The β-Globin Locus Control Region in Combination With the EF1α Short Promoter Allows Enhanced Lentiviral Vector-mediated Erythroid Gene Expression With Conserved Multilineage Activity

Some gene therapy strategies are compromised by the levels of gene expression required for therapeutic benefit, and also by the breadth of cell types that require correction. We designed a lentiviral vector system in which a transgene is under the transcriptional control of the short form of constitutively acting elongation factor 1 alpha promoter (EFS) combined with essential elements of the locus control region of the beta-globin gene (beta-LCR). We show that the beta-LCR can upregulate EFS activity specifically in erythroid cells but does not alter EFS activity in myeloid or lymphoid cells. Experiments using the green fluorescent protein (GFP) reporter or the human adenosine deaminase (ADA) gene demonstrate 3-7 times upregulation in vitro but >20 times erythroid-specific upregulation in vivo, the effects of which were sustained for 1 year. The addition of the beta-LCR did not alter the mutagenic potential of the vector in in vitro mutagenesis (IM) assays although microarray analysis showed that the beta-LCR upregulates similar to 9% of neighboring genes. This vector design therefore combines the benefits of multilineage gene expression with high-level erythroid expression, and has considerable potential for correction of multisystem diseases including certain lysosomal storage diseases through a hematopoietic stem cell (HSC) gene therapy approach. Received 21 December 2011; accepted 20 February 2012; advance online publication 20 March 2012. doi:10.1038/mt.2012.50