RNA interference by nanofiber-based siRNA delivery system

SiRNA delivery has found useful applications particularly as therapeutic agents against genetic diseases. Currently, the delivery of siRNA typically takes the form of nanoparticles. In order to expand the applications of these potent but labile molecules for long-term use required by tissue engineering and regenerative medicine, alternative delivery vehicles are required. This work presents a scaffold-mediated approach to siRNA delivery. By encapsulating siRNA within polycaprolactone (PCL) nanofibers (300-400. nm in diameter) controlled release of intact siRNA could be achieved for at least 28. days under physiological conditions. The successful transfection of HEK 293 cells with GAPDH siRNA released from fibrous scaffolds at day 5, 15 and 30 demonstrated that the encapsulated molecules remained bioactive throughout the period of sustained release, providing silencing efficiency of 61-81% that was comparable to conventional siRNA transfection. Direct seeding of cells on these biofunctional scaffolds, with and without transfection reagent, demonstrated enhanced cellular uptake and efficient GAPDH gene-silencing. This work demonstrates the potential of nanofibrous scaffold-mediated siRNA delivery for long-term gene-silencing applications. The combination of topographical features provided by nanofibrous scaffolds may provide synergistic contact guidance and biochemical signals to mediate and support cellular development in regenerative medicine.