RETROVIRAL VECTOR-MEDIATED GENE-TRANSFER INTO HUMAN PRIMARY MYOGENIC CELLS LEADS TO EXPRESSION IN MUSCLE-FIBERS IN-VIVO

Primary human myogenic cells isolated from fetal and adult muscle were infected with a high-titer, Moloney murine leukemia virus (MoMLV)-der ived retroviral vector expressing a bacterial beta-galactosidase (beta -gal) gene under long terminal repeat (LTR) control. Gene transfer eff iciency averaged 50% in both fetal myoblasts and adult satellite cells , as revealed by beta-gal staining. The reporter gene was stably integ rated, faithfully inherited, and expressed at significant levels in my ogenic cells for at least 10 generations under clonal growth condition s, and throughout the culture life span upon differentiation into myot ubes. Comparable gene transfer efficiency was obtained in myogenic cel ls from muscle biopsies of patients affected by a number of genetic or acquired myopathies, including Duchenne muscular dystrophy. Transduce d normal human satellite cells were injected into regenerating muscle of immunodeficient mice, where they formed new muscle fibers in which the product of the reporter gene was detectable for 2 months after inj ection. These results show that retroviral vectors can be used to tran sfer foreign genes with high efficiency into normal or abnormal primar y human myogenic cells, leading to stable expression into mature muscl e. Satellite cells engineered in this way might represent an effective tool for gene therapy of muscular dystrophies as well as for systemic delivery of recombinant gene products for correction of inherited and acquired disorders. The human-mouse model described here will allow i n vivo testing of such gene therapy approaches.