Human somatic cell gene therapy.

The prelude to successful human somatic gene therapy, i.e. the efficient transfer and expression of a variety of human genes into target cells, has already been accomplished in several systems. Safe methods have been devised to do this using non-viral and viral vectors. Potentially therapeutic genes have been transferred into many accessible cell types, including hematopoietic cells, hepatocytes and cancer cells, in several different approaches to ex vivo gene therapy. Successful in vivo gene therapy requires improvements in tissue-targeting and new vector design, which are already being sought. Gene-transfer protocols have been approved for human use in inherited diseases, cancer and acquired disorders. Although the results of these trials to date have been somewhat disappointing, human somatic cell gene therapy promises to be an effective addition to the arsenal of approaches to the therapy of many human diseases in the 21st century if not sooner.