Intestinal transplantation in children: current status

Skipped Aganglionic Lengthening Transposition (SALT) is highly effective to achieve enteral autonomy in selected patients with intestinal failure secondary to total intestinal aganglionosis

BACKGROUND

Intestinal Failure, parenteral nutrition (PN) dependence, and subsequent liver disease are the most challenging and life-threatening complications of short bowel syndrome experienced by patients with total intestinal aganglionosis. Skipped Aganglionic Lengthening Transposition (SALT) showed to be a promising procedure to overcome such problems. We herein report the results of two patients who underwent SALT at the Umberto Bosio Center for Digestive Diseases.

PATIENTS AND METHODS

Between November 2019 and July 2022, 2 patients with total intestinal aganglionosis underwent SALT as autologous intestinal lengthening procedure. Perioperative data and long-term outcomes are reported. Patient #1-A 18 month-old male (PN dependant) with 30 cm of ganglionated bowel at birth experienced a 35% increase of intestinal length after SALT (from 43 to 58 cm) thanks to three 5 cm interposed aganglionic loops. Postoperative course was uneventful and he was totally weaned by PN after 28 months postoperatively. He is without PN only receiving enteric feeding 53 months after the procedure. Patient #2-A 11 year-old female (PN dependant) with 100 cm of ganglionated jejunum underwent SALT at 11 years and experienced a 19% increase of bowel length thanks to four 5 to 7 cm interposed aganglionic loops. Postoperatively she required excision of two out of the four loops due to severe strictures and inadequate perfusion with a subsequent overall 10% increase of length after SALT. Of note, she improved significantly with a progressive reduction of PN that has been stopped after 18 months.

CONCLUSION

Skipped aganglionic lengthening transposition (SALT) seems to be very effective in improving nutrients absorption in patients with total intestinal aganglionosis by increasing absorptive bowel surface and decelerating intestinal flow for a longer and more effective contact of enteric material with ileal mucosa. Provided these impressive results are confirmed in the very long-term, SALT could become a valid alternative for the treatment of patients with total intestinal aganglionosis carrying at birth at least 20 to 30 cm of ganglionated jejunum.

Engineered Synthetic Matrices for Human Intestinal Organoid Culture and Therapeutic Delivery

Human intestinal organoids (HIOs) derived from pluripotent stem cells or adult stem cell biopsies represent a powerful platform to study human development, drug testing, and disease modeling in vitro, and serve as a cell source for tissue regeneration and therapeutic advances in vivo. Synthetic hydrogels can be engineered to serve as analogs of the extracellular matrix to support HIO growth and differentiation. These hydrogels allow for tuning the mechanical and biochemical properties of the matrix, offering an advantage over biologically derived hydrogels such as Matrigel. Human intestinal organoids have been used for repopulating transplantable intestinal grafts and for in vivo delivery to an injured intestinal site. The use of synthetic hydrogels for in vitro culture and for in vivo delivery is expected to significantly increase the relevance of human intestinal organoids for drug screening, disease modeling, and therapeutic applications.

Innovative surgical techniques in the intestine and multivisceral transplant

PURPOSE OF REVIEW

This timely review delves into the evolution of multivisceral transplantation (MVT) over the past six decades underscoring how advancements in surgical techniques and immunosuppression have driven transformation, to provide insight into the historical development of MVT, shedding light on its journey from experimentation to a valuable clinical approach.

RECENT FINDINGS

The review presents contemporary enhancements in surgical methods within the context of intestinal transplantation. The versatility of MVT is emphasized, accommodating diverse organ combinations and techniques. Both isolated intestinal transplantation (IIT) and MVT have seen expanded indications, driven by improved parenteral nutrition, transplantation outcomes, and surgical innovations. Surgical techniques are tailored based on graft type, with various approaches for isolated transplantation. Preservation strategies and ostomy techniques are also covered, along with graft assessment advancements involving donor-specific antibodies.

