Domino Liver Transplant in Maple Syrup Urine Disease: Technical Details of Cases in Which the First Surgery Involved a Living Donor

Evaluation of living donors for hereditary liver disease (siblings, heterozygotes)

Living donor liver transplantation (LDLT) is recognised as an alternative treatment modality to reduce waiting list mortality and expand the donor pool. Over recent decades, there have been an increasing number of reports on the use of LT and specifically LDLT for familial hereditary liver diseases. There are marginal indications and contraindications that should be considered for a living donor in paediatric parental LDLT. No mortality or morbidity related to recurrence of metabolic diseases has been observed with heterozygous donors, except for certain relevant cases, such as ornithine transcarbamylase deficiency, protein C deficiency, hypercholesterolemia, protoporphyria, and Alagille syndrome, while donor human leukocyte antigen homozygosity also poses a risk. It is not always essential to perform preoperative genetic assays for possible heterozygous carriers; however, genetic and enzymatic assays must hereafter be included in the parental donor selection criteria in the aforementioned circumstances.

Expanding the living donor pool using domino liver transplantation: a systematic review

INTRODUCTION

To this day, a discrepancy exists between donor liver demand and supply. Domino liver transplantation (DLT) can contribute to increasing the number of donor livers available for transplantation.

METHODS

The design of this systematic review was based on the Preferred Reporting Items for Systematic Reviews (PRISMA). A qualitative analysis of included studies was performed. Primary outcomes were mortality and peri- and postoperative complications related to DLT.

RESULTS

Twelve studies met the inclusion criteria. All included studies showed that DLT outcomes were comparable to outcomes of deceased donor liver transplantation (DDLT) in terms of mortality and complications. One-year patient survival rate ranged from 66.7% to 100%. Re-transplantation rate varied from 0 to 12.5%. Most frequent complications were related to biliary (3.7%-37.5%), hepatic artery (1.6%-9.1%), portal vein (12.5-33.3%) and hepatic vein events (1.6%), recurrence of domino donor disease (3.3%-17.4%) and graft rejection (16.7%-37.7%). The quality of the evidence was rated as moderate according to the Newcastle-Ottawa scale (NOS).

CONCLUSION

DLT outcomes were similar to DDLT in terms of mortality and complications. Even though DLT will not solve the entire problem of organ shortage, transplant programs should always consider using this tool to maximize the availability of liver grafts.

Surgical technique and the long-term outcomes of pediatric living donor domino liver transplantation from patients with maple syrup urine disease

BACKGROUND

The native liver of patients with maple syrup urine disease (MSUD) (1st recipients) can be used as a graft for non-MSUD patients with end-stage liver disease (2nd recipients). This study aimed to demonstrate the optimal operational procedures and the long-term outcomes of 2nd recipients.

METHODS

Six 2nd recipients of living donor domino liver transplantation (LD-DLT) (age: 42.5 [22-169] months at DLT) received a native liver as a graft from an MSUD patient at our hospital between June 2014 and April 2020. We reviewed the operational procedures and outcomes of 2nd recipients after LD-DLT.

RESULTS

The 2nd recipients' original diseases included biliary atresia, congenital hepatic fibrosis, congenital protein C deficiency, familial hypercholesterolemia, hepatoblastoma, and mitochondrial hepatopathy. Five of the six recipients had a whole liver and one had a right lobe graft. The site at which the vessels of the MSUD liver were dissected prioritized the safety of the 1st recipient. At the end of follow-up, all recipients were doing well without surgical complications. The mean serum amino acid values of the 2nd recipients did not exceed the upper limit of the reference values during the long-term observation period. All patients showed normal growth while maintaining the same z-score of height and weight after LD-DLT as the preoperative level.

CONCLUSION

The liver of patients with MSUD can be used safely without concern regarding long-term complications or de novo MSUD development. LD-DLT using the MSUD liver can expand the donor pool as an alternative graft in pediatric LT.

Domino transplantation for pediatric liver recipients: Obstacles, challenges, and successes

BACKGROUND

Domino liver transplantation aims to address the need to increase the liver donor supply. In a domino liver transplant, the domino recipient receives the explanted liver from the recipient of a traditional liver transplant. The domino donor typically requires liver transplant to correct a metabolic disorder; the explanted liver thus has a single gene defect but otherwise normal structure and function.

METHODS

In this review, we detail the history of domino liver transplantation, appropriate domino donor indications, the technical advances to the surgical approach, current outcomes, and future opportunities.

RESULTS

Development of de novo disease in the domino recipient has relegated adult domino liver transplant to be considered a source of marginal donor livers. However, pediatric domino liver transplant has leveraged certain metabolic disorders, especially maple syrup urine disease, in which the liver enzyme deficiency can be compensated by the systemic presence of sufficient enzyme. Advances in the surgical aspects of assuring adequate length of vasculature have improved the safety of the procedure in both domino donors and recipients.

