Pediatric Intestinal Transplantation

Maturation and development of fetal pig intestinal tissue in immunodeficient mice

PURPOSE

This study aimed to compare the degree of maturation and development of fetal pig segmental intestinal tissue with that of spheroids created by in-vitro reaggregation of dissociated fetal intestinal cells after transplantation into immunodeficient mice.

METHODS

Fetal pig small intestines were transplanted as segmental grafts into the omentum and subrenal capsules of immunodeficient mice or enzymatically treated to generate single cells. Spheroids made by in-vitro reaggregation of these cells were transplanted into the subrenal capsules of immunodeficient mice. The segmental grafts and spheroids were harvested four and eight weeks after transplantation, and the structural maturity and in-vivo development of these specimens were histologically evaluated.

RESULTS

The spheroids were engrafted and supplied blood vessels from the host mice, but an intestinal layered structure was not clearly observed, and there was almost no change in size. On the other hand, the segmental grafts formed deep crypts in the mucus membrane, the inner circular layer, and outer longitudinal muscles. The crypts of the transplanted grafts harvested at eight weeks were much deeper, and the smooth muscle layer and the enteric nervous system were more mature than those of grafts harvested at the fourth week, although the intestinal peristaltic wave was not observed.

CONCLUSIONS

Spheroids created from fetal small intestinal cells could not form layered structures or mature sufficiently. Conversely, segmental tissues structurally matured and developed after in-vivo transplantation and are therefore potential grafts for transplantation.

Current Anesthetic Management in a 20-Month-Old Pediatric Patient With Intestinal Transplantation Due to Microvillous Inclusion Disease

Intestinal transplantation is a complex procedure both in terms of anesthesia and surgery. In particular, pediatric anesthesia management during intestinal transplant surgery can become even more complicated. It has been stated that propofol, remifentanil, and sevoflurane reduce patient mortality by reducing the incidence of intestinal ischemiareperfusion injury. Although studies of these agents continue to be conducted in vivo or in vitro, these anesthetics are currently used for specific procedures that have a high risk of incurring ischemia-reperfusion injury. Herein, we present the case of a male child, aged 20 months, who was dependent on total parenteral nutrition and was found to have intestinal failure associated with liver disease type 1. Hematologic tests showed findings of anemia and metabolic acidosis. Propofol was administered for induction of anesthesia. Anesthesia maintenance was achieved using sevoflurane with remifentanil infusion. We ensured safe and adequate vascular access in the patient and performed hematologic and biochemical tests with detailed system controls. Before the procedure, we prepared a leukocyte-poor erythrocyte suspension, leukocyte-poor random or apheresis platelets, and ABO- and Rh-compatible fresh frozen plasma. We monitored for signs of acidosis, hypotension, coagulation disorders, and hyperkalemia during the reperfusion period.We maintained patient normothermia. In this case report on the anesthetic management of a pediatric patient aged 20 months who received a small bowel transplant due to microvillous inclusion disease, we found that the selection of anesthetic agents may affect the prognosis of future surgical procedures.

Pediatric intestine and multivisceral transplant

PURPOSE OF REVIEW

Intestinal and multivisceral transplantation (ITx, MVTx) is the cornerstone in treatment of irreversible intestinal failure (IF) and complications related to parenteral nutrition. This review aims to highlight the unique aspects of the subject in pediatrics.

RECENT FINDINGS

Etiology of intestinal failure (IF) in children shares some similarity with adults but several unique considerations when being evaluated for transplantation will be discussed. Owing to significant advancement in IF management and home parenteral nutrition (PN), indication criteria for pediatric transplantation continues to be updated. Outcomes have continued to improve with current long-term patient and graft survival in multicenter registry reports reported at 66.1% and 48.8% at 5 years, respectively. Pediatric specific surgical challenges such abdominal closure, post transplantation outcomes, and quality of life are discussed in this review.

SUMMARY

ITx and MVTx remain lifesaving treatment for many children with IF. However long-term graft function is still a major challenge.

Intestinal twin-to-twin transplant for short gut: Review of the literature and discussion of a complex case

Paediatric Intestinal Transplantation (IT) presents the highest mortality on the waiting-list due to anatomical disproportion. Living-Donor IT (LDIT) offers the best advantages and when performed among identical monozygotic twins, it also benefits from unique immunology. According to MEDLINE/Pubmed, twin-to-twin LDIT has been performed in seven cases (6:7 males, median age of 32 years). None of the patients received immunosuppression postoperatively. Only one paediatric twinto- twin LDIT was carried out with a 160-cm mid-ileum tract: an interposed 4/5-cm arterial graft was required to ensure a tensionfree anastomosis to the anterior wall of the infra-renal abdominal aorta. In contrast, venous anastomosis was done directly to the inferior cava vein. We present a case for debate of a 13- month-old SBS patient where a twin-LDIT was discussed with parents, who decided to wait after careful analysis and ethical considerations.

Pediatric intestinal transplantation

Advancements in donor management, organ preservation and operative techniques, as well as immunosuppressive therapies, have provided children with intestinal failure and its complications a chance not only for enteral autonomy but also long-term survival through intestinal transplantation (ITx). First described in the 1960's, experience has grown in managing these complex patients both pre- and post-transplant. The goals of this review are to provide a brief history of intestinal transplantation and intestinal rehabilitation in pediatric patients, followed by focused discussions of the indications for ITx, induction and maintenance immunosuppression therapies, common post-operative complications, and outcomes/quality of life post-transplant.

