(730a) Enhancing Nonviral Gene Delivery by Manipulating Cell-Material Interactions

Gene delivery approaches serve as a platform to modify gene expression of a cell population with applications including functional genomics, tissue engineering, and gene therapy. The delivery of exogenous genetic material via nonviral vectors has proven to be less toxic and to cause less of an immune response in comparison to viral vectors, but with decreased efficiency of gene transfer. Attempts have been made to improve nonviral gene transfer efficiency by modifying physicochemical properties of gene delivery vectors as well as developing new delivery techniques. In order to further improve and understand nonviral gene delivery mechanisms, our approach focuses on the cell-material interface, since materials are known to modulate cell behavior, potentially rendering cells more responsive to nonviral gene transfer.  In this study, self-assembled monolayers of alkanethiols on gold were employed as model biomaterial interfaces with varying surface chemistries. NIH/3T3 mouse fibroblasts were seeded on the modified surfaces, transfected after 18 hours, and assayed for transfection efficiency 24 hours thereafter. In comparison to polystyrene and gold surface controls, transfection efficiency was increased on charged surfaces presenting -COO^- and -NH₃⁺ terminal functional groups, while hydrophilic and hydrophobic uncharged surfaces (-OH and –CH₃) demonstrated dramatically reduced transfection efficiencies. Cellular cytoskeleton, focal adhesions, nuclei, and cytoplasm were labeled to further characterize cell-surface interactions. We demonstrate that cellular morphological characteristics, such as focal adhesions and cytoskeletal stress fibers, that have been shown to be influenced by surface characteristics, could be related to transfection efficiency. We demonstrate that simple modifications of surfaces lead to increased efficiency of nonviral gene delivery. Understanding the cell-biomaterial interface as it pertains to enhancing transfection efficiency heralds the development of precisely tunable substrates for biotechnological and tissue engineering applications.