Factors Influencing Outcome After Intestinal Transplantation in Children

Twenty Years of Gut Transplantation for Chronic Intestinal Pseudo-obstruction: Technical Innovation, Long-term Outcome, Quality of Life, and Disease Recurrence

OBJECTIVE

To define long-term outcome, predictors of survival, and risk of disease recurrence after gut transplantation (GT) in patients with chronic intestinal pseudo-obstruction (CIPO).

BACKGROUND

GT has been increasingly used to rescue patients with CIPO with end-stage disease and home parenteral nutrition (HPN)-associated complications. However, long-term outcome including quality of life and risk of disease recurrence has yet to be fully defined.

METHODS

Fifty-five patients with CIPO, 23 (42%) children and 32 (58%) adults, underwent GT and were prospectively studied. All patients suffered gut failure, received HPN, and experienced life-threatening complications. The 55 patients received 62 allografts; 43 (67%) liver-free and 19 (33%) liver-contained with 7 (13%) retransplants. Hindgut reconstruction was adopted in 1993 and preservation of native spleen was introduced in 1999. Immunosuppression was tacrolimus-based with antilymphocyte recipient pretreatment in 41 (75%).

RESULTS

Patient survival was 89% at 1 year and 69% at 5 years with respective graft survival of 87% and 56%. Retransplantation was successful in 86%. Adults experienced better patient (P = 0.23) and graft (P = 0.08) survival with lower incidence of post-transplant lymphoproliferative disorder (P = 0.09) and graft versus host disease (P = 0.002). Antilymphocyte pretreatment improved overall patient (P = 0.005) and graft (P = 0.069) survival. The initially restored nutritional autonomy was sustainable in 23 (70%) of 33 long-term survivors with improved quality of life. The remaining 10 recipients required reinstitution of HPN due to allograft enterectomy (n = 3) or gut dysfunction (n = 7). Disease recurrence was highly suspected in 4 (7%) recipients.

CONCLUSIONS

GT is life-saving for patients with end-stage CIPO and HPN-associated complications. Long-term survival is achievable with better quality of life and low risk of disease recurrence.

Intestinal transplantation: current improvements and perspectives

PURPOSE OF REVIEW

This review summarizes the most recent relevant knowledge in clinical practice in the field of intestinal transplantation.

RECENT FINDINGS

Three important factors that have allowed improving results during the last few years are reviewed here. The first relates to the development of a different approach to tackle the underlying cause of intestinal failure and to the patient's characteristics in terms of liver function, age, and body size. The second involves immune modulation and especially the immunosuppressive regimen at induction. The third refers to posttransplantation monitoring, in particular the diagnosis and treatment of intestinal graft rejection and lymphoproliferative disorders. Patient status and referral for intestinal transplantation remain debated. The Intestinal Transplant Registry and a report from an individual program have demonstrated the relationship between a patient's pretransplant status and outcome. Candidacy for intestinal transplantation was analysed in a European survey of home parenteral nutrition patients. Early referral and listing are important for successful outcomes after intestinal grafting.

SUMMARY

Patient management should include therapies adapted to each stage of intestinal failure based on a multidisciplinary approach in centers involving surgery, gastroenterology, parenteral nutrition expertise, home parenteral nutrition programs, and liver-intestinal transplantation experience. Timing for referral of patients in specialized centers remains a crucial issue.

Assessment and outcome of children with intestinal failure referred for intestinal transplantation

BACKGROUND & AIMS

Chronic intestinal failure (CIF) requires long term parenteral nutrition (PN) and, in some patients, intestinal transplantation (ITx). Indications and timing for ITx remain poorly defined. In the present study we aimed to analyze causes and outcome of children with CIF.

METHODS

118 consecutive patients referred to our institution were assessed by a multidisciplinary team and four different categories were defined retrospectively based on their clinical course: Group 1: patients with reversible intestinal failure; group 2: patients unsuitable for ITx, group 3: patients listed for ITx; group 4: patients stable under PN. Analysis involved comparison between groups for nutritional status, central venous catheter (CVC) related complications, liver disease, and outcome after transplantation by using non parametric tests, Mann-Whitney tests, Kruskal-Wallis, Wilcoxon signed rank tests and chi square distribution for percentage.