H2S donor molecules against cold ischemia-reperfusion injury in preclinical models of solid organ transplantation

Cold ischemia-reperfusion injury (IRI) is an inevitable and unresolved problem that poses a great challenge in solid organ transplantation (SOT). It represents a major factor that increases acute tubular necrosis, decreases graft survival, and delays graft function. This complicates graft quality, post-transplant patient care and organ transplantation outcomes, and therefore undermines the success of SOT. Herein, we review recent advances in research regarding novel pharmacological strategies involving the use of different donor molecules of hydrogen sulfide (H₂S), the third established member of the gasotransmitter family, against cold IRI in different experimental models of SOT (kidney, heart, lung, liver, pancreas and intestine). Additionally, we discuss the molecular mechanisms underlying the effects of these H₂S donor molecules in SOT, and suggestions for clinical translation. Our reviewed findings showed that storage of donor organs in H₂S-supplemented preservation solution or administration of H₂S to organ donor prior to organ procurement and to recipient at the start and during reperfusion is a novel, simple and cost-effective pharmacological approach to minimize cold IRI, limit post-transplant complications and improve transplantation outcomes. In conclusion, experimental evidence demonstrate that H₂S donors can significantly mitigate cold IRI during SOT through inhibition of a complex cascade of interconnected cellular and molecular events involving microcirculatory disturbance and microvascular dysfunction, mitochondrial injury, inflammatory responses, cell damage and cell death, and other damaging molecular pathways while promoting protective pathways. Translating these promising findings from bench to bedside will lay the foundation for the use of H₂S donor molecules in clinical SOT in the future.

Intestinal Failure: A Description of the Problem and Recent Therapeutic Advances

Pediatric intestinal failure occurs when gut function is insufficient to meet the nutrient and hydration needs of the growing child. The commonest cause is short bowel syndrome with maldigestion and malabsorption following massive bowel loss. The remnant bowel adapts during the process of intestinal rehabilitation. Management promotes the achievement of enteral autonomy while mitigating the risk of comorbid disease. The future of care is likely to see expansion of pharmacologic methods for augmenting bowel adaptation, tissue engineering techniques enabling immune suppression-free autologous bowel transplant, and the development of electronic health record tools for efficient, collaborative study and care improvement.

Current outcomes after pediatric and adult intestinal transplantation

PURPOSE OF REVIEW

In this article, we will review the outcomes of patients with intestinal transplant (ITx) with a focus on factors affecting long-term graft and patient survival.

RECENT FINDINGS

The most recent International Intestinal Transplant Registry reports a 1-, 5-, and 10-year graft survival of 71%, 50%, and 41% respectively, for ITx grafts transplanted since 2000. Over the past decades, significant improvements have been achieved in short-term graft and patient outcomes for ITx recipients. The improvement in short-term outcomes may be related to the focused treatment of antihuman leukocyte antigen antibodies, the use of induction immunotherapy protocols, refinements in surgical techniques, establishment of dedicated ITx units, and improved postoperative management.However, long-term graft and patient outcomes for ITx recipients remain stagnant. Issues impairing long-term outcomes of ITx include the challenges in the diagnosis and treatment of chronic rejection and antibody-mediated rejection, progressive decline in renal function, and long-term infectious and malignancy risks especially related to cytomegalovirus, Epstein-Barr virus and posttransplant lymphoproliferative disorder after ITx.

SUMMARY

Addressing and preventing early and late complications is the key to improving short-term and long-term outcomes after ITx.

A Comparison of Sterilization Techniques for Production of Decellularized Intestine in Mice

Tissue-engineered small intestinal implants are being widely investigated as a potential treatment for children with short bowel syndrome, yet are currently limited by their growth potential and relatively low surface area. To address this gap in the field, several investigators have utilized whole organ decellularization of the small intestine as a platform for subsequent growth of intestinal tissue. However, such scaffold-cell constructs require sterilization as a prerequisite for implantation, and the effects of the different pathogen-clearance techniques used on the tissue architecture remains unknown. The effects of four different published protocols for pathogen clearance of decellularized intestine, namely 0.1% peracetic acid (PAA), 0.18% PAA +4.8% ethanol (EtOH), 0.08% PAA +1% hydrogen peroxide (H2O2), and ultraviolet (UV) sterilization were compared using qualitative and quantitative techniques to assess changes to the extracellular matrix, cytocompatibility, and biocompatibility. All methods of sterilization of decellularized intestine were found to be equally effective and each method had similar histologic and scanning electron microscopy appearance of the sterilized tissue. In addition, collagen and glycosaminoglycan quantities, and the ability to support cell growth were similar among all methods. This study provides insights into the change in crypt villous architecture of the extracellular matrix with all sterilization techniques studied. Our findings demonstrate that sterilization affects the microarchitecture significantly, which has not been well accounted for in studies to date, and we were unable to identify a single best agent to achieve tissue sterilization while preserving the microarchitectural features of the tissue.

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.

Surgeon's perspective on short bowel syndrome: Where are we?

Short bowel syndrome (SBS) is due to a massive loss of small bowel: the reduction of gut function is below the minimum necessary to maintain health (in adults) and growth (in children) so intravenous supplementation is required. Parenteral nutrition represents the milestone of treatment and surgical attempts should be limited only when the residual bowel is sufficient to increase absorption, reducing diarrhea and slowing the transit time of nutrients, water and electrolytes. The surgical techniques lengthen the bowel (tapering it) or reverse a segment of it: developed in children, nowadays are popular also among adults. The issue is mainly represented by the residual length of the small bowel where ileum has shown increased adaptive function than jejunum, but colon should be considered because of its importance in the digestive process. These concepts have been translated also in intestinal transplantation, where a colonic graft is nowadays widely used and the terminal ileum is the selected segment for a living-related donation. The whole replacement by a bowel or multivisceral transplant is still affected by poor long term outcome and must be reserved to a select population of SBS patients, affected by intestinal failure associated with irreversible complications of parenteral nutrition.