A novel means of drug delivery: Myoblast-mediated gene therapy and regulatable retroviral vectors

A potentially powerful approach to drug delivery in the treatment of diseas e involves the use of cells to introduce genes encoding therapeutic protein s into the body. Candidate genes for delivery include those encoding secret ed factors that could have broad applications ranging from treatment of inh erited single-gene deficiencies to acquired disorders of the vasculature or cancer. Myoblasts, the proliferative cell type of skeletal muscle tissues, are potent tools for stable delivery of a gene of interest into the body, as they become an integral part of the muscle into which they are injected, in close proximity to the circulation. The recent development of improved tetracycline-inducible retroviral vectors allows for fine control of recomb inant gene expression levels. The combination of ex vivo gene transfer usin g myoblasts and regulatable retroviral vectors provides a powerful toolbox with which to develop gene therapies for a number of human diseases.