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Creation of a mouse expressing defective human factor IX
Da-Yun Jin1, Tai-Ping Zhang, Tong Gui
1Gene Therapy Center, Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
Blood
|June 5, 2004
Summary
A new R333Q-hFIX mouse model mimics human hemophilia B by expressing a mutant human factor IX. This model shows promise for studying factor IX gene therapy, unlike existing knockout models.
Area of Science:
- * Hemostasis and Thrombosis Research
- * Genetic Disease Modeling
- * Gene Therapy Development
Background:
- * Human hemophilia B predominantly results from missense mutations in the coagulation factor IX gene.
- * Existing factor IX knockout (FIXKO) mouse models lack factor IX, failing to replicate the dominant human phenotype.
- * A need exists for hemophilia B models that express a partially functional, mutated factor IX.
Purpose of the Study:
- * To create and characterize a novel mouse model of hemophilia B expressing a human missense mutation in factor IX.
- * To evaluate the utility of this model for gene therapy studies, particularly regarding immune responses.
- * To provide a complementary model to FIXKO mice for investigating factor IX kinetics and therapeutic strategies.
Main Methods:
- * Homologous recombination in embryonic stem cells to generate the R333Q-hFIX mouse model.
- * Expression analysis of mutant human factor IX mRNA and protein throughout development.
- * Assessment of factor IX activity and phenotypic characterization of the R333Q-hFIX mice.
- * Adeno-associated virus-mediated gene therapy challenge to evaluate factor IX expression and antibody development.
Main Results:
- * The R333Q-hFIX mouse model expresses detectable levels of mutant human factor IX, with activity below 1%, exhibiting a hemophilic phenotype.
- * Intramuscular adeno-associated virus delivery of human factor IX in R333Q-hFIX mice led to successful factor IX expression without antibody formation.
- * In contrast, FIXKO mice developed antibodies when subjected to the same gene therapy challenge.
Conclusions:
- * The R333Q-hFIX mouse model accurately replicates key aspects of human hemophilia B, including the presence of a partially functional factor IX.
- * This model is suitable for studying factor IX gene therapy and offers advantages over FIXKO models in assessing immune tolerance.
- * The R333Q-hFIX mice will serve as a valuable tool to complement FIXKO models for research in factor IX replacement therapy and circulating kinetics.