RESULTS

118 children (72 boys) with a median age of 15 months at referral (2 months-16 years) were assessed. Etiology of IF was short bowel syndrome [n = 47], intractable diarrhea of infancy [n = 37], total intestinal aganglionosis [n = 18], and chronic intestinal pseudoobstruction [n = 17]. Most patients (89.8%) were totally PN dependent, with 48 children (40.7%) on home-PN prior to admission. Nutritional status was poor with a median body weight at -1.5 z-score (ranges: -5 to +2.5) and median length at -2.0 z-score (ranges: -5.5 to +2.3). The mean number of CVC inserted per patient was 5.2 (range 1-20) and the mean number of CRS per patient was 5.5 (median: 5; range 0-12) Fifty-five patients (46.6%) had thrombosis of ≥2 main venous axis. At admission 34.7% of patients had elevated bilirubin (≥50 μmol/l), and 19.5% had platelets <100,000/ml, and 15% had both. Liver biopsy performed in 79 children was normal (n = 4), or showed F1 or F2 fibrosis (n = 29), bridging fibrosis F3 (n = 20), or cirrhosis (n = 26). Group 1 included 10 children finally weaned from PN (7-years survival: 100%). Group 2 included 12 children with severe liver disease and associated disorders unsuitable for transplantation (7-years survival: 16.6%). Group 3 included 66 patients (56%) who were listed for small bowel or liver-small bowel transplantation, 62/66 have been transplanted (7 years survival: 74.6%). Factors influencing outcome after liver-ITx were body weight (p < .004), length (p < .001), pre-Tx bilirubin plasma level (p < .001) and thrombosis (p < .01) for isolated ITx, Group 4 included 30 children (25.4%) with irreversible IF considered as potential candidates for isolated ITx. Four children were lost from follow up and 3 died within 2 years (survival 88.5%). Among potential candidates, the following parameters improved significantly during the first 12 months of follow up: Body weight (p.0001), length (p < .0001) and bilirubin (p < .0001).

CONCLUSIONS

many patients had a poor nutritional status with severe complications especially liver disease. PN related complications were the most relevant indication for ITx, but also a negative predictor for outcome. Early patient referral for Tx-assessment might help to identify and separate children with irreversible IF from children with transient IF or uncomplicated long-term PN, allowing to adapt a patient-based treatment strategy including or not ITx.

Antibody-mediated rejection after intestinal transplantation

PURPOSE OF REVIEW

In spite of impressive improvements in short-term outcomes for intestine transplant recipients, late allograft loss continues to plague the field. Attention has mostly been focused on T-cell-mediated cellular mechanisms of allograft rejection to explain these losses; however, as in other forms of solid-organ transplantation, especially kidney and heart, antibody-mediated mechanisms of acute and chronic allograft injury are increasingly being implicated. In this review, the mechanisms of B-cell- and humoral-mediated allograft injury will be briefly discussed along with the limited evidence that exist for invoking antibody-mediated rejection (AMR) as important in intestine transplantation.

RECENT FINDINGS

The presence of donor-specific antibody has been reported to increase the incidence and severity of intestine allograft rejection and to worsen the overall prognosis for graft and patient. C4d staining in intestine biopsies is unreliable, and currently it is not possible to diagnose AMR with certainty in intestine transplantation. Treatment of presumed AMR in intestine recipients is purely anecdotal at this time.

SUMMARY

Further basic and clinical research needs to be conducted to more confidently diagnose and treat AMR in intestinal transplantation.

Short bowel syndrome in the NICU

Short bowel syndrome (SBS) is the most common cause of intestinal failure in infants. In neonates and young infants, necrotizing enterocolitis, gastroschisis, intestinal atresia, and intestinal malrotation/volvulus are the leading causes of SBS. Following an acute postsurgical phase, the residual gastrointestinal tract adapts with reorganization of the crypt-villus histoarchitecture and functional changes in nutrient absorption and motility. A cohesive, multidisciplinary approach can allow most neonates with SBS to transition to full enteral feeds and achieve normal growth and development. In this article, the clinical features, management, complications, and prognostic factors in SBS are reviewed.