SUMMARY

This review's findings underscore the remarkable evolution of MVT from experimental origins to a comprehensive clinical practice. The progress in surgical techniques and immunosuppression has broadened the spectrum of patients who can benefit from intestinal transplant, including both IIT and MVT. The expansion of indications offers hope to patients with complex gastrointestinal disorders. The detection of donor-specific antibodies in graft assessment advances diagnostic accuracy, ultimately improving patient outcomes.

Nutrition support considerations in pediatric small bowel transplantation

Enteral autonomy is the primary goal of intestinal failure therapy. Intestinal transplantation (ITx) is an option when enteral autonomy cannot be achieved and management complications become life-threatening. The purpose of this review is to summarize existing medical literature related to nutrition requirements, nutrition status, and nutrition support after pediatric ITx. Achieving or maintaining adequate growth after intestinal transplant in children can be challenging because of episodes of rejection that require the use of corticosteroids, occurrences of infection that require a reduction or discontinuation of enteral or parenteral support, and fat malabsorption caused by impaired lymphatic circulation. Nutrient requirements should be assessed and modified regularly based on nutrition status, growth, ventilatory status, wound healing, and the presence of complications. Parenteral nutrition (PN) should be initiated as a continuous infusion early postoperatively. Enteral support should be initiated after evidence of graft bowel function and in the absence of clinical complications. Foods high in simple carbohydrates should be limited, as consumption may result in osmotic diarrhea. Short-term use of a fat-free diet followed by a low-fat diet may reduce the risk of the development of chylous ascites. Micronutrient deficiencies and food allergies are common occurrences after pediatric ITx. Enteral/oral vitamin and mineral supplementation may be required after PN is weaned. Nutrition management of children after ITx can be challenging for all members of the healthcare team. Anthropometric parameters and micronutrient status should be monitored regularly so that interventions to promote growth and prevent or reverse nutrient deficiencies can be implemented promptly.

Intestinal and Multivisceral Transplantation: Indications and Surgical Techniques

Intestinal transplantation and multivisceral transplantation are technically challenging and complex procedures mainly performed on patients with irreversible and non-medically manageable end-stage intestinal failure. Increasingly, other organs besides small intestines are included in the allograft for which the terms "composite intestinal transplantation" and "multivisceral transplantation" are used. Commonly, complex vascular reconstructions are used for these procedures. Knowledge of surgical anatomy hence is essential for accurate interpretation of postoperative imaging in these patients. This article reviews the indications and most common surgical techniques for intestinal and multivisceral transplantations.

Bioengineering human intestinal mucosal grafts using patient-derived organoids, fibroblasts and scaffolds

Tissue engineering is an interdisciplinary field that combines stem cells and matrices to form functional constructs that can be used to repair damaged tissues or regenerate whole organs. Tissue stem cells can be expanded and functionally differentiated to form 'mini-organs' resembling native tissue architecture and function. The choice of the scaffold is also pivotal to successful tissue reconstruction. Scaffolds may be broadly classified into synthetic or biological depending upon the purpose of the engineered organ. Bioengineered intestinal grafts represent a potential source of transplantable tissue for patients with intestinal failure, a condition resulting from extensive anatomical and functional loss of small intestine and therefore digestive and absorptive capacity. Prior strategies in intestinal bioengineering have predominantly used either murine or pluripotent cells and synthetic or decellularized rodent scaffolds, thus limiting their translation. Microscale models of human intestinal epithelium on shaped hydrogels and synthetic scaffolds are more physiological, but their regenerative potential is limited by scale. Here we present a protocol for bioengineering human intestinal grafts using patient-derived materials in a bioreactor culture system. This includes the isolation, expansion and biobanking of patient-derived intestinal organoids and fibroblasts, the generation of decellularized human intestinal scaffolds from native human tissue and providing a system for recellularization to form transplantable grafts. The duration of this protocol is 12 weeks, and it can be completed by scientists with prior experience of organoid culture. The resulting engineered mucosal grafts comprise physiological intestinal epithelium, matrix and surrounding niche, offering a valuable tool for both regenerative medicine and the study of human gastrointestinal diseases.

