A bioreducible polypeptide for efficient gene transfection both in vitro and in vivo

A disulfide bond containing polypeptide, PolyK₆-R₈, was designed and prepared by oxidative polymerization between terminal cysteinyl thiol groups of CHK₆HC and CR₈C. The molar ratio between CHK₆HC and CR₈C within obtained PolyK₆-R₈ was 9:1, and PolyK₆-R₈ could combine DNA compactly when weight ratio reached 5. Through in vitro investigation, it was found that PolyK₆-R₈ was an efficient gene vector with low cytotoxicity for delivering DNA in both COS-7 and HeLa cells. Cellular uptake of DNA mediated by PolyK₆-R₈/DNA complexes was promoted after incubation for 4 h. Moreover, by examining the histological sections of hindlimb ischemia rats through immunohistochemistry, PolyK₆-R₈/VEGF complexes were proved to be effective in both VEGF protein expression and succeeding vessel formation. The results indicated that polypeptide-based PolyK₆-R₈ is a promising gene vector for the limb ischemia treatment.