Perspectives in gene therapy

Gene therapy is understood to be both the restitution of genetic alterations caused by mutation or deletion and the control of overexpressed genes. The concept of gene therapy can also encompass molecular strategies to induce cell death in tumor cell by either the so-called "suicided genes" or by certain viral genes that induce a more selective cell death among the transformed cells. The prospect for the clinical application of gene therapy are enormous and, at least theoretically, its utilization can be extended to a number of diseases known to have a genetic basis, and to neoplastic processes. This review summarizes some of the projects that are currently underway involving neoplastic diseases, liver diseases, hematopoietic cells and respiratory tract cells. The results of most of the ongoing protocols are not yet conclusive, and presumibly, their clinical application is still some years away. One of the major limitations is the method of introducing the genetic sequences into the cells and achieving their constitutive expression by the cells. For ethical reasons, this approach should not be done in germ cells, but at the level of the tissue or cells most closely involved in the development of each gene-based disease. The methods employed in gene therapy are discussed, focusing on those mediated by the application of viral vectors, as well as those requiring the use of liposomes and others.