Regulated expression systems for gene therapy

Gene therapy is a promising and rapidly developing field of modern medicine and is expected to improve or even cure the diseases that are incurable with classical therapies. The logics of the development of gene therapy in the nearest future will require the systems wherein a regulation is possible for expression of therapeutic genes. The review considers the currently available regulated gene therapeutic systems, which can be divided into two main classes. One includes the systems wherein external inducers are used to trigger therapeutic gene expression. Systems of the other class are autoregulated and function without an external inducer. The most important first-class expression systems are based on the regulation by tetracycline, rapamycin derivative-induced dimerization, steroid hormones, regulatory RNAs, and physical factors. The most important systems of the second class are regulated by oxygen or glucose levels.