Overview of Physical, Neurocognitive, and Psychosocial Outcomes in Pediatric Intestinal Failure and Transplantation

PURPOSE OF REVIEW

Intestinal failure and transplantation may significantly impact physical, neurocognitive, and psychosocial development in pediatric patients. Currently, there is a paucity of literature on the effects of intestinal failure and transplantation on these aspects of development. This article will review the current literature and discuss the short and long-term impacts as well as interventions to improve clinical outcomes in children with intestinal failure or those undergoing transplantation.

RECENT FINDINGS

Psychological disorders, neurodevelopmental delay, and social maladaptation are frequently encountered in this patient population. While the main focus is often on medical management, equal emphasis should be placed on other aspects of development such as increasing social support and improving school performance. The transition to adulthood also presents many obstacles for patients and healthcare providers should anticipate challenges such as childbirth, employment, and raising a family. The pre-operative, perioperative, and post-operative periods all represent opportunities for medical intervention. Frequent monitoring of physical, psychosocial, and neurocognitive status helps to improve clinical outcomes and long-term quality of life. Future research should emphasize continued development of multidisciplinary programs and specialized services to help address the physical and psychosocial needs of children with intestinal failure as well as transplant recipients.

Building gut from scratch - progress and update of intestinal tissue engineering

Short bowel syndrome (SBS), a condition defined by insufficient absorptive intestinal epithelium, is a rare disease, with an estimated prevalence up to 0.4 in 10,000 people. However, it has substantial morbidity and mortality for affected patients. The mainstay of treatment in SBS is supportive, in the form of intravenous parenteral nutrition, with the aim of achieving intestinal autonomy. The lack of a definitive curative therapy has led to attempts to harness innate developmental and regenerative mechanisms to engineer neo-intestine as an alternative approach to addressing this unmet clinical need. Exciting advances have been made in the field of intestinal tissue engineering (ITE) over the past decade, making a review in this field timely. In this Review, we discuss the latest advances in the components required to engineer intestinal grafts and summarize the progress of ITE. We also explore some key factors to consider and challenges to overcome when transitioning tissue-engineered intestine towards clinical translation, and provide the future outlook of ITE in therapeutic applications and beyond.

Patient-level costing analysis of paediatric short bowel syndrome care in a specialist tertiary centre

PURPOSE

To undertake a pilot study estimating patient-level costs of care for paediatric short bowel syndrome (SBS) from the healthcare provider perspective.

METHODS

A pilot group of patients with anatomical SBS was selected at a single specialist tertiary centre in the United Kingdom. The Patient Level Information and Costing System (PLICS) was used to extract costing data for all hospital-based activities related to SBS, from the implementation of PLICS in 2016 to April 2021. Patient-specific and pooled data were reported descriptively in per patient-year terms.

RESULTS

Five patients had full PLICS data available for the 5-year study period and 2 patients had 4 years of data. The median cost for hospital care of SBS was £52,834 per patient-year (range £1804-£331,489). The key cost drivers were inpatient beds, pharmacy, and staffing costs, which made up > 60% of annual costs. In the first 3 years following index admission (n = 2), there was a steady decline in the annual cost of care to a level comparable with patients with established SBS.

CONCLUSION

Patient-level cost of care analysis for SBS is feasible using PLICS. Hospital-related costs vary widely between and within individual patients over time. Key drivers of cost are related to complications of SBS.

Regenerative medicine for childhood gastrointestinal diseases

Several paediatric gastrointestinal diseases result in life-shortening organ failure. For many of these conditions, current therapeutic options are suboptimal and may not offer a cure. Regenerative medicine is an inter-disciplinary field involving biologists, engineers, and clinicians that aims to produce cell and tissue-based therapies to overcome organ failure. Exciting advances in stem cell biology, materials science, and bioengineering bring engineered gastrointestinal cell and tissue therapies to the verge of clinical trial. In this review, we summarise the requirements for bioengineered therapies, the possible sources of the various cellular and non-cellular components, and the progress towards clinical translation of oesophageal and intestinal tissue engineering to date.

Donor-specific antibody and sensitized patients in intestinal transplantation

PURPOSE OF REVIEW

It has been well established that antibody to donor HLA pretransplant and the development of anti-human leukocyte antigen (HLA) antibodies posttransplant contribute to inferior graft survival outcomes. This article serves to review the current status of the management of pretransplant sensitized intestinal transplant candidate as well as to review posttransplant care of patients that harbor antidonor HLA antibodies.

