Background: Chitosan shows particularly high biocompatibility and fairly low cytotoxicity. However, chitosan is insoluble at physiological pH. Moreover, it lacks charge, so shows poor transfection. In order to develop a new type of gene vector with high transfection efficiency and low cytotoxicity, amphiphilic chitosan was synthesized and linked with low-molecular weight polyethylenimine (PEI).
Methods: We first synthesized amphiphilic chitosan - N-octyl-N-quatenary chitosan (OTMCS), then prepared degradable PEI derivates by cross-linking low-molecular weight PEI with amphiphilic chitosan to produce a new polymeric gene vector (OTMCS-PEI). The new gene vector was characterized by various physicochemical methods. We also determined its cytotoxicity and gene transfecton efficiency in vitro and in vivo.
Results: The vector showed controlled degradation. It was very stable and showed excellent buffering capacity. The particle sizes of the OTMCS-PEI/DNA complexes were around 150-200 nm with proper zeta potentials from 10 mV to 30 mV. The polymer could protect plasmid DNA from being digested by DNase I at a concentration of 2.25 U DNase I/μg DNA. Furthermore, they were resistant to dissociation induced by 50% fetal bovine serum and 1100 μg/mL sodium heparin. OTMCS-PEI revealed lower cytotoxicity, even at higher doses. Compared with PEI 25 KDa, the OTMCS-PEI/DNA complexes also showed higher transfection efficiency in vitro and in vivo.
Conclusion: OTMCS-PEI was a potential candidate as a safe and efficient gene vector for gene therapy.
Keywords: cytotoxicity; nonviral gene vector; polyethylenimine; transfection efficiency.