Age-based disparity in outcomes of intestinal transplants in pediatric patients

Outcomes of intestinal transplants (ITx; n = 977) for pediatric patients are examined using the United Network for Organ Sharing data from 1987 to 2009. Recipients were divided into four age groups: (1) <2 years of age (n = 569), (2) 2-6 years (n = 219), (3) 6-12 years (n = 121) and (4) 12-18 years (n = 68). Of 977 ITx, 287 (29.4%) were isolated ITx and 690 (70.6%) were liver and ITx (L-ITx). Patient survival for isolated ITx at 1, 3 and 5 years, 85.3%, 71.3% and 65.0%, respectively, was significantly better than L-ITx, 68.4%, 57.0% and 51.4%, respectively, (p = 0.0001); this was true for all age groups, except for patients <2 years of age. The difference in graft survival between isolated ITx and L-ITx was significant at 1 and 3 years (Wilcoxon test, p = 0.0012). After attrition analysis of graft survival of patients who survived past first year, 3 and 5 years, graft survival for L-ITx patient was significantly better than those for isolated ITx. Isolated ITx should be considered early before the onset of liver disease in children >2 with intestinal failure but is not advantageous in patients <2 years.

Small-Bowel Allograft Biopsies in the Management of Small-Intestinal and Multivisceral Transplant Recipients: Histopathologic Review and Clinical Correlations

Context.—Intestinal transplant has become a standard treatment option in the management of patients with irreversible intestinal failure. The histologic evaluation of small-bowel allograft biopsy specimens plays a central role in assessing the integrity of the graft. It is essential for the management of acute cellular and chronic rejection; detection of infections, particularly with respect to specific viruses (cytomegalovirus, adenovirus, Epstein-Barr virus); and immunosuppression-related lymphoproliferative disease.

Objective.—To provide a comprehensive review of the literature and illustrate key histologic findings in small-bowel biopsy specimen evaluation of patients with small-bowel or multivisceral transplants.

Data Sources.—Literature review using PubMed (US National Library of Medicine) and data obtained from national and international transplant registries in addition to case material at Columbia University, Presbyterian Hospital, and Mount Sinai Medical Center, New York, New York.

Conclusions.—Key to the success of small-bowel transplantation and multivisceral transplantation are the close monitoring and appropriate clinical management of patients in the posttransplant period, requiring coordinated input from all members of the transplant team with the integration of clinical, laboratory, and histopathologic parameters.

Intestinal retransplantation: analysis of Organ Procurement and Transplantation Network database

BACKGROUND

We evaluated the outcomes of intestinal retransplantation in children and adults in the United States.

METHODS

The United Network for Organ Sharing data were analyzed from October 1987 to August 2009.

RESULTS

In adult isolated intestinal transplant (ITx) retransplants (n=41), patient survival was 80.1%, 47.4%, and 28.5% at 1, 3, and 5 years, which was worse than primary isolated ITx (P=0.005). For liver ITx (L-ITx) retransplants (n=31), patient survival was 63.1%, 56.1%, and 46.8% and was not significantly different than primary L-ITx. In pediatric isolated ITx retransplants (n=28), patient survival at 1, 3, and 5 years was 80.7%, 74%, and 57.5%; graft survival was 76.4%, 56.6%, and 44%. In L-ITx retransplants (n=49), patient survival was 42%, 42%, and 42%; graft survival was 39%, 39%, and 39%. Patient and graft survival in adult L-ITx retransplants were better in era 2 (January 2001-August 2009) than era 1 (October 1987-December 2000) (P=0.01). Among pediatric L-ITx retransplants, outcomes were worst in children younger than 2 years (n=12). In regression analysis, prior hospitalization was a negative predictor for all the groups of patients (relative risk, 5.4).

