(93g) Immobilization of Liposome/DNA Complex by Surface Induced-Biomineralization for Enhanced Gene Transfer

Delivering genetic materials to mediate functions of cells present in tissue scaffolds holds great promise for regenerative medicine. Systemic approaches of gene transfer are unable to transport genes across the barriers of tissue scaffolds and thus limit the availability of DNA to cells. Surface-induced biomineralization represents a flexible approach to immobilize DNA onto surfaces with a highly localized level of DNA accessible for cells. More importantly, the level of transgene expression can be easily tuned by manipulating the composition of mineral solutions. However, immobilized naked DNA is uniformly embedded in thin films of biominerals. Depending on microenvironment of different cells, majority of DNA may be either trapped in the thin films or dissociated with biominerals before entering cells. As a result, a low level of DNA gains access to cells and/or nuclei for subsequent transcription. In this study, DNA molecules were initially complexed with liposomes to form nanocomplex. Subsequently, these nanocomplexes were immobilized onto a cell-culture substrate through surface-induced biomineralization. The nanocomplexes formed under different DNA to liposome ratios modulated the architecture of biominerals while biominerals anchored the nanocomplexes onto the surface. Regardless of the formulation of mineral solutions and the ratio of DNA to liposomes, nanocomplexes were efficiently deposited onto the surface. The levels of intracellular DNA uptake and transgene expression were greatly enhanced in neural cells compared to that obtained by immobilized naked DNA and comparable to that obtained by commercial transfection agent. The level of transgene expression of neural cells was also tunable by manipulating the composition of mineral solutions. In addition, the nanocomplexes pose minimal cytotoxicity to neural cells.