Effect of pluronic-block copolymers on the reduction of serum-mediated inhibition of gene transfer of polyethyleneimine-DNA complexes

Serum stability of non-viral vectors is a crucial factor for successful in vivo gene delivery. Pluronic-block copolymers consisting of hydrophilic ethylene oxide and hydrophobic propylene oxide blocks were tested to prevent the reduction of serum-mediated inhibition of gene transfer of polyethyleneimine (PEI)-DNA complexes in NIH/3T3 cells. The order of hydrophilic-lipophilic balance (HLB) of six different types of Pluronics used in this study was F68 > F 127 > P105 > P94 > L122 > L61. Transfection activities of NIH/3T3 cells with PEI-DNA complexes containing Pluronics with higher HLB showed marked improvement of gene-expression levels in serum media from 10 to 50% fetal bovine serum compared with PEI-DNA complexes alone. Also, higher concentrations (1 and 3%) of Pluronics with higher HLB in the PEI/DNA dispersion provided a stronger steric hindrance in resisting serum components than those obtained in a lower concentration (0.1%). These results suggested that non-viral vectors incorporated with higher HLB of Pluronics may be used as potential vehicles for in vivo delivery of DNA.