ISMJ

Background: Mesenchymal stem cells (MSCs) are appropriate target for gene and cell-based therapy of hemophilia B patients. MSCs possess several unique properties such as capability of differentiating into multiple lineages and lower immunogenecity in transplant procedure that make them attractive candidates for cell and gene therapy. One of the challenges in the gene therapy is the low expression level of transgene. To improve expression, strong regulatory elements in the context of vectors could contribute to improve efficacy of gene therapy strategies. In this study four human factor IX (hFIX)-expressing plasmids equipped with various combination of human -globin (hBG) introns and Kozak sequence were transfected into the MSCs and expression of the hFIX was evaluated in vitro. Material and Methods: MSCs were obtained from tibias and the femora of rats and phenotypic characterization of the MSCs was determined by flow cytometry. Four hFIX-expressing plasmids were introduced into the culture-expanded MSCs using transfection agent. 48 hours after transfection, ability of the MSCs for expression of the hFIX and efficacies of the plasmids were evaluated by performing sandwich ELISA on cultured media as well as semi-quantitative RT-PCR. All analyses were performed with One-way ANOVA using SPSS software. Results:The highest expression level of the hFIX was obtained from intron-less and hBG intron-I containing construct. The highest biological activity was obtained from hBG intron-I,II containing construct. Conclusion:Successful expression of the hFIX was obtained from recombinant MSCs. MSCs were able to splice heterologous hBG intron-I from the hFIX-cDNA. Application of thehBG introns reduced the hFIX expression levels, probably due to improper splicing of the hBG introns.