Retroviral vector-mediated gene expression in hematopoietic cells

Gene transfer vectors based on simple retroviruses and more complex lentiviruses are currently the most reliable tools for stable establishment of transgenes in hematopoietic cells. While important hurdles in basic gene transfer technologies have been overcome in recent years, there is still some uncertainty in the choice of the cis-regulatory elements of the vector. These elements dictate the overall level, clonal variability, response to differentiation and persistence of transgene expression in vivo and thus have a significant influence on the outcome of therapeutic applications of somatic gene transfer. The rationale underlying the further improvement of such cis-elements is reviewed here.