CONCLUSION

Patient and graft survival in adult isolated ITx are less favorable after a retransplant compared with a primary transplant. Patient and graft survival are also poor in pediatric L-ITx after a retransplant, especially for children younger than 2 years of age. L-ITx retransplant results improved significantly in era 2 in adult recipients.

Pediatric intestinal transplantation: normal radiographic appearance and complications

We present a pictorial essay on pediatric intestinal transplantation that describes the indications for pediatric intestinal transplantation, surgical technique, and the role of imaging in the pre-transplant work-up and detection of post-transplant complications. We illustrate the normal post-transplant imaging appearance and common complications, including rejection, infection, post-transplant lymphoproliferative disease (PTLD), mechanical dysfunction and vascular complications. We conclude with an imaging algorithm for suspected post-transplant complications based on clinical scenarios.

Intractable diarrhea with tufting enteropathy: a favorable outcome is possible

BACKGROUND AND OBJECTIVE

Tufting enteropathy (TE) is a congenital abnormality of intestinal mucosa development characterized by severe intestinal failure requiring parenteral nutrition (PN) and, in some cases, small bowel transplantation. A few patients have had a more favorable outcome. The objective of this study was to evaluate possible correlations between histological lesion severity in duodenal biopsies and clinical outcomes in children with TE.

PATIENTS AND METHODS

We retrospectively reviewed the records of patients diagnosed with TE between 1993 and 2003 at our institution based on intractable neonatal-onset diarrhea with prolonged dependence on PN and duodenal biopsy findings of villous atrophy, epithelial dysplasia with enterocyte dedifferentiation and disorganization (tufting) of the surface epithelium, and crypt abnormalities. The histological lesions were assessed semiquantitatively and compared with the clinical outcomes including dependence on PN.

RESULTS

Seven children, all from consanguineous parents, were studied for a median of 6.5 years. Three were permanently weaned off PN and experienced normal growth without nutritional assistance. Initial biopsies in all 3 children showed severe diffuse histological lesions. At weaning off PN, 2 of these 3 patients had persistent, although less diffuse, histological lesions.

CONCLUSIONS

Progressive weaning off PN is possible in some children with TE. In our experience, this favorable outcome was not predicted by histological lesion severity, although the lesions improved in some patients. New biomarkers for identifying the histological lesions and predicting the outcome would be useful.

Effect of recombinant human growth hormone on intestinal absorption and body composition in children with short bowel syndrome

This prospective study aimed to establish the effect of recombinant human growth hormone (rhGH) on intestinal function in children with short bowel syndrome (SBS). Eight children with neonatal SBS were included. All were dependent on parenteral nutrition (PN) for >3 years (range, 3.8-11.6 years), with PN providing >50% of recommended dietary allowance for age (range, 50%-65%). The subjects received rhGH (Humatrope) 0.13 mg/kg/d subcutaneously over a 12-week period. The follow-up was continued over a 12-month period after rhGH discontinuation. Clinical and biological assessments were performed at baseline, at the end of the treatment period, and 12 months after the end of treatment. No side effects related to rhGH were observed. PN requirements were decreased in all children during the course of rhGH treatment. Between baseline and the end of treatment, significant increases were observed in concentrations (mean ± standard deviation) of serum insulin-like growth factor 1 (103.1 ± 49.9 µg/L vs 153.5 ± 82.2 µg/L; P < .01), serum insulin-like growth factor-binding protein 3 (1.7 ± 0.6 mg/L vs 2.5 ± 0.9 mg/L; P < .001), and plasma citrulline (16.5 ± 14.8 µmol/L vs 25.2 ± 18.3 µmol/L; P < .05). A median 54% increase in enteral intake (range, 10%-244%) was observed (P < .001) and net energy balance improved significantly (P < .002). It was necessary for 6 children to be maintained on PN or restarted after discontinuation of rhGH treatment, and they remained on PN until the end of the follow-up period. A 12-week high-dose rhGH treatment allowed patients to decrease PN, but only 2 patients could be definitively weaned from PN. Indications and cost-effectiveness of rhGH treatment for SBS pediatric patients need further evaluation.

