[Gene therapy: current situation and expectations].

In this review the current situation of gene therapy is described in hematological diseases, immunological conditions, and cancer. In all of them, the principal objective of various approaches with gene therapy is transduction of therapeutic genes in most of target cells. In chronic or immunological diseases, a stable expression of therapeutic genes is also required; in tumor cells, the efficiency or percentage of transduced cells make conditional on the treatment success. Consequently, vectors are one of the basic elements to optimize gene therapy approaches and protocols in view of the facts that we know that with liposomes less than 10% of cells are transduced, that retrovirus only infect cells in replication, and that adenovirus give rise to an important inflammatory response and a transitory transduction of the therapeutic gene. In addition recent approaches in cancer gene therapy with selective replication virus, suicidal genes, etc., are discussed.