Doubly self-assembled dermatan sulfate/chitosan nanoparticles for targeted siRNA delivery in cancer therapy

RNA interference, a naturally occurring regulatory mechanism in which small interfering RNA (siRNA) molecules are responsible for the sequence-specific suppression of gene expression, emerged as one of the most promising gene therapies in cancer. In this work, we investigate a microfluidics double self-assembly method based on micellization and polyelectrolyte complex formation for the encapsulation of siRNA targeting the BIRC5 gene, a member of the inhibitor of apoptosis gene family, that codes for survivin a protein of theinhibitorof apoptosis protein family that is involved in triple-negative breast cancer (TNBC) proliferation and metastasis within nanoparticles of an amphiphilic chitosan-graft-poly(methyl methacrylate) copolymer and low-molecular weight dermatan sulfate, a polysaccharide targeting the CD44 receptor overexpressed in this tumor. Nanoparticles are spherical and display a hydrodynamic diameter of ∼ 200 nm, as measured by dynamic light scattering and scanning electron microscopy. In addition, these colloidal systems exhibit a strongly negative zeta-potential that confers them excellent physical stability for at least four months owing to electrostatic repulsion and evidences the exposure of the polyanionic dermatan sulfate on the surface. The key role of dermatan sulfate in the active targeting and intracellular delivery of the cargo in the murine breast cancer cell line 4T1, a model of TNBC, is confirmed by confocal laser scanning microscopy and imaging flow cytometry. Finally, the silencing efficiency is demonstrated in 4T1 cell viability, migration, proliferation and spheroid formation assays in vitro. Overall results highlight the promise of this simple, reproducible and scalable method for the nanoencapsulation of siRNA and other therapeutic nucleic acids.