Metallic Nanorods Shuttle Genes

Article excerpt

Delivery of health-promoting genes into cells of the body holds enormous promise for preventing and treating diseases. However, the vehicles for those genes in current approaches to gene therapy are generally viruses or synthetic materials, including polymers. The former can elicit harmful immune responses, and the latter can be toxic (SN: 1/18/03, p. 43). Now, biomedical engineers have devised a technique that uses metallic nanorods as gene carriers, which the researchers say could avoid those risks.

In the October Nature Materials, Kam Leong of Johns Hopkins University in Baltimore and his colleagues describe how they fabricated dual-metal rods measuring 200 nanometers in length and 100 nanometers in diameter. One half of the rod's length is made of nickel; the other half is gold. To the nickel segment, the researchers attached DNA bearing a gene that coded for one of two proteins that make fireflies and some jellyfish glow. To the gold segment, the researchers attached a cell-targeting protein called transferrin.

When added to a lab dish containing cultured mammalian cells, the nanorods bound to receptors inside tiny pits on the cells' surfaces. The pits then closed off and formed vesicles holding the nanorods. Carried into the cell in this way, the DNA eventually detached from the nanorods and entered the nucleus. There, the cell's machinery translated the gene into the light-producing protein, indicating successful gene delivery and expression.

The Johns Hopkins team also delivered DNA into mice by using a so-called gene gun to propel small doses of the nanorods under the animals' skin. After 1 day, the amount of glowing protein produced by the mice was similar to that needed for genetic vaccines, says Leong. This form of gene therapy delivers a single gene that produces a protein known to boost the body's immune response to, say, a particular virus. …