en Pediatric Hematology & Oncology Pediatric Hematology & Oncology پژوهشي Original Article Background: Hemophilia B is an X-linked hereditary disorder of blood coagulation system which is caused by factor IX (FIX) deficiency. Factor IX is a plasma glycoprotein that participates in the coagulation process leading to the generation of fibrin. Replacement of factor IX with plasma-derived or recombinant factor IX is the conventional treatment for hemophilia B to raise the factor IX level to therapeutic range. Recently, gene therapy has been regarded as a promising approach to treat hemophilia B. This study was aimed to express the factor IX in human amniotic membrane-derived mesenchymal stem cells (hAM-MSCs). Materials and Methods: Human amniotic membrane-derived mesenchymal stem cells were isolated and characterized from amnion membrane. Factor IX from commercially available plasmid was sub-cloned into pcDNA3.1 vector. Recombinant pcDNA3.1-FIX construct was confirmed by PCR, enzymatic digestion and DNA sequencing. Mesenchymal stem cells were transfected with the recombinant vector. Expression of factor IX was determined by RT-PCR, ELISA and its biological activity assay was performed using aPTT. Results: Isolated hAM-MSCs expressed specific mesenchymal stem cells markers and were able to differentiate to osteocytes and adipocytes lineages. hAM-MSCs expressed hrFIX at mRNA and protein level. The maximum amount of hrFIX was 120 ng/ml at 72 hrs after hAM-MSCs transfection. This hrFIX was biologically active (11% activity), formed fibrin clot in aPTT test and caused more than two fold decrease in clotting time. Conclusion: The hAM-MSCs expressing factor IX would be useful for gene therapy of hemophilia B. However further studies are required to prove these finding. Key words: Hemophilia B, amnion membrane, mesenchymal stem cell, factor IX, gene therapy. Hemophilia B, amnion membrane, mesenchymal stem cell, factor IX, gene therapy 133 141 http://ijbc.ir/browse.php?a_code=A-10-1-75&slc_lang=en&sid=1 Mostafa Paridar 10031947532846002354 10031947532846002354 Yes Naser Amirizadeh 10031947532846002355 10031947532846002355 No Mahyar Habibi Roudkenar 10031947532846002356 10031947532846002356 No Fatemeh Amiri 10031947532846002357 10031947532846002357 No Hassan Abolghasemi 10031947532846002358 10031947532846002358 No Mohammad Ali Jalili 10031947532846002359 10031947532846002359 No