CONCLUSIONS

Pediatric domino liver transplant utilizing domino donors with specific metabolic liver diseases should be considered a viable live donor option for children awaiting liver transplant.

Pancreatic cancer: branched-chain amino acids as putative key metabolic regulators?

Branched-chain amino acids (BCAA) are essential amino acids utilized in anabolic and catabolic metabolism. While extensively studied in obesity and diabetes, recent evidence suggests an important role for BCAA metabolism in cancer. Elevated plasma levels of BCAA are associated with an increased risk of developing pancreatic cancer, namely pancreatic ductal adenocarcinoma (PDAC), a tumor with one of the highest 1-year mortality rates. The dreadful prognosis for PDAC patients could be attributable also to the early and frequent development of cancer cachexia, a fatal host metabolic reprogramming leading to muscle and adipose wasting. We propose that BCAA dysmetabolism is a unifying component of several pathological conditions, i.e., obesity, insulin resistance, and PDAC. These conditions are mutually dependent since PDAC ranks among cancers tightly associated with obesity and insulin resistance. It is also well-established that PDAC itself can trigger insulin resistance and new-onset diabetes. However, the exact link between BCAA metabolism, development of PDAC, and tissue wasting is still unclear. Although tissue-specific intracellular and systemic metabolism of BCAA is being intensively studied, unresolved questions related to PDAC and cancer cachexia remain, namely, whether elevated circulating BCAA contribute to PDAC etiology, what is the biological background of BCAA elevation, and what is the role of adipose tissue relative to BCAA metabolism during cancer cachexia. To cover those issues, we provide our view on BCAA metabolism at the intracellular, tissue, and whole-body level, with special emphasis on different metabolic links to BCAA intermediates and the role of insulin in substrate handling.

Muscle-directed AAV gene therapy rescues the maple syrup urine disease phenotype in a mouse model

Maple syrup urine disease (MSUD) is a rare, inherited metabolic disorder characterized by a dysfunctional mitochondrial enzyme complex, branched-chain alpha-keto acid dehydrogenase (BCKDH), which catabolizes branched-chain amino acids (BCAAs). Without functional BCKDH, BCAAs and their neurotoxic alpha-keto intermediates can accumulate in the blood and tissues. MSUD is currently incurable and treatment is limited to dietary restriction or liver transplantation, meaning there is a great need to develop new treatments for MSUD. We evaluated potential gene therapy applications for MSUD in the intermediate MSUD (iMSUD) mouse model, which harbors a mutation in the dihydrolipoamide branched-chain transacylase E2 (DBT) subunit of BCKDH. Systemic delivery of an adeno-associated virus (AAV) vector expressing DBT under control of the liver-specific TBG promoter to the liver did not sufficiently ameliorate all aspects of the disease phenotype. These findings necessitated an alternative therapeutic strategy. Muscle makes a larger contribution to BCAA metabolism than liver in humans, but a muscle-specific approach involving a muscle-specific promoter for DBT expression delivered via intramuscular (IM) administration only partially rescued the MSUD phenotype in mice. Combining the muscle-tropic AAV9 capsid with the ubiquitous CB7 promoter via IM or IV injection, however, substantially increased survival across all assessed doses. Additionally, near-normal serum BCAA levels were achieved and maintained in the mid- and high-dose cohorts throughout the study; this approach also protected these mice from a lethal high-protein diet challenge. Therefore, administration of a gene therapy vector that expresses in both muscle and liver may represent a viable approach to treating patients with MSUD.

Hyperleucinosis during infections in maple syrup urine disease post liver transplantation

Maple syrup urine disease (MSUD) is due to biallelic variants in one of the three genes: BCKDHA, BCKDHB, and DBT. Branched-chain alpha-ketoacid dehydrogenase complex deficiency and elevated leucine, valine, isoleucine and alloisoleucine in body fluids are the results. We report hyperleucinosis during intercurrent illnesses in six patients with MSUD post liver transplantation. Patient charts were retrospectively reviewed. Data was entered into an Excel Database. Literature was reviewed. Six patients with MSUD were included who had post liver transplantation hyperleucinosis during an intercurrent illness. Five had encephalopathy. One received hemodialysis for the management of hyperleucinosis. All patients had unrestricted diet. Additionally, there were five patients (one patient included into the current study) reported in the literature. We suggested management considerations for the follow-up of patients with MSUD post liver transplantation after the first episode of unexplained encephalopathy or signs of acute hyperleucinosis during intercurrent illness due to our clinical experience: 1) Healthy: Unrestricted diet and monitoring of leucine levels; 2) Illness: a) home illness management: increased carbohydrate intake b) illness management at hospital: intravenous dextrose, intravenous lipid and daily plasma amino acid monitoring. We report hyperleucinosis and/or encephalopathy as a rare event post liver transplantation in MSUD as a multicenter case series. Hyperleucinosis and/or encephalopathy may occur in both related and unrelated donor liver transplantation. Based on the long-term follow-up of those patients, these suggested management considerations may be revised as per the patients' needs.

