Challenges and future expectations of reversed gene therapy.

Gene therapy is a genetic intervention used for the prevention or treatment of diseases by targeting selected genes with specific nucleotides. The most common form of gene therapy involves the establishment of a function by transfer of functional genes or correction of mutated genes. In other situations, suppression or abolishment of a function is required in order to balance a complicated regulatory system or to deplete cellular molecules crucial for pathogen infection. The latter in fact employs an opposite strategy compared to those used in classical gene therapy, and can be defined as reversed gene therapy. This paper takes CCR5-based stem cell gene therapy as an example to discuss the challenges and future expectations of reversed gene therapy.