The effect of serum in culture on RNAi efficacy through modulation of polyplexes size.

The effect of serum in culture on RNAi efficacy through modulation of polyplexes size. Biomaterials. 2013 Oct 10; Authors: Zhang W, Liu J, Tabata Y, Meng J, Xu H Abstract Serum in the culture medium is one crucial factor that compromises RNAi efficiency of non-viral vectors. However, mechanistic roles of serum in siRNA delivery remain unknown. In this work, we took one cationic polymer, pullulan chemically modified by spermine (termed as pullulan-spermine, Ps), as a siRNA carrier model to investigate the effects of serum on key steps in siRNA delivery including formation of Ps and siRNA polyplexes (Ps-siRNA), cellular uptake, lysosomal escape, and cytotoxicity. We demonstrate that low serum concentration (1.25% and 2.5%) in culture medium results in large particles of Ps-siRNA, while high serum concentration (10%-40%) leads to small particles of Ps-siRNA. The larger particles initiated the internalization of siRNA more effectively in comparison to the smaller ones. The engulfed Ps-siRNA particles mainly locate in lysosomes. The large particles exhibited stronger abilities of destabilizing lysosomes than that of the small particles as large Ps-siRNA particles contain more amines and subsequently elicit a stronger proton sponge effect which results in more effective lysosomal escape of siRNA. Despite the lower RNAi efficiency, the small particle of Ps-siRNA in the high serum medium generates much lower cytotoxicity. These findings explain why s...
Source: Biomaterials - Category: Materials Science Authors: Tags: Biomaterials Source Type: research