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Patients with MSUD can present with hyperleucinosis during intercurrent illness post liver transplantation.

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Hyperleucinosis in MSUD post liver transplantation can occur in related and unrelated donor liver transplantation.

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Monitoring of patients with MSUD is required after their first episode of hyperleucinosis post liver transplantation.

Successful living donor liver transplantation plus domino-auxiliary partial orthotopic liver transplantation for pediatric patients with metabolic disorders

PURPOSE

To investigate the efficacy of living donor liver transplantation (LDLT) plus domino-auxiliary partial orthotopic liver transplantation (D-APOLT) in pediatric patients with metabolic disorders.

METHODS

From May 2017 to October 2018, two patients with ornithine aminotransferase deficiency (OTCD) and one patient with type I Crigler-Najjar syndrome (CNS1) received LDLT, their livers were prepared as donors for D-APOLT. Two patients with CNS1 received domino liver grafts from OTCD patients; one OTCD patient received a domino liver graft from a CNS1 patient.

RESULTS

The mean follow-up was 26.6 months. The liver function and ammonia remained in the normal range at the end of the follow-up in all recipients. One D-APOLT patient experienced portal vein thrombosis 2 days after transplantation and required reoperation, this patient presented an imbalance of portal blood perfusion between the native and the domino liver at 8 months after liver transplant. The imbalance was improved by interventional radiology treatment. Two LDLT patients experienced early mild acute rejection.

CONCLUSIONS

The non-cirrhotic livers from pediatric patients with metabolic liver disease can be used as domino donor grafts for selected pediatric patients with different metabolic liver disease. D-APOLT achieves ideal recipient outcomes and provides a strategy to expand donor source for children.

The concept of "domino" in liver and hepatocyte transplantation

Although orthotopic liver transplantation remains the only proven treatment for end-stage liver disease and inherited metabolic liver disease, its application has been limited by the scarcity of donor organs available for transplantation. Among feasible approaches developed to expand the donor organ pool, domino liver transplantation is a strategy in which explanted genetically defective livers of liver transplant recipients are used as grafts in other patients. Another promising therapeutic strategy is hepatocyte transplantation, an alternative to liver transplantation for certain groups of patients. However, the availability of primary hepatocytes is also hindered by the shortage of donor liver tissues. Against this background, domino hepatocyte transplantation, a strategy that utilizes the hepatocytes derived from the explanted livers of liver transplant recipients with noncirrhotic inherited metabolic liver diseases as the source of primary hepatocytes, may help increase the supply of liver cells available for transplantation. In this review, we focus on the status quo of domino liver transplantation and domino hepatocyte transplantation. We also describe recent innovative transplant strategies based on domino transplantation.

Domino Liver Transplantation: Where are we Now?

BACKGROUND

Domino transplant occurs when a recipient explanted graft is used for a second recipient.

INTRODUCTION

The first experience came from thoracic surgery by the observation that many patients during heart-lung transplantation actually showed a functional heart that could be employed in other subjects with a good result.

RESULTS

This concept was then extended to the field of liver transplantation. At present, some patients transplanted for an inborn metabolic disease may be considered as excellent domino liver donors.

CONCLUSION

The results, limitations, clinical challenges and the donor and recipient features of domino liver transplantation are discussed in this manuscript.

Information and Diagnosis Networks - tools to improve diagnosis and treatment for patients with rare genetic diseases

Brazil is a country of continental dimensions and most genetic services are concentrated in the Southeast and South, including the Medical Genetics Service of the Hospital de Clínicas de Porto Alegre (MGS/HCPA). As many areas on the country do not have adequate medical genetics support, networks were designed to extend the service of the MGS/HCPA reference center. This paper presents the information and diagnosis networks that have their headquarters at MGS/HCPA: SIAT (National Information System on Teratogenic Agents), SIEM (Information Service on Inborn Errors of Metabolism), Alô Genética (Hello Genetics - Medical Genetics Information Service for Primary Health Care Professionals); Rede MPS Brasil (MPS-Mucopolysaccharidosis Brazil Network); Rede EIM Brasil (IEM-Inborn Errors of Metabolism Brazil Network), Rede NPC Brasil (Niemann-Pick C - NPC Brazil Network), Rede DLD Brasil (LSD-Lysosomal Storage Disorders Brazil Network), Rede DXB (MSUD-Maple Syrup Urine Disease Network), RedeBRIM (Brazilian Network of Reference and Information in Microdeletion Syndromes Project), Rede Neurogenética (Neurogenetics Network), and Rede Brasileira de Câncer Hereditário (Brazilian Hereditary Cancer Network). These tools are very useful to provide access to a qualified information and/or diagnostic service for specialized and non-specialized health services, bypassing difficulties that preclude patients to access reference centers.