The new self-inactivating lentiviral vector for thalassemia gene therapy combining two HPFH activating elements corrects human thalassemic hematopoietic stem cells.

ABSTRACT: To address how low titer, variable expression, and gene silencing affect gene therapy vectors for hemoglobinopathies, in a previous study we successfully used the HPFH (hereditary persistence of fetal hemoglobin)-2 enhancer in a series of oncoretroviral vectors. On the basis of these data, we generated a novel insulated self-inactivating (SIN) lentiviral vector, termed GGHI, carrying the (A)?-globin gene with the -117 HPFH point mutation and the HPFH-2 enhancer and exhibiting a pancellular pattern of (A)?-globin gene expression in MEL-585 clones. To assess the eventual clinical feasibility of this vector, GGHI was tested on CD34(+) hematopoietic stem cells from nonmobilized peripheral blood or bone marrow from 20 patients with ?-thalassemia. Our results show that GGHI increased the production of ?-globin by 32.9% as measured by high-performance liquid chromatography (p=0.001), with a mean vector copy number per cell of 1.1 and a mean transduction efficiency of 40.3%. Transduced populations also exhibited a lower rate of apoptosis and resulted in improvement of erythropoiesis with a higher percentage of orthochromatic erythroblasts. This is the first report of a locus control region (LCR)-free SIN insulated lentiviral vector that can be used to efficiently produce the anticipated therapeutic levels of ?-globin protein in the erythroid progeny of primary human thalassemic hematopoietic stem cells in vitro.

SUBMITTER: Papanikolaou E 

PROVIDER: S-EPMC3260446 | biostudies-literature | 2012 Jan

REPOSITORIES: biostudies-literature