Delivery of magic bullets: on the still rocky road to gene therapy.

In this issue, the promises, problems and current progress towards gene therapy are examined in a themed set of six reviews. These cover the major methodologies deployed over the last twenty to thirty years to deliver a gene or other potentially therapeutic molecules into an organism. Initial enthusiasm and optimism concerning the prospects for gene therapy and more generally, the delivery of magic bullets, arose after the pioneering discoveries of monoclonal antibodies and retroviral infection during the 1970's and were fuelled by strategies to make synthetic viruses and the advent of chemical vectors over the succeeding twenty years. However, despite significant advances, to date, the early hopes of widespread gene therapy still remain largely unfulfilled.