Differential expression and secretion of alpha I antitrypsin between direct DNA injection and implantation of transfected myoblast

Muscle can be used for systemic delivery of non-muscle proteins. In order to investigate the relative effectiveness of direct DNA plasmid injection versus implantation of genetically modified myogenic cell lines, we have used the human alpha 1 anti-trypsin (alpha 1AT) cDNA driven by either cytomegalovirus (CMV) or the muscle creatine kinase 3.3 kb (MCK) promoter in immunodeficient mice. We demonstrate that the implantation of transfected myoblasts stably expressing the human alpha 1AT cDNA generates a more persistent production of alpha 1AT than does direct intramuscular injection of the same construct as plasmid DNA. Moreover immunohistological labelling of muscle sections implanted with myoblasts show that the newly formed muscle fibres are those containing the human protein.