Use of DNA Stabilizers to Extend Plasmid Biological Activity

Background: Storage stability of plasmid biopharmaceuticals is a critical issue that needs to be addressed during clinical and process development. Objectives: The goal of this work was to evaluate the ability of stabilizers to prolong the stability of plasmid DNA solutions and extend the duration of transgene expression of transfected cells. Methods: A plasmid harboring the GFP gene and Chinese Hamster Ovary (CHO) cells were used as models. Plasmid solutions were formulated with the stabilizer DNAstablePlusTM, 300 mM trehalose and 300 mM cellobiose. The biological activity was monitored by transfecting CHO cells with the preparations using Lipofectamine. Results: Protection against denaturation conferred by DNAstablePlusTM at 60 °C was outstanding, with 94% of the activity preserved after 7 days compared to 76% with trehalose, 70% with cellobiose and <10% without stabilizers. While plasmid DNA stored at room temperature lost 95% of its ability to express GFP in the first month, trehalose, cellobiose and DNAstablePlusTM were able to preserve it for 6, 8 and at least 12 months, respectively. The incorporation of trehalose, cellobiose and DNAstablePlusTM in lipoplexes also contributed to extend the expression of GFP in transfected cells. While a significant loss of GFP-expressing cells (~10%) was observed after 7days with no stabilizers, formulation with DNAstablePlusTM, cellobiose and trehalose increased the number of cells GFP-expressing cells to more than 50%. Conclusions: The biological activity of plasmid DNA solutions stored at room temperature was extended several fold by incorporating cellobiose, trehalose and DNAstablePlusTM in the formulations.