Expression of beta-globin in primary erythroid progenitors of beta-thalassemia patients using an SV40-based gene delivery system

SV40-based vectors are very efficient in gene delivery into human hematopoi etic cells. In the present work, we investigated the expression off constru cts carrying the human beta-globin gene that were delivered as beta-globin pseudovirions, Expression studies were performed by RNA analysis of primary human erythroid progenitors cultivated from peripheral blood of beta(o)-th alassemia patients who are unable to produce normal beta-globin RNA. This e rythroid culture system recapitulates in vitro the process of growth, diffe rentiation, and maturation of authentic erythroid precursors. The progenito rs were induced to differentiate by the addition of erythropoietin (EPO). F ive days later, the cells were infected with pseudovirions containing the n ormal beta-globin gene, and RNA was harvested on day 8, The results showed significant levels of normal beta-globin gene mRNA, A small DNA fragment de rived from the 5'-region of the HSII element of the human beta-globin locus control region (LCR) enhanced expression of the linked beta-globin gene 20 -30-fold. Normal beta-globin mRNA expression was in direct correlation to t he multiplicity of infection. These studies suggest the potential feasibili ty of using the beta-globin delivery system for gene therapy of beta-thalas semia.