RECENT FINDINGS

The intestinal transplant candidate oftentimes presents for transplant listing with high levels of anti-HLA antibodies that necessitate a careful preoperative strategy to avoid a donor-recipient pair that would result in a positive crossmatch. In the end, donor intestine offer acceptance is based on a balance between recipient clinical needs and allowable immunologic risk tolerance. The use of virtual crossmatching (VXM) enables the transplant center to effectively gauge the immunologic risk of each potential donor-recipient pair far in advance of allocating resources toward pursuing a donor organ. In those candidates with high levels of preformed donor anti-HLA antibodies, desensitization with a novel technique of donor splenic perfusion has been described as well as a single-center experience with a conventional desensitizing protocol. Posttransplant, with the use of a denovo donor-specific antibody (dnDSA) monitoring and treatment protocol, the well known deleterious effects of dnDSA can potentially be ameliorated, thus improving outcome. Efforts to establish a formal histologic criteria for antibody-mediated rejection (ABMR) in the intestinal graft continues to evolve with recent findings describing the relationship between DSA and histopathologic findings.

SUMMARY

Techniques such as the use of VXM, novel desensitization methods and protocols, monitoring and eradicating dnDSA, along with establishing new criteria for ABMR have all contributed to improving the outcomes in transplanting the immunologically challenging intestine.

Engineering transplantable jejunal mucosal grafts using patient-derived organoids from children with intestinal failure

Intestinal failure, following extensive anatomical or functional loss of small intestine, has debilitating long-term consequences for children1. The priority of patient care is to increase the length of functional intestine, particularly the jejunum, to promote nutritional independence2. Here we construct autologous jejunal mucosal grafts using biomaterials from pediatric patients and show that patient-derived organoids can be expanded efficiently in vitro. In parallel, we generate decellularized human intestinal matrix with intact nanotopography, which forms biological scaffolds. Proteomic and Raman spectroscopy analyses reveal highly analogous biochemical profiles of human small intestine and colon scaffolds, indicating that they can be used interchangeably as platforms for intestinal engineering. Indeed, seeding of jejunal organoids onto either type of scaffold reliably reconstructs grafts that exhibit several aspects of physiological jejunal function and that survive to form luminal structures after transplantation into the kidney capsule or subcutaneous pockets of mice for up to 2 weeks. Our findings provide proof-of-concept data for engineering patient-specific jejunal grafts for children with intestinal failure, ultimately aiding in the restoration of nutritional autonomy.

Treatment in a Tertiary Intestinal Rehabilitation Center Improves Outcome for Children With Short Bowel Syndrome

The aim of this study was to determine prognostic factors in pediatric patients with short bowel syndrome and very short bowel syndrome (defined as less than 25 cm of the bowel with or without colon). This was a retrospective, single-center, observational study that included patients with intestinal failure. Thirty-eight children with short bowel syndrome were included in the study (mean age at diagnosis = 8.4 [range = 0-48] months; female/male = 20/18); 12 children (31.6%) had very short bowel syndrome. Weaning from parenteral nutrition was achieved in 29 (74.5%) of children with short bowel syndrome but only in 4 (33%) in the very short bowel syndrome group. Positive prognostic factors associated with successful weaning from parenteral nutrition were an absolute higher length of the residual intestine, a remnant of at least some part of the colon, and treatment in an experienced center from the diagnosis. Patients with short bowel syndrome and very short bowel syndrome should be treated in a center experienced in intestinal rehabilitation.

The evolution of the serial transverse enteroplasty for pediatric short bowel syndrome at a single institution

PURPOSE

The serial transverse enteroplasty (STEP) tapers and lengthens the gut to improve adaptation. Mortality has decreased with multidisciplinary intestinal rehabilitation programs (IRP) allowing more time to reach adaptive potential. We reviewed our STEP experience to compare surgical outcomes between early and late eras of our IRP.

