An in vitro system for efficiently evaluating gene therapy approaches to hemoglobinopathies

A variety of gene therapy strategies are under development for the treatment of sickle cell anemia and other hemoglobinopathies. A number of alternative vectors have been developed to transfer and express the beta-globin gene and other therapeutic molecules, but none has resulted in efficient transduction and stable long-term expression in primary hematopoietic cells. One reason for this problem is that most vectors are initially evaluated in immortalized cell lines which may not faithfully recapitulate the biology of primary erythroid cells. In order to provide a more relevant system for efficiently evaluating alternative vector constructs for beta-globin disorders, we have developed (I) a simple method for generating primary human red blood cell (RBC) precursors in liquid culture established with mononuclear cells obtained from normal donors as well as patients with Hb SC disease; (2) a high titer retroviral vector which can be easily modified to optimize gene transfer and transgene expression, and (3) methods for transducing the RBC precursors at high efficiency. The development of simple and efficient methods and reagents for generating and transducing primary human RBC precursors provides a facile and effective means for screening alternative gene therapy strategies.