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E A Kvittingen - One of the best experts on this subject based on the ideXlab platform.
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Rapid Publication Hereditary Tyrosinemia Type I Self-induced Correction of the Fumarylacetoacetase Defect
2016Co-Authors: E A Kvittingen, H Rootwelt, T A. Bergan, R. BergerilAbstract:Two Norwegian patients with chronic tyrosinemia type I showed> 50 % residual Fumarylacetoacetase activity in liver samples obtained during liver transplantation. The enzyme characteristics of both patients were comparable with those of a normal control. Immunohistochemistry on liver sections from these patients and from three other Norwegian tyrosinemia pa-tients revealed a mosaicism of Fumarylacetoacetase immunore-activity corresponding completely or partly to some of the re-generating nodules. This appearance of enzyme protein is pre-sumably induced by the disease process. The mechanism involved remains unclear and could be caused by a genetic alter-ation, regained translation of messenger RNA, or to enhanced stability of an abnormal enzyme. (J. Clin. Invest. 1993. 91:1816-1821.) Key words: liver disease * amino acid metabo-lism * mosaicism * immunohistochemistry * mutagenesi
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deficiency of Fumarylacetoacetase without hereditary tyrosinemia
Clinical Genetics, 2008Co-Authors: E A Kvittingen, A L Borresen, Oddvar Stokke, C B Van Der Hagen, S O LieAbstract:A variant of the enzyme Fumarylacetoacetase (FAH) (E.C.3.7.1.2) in healthy individuals, determined by the enzyme activity, is reported. Analysis of family members of probands with low FAH activity suggests that the enzyme variant causing low activity could be the product of a pseudodeficiency gene. Assumed homozygotes for this gene have only slightly higher enzyme activity than patients with the metabolic disorder hereditary tyrosinemia I (hepatorenal type). No clinical abnormalities have been found in association with the postulated gene.
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tyrosinaemia type i de novo mutation in liver tissue suppressing an inborn splicing defect
Journal of Molecular Medicine, 2005Co-Authors: Y. T. Bliksrud, E Brodtkorb, P. A. Andresen, I. E. T. Van Den Berg, E A KvittingenAbstract:Many patients with tyrosinaemia type 1 have a mosaic pattern of Fumarylacetoacetase (FAH) immunopositive or immunonegative nodules in liver tissue. This phenomenon has been explained by a spontaneous reversion of the mutation in one allele to a normal genotype, but only a few nodules have been examined. We now report on a Norwegian patient, compound heterozygous for the mutations IVS12g+5→a and G1009→A, with liver mosaicism, but with an immunopositive nodule in which both primary mutations were intact. In the immunopositive hepatocytes of this nodule, genetic analyses showed a new mutation, C1061→A, 6 bp upstream of the primary mutation IVS12g+5→a in the FAH gene. The splicing defect caused by the primary mutation is most likely suppressed by the new mutation due to improvement of the splicing site. In the same liver we demonstrate another nodule of regenerating immunopositive tissue due to reversion of one of the primary mutations to a normal genotype. Together with the original cells this makes a triple mosaicism of hepatocytes with one, two or three point mutations in the FAH gene.
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Fumarylacetoacetase mutations in tyrosinaemia type i
Human Mutation, 1996Co-Authors: Helge Rootwelt, Kari Hoie, Ruud Berger, E A KvittingenAbstract:Sixty-two hereditary tyrosinaemia type I (HT1) patients of various ethnic origins were classified clinically into acute, chronic, or intermediate phenotypes and screened for the 14 published causal mutations in the Fumarylacetoacetase (FAH) gene. Restriction analysis of PCR amplified genomic DNA identified 74% of the mutated alleles. IVS12 + 5G --> A, predominant in the French Canadian HT1 patients, was the most common mutation found in 32 alleles in patients from Europe, Pakistan, Turkey, and the United States. IVS6-1G --> T, encountered in 14 alleles, was common in Central and Western Europe. There was an apparent "Scandinavian" 1009G --> A combined splice and missense mutation (12 alleles), a "Pakistani" 192G --> T splice mutation (11 alleles), a "Turkish" D233V mutation (6 alleles), and a "Finnish" or northern European W262X mutation (7 alleles). The remaining mutations were rare. Some of the mutations seem to predispose for acute and other for more chronic forms of HT1, but in our material no clearcut genotype phenotype correlation could be established.