[Intraabdominal infection in inmunodepressed patients]

Diseases of the gastrointestinal system frequently complicate immunosuppressed patients. Endogenous flora is the principal source of infection in humans, especially in patients with dysfunction of the digestive epithelial barrier due to various factors. Bacterial translocation, traumatisms, ischemia and surgery are frequent events in the general population. In addition, important risk factors for abdominal infections in specific patients include tumoral infiltration, mucositis complicating chemotherapy and/or radiotherapy, hypoproteinemia, neutropenia and lymphocyte deficiency. Clinical pictures vary according to patients' baseline condition and the environmental setting, including nosocomial infections. The differential clinical characteristics of abdominal infections observed in distinct types of immunosuppressed patients are reviewed.

Long-term outcome of chronic intestinal pseudo-obstruction adult patients requiring home parenteral nutrition

OBJECTIVES

Chronic intestinal pseudo-obstruction (CIPO) is a rare, disabling disorder responsible for motility-related intestinal failure. Because it induces malnutrition, CIPO is a significant indication for home parenteral nutrition (HPN). The objective of the study was to evaluate long-term outcome of CIPO patients requiring HPN during adulthood.

METHODS

In total, 51 adult CIPO patients (18 men/33 women, median age at symptom occurrence 20 (0-74) years, 34/17 primary/secondary CIPO) followed up at our institution for HPN management between 1980 and 2006 were retrospectively studied for survival and HPN dependence rates using univariate and multivariate analysis.

RESULTS

Follow-up after diagnosis was 8.3 (0-29) years. Surgery was required in 84% of patients. The number of interventions was 3 +/- 3 per patient (mean +/- s.d.), leading to short bowel syndrome in 19 (37%) patients. Actuarial survival probability was 94, 78, 75, and 68% at 1, 5, 10, and 15 years, respectively. Multivariate analysis showed that lower mortality was associated with the ability to restore oral feeding at baseline (hazard ratio (HR) = 0.2 (0.06-0.65), P = 0.008) and symptom occurrence before the age of 20 years (HR=0.18 (0.04-0.88), P = 0.03). Higher mortality was associated with systemic sclerosis (HR=10.4 (1.6-67.9), P = 0.01). Actuarial HPN dependence was 94, 75, and 72% at 1, 2, and 5 years, respectively.

CONCLUSIONS

In this large cohort of CIPO adult patients with severe intestinal failure, i.e., those requiring HPN, we found a higher survival probability than previously reported. These results should be taken into account when considering intestinal transplantation.

Intestinal transplantation for total intestinal aganglionosis: a series of 12 consecutive children

BACKGROUND

Management of patients with total intestinal aganglionosis (TIA) is a medical challenge because of their dependency on parenteral nutrition (PN). Intestinal transplantation (ITx) represents the only alternative treatment for patients with irreversible intestinal failure for achieving intestinal autonomy.

METHODS

Among 66 patients who underwent ITx in our center, 12 had TIA. They received either isolated ITx (n = 4) or liver-ITx (LITx, n = 8) after 10 to 144 months of total PN. All grafts included the right colon.

RESULTS

After a median follow-up of 57 months, the survival rate was 62.5% in the LITx group and 100% in the ITx patients. The graft survival rate was 62.5% in the LITx group and 75% in the ITx group. All the surviving patients were fully weaned from total PN, after a median of 57 days. Pull through of the colon allograft was carried out in all patients. Fecal continence is normal in all but one of the surviving children.

CONCLUSION

These results suggest that ITx with colon grafting should be the preferred therapeutic option in TIA. Early referral to a transplantation center after diagnosis of TIA is critical to prevent PN-related cirrhosis and thereby to permit ITx, which is associated with a good survival rate.

Pediatric intestinal and multivisceral transplantation: a new challenge for the pediatric intensivist

INTRODUCTION

With increasing survival rates, intestinal transplantation (ITx) and multivisceral transplantation have reached the mainstream of medical care. Pediatric candidates for ITx often suffer from severe multisystem impairments that pose challenges to the medical team. These patients frequently require intensive care preoperatively and have unique intensive care needs postoperatively.

