Abstract
Gene therapy using siRNA can be a new potent strategy to treat many
incurable diseases, including cancer and viral infection, at the genetic
level. Therapies using siRNA essentially need an efficient and safe
method of siRNA delivery into cells while maintaining the stability of
the siRNA. Here, we designed new fusion peptides of SPACE and oligo
arginine. Fusion peptides formed uniform self-assembled nano-complexes
without additional reactions. Moreover, siRNAs were stable in
nano-complexes for four days in 10% fetal bovine serum. Cellular uptake
efficiency of each complex was similar or higher than that of
commercialized available Lipofectamine™ 2000. GAPDH-siRNA/peptide
complex knock GAPDH mRNA down similar to that mediated by Lipofectamine™
2000. The increase of arginine residues in fusion peptides induced
higher siRNA stability, which enhanced GAPDH knockdown. Co-localization
and cellular internalization of siRNA/S-R15 complexes were verified
peripherally around the nucleus. The endocytosis pathway of the
siRNA/S-R15 complex was identified via lipid-raft mediated endocytosis.
Besides, the biosafety of each fusion peptide was proven under a
particular concentration. Therefore, a safe and stable self-assembled
complex could be expected to deliver siRNA into cells efficiently for
the treatment of many diseases.