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identification of a frequent pseudodeficiency mutation in the Fumarylacetoacetase gene with implications for diagnosis of tyrosinemia type i
American Journal of Human Genetics, 1994Co-Authors: Helge Rootwelt, E Brodtkorb, E A KvittingenAbstract:In healthy individuals, Fumarylacetoacetase (FAH) activities close to the range found in hereditary tyrosinemia type 1 (HT1) patients indicated the existence of a "pseudodeficiency" allele. In an individual homozygous for pseudodeficiency of FAH and in three HT1 families also carrying the pseudodeficiency allele, western blotting of fibroblast extracts showed that the pseudodeficiency allele gave very little immunoreactive FAH protein, whereas northern analysis revealed a normal amount of FAH mRNA. Sequencing revealed an identical mutation, C1021-->T (Arg341Trp), in all the pseudodeficiency alleles. Site-directed mutagenesis and expression in a rabbit reticulocyte lysate system demonstrated that the C1021-->T mutation gave reduced FAH activity and reduced amounts of the full-length protein. Bs1EI restriction digestion of PCR products distinguished between the normal and the mutated sequences. Among 516 healthy volunteers of Norwegian origin, the C1021-->T mutation was found in 2.2% of the alleles. Testing for the C1021-->T mutation may solve the problem of prenatal diagnosis and carrier detection in families with compound heterozygote genotypes for HT1 and pseudodeficiency.
Robert M. Tanguay - One of the best experts on this subject based on the ideXlab platform.
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involvement of endoplasmic reticulum stress in hereditary tyrosinemia type i
Journal of Biological Chemistry, 2006Co-Authors: Anne Bergeron, Rossana Jorquera, Diana Orejuela, Robert M. TanguayAbstract:Abstract Hereditary tyrosinemia type I (HTI) is the most severe disease of the tyrosine degradation pathway. HTI is caused by a deficiency of fumarylacetoacetate hydrolase (FAH), the enzyme responsible for the hydrolysis of fumarylacetoacetate (FAA). As a result, there is an accumulation of metabolites such as maleylacetoacetate, succinylacetone, and FAA. The latter was shown to display mutagenic, cytostatic, and apoptogenic activities and to cause chromosomal instability. Herein, we demonstrate that FAA also causes a cellular insult leading to the endoplasmic reticulum (ER) stress signaling. Treatment of V79 Chinese hamster lung cells with an apoptogenic dose of FAA (100 μm) causes an early induction of the ER resident chaperone GRP78/BiP and a simultaneous phosphorylation of the eIF2α. FAA treatment also causes a subsequent induction of the proapoptotic CHOP (CEBP homologous protein) transcription factor as well as a late activation of caspase-12. Data obtained from fah–/– mice taken off the therapeutic 2-(2-nitro-4-trifluoromethylbenzoyl)-1,3 cyclohexanedione drug are similar. However, in this mouse model, there is also an increase in proteasome activity indicative of ER-associated degradation. This difference observed between the two models may be due to the fact that the murine model measures the effects of all metabolites accumulating in hereditary tyrosinemia type I as opposed to the cellular model that only measures the effects of exogenous FAA.
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Genotyping of a case of tyrosinaemia type I with normal level of succinylacetone in amniotic fluid
Prenatal diagnosis, 1999Co-Authors: Jacques Poudrier, Francine Lettre, Maryse St.-louis, Robert M. TanguayAbstract:Tyrosinaemia type I is caused by a deficiency of fumarylacetoacetate hydrolase and mainly affects the liver. This disease is characterized by the presence of a high level of succinylacetone. This metabolite has been used for prenatal diagnosis from amniotic fluid samples. One case with a normal level of succinylacetone in amniotic fluid has recently been described (Grenier et al., 1996). Here, we report that this patient is a compound heterozygote for two known mutations: E364X and IVS6-1g-->t. The low level of succinylacetone cannot be explained by these mutations.
