Application of magnetic nanoparticles to gene delivery

Abstract

Nanoparticle technology is being incorporated into many areas of molecular science and biomedicine. Because nanoparticles are small enough to enter almost all areas of the body, including the circulatory system and cells, they have been and continue to be exploited for basic biomedical research as well as clinical diagnostic and therapeutic applications. For example, nanoparticles hold great promise for enabling gene therapy to reach its full potential by facilitating targeted delivery of DNA into tissues and cells. Substantial progress has been made in binding DNA to nanoparticles and controlling the behavior of these complexes. In this article, we review research on binding DNAs to nanoparticles as well as our latest study on non-viral gene delivery using polyethylenimine-coated magnetic nanoparticles.

Keywords: Magnetofection; gene delivery; magnetic nanoparticles; polyethylenimine.

Figure 1

MNP gene delivery system (Magnetofection). Plasmids are bound to MNPs, which then move from the media to the cell surface by applying a magnetic force.

Figure 2

Strategy for cell transplantation therapy. A patient’s cells are cultured in chemically defined media. MNP-transfected cells by the introduced gene are isolated by FACS. FACS-purified differentiated cells are transplanted into the patient.

Figure 3

Gene delivery systems using a transfection reagent (cationic polymer) and MNPs: (A) Gene delivery system using transfection reagent. The polyplex moves randomly in culture medium; (B) Magnetofection system. The magnetoplex only moves to the cell surface.

Figure 4

Optimum conditions for PEI max-MNPs magnetofection. To optimize conditions, we varied volume (A) and time on the magnetic plate (B). These results were evaluated by quantitative real-time RT-PCR. The relative expression level (GFP/GAPDH) in the human fetal lung-derived fibroblasts (TIG-1 cells) treated with PEI max alone (A), and in the absence of magnetic force (0 h) (B) was defined as 1. Optimal transfection conditions were established when TIG-1 cells were treated with 0.8 μg PEI max-MNPs and 2.0 μg pCAG-GFP for 8 h on the magnetic plate in either a six-well plate or a 35 mm dish. The asterisk (*) indicates a significant difference (P < 0.05).

Figure 5

Transfection of TIG-1 cells with multiple genes using PEI max-MNPs. TIG-1 cells were simultaneously transfected with GFP, CFP, and YFP expression vector plasmids. TIG-1 cells were treated with 0.8 μg of PEI max-MNPs and 0.7 μg each of pCAG-GFP (GFP, provided by Dr. Nishino), pPhi-Yellow-N (YFP, Evrogen), and pAmCyan1-C1 (CFP, Clonetech) for 8 h on the magnetic plate in a six-well plate or a 35 mm dish. White bar indicates 200 μm.