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Particle-mediated gene transfer to ocular surface epithelium.

When molecular cloning was introduced in the early 1970s, gene therapy became a real possibility in curing congenital diseases caused by gene mutations, e.g., thalassemia. Since then, advances in technology have extended in attempts to cure acquired diseases such as cancer, wound healing, metabolic diseases and immune disorders. Nevertheless, gene therapy is still in its infancy. Although some promising results have been obtained, in general no procedure can yet be used to successfully cure congenital or acquired diseases. Despite technological advances sustaining the field of gene therapy, few individual patients have benefited from it so far. The reasons for its limited success are due to difficulties in efficient gene transfer, and sustained and controlled expression of the transgenes leading to production of therapeutic quantity of proteins, as well as complications of the introduction of foreign genes to humans. For example, the widely used viral vectors can produce considerable side effects of host immune responses to the viral proteins, which prohibit its repetitive uses for effective treatment. The other techniques—non-viral vehicles, i.e., liposomes, and physical means, i.e., particle-mediated gene transfers and electric pulse-also have not yielded satisfactory results.