Non-viral gene vectors are increasingly used in various gene therapy strategies due to safety concerns with viral vectors, but are plagued by low transfection efficiency and cellular gene expression. There have been extensive efforts to design the delivery vector to increase the efficiency of non-viral gene delivery. In contrast, the role of the cellular environment in DNA uptake has been underappreciated. Recently, we found that the mechanical properties (e.g., rigidity) and the spatial organization of cell adhesion ligands (e.g., overall density of cell adhesion ligands and their spacing at the nanometer scale) of the substrate to which a cell adheres mediate many aspects of cell function, including proliferation, apoptosis, and differentiation [1, 2]. These results suggest that the mechanics and chemistry of the cell adhesion substrate may regulate a cell's ability to transfer exogeneous gene vectors as well. In this talk, we will present a critical role of the cell adhesion substrate in regulating the level of gene transfer to MC3T3 pre-osteoblasts and and subsequent cellular gene expression. We will also address the mechanism of this effect, which relates to material control over cell proliferation utilizing a fluorescent resonance energy transfer (FRET) technique [3]. The results of this study are providing a new approach to control the non-viral gene delivery by engineering cellular niches.

References 1. Kong, H. J., Polte, T., Alsberg, E., & Mooney, D. J. FRET measurements of cell-traction forces and nano-scale clustering of adhesion ligands varied by substrate stiffness, Proc. Nat. Acad. Sci. (USA) 102, 4300 (2005). 2. Lee, K.Y., Alsberg, E., Hsiong, S., Comisar, W., Linderman, J., Ziff, R., Mooney, D. J., Nanoscale adhesion ligand regulates osteoblast proliferation and differentiation. Nano Letters 4, 1501 (2004). 3. Kong, H. J. Liu, J. Riddle, K., Matsumoto, T., Leach, K. Mooney, D. J. Non-Viral Gene Delivery Regulated by Stiffness of Cell Adhesion Substrates. Nature Mater. 4, 460 (2005).