ABSTRACT
Crigler Najjar Syndrome type I (CNSI) is a rare recessive disorder caused by mutations in the Ugt1a1 gene. There is no permanent cure except for liver transplantation, and current therapies present several shortcomings. Since stem cell-based therapy offers a promising alternative for the treatment of this disorder, we evaluated the therapeutic potential of human liver stem cells (HLSC) in immune-compromised NOD SCID Gamma (NSG)/Ugt1-/- mice, which closely mimic the pathological manifestations in CNSI patients. To assess whether HLSC expressed UGT1A1, decellularised mouse liver scaffolds were repopulated with these cells. After 15 days' culture ex vivo, HLSC differentiated into hepatocyte-like cells showing UGT1A1 expression and activity. For the in vivo human cell engraftment and recovery experiments, DiI-labelled HLSC were injected into the liver of 5 days old NSG/Ugt1-/- pups which were analysed at postnatal Day 21. HLSC expressed UGT1A1 in vivo, induced a strong decrease in serum unconjugated bilirubin, thus significantly improving phenotype and survival compared to untreated controls. A striking recovery from brain damage was also observed in HLSC-injected mutant mice versus controls. Our proof-of-concept study shows that HLSC express UGT1A1 in vivo and improve the phenotype and survival of NSG/Ugt1-/- mice, and show promises for the treatment of CNSI.
Subject(s)
Crigler-Najjar Syndrome/therapy , Glucuronosyltransferase/metabolism , Liver/cytology , Stem Cells/metabolism , Animals , Bilirubin/blood , Brain/pathology , Cell Differentiation , Crigler-Najjar Syndrome/immunology , Crigler-Najjar Syndrome/mortality , Crigler-Najjar Syndrome/pathology , Disease Models, Animal , Glucuronosyltransferase/genetics , Hepatocytes/cytology , Humans , Liver/pathology , Mice, SCID , Phenotype , Stem Cell Transplantation , Stem Cells/immunologyABSTRACT
Crigler-Najjar type I (CNI) syndrome is a recessively inherited disorder characterized by severe unconjugated hyperbilirubinemia caused by uridine diphosphoglucuronosyltransferase 1A1 (UGT1A1) deficiency. The disease is lethal due to bilirubin-induced neurological damage unless phototherapy is applied from birth. However, treatment becomes less effective during growth, and liver transplantation is required. To investigate the pathophysiology of the disease and therapeutic approaches in mice, we generated a mouse model by introducing a premature stop codon in the UGT1a1 gene, which results in an inactive enzyme. Homozygous mutant mice developed severe jaundice soon after birth and died within 11 d, showing significant cerebellar alterations. To rescue neonatal lethality, newborns were injected with a single dose of adeno-associated viral vector 9 (AAV9) expressing the human UGT1A1. Gene therapy treatment completely rescued all AAV-treated mutant mice, accompanied by lower plasma bilirubin levels and normal brain histology and motor coordination. Our mouse model of CNI reproduces genetic and phenotypic features of the human disease. We have shown, for the first time, the full recovery of the lethal effects of neonatal hyperbilirubinemia. We believe that, besides gene-addition-based therapies, our mice could represent a very useful model to develop and test novel technologies based on gene correction by homologous recombination.
Subject(s)
Crigler-Najjar Syndrome/genetics , Disease Models, Animal , Genetic Therapy/methods , Glucuronosyltransferase/genetics , Animals , Animals, Newborn , Bilirubin/blood , Blotting, Northern , Blotting, Western , Cerebellum/enzymology , Cerebellum/metabolism , Cerebellum/pathology , Crigler-Najjar Syndrome/enzymology , Crigler-Najjar Syndrome/mortality , Dependovirus/classification , Dependovirus/genetics , Gene Expression Regulation, Enzymologic , Gene Transfer Techniques , Genetic Vectors/genetics , Glucuronosyltransferase/deficiency , Humans , Mice , Mice, Inbred C57BL , Mice, Transgenic , Muscle, Skeletal/enzymology , Muscle, Skeletal/metabolism , Mutation , Reverse Transcriptase Polymerase Chain Reaction , Survival RateABSTRACT
BACKGROUND: Crigler-Najjar syndrome is a rare metabolic disorder characterized by severe unconjugated hyperbilirubinemia resulting in deficiency of bilirubin uridine diphosphate (UDP) glucuronosyltransferase activity in the liver. AIM: To study the clinical, genetic therapeutic aspects and the outcome of Crigler Najjar type 1 in Tunisia. METHODS: This is a retrospective report of Crigler Najjar cases who were hospitalised in pediatric department of Hédi Chaker hospital during 21 years (from 1st January to 31 December 2006). RESULTS: Our study included 30 cases of Crigler-Najjar syndrome; there were 10 females and 20 males (sex ratio = 2). The mean age of our patients was 41 days (4 days - 9 months). All patients were presented with intense jaundice. Sixteen patients had neurologic disorders since admission. Genetic analysis was performed in 9 patients; we identified the same mutation in all cases: -C1070>G in exon 3 of the UDP glucuronyl transferase. Concerning therapeutic measurements, conventional phototherapy was used in all patients. A fatal out come was observed in 28 case; they died of kernicterus. CONCLUSION: Crigler-Najjar syndrome is a serious disorder which, when not treated, ultimately leads to brain damage (bilirubin encephalopathy) and death. That's why we must promote prenatal diagnosis and genetic council especially because of the big frequency of consanguinity in our country.