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Hepatocytes corrected by gene therapy are selected in vivo in a murine model of hereditary tyrosinaemia type I
Nature genetics, 1996Co-Authors: Ken Overturf, Muhsen Al-dhalimy, Milton J Finegold, Robert M. Tanguay, Mark L. Brantly, Markus GrompeAbstract:Current strategies for hepatic gene therapy are either quantitatively inefficient or suffer from lack of permanent gene expression. We have utilized an animal model of hereditary tyrosinaemia type I (HT1), a recessive liver disease caused by deficiency of fumarylacetoacetate hydrolase (FAH), to determine whether in vivo selection of corrected hepatocytes could improve the efficiency of liver gene transfer. As few as 1,000 transplanted wild-type hepatocytes were able to repopulate mutant liver, demonstrating their strong competitive growth advantage. Mutant hepatocytes corrected in situ by retroviral gene transfer were also positively selected. In mutant animals treated by multiple retrovirus injections >90% of hepatocytes became FAH positive and liver function was restored to normal. Our results demonstrate that in vivo selection is a useful strategy for hepatic gene therapy and may lead to effective treatment of human HT1 by retroviral gene transfer.
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A CASE OF TYROSINAEMIA TYPE I WITH NORMAL LEVEL OF SUCCINYLACETONE IN THE AMNIOTIC FLUID
Prenatal Diagnosis, 1996Co-Authors: A. Grenier, S. Cederbaum, Claude Laberge, Richard Gagné, C.a.j.m. Jakobs, Robert M. TanguayAbstract:Prenatal diagnosis of tyrosinaemia type I can be achieved in cultured amniotic cells and in chorionic villus material by testing the activity of fumarylacetoacetate hydrolase and by DNA analysis, and in amniotic fluid by succinylacetone measurement. This specific metabolite can be measured either by gas chromatography-mass spectrometry or by delta-aminolevulinate dehydratase inhibition assay. In a series of 65 at-risk cases tested with the enzyme inhibition assay, one case out of the 18 with the disease had a normal level of succinylacetone. This case is presented.
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frequency of the ivs12 5g a splice mutation of the fumarylacetoacetate hydrolase gene in carriers of hereditary tyrosinaemia in the french canadian population of saguenay lac st jean
Prenatal Diagnosis, 1996Co-Authors: Jacques Poudrier, Francine Lettre, Karine Gibson, Claude Prévost, Jean Larochelle, Maryse Stlouis, Robert M. TanguayAbstract:Hereditary tyrosinaemia type I (HTI), an autosomal recessive inborn error of metabolism, is caused by a deficiency of the enzyme fumarylacetoacetate hydrolase. The highest incidence of HTI is observed in the Saguenay-Lac-St-Jean region (SLSJ) (Quebec, Canada), where 1 out of 22 individuals is thought to be a carrier. A splice mutation (IVS12+5G|adA) has recently been identified in this particular region. Here, we have determined the frequency of this mutation in a population of obligate carriers from the SLSJ region by allele-specific oligonucleotide hybridization and a method using a restriction enzyme digestion. Over 95 per cent of the HTI carriers were found to have the IVS12+5G|adA splice mutation. Screening for this mutation based on the two methods reported here is thus a reliable and rapid way of detecting carriers of hereditary tyrosinaemia type I in that region at high risk.
Helge Rootwelt - One of the best experts on this subject based on the ideXlab platform.
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hereditary tyrosinaemia type i in norway incidence and three novel small deletions in the Fumarylacetoacetase gene
Scandinavian Journal of Clinical & Laboratory Investigation, 2012Co-Authors: Y. T. Bliksrud, E Brodtkorb, Paul Hoff Backe, Berit Woldseth, Helge RootweltAbstract:A total of 28 Norwegians have been diagnosed with hereditary tyrosinaemia type I (HT1) over the last 30 years. In this study, 19 of these patients were investigated. Three novel small deletions were found (NM_000137.1(FAH): c.615delT, p.Phe205LeufsX2, NM_000137.1(FAH): c.744delG, p.Pro249HisfsX55 and NM_000137.1(FAH):c835delC) pGln279ArgfsX25, all of them leading to a change in the reading frame and a premature stop codon. We hereby genetically characterized 51 of the 56 disease-causing alleles, identifying nine different disease-causing mutations in the Norwegian population. We found that 65% of the Norwegian HT1 patients are compound heterozygous for different mutations. Thus, the relatively high incidence of HT1 in Norway of 1 in 74,800 live births is not due to single founder effects or high incidence of parental consanguinity.
