BVL-1-like VL30 promoter sustains long-term expression in erythroid progenitor cells.

Congenital blood disorders are common and yet clinically challenging globin disorders. Gene therapy continues to serve as a potential therapeutic method to treat these disorders. While tremendous advances have been made in vivo, gene delivery protocols and vector prototypes still require optimization. Alternative cis-acting promoter elements derived from VL30 retroelements have been effective in expressing tissue-specific transgene expression in vivo in nonerythroid cells. VL30 promoter elements were isolated from ELM-I-1 erythroid progenitor cells upon erythropoietin (epo) treatment. These promoters were inserted into a VL30-derived expression vector and reintroduced into the ELM-I-1 cells. beta-Galactosidase reporter gene activity from the ELM 5 clone, a BVL-1-like VL30 promoter, was capable of expressing sustained levels of the transgene expression over a 16-week assay period. These findings delineate the potential utility of these retroelement promoters as transcriptionally active, erythroid-specific, long terminal repeat (LTR) components for current globin vector constructs.