METHODS

We reviewed the literature on intensive care of pediatric intestinal transplantation as well as our own experience. This review is not aimed only at pediatric intensivists from ITx centers; these patients frequently require ICU care at other institutions.

RESULTS

Preoperative management focuses on optimization of organ function, minimizing ventilator-induced lung injury, preventing excessive edema yet maintaining adequate organ perfusion, preventing and controlling sepsis and bleeding from varices at enterocutaneous interfaces, and optimizing nutritional support. The goal is to extend life in stable condition to the point of transplantation. Postoperative care focuses on optimizing perfusion of the mesenteric circulation by maintaining intravascular volume, minimizing hypercoagulability, and providing adequate oxygen delivery. Careful monitoring of the stoma and its output and correction of electrolyte imbalances that may require renal replacement therapy is critical, as are monitoring for and aggressively treating infections, which often present with only subtle clinical clues. Signs of intestinal rejection may be non-specific, and early differentiation from other causes of intestinal dysfunction is important. Understanding of the expanding armamentarium of immunosuppressive agents and their side-effects is required.

CONCLUSIONS

As outcomes of ITx improve, transplant teams accept patients with higher pre-operative morbidity and at higher risk for complications. Many ITx patients would benefit from earlier referral for transplant evaluation before severe liver disease, recurrent central venous catheter-related sepsis and venous thromboses develop.

Survival of patients identified as candidates for intestinal transplantation: a 3-year prospective follow-up

BACKGROUND & AIMS

The US Medicare indications for intestinal transplantation are based on failure of home parenteral nutrition. The American Society of Transplantation also includes patients at high risk of death from their primary disease or with high morbidity intestinal failure. A 3-year prospective study evaluated the appropriateness of these indications.

METHODS

Survival on home parenteral nutrition or after transplantation was analyzed in 153 (97 adult, 56 pediatric) candidates for transplantation and 320 (262 adult, 58 pediatric) noncandidates, enrolled through a European multicenter cross-sectional survey performed in 2004. Kaplan-Meier and chi-square test statistics were used.

RESULTS

The 3-year survival was 94% (95% CI, 92%-97%) in noncandidates and 87% (95% CI, 81%-93%) in candidates not receiving transplants (P = .007). Survival was 80% (95% CI, 70%-89%), 93% (95% CI, 86%-100%), and 100% in parenteral nutrition failure, high-risk primary disease, and high-morbidity intestinal failure, respectively (P = .034). Fifteen candidates underwent transplantation. Six died, including all 3 of those who were in hospital, and 25% of those who were at home at time of transplantation (P = .086). Survival in the 10 patients receiving a first isolated small bowel transplant was 89% (95% CI, 70%-100%), compared with 85% (95% CI, 74%-96%) in the candidates with parenteral nutrition failure not receiving transplants because of central venous catheter complications, or 70% (95% CI, 53%-88%) in those with parenteral nutrition-related liver failure (P = .364).

CONCLUSIONS

The results confirm home parenteral nutrition as the primary therapeutic option for intestinal failure and support the appropriateness and potential life-saving role of timely intestinal transplantation for patients with parenteral nutrition failure.

Evaluation of c4d deposition and circulating antibody in small bowel transplantation

Antibody-mediated rejection (AMR) consensus criteria are defined in kidney and heart transplantation by histological changes, circulating donor-specific antibody (DSA), and C4d deposition in affected tissue. AMR consensus criteria are not yet identified in small bowel transplantation (SBTx). We investigated those three criteria in 12 children undergoing SBTx, including one retransplantation and four combined liver-SBTx (SBTx), with a follow-up of 12 days to 2 years. All biopsies (91) were evaluated with a standardized grading scheme for acute rejection (AR), vascular lesions and C4d expression. Sera were obtained at day 0 and during the follow-up. C4d was expressed in 37% of biopsies with or without AR, but in 50% of biopsies with severe vascular lesions. In addition, vascular lesions were always associated with AR and a poor outcome. All children with AR (grade 2 or 3) observed before the third month died or lost the graft. DSA were never found in any studied sera. We found no evidence that C4d deposition was of any clinical relevance to the outcome of SBTx. However, the grading of vascular lesions may constitute a useful marker to identify AR that is potentially resistant to standard treatment, and for which an alternative therapy should be considered.