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Fumarylacetoacetase mutations in tyrosinaemia type i
Human Mutation, 1996Co-Authors: Helge Rootwelt, Kari Hoie, Ruud Berger, E A KvittingenAbstract:Sixty-two hereditary tyrosinaemia type I (HT1) patients of various ethnic origins were classified clinically into acute, chronic, or intermediate phenotypes and screened for the 14 published causal mutations in the Fumarylacetoacetase (FAH) gene. Restriction analysis of PCR amplified genomic DNA identified 74% of the mutated alleles. IVS12 + 5G --> A, predominant in the French Canadian HT1 patients, was the most common mutation found in 32 alleles in patients from Europe, Pakistan, Turkey, and the United States. IVS6-1G --> T, encountered in 14 alleles, was common in Central and Western Europe. There was an apparent "Scandinavian" 1009G --> A combined splice and missense mutation (12 alleles), a "Pakistani" 192G --> T splice mutation (11 alleles), a "Turkish" D233V mutation (6 alleles), and a "Finnish" or northern European W262X mutation (7 alleles). The remaining mutations were rare. Some of the mutations seem to predispose for acute and other for more chronic forms of HT1, but in our material no clearcut genotype phenotype correlation could be established.
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identification of a frequent pseudodeficiency mutation in the Fumarylacetoacetase gene with implications for diagnosis of tyrosinemia type i
American Journal of Human Genetics, 1994Co-Authors: Helge Rootwelt, E Brodtkorb, E A KvittingenAbstract:In healthy individuals, Fumarylacetoacetase (FAH) activities close to the range found in hereditary tyrosinemia type 1 (HT1) patients indicated the existence of a "pseudodeficiency" allele. In an individual homozygous for pseudodeficiency of FAH and in three HT1 families also carrying the pseudodeficiency allele, western blotting of fibroblast extracts showed that the pseudodeficiency allele gave very little immunoreactive FAH protein, whereas northern analysis revealed a normal amount of FAH mRNA. Sequencing revealed an identical mutation, C1021-->T (Arg341Trp), in all the pseudodeficiency alleles. Site-directed mutagenesis and expression in a rabbit reticulocyte lysate system demonstrated that the C1021-->T mutation gave reduced FAH activity and reduced amounts of the full-length protein. Bs1EI restriction digestion of PCR products distinguished between the normal and the mutated sequences. Among 516 healthy volunteers of Norwegian origin, the C1021-->T mutation was found in 2.2% of the alleles. Testing for the C1021-->T mutation may solve the problem of prenatal diagnosis and carrier detection in families with compound heterozygote genotypes for HT1 and pseudodeficiency.
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novel splice missense and nonsense mutations in the Fumarylacetoacetase gene causing tyrosinemia type 1
American Journal of Human Genetics, 1994Co-Authors: Helge Rootwelt, R Berger, Turgay Coşkun, G Gray, D A Kelly, E A KvittingenAbstract:Abstract In six unrelated patients with hereditary tyrosinemia type 1 (HT1), three different disease-causing mutations were found by DNA sequencing. Two Pakistani patients, with acute and intermediate forms of HT1, were homozygous for a G192-->T mutation in the last nucleotide of exon 2. This caused aberrant splicing with partial intron 2 retention and premature termination. Three Turkish patients with chronic and intermediate forms of HT1 were homozygous for an A698-->T mutation substituting aspartic acid 233 with valine. A Norwegian patient with an intermediate clinical phenotype was heterozygous for G786-->A, introducing a TGA stop codon for Trp262 (W262X). Site-directed mutagenesis and expression in a rabbit reticulocyte lysate system demonstrated that the nonsense and missense mutations abolished Fumarylacetoacetase activity and gave reduced amounts of a truncated and a full-length protein, respectively. Simple tests were established to identify the three mutations by restriction digestion of PCR-amplified genomic DNA. Among 30 additional HT1 patients investigated, 2 were found to be homozygous and 1 heterozygous for G192-->T. Two other patients were homozygous and one was heterozygous for W262X.
