Carbon nanotubes offer a new approach to gene therapy (Nano Stuff)

[Guest guest]

Hello to all:

Heres a cool article.

http://www.news-medical.net/?id=5469

Many genes that are related to particular diseases have now been

identified. Scientists are trying to use this knowledge to treat

diseases.

It is thought that defective or missing genes could be replaced by

introducing the relevant gene into cells from the outside. This is

not so