MicroRNAs (miRNAs) represent endogenous small RNAs that post-transcriptionally regulate gene expression and, thus they are involved in the onset and progression of various diseases and conditions (Bader et al., 2010) such as for overweight and obesity. Antiadipogenic miRNA-27a is a negative regulator in fat metabolism, which inhibits adipocyte differentiation through downregulation of adipogenic marker genes (e.g. PPARγ) (Kim et al., 2010). Reduced miRNA-27a levels are often associated with the development of obesity and, therefore, this miRNA might represent a promising candidate for miRNA mimic replacement therapy (Lin et al., 2009). However, the application of naked RNAs has shown low membrane permeability, cellular uptake, and rapid degradation in the circulation. The present study aimed to develop a cationic, lipid-based nanoparticle system for targeting adipose tissue and delivering miRNA-27a. These systems are composed of positively charged nanostructured lipid carriers (cNLCs) and negatively charged miRNAs, which results in complex formation based on electrostatic interactions between these components. Materials and methods