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tyrosinemia type 1 complex splicing defects and a missense mutation in the Fumarylacetoacetase gene
Human Genetics, 1994Co-Authors: Helge Rootwelt, Kari Hoie, Ruud Berger, Tom Kristensen, E A KvittingenAbstract:Two mutations are reported in six tyrosinemia type 1 patients from northern Europe. In four patients, a G to A transition at nucleotide position 1009 (G1009→A) of the Fumarylacetoacetase (FAH) coding sequence caused aberrant splicing by introducing an acceptor splice site within exon 12, thereby deleting the first 50 nucleotides of this exon. The following exon-intron boundary was frequently missed, and a cryptic donor splice site within intron 12 caused a partial intron 12 retention of 105 bp. This point mutation alternatively gave a glycine 337 to serine substitution in instances of correct splicing. The mutation is rapidly detected by PvuII digestion of polymerase chain reaction (PCR)-amplified genomic DNA. Another mutation, g+5→a in the intron 12 donor splice site consensus sequence (IVS12 g+5→a), was found in five of the patients. This caused alternative splicing with retention of the first 105 nucleotides of intron 12, exon 12 skipping, and a combined deletion of exons 12 and 13. Rapid detection of this mutation is achieved by restriction digestion of PCR-amplified genomic DNA; a mismatch primer combined with the point mutation creates a Tru9I restriction site. One patient who was homozygous for the G1009→A mutation had a chronic form of tyrosinemia. Three patients were combined heterozygotes for G1009→A and TVS12 g+5→a. Their clinical phenotypes varied from acute to chronic, indicating the impact of background genes and/or external factors on the presentation of typrosinemia type 1.
Xin Xie - One of the best experts on this subject based on the ideXlab platform.
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chemical cocktails enable hepatic reprogramming of mouse fibroblasts with a single transcription factor
Stem cell reports, 2017Co-Authors: Ren Guo, Xin Wang, Wei Tang, Qianting Yuan, Lijian Hui, Xin XieAbstract:Summary Liver or hepatocytes transplantation is limited by the availability of donor organs. Functional hepatocytes independent of the donor sources may have wide applications in regenerative medicine and the drug industry. Recent studies have demonstrated that chemical cocktails may induce reprogramming of fibroblasts into a range of functional somatic cells. Here, we show that mouse fibroblasts can be transdifferentiated into the hepatocyte-like cells (iHeps) using only one transcription factor (TF) ( Foxa1 , Foxa2 , or Foxa3 ) plus a chemical cocktail. These iHeps show typical epithelial morphology, express multiple hepatocyte-specific genes, and acquire hepatocyte functions. Genetic lineage tracing confirms the fibroblast origin of these iHeps. More interestingly, these iHeps are expandable in vitro and can reconstitute the damaged hepatic tissues of the fumarylacetoacetate hydrolase-deficient ( Fah − / − ) mice. Our study provides a strategy to generate functional hepatocyte-like cells by using a single TF plus a chemical cocktail and is one step closer to generate the full-chemical iHeps.
