Bone marrow mesenchymal stem cells: Improving transgene expression level, transfection efficiency and cell viability

Purpose: Advanced cancer is a catastrophic medical condition that is generally treated with surgery and conventional anticancer drugs, which are very toxic and often fail. A promising alternative is using genetically engineered mesenchymal stem cells. A popular method for genetically engineering mesenchymal stem cells (MSCs) is by employing transfection reagents. Nevertheless, a serious limitation of this procedure is its consistently low transfection efficiency. Therefore, the utility of transfection reagents in regenerative medicine - including cancer treatment - might increase strikingly by increasing their transfection efficiency and maintaining, to the greatest extent possible, cell viability and transgene expression levels. The purpose of this study was to analyze various effects on gene expression level, transfection efficiency, and cell viability by increasing the volume of transfection reagents and the plasmid DNA mass. Methods: Mouse bone marrow MSCs were transfected with trademarked Xfect®, Turbofect® or Lipofectamine 3000® and the plasmid pTracer-EF-His-A® expressing the green fluorescent protein (GFP). Additionally, we tested a protocol modification recommended by the Xfect manufacturer. The GFP expression level, transfection efficiency, and cell viability were evaluated together using a performance index. Results: By doubling the quantities recommended by the manufacturers (reagent volume), plasmid DNA mass or both variables and by following a modified Xfect method, the transfection efficiency improved to 70%, the cell viability did not diminish, and the performance index increased to 47.7% with respect to the values determined using the original Xfect protocol. Conclusion: Transgene expression levels, transfection efficiency, and cell viability may be strikingly improved, by increasing the volume of the transfectant agent, the plasmid DNA mass or both, beyond those recommended by transfection kit manufacturers.