(251f) Interplay of Matrix Rigidity and Cell Type for Non-Viral Gene Delivery

Non-viral gene delivery has the potential to treat a wide array of ailments through the transfer of genetic material.  Towards this end, extensive efforts have been made to synthesize vectors for plasmid DNA delivery in order to improve the uptake and expression of delivered genes.  Unfortunately, non-viral gene delivery has been hampered by limited expression in vivo following injection to target tissues, possibly due to a limited understanding of the interactions between target cells and their extracellular microenvironment.  Recent studies have reported that the spacing of cell adhesion ligands and stiffness presented by a synthetic extracellular matrix regulate non-viral gene delivery for pre-osteoblasts.^1,2  However, it is unclear whether such influence from the extracellular microenvironment is universally valid to various cell populations that reside within a target tissue.

This study examines the role of matrix rigidity on gene delivery as mediated by cell type.  In this study, poly(ethylene glycol) diacrylate (PEGDA) hydrogels of varying stiffness modified with fibronectin were used as synthetic extracellular matrices.  The elastic moduli of the hydrogels were varied over a wide range to mimic both soft and hard tissues.  Plasmid DNA (pDNA) encoding bone morphogenetic protein (BMP)-2 was delivered to NIH3T3 fibroblasts, D1 bone marrow stromal cells, and C2C12 myoblasts cultured on hydrogels of varying stiffness.

Both the cellular uptake of pDNA and the resulting gene expression were found to increase with increasing matrix stiffness.  Gene expression from fibroblasts exhibited the greatest dependency on matrix stiffness as compared with that from bone marrow stromal cells and myoblasts.  The effects of matrix stiffness and cell type on non-viral gene delivery were further related to cellular proliferation and nuclear morphology.  Overall, the results of this study may be useful for the development of gene delivery strategies and the design of tissue engineering scaffolds for gene-based tissue regeneration therapies.

1.  Kong, H.J., et al.  Nat Mater 2005, 4, 460 – 464.

2.  Kong, H.J., et al.  Nano Lett 2007, 7, 161 – 166.