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Chemical Cocktails Enable Hepatic Reprogramming of Mouse Fibroblasts with a Single Transcription Factor
Elsevier, 2017Co-Authors: Ren Guo, Xin Wang, Wei Tang, Qianting Yuan, Lijian Hui, Xin XieAbstract:Summary: Liver or hepatocytes transplantation is limited by the availability of donor organs. Functional hepatocytes independent of the donor sources may have wide applications in regenerative medicine and the drug industry. Recent studies have demonstrated that chemical cocktails may induce reprogramming of fibroblasts into a range of functional somatic cells. Here, we show that mouse fibroblasts can be transdifferentiated into the hepatocyte-like cells (iHeps) using only one transcription factor (TF) (Foxa1, Foxa2, or Foxa3) plus a chemical cocktail. These iHeps show typical epithelial morphology, express multiple hepatocyte-specific genes, and acquire hepatocyte functions. Genetic lineage tracing confirms the fibroblast origin of these iHeps. More interestingly, these iHeps are expandable in vitro and can reconstitute the damaged hepatic tissues of the fumarylacetoacetate hydrolase-deficient (Fah−/−) mice. Our study provides a strategy to generate functional hepatocyte-like cells by using a single TF plus a chemical cocktail and is one step closer to generate the full-chemical iHeps. : In this article, Xie and colleagues show that mouse fibroblasts can be transdifferentiated into the hepatocyte-like cells (iHeps) using only one transcription factor plus a chemical cocktail. Genetic lineage tracing confirms the fibroblast origin of these iHeps. These iHeps are expandable in vitro and can reconstitute the damaged hepatic tissues of the fumarylacetoacetate hydrolase-deficient mice. Keywords: reprogramming, hepatic transdifferentiation, hepatocyte, induced hepatocyte, chemically induced hepatocyte, fibroblast, chemical cocktail, regenerative medicin
Markus Grompe - One of the best experts on this subject based on the ideXlab platform.
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Adeno-associated virus gene repair corrects a mouse model of hereditary tyrosinemia in vivo. Hepatology 51
2010Co-Authors: Nicole K. Paulk, Milton J Finegold, Karsten Wursthorn, Zhongya Wang, Mark A. Kay, Markus GrompeAbstract:Adeno-associated virus (AAV) vectors are ideal for performing gene repair due to their ability to target multiple different genomic loci, low immunogenicity, capability to achieve targeted and stable expression through integration, and low mutagenic and oncogenic potential. However, many handicaps to gene repair therapy remain. Most notable is the low frequency of correction in vivo. To date, this frequency is too low to be of therapeutic value for any disease. To address this, a point-mutation–based mouse model of the metabolic disease hereditary tyrosinemia type I was used to test whether targeted AAV integration by homologous recombination could achieve high-level stable gene repair in vivo. Both neonatal and adult mice were treated with AAV serotypes 2 and 8 carrying a wild-type genomic sequence for repairing the mutated Fah (fumarylacetoacetate hydrolase) gene. Hepatic gene repair was quantified by immunohistochemistry and supported with reverse transcription polymerase chain reaction and serology for functional correction parameters. Successful gene repair was observed with both serotypes but was more efficient with AAV8. Correction frequencies of up to 10 �3 were achieved and highly reproducible within typical dose ranges. In this model, repaired hepatocytes have a selective growth advantage and are thus able to proliferate to efficiently repopulate mutant livers and cure the underlying metabolic disease. Conclusion: AAV-mediated gene repair is feasible in vivo and can functionally correct an appropriate selection-based metabolic liver disease in both adults and neonates. (HEPATOLOGY 2010;51: 1200-1208.) Gene therapy is a promising means to cure many monogenic diseases. However, traditional gene therapies are best suited to treat diseases of deficient or absent gene products rather than those diseases Abbreviations: AAV, adeno-associated virus; AST, aspartate aminotransferase; dGE, diploid genome equivalent; FAH, fumarylacetoacetate hydrolase; GAPDH, glyceraldehyde 3-phosphate dehydrogenase; hAAT, human alpha-1 antitrypsin; HTI, hereditary tyrosinemia type I; LD-PCR, long-distance polymerase chain reaction
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robust expansion of human hepatocytes in fah rag2 il2rg mice
Nature Biotechnology, 2007Co-Authors: Hisaya Azuma, Milton J Finegold, Nicole K. Paulk, Mark A. Kay, Muhsen Aldhalimy, Stephen C. Strom, Aarati Ranade, Craig Dorrell, Ewa Ellis, Markus GrompeAbstract:Mice that could be highly repopulated with human hepatocytes would have many potential uses in drug development and research applications. The best available model of liver humanization, the uroplasminogen-activator transgenic model, has major practical limitations. To provide a broadly useful hepatic xenorepopulation system, we generated severely immunodeficient, fumarylacetoacetate hydrolase (Fah)-deficient mice. After pretreatment with a urokinase-expressing adenovirus, these animals could be highly engrafted (up to 90%) with human hepatocytes from multiple sources, including liver biopsies. Furthermore, human cells could be serially transplanted from primary donors and repopulate the liver for at least four sequential rounds. The expanded cells displayed typical human drug metabolism. This system provides a robust platform to produce high-quality human hepatocytes for tissue culture. It may also be useful for testing the toxicity of drug metabolites and for evaluating pathogens dependent on human liver cells for replication.