Future horizons in the treatment of enteric neuropathies

Enteric neuropathies comprise a vast and disparate array of congenital and acquired disorders of the enteric nervous system (ENS), reflecting both the complexity of its neuronal composition and the many interactions that modulate its function. Although present therapeutic strategies, largely limited to surgery and the provision of artificial nutrition, have transformed the early survival and life of sufferers, levels of morbidity and mortality remain unacceptably high. This highlights the need to develop new treatments for enteric neuropathies. In the last decade, the tremendous advances in molecular biology and genetics have significantly enhanced our understanding of ENS development and function. Coupled with equivalent progress in the fields of pharmacology and stem-cell biology, this has led to the identification of novel tools and targets for therapy, which either aim to optimise the function of the intrinsic ENS or replace/replenish components of an inadequate or dysfunctional ENS. This article reviews current work on a number of these interventions with a particular focus on the use of ENS stem cells as potential therapeutic tools for enteric neuropathies.

Treatment of intestinal failure: intestinal transplantation

Over the past 15 years, intestinal transplantation for the treatment of intestinal failure has changed from a desperate last-ditch effort into a standard therapy for which a good outcome is expected. Patient survival after intestinal transplantation has improved in the past 3-5 years and now approaches that of other solid organ allograft recipients, including liver and kidney, and is similar to survival on permanent therapy with parenteral nutrition. Complications are more common and often more severe during the initial hospitalization period after intestinal transplantation than they are after transplantation of other solid organs. After intestinal transplantation the initial hospitalization period is, therefore, usually 3-8 weeks long. Nearly all patients discharged after intestinal transplantation have good allograft function and have been weaned from total parenteral nutrition. The cost of the initial hospitalization period is one to two times the cost of permanent total parenteral nutrition for 1 year, which means that, in most cases, intestinal transplantation is cost-saving within 2 years of transplantation. In addition, quality of life after intestinal transplantation, as determined by standardized quality of life measures, is good or normal.

Comparison of polyester scaffolds for bioengineered intestinal mucosa

INTRODUCTION

Biodegradable polyester scaffolds have proven useful for growing neointestinal tissue equivalents both in vitro and in vivo. These scaffolds allow cells to attach and grow in a 3-dimensional space while nutrient flow is maintained throughout the matrix. The purpose of this study was to evaluate different biopolymer constructs and to determine mucosal engraftment rates and mucosal morphology.

HYPOTHESIS

We hypothesized that different biopolymer constructs may vary in their ability to provide a good scaffolding onto which intestinal stem cell organoids may be engrafted.

STUDY DESIGN

Eight different microporous biodegradable polymer tubes composed of polyglycolic acid (PGA), polylactic acid, or a combination of both, using different fabrication techniques were seeded with intestinal stem cell clusters obtained from neonatal rats. Three different seeded polymer constructs were subsequently placed into the omentum of syngeneic adult recipient rats (n = 8). Neointestinal grafts were harvested 4 weeks after implantation. Polymers were microscopically evaluated for the presence of mucosal growth, morphology, scar formation and residual polymer.

RESULTS

Mucosal engraftment was observed in 7 out of 8 of the polymer constructs. A maximal surface area engraftment of 36% (range 5-36%) was seen on nonwoven, randomly entangled, small fiber PGA mesh coated with aerosolized 5% poly-L-lactic acid. Villous and crypt development, morphology and created surface area were best on PGA nonwoven mesh constructs treated with poly-L-lactic acid. Electrospun microfiber PGA had poor overall engraftment with little or no crypt or villous formation.

CONCLUSION

Intestinal organoids can be engrafted onto biodegradable polyester scaffoldings with restitution of an intestinal mucosal layer. Variability in polymer composition, processing techniques and material properties (fiber size, luminal dimensions and pore size) affect engraftment success. Future material refinements should lead to improvements in the development of a tissue-engineered intestine.