METHODS

A retrospective cohort study of all STEP patients managed by our IRP (Jan 2003-Dec 2016; era 1 2003-2005, era 2 2006-2016) was completed. Patient demographics, operative data, complications, and outcome data were collected. Univariate analysis between eras with nonparametric statistics was performed.

RESULTS

Thirty-six patients received STEP (Era 1 = 12; Era 2 = 24) [median age 5mo; males 22/36 (61.1%)]. In Era 2 a higher proportion had gastroschisis (8.3% vs 58.3%); p = 0.004) and shorter pre-STEP small bowel remnant (48 vs 111 cm, p = 0.001). The median increase in bowel length post-STEP was 52.9%. Overall, 42% of patients reached enteral autonomy (Era 1 7/12 (58%) vs Era 2 8/24 (33%); p = 0.15). Median time to PN discontinuation was shorter in Era 1 (259 vs 968 days, p = .208). Staple line complications were higher in Era 1 (16.7% vs 0%; p = 0.040).

CONCLUSION

Presently, STEP is reserved for a specific subset of IRP patients, allowing 42% to wean off PN. STEP's use should be under the umbrella of a multidisciplinary IRP.

TYPE OF STUDY

Retrospective cohort study.

LEVEL OF EVIDENCE

III.

Short bowel syndrome in children and adults: from rehabilitation to transplantation

Short bowel syndrome (SBS) is a dramatic clinical condition in both children and adults; the residual bowel length is not sufficient to avoid intestinal failure, with subsequent malnutrition and growth retardation, and intravenous support is required to provide the nutrients normally coming from the intestine. Apart from the primary disease, the medical status can be worsened by complications of intestinal failure: if there are irreversible, the prognosis is poor unless a successful intestinal rehabilitation is achieved. Areas covered: The rescue of the remnant small bowel requires a multidisciplinary expertise to achieve digestive autonomy. The use of intestinal trophic factors has shown encouraging results in improving the intestinal adaptation process. Whenever the residual bowel length is inadequate, in a well-selected population weaning parenteral nutrition (PN) off could be attempted by surgery through lengthening procedures. A further subset of patients, with total and irreversible intestinal failure and severe complications on PN, may have an indication to intestinal transplantation. This procedure is still affected by poor long-term results. Expert commentary: Novel approaches developed through a multidisciplinary team work, such as manipulation of microbiota or tissue bioengineering, should be added to current therapies to treat successfully SBS.

Donor-Specific Antibodies in Pediatric Intestinal and Multivisceral Transplantation: The Role of Liver and Human Leukocyte Antigen Mismatching

Rejection is one of the most important drawbacks for graft and patient survival in intestinal and multivisceral transplantation. However, there is no consensus on the diagnostic criteria for humoral rejection, and the literature about the role of donor-specific antibodies (DSA) on allograft outcome and the risk factors that contribute to their development is scant with contradictory results. The present study analyzes the role of DSA exclusively in a pediatric cohort of 43 transplants. Among our patients, 11.6% showed preformed DSA, but they did not correlate with more rejection or less allograft survival. Having previous transplants was the main sensitization factor with an odds ratio (OR) = 44.85 (P = 0.001). In total, 16.3% of recipients developed de novo donor-specific antibodies (dnDSA), mostly directed against human leukocyte antigen (HLA) class II, polyspecific and complement fixing. Additionally, the presence of dnDSA had a deleterious effect on graft rejection (hazard ratio [HR] = 11.00; P = 0.01) and survival (HR = 66.52; P < 0.001) in an observational period of 5 years after transplantation. The inclusion of the liver emerged as the main protective factor against dnDSA development with an OR = 0.07 (P = 0.007). The analysis of HLA compatibility at the serological and epitope level with the computational tools HLAMatchmaker and PIRCHE revealed no association between HLA mismatching and dnDSA. In conclusion, this study performed in pediatric recipients shows the deleterious effect of dnDSA on intestinal transplantation supported by the complement-fixing activity observed. Additionally, the liver inclusion in the allografts showed to be a protective factor against dnDSA generation.

