reimplanted into normal intestinal continuity. Pigs were studied after another 28 days. Function was assessed by motility, mucosal enzyme activity, barrier function, and intestinal ion transport.

RESULTS

Lengthened segments were significantly longer than control segments and had nearly 2-fold greater surface area. Bowel lengthening was maintained 4 weeks after reimplantation. Motility after reimplantation was similar to nonoperated pigs. Barrier function, mucosal disaccharidase levels, and electrophysiologic measures declined immediately after lengthening but returned to nearly normal levels 28 days after reimplantation.

CONCLUSION

Bowel lengthening results in a transient decline in mucosal absorptive function and smooth muscle contractility. However, function approaches that of normal bowel after reimplantation into enteric flow. These data may support the use of this technique as a potential new option for the treatment of patients with short bowel syndrome.

Pretransplant predictors of survival after intestinal transplantation: analysis of a single-center experience of more than 100 transplants

INTRODUCTION

Outcomes after intestinal transplantation (ITx) have steadily improved. There are few studies that assess factors associated with these enhanced results. The purpose of this study was to examine peri-ITx variables and survival.

METHODS

A review of a prospectively maintained database was undertaken and included all patients undergoing ITx from 1991 to 2010. The study endpoints were patient and graft survival. Data collection included 44 variables. Survival was computed using Kaplan-Meier methods. Univariate analysis was conducted (log-rank test) with significance set at P less than or equal to 0.20. Multivariate analysis of significant variables was conducted using model reduction by backward elimination variable selection method with significance set at P less than 0.05.

RESULTS

Eighty-eight patients received 106 ITx. The majority of recipients were male, Latino, and children. The leading causes of intestinal and liver failure were gastroschisis and parenteral nutrition. Grafts transplanted were isolated intestine (24%), liver-intestine (62%), and multivisceral (14%). Overall 1- and 5-year patient and graft survival were 80% and 65%, and 74% and 64%, respectively. Significant univariate survival predictors were weight less than 20 kg, children, liver-inclusive allograft, panel reactive antibody less than 20%, absence of donor-specific antibody, negative crossmatch, warm ischemia time less than 60 min, absence of recipient splenectomy, interleukin-2 receptor antagonist induction, and era. Significant multivariate survival predictors were absence of donor-specific antibody, absence of recipient splenectomy, and liver-inclusive graft type.

CONCLUSION

This large, single-center ITx experience confirms a marked improvement in outcome over time. Several important factors were associated with survival, and these factors can potentially be adjusted before ITx. These findings should refocus future efforts on strategies to improve treatment and prevent graft loss.