The possibility of blocking the expression of selected genes raises great hopes for the treatment of incurable diseases so far , such as neurodegenerative diseases , autoimmune diseases and cancer . The RNA molecule due to its biochemical properties of a promising therapeutic tool . The discovery of RNA interference (RNAi ) started the new tests for inhibition of expression of selected genes by small interfering RNA ( siRNA) in mammalian cells. This technique uses a natural process of gene silencing the expression of double-stranded RNA -dependent .