Pediatric Intestinal Transplantation

Pediatric intestinal transplantation has moved from the theoretic to an actual therapy for children with irreversible intestinal failure who are suffering from complications of total parenteral nutrition. Owing to significant advancement in the management of intestinal failure and prevention of parenteral nutrition-related complications that have led to reduction in incidence of parenteral nutrition-associated liver disease and have improved intestinal adaptation, the indications for intestinal transplantation are evolving. Long-term outcomes have improved, but challenges in long-term graft function owing to chronic rejection and immunosuppressant-related complications remain the major opportunities for improvement.

Radiographic measurement of intestinal length among children with short bowel syndrome: Retrospective determination remains problematic

PURPOSE

Small bowel length is the most reliable predictor of enteral independence in pediatric short bowel syndrome. Retrospectively measured bowel lengths on upper GI with small bowel follow-through (UGI/SBFT) were compared to operative measurements.

METHODS

A pediatric radiologist and surgical trainees blinded to operative measurements retrospectively analyzed UGI/SBFT studies using the digital radiography curved measurement tool. Children with SBS and severe intestinal failure (parenteral nutrition >90days) at a multidisciplinary intestinal failure program 2002-2015 were included. Data were expressed as median (Q1, Q3).

RESULTS

Thirty-six children aged 0.8 (0.4, 3.7) years were analyzed. Fifty-six percent had intestinal malrotation, and 58% had prior serial transverse enteroplasty. Studies were conducted within 10 (7, 20) days of surgery. Intraoperative bowel length was 90cm (45, 142), while UGI/SBFT measurement by radiologist was 45cm (28, 63), with a mean difference of 47cm (SD 58cm, p<0.001) and a mean percent error of 50%. Radiographic assessment underestimated intestinal length in 83% of patients.

CONCLUSION

Bowel length measured retrospectively from upper GI with small bowel follow-through studies usually underestimated intraoperative bowel length. The limits of agreement were too wide for this technique to be clinically useful. Operative measurement remains necessary to assess intestinal length and rehabilitation potential.

TYPE OF STUDY

Study of Diagnostic Test.

LEVEL OF EVIDENCE

Level III.

Long-term outcomes of pediatric intestinal failure

Management of pediatric intestinal failure has evolved in recent decades, with improved survival since the advent of specialized multidisciplinary intestinal failure centers. Though sepsis and intestinal failure associated liver disease still contribute to mortality, we now have growing data on the long-term outcomes for this population. While intestinal adaptation and parenteral nutrition weaning is most rapid during the first year on parenteral support, achievement of enteral autonomy is possible even after many years as energy and protein requirements decline dramatically with age. Intestinal transplant is an option for patients experiencing complications of long-term parenteral nutrition who are expected to have permanent intestinal failure, but outcomes are hindered by immunosuppression-related complications. Much of the available data comes from single center retrospective reports, with variable inclusion criteria, intestinal failure definitions, and follow-up durations; this limits the ability to analyze outcomes and identify best practices. As most children now survive long-term, the focus of management has shifted to the avoidance and management of comorbidities, support of normal growth and development, and optimization of quality of life for these medically and surgically complex patients.

Treatment of short bowel syndrome in children. Value of the Intestinal Rehabilitation Program

The main cause of acute intestinal failure is short bowel syndrome, generally as a result of resection of extensive segments of small intestine. As a result, the main symptoms are watery diarrhea, malabsorption syndrome, chronic malnutrition, and death, if the patient is not properly treated. If the length of the remaining intestine is greater than 30 cm, complete adaptation is possible and the patient may not require parenteral nutrition. The currently recommended treatment includes the use of prolonged parenteral nutrition and enteral nutrition, always aimed at constant weight gain, in conjunction with surgeries aimed at elongating the dilated bowel. This set of procedures constitutes what is called an Intestinal Rehabilitation Program. This therapy was used in 16 children in periods ranging from 8 months to 7.5 years, with survival in 75% of the cases. Finally, the last resort to be used in children with complete resection of the small bowel is an intestinal transplant. However, to date there is no record of a Brazilian child that has survived this procedure, despite it being attempted in seven patients. We conclude that the results of the intestinal rehabilitation program are encouraging for the continuation of this type of treatment and stimulate the creation of the program in other pediatric care institutions.