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In Vivo Genetic Selection of Renal Proximal Tubules
Molecular Therapy, 2005Co-Authors: Patrice K. Held, Muhsen Al-dhalimy, Yassmine Akkari, Yumi Torimaru, Susan Olson, William H Fleming, Holger Willenbring, Shuguang Jiang, Milton J Finegold, Markus GrompeAbstract:Repopulation by transplanted cells can result in effective therapy for several regenerative organs including blood, liver, and skin. In contrast, cell therapies for renal diseases are not currently available. Here we developed an animal model in which cells genetically resistant to a toxic intermediate of tyrosine metabolism, homogentisic acid (HGA), were able to repopulate the damaged proximal tubule epithelium of mice with fumarylacetoacetate hydrolase (Fah) deficiency. HGA resistance was achieved by two independent mechanisms. First, Fah+ transplanted bone marrow cells produced significant replacement of damaged proximal tubular epithelium (up to 50%). The majority of bone marrow-derived epithelial cells were generated by cell fusion, not transdifferentiation. In addition to regeneration by fusion-derived epithelial cells, proximal tubular repopulation was also observed by host epithelial cells, which had lost the homogentisic acid dioxygenase gene. These data demonstrate that extensive regeneration of the renal proximal tubule compartment can be achieved through genetic selection of functional cells.
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Cell fusion is the principal source of bone-marrow-derived hepatocytes
Nature, 2003Co-Authors: Xin Wang, Muhsen Al-dhalimy, Yassmine Akkari, Yumi Torimaru, Holger Willenbring, Milton J Finegold, Mark Foster, Eric Lagasse, Susan B. Olson, Markus GrompeAbstract:Evidence suggests that haematopoietic stem cells might have unexpected developmental plasticity, highlighting therapeutic potential. For example, bone-marrow-derived hepatocytes can repopulate the liver of mice with fumarylacetoacetate hydrolase deficiency and correct their liver disease. To determine the underlying mechanism in this murine model, we performed serial transplantation of bone-marrow-derived hepatocytes. Here we show by Southern blot analysis that the repopulating hepatocytes in the liver were heterozygous for alleles unique to the donor marrow, in contrast to the original homozygous donor cells. Furthermore, cytogenetic analysis of hepatocytes transplanted from female donor mice into male recipients demonstrated 80,XXXY (diploid to diploid fusion) and 120,XXXXYY (diploid to tetraploid fusion) karyotypes, indicative of fusion between donor and host cells. We conclude that hepatocytes derived form bone marrow arise from cell fusion and not by differentiation of haematopoietic stem cells.
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Serial transplantation reveals the stem-cell-like regenerative potential of adult mouse hepatocytes.
The American journal of pathology, 1997Co-Authors: Ken Overturf, Muhsen Al-dhalimy, Milton J Finegold, Markus GrompeAbstract:Previous work has shown that adult mouse hepatocytes can divide at least 18 times in vivo. To test whether this represents the upper limit of their regenerative capacity, we performed serial transplantation of hepatocytes in the fumarylacetoacetate hydrolase deficiency murine model of liver repopulation. Hepatocytes from adult donors were serially transplanted in limiting numbers six times and resulted in complete repopulation during each cycle. This corresponds to a minimal number of 69 cell doublings or a 7.3 x 10(20)-fold expansion. No evidence for abnormal liver function or altered hepatic architecture was found in repopulated animals. We conclude that a fraction of adult mouse hepatocytes have growth potential similar to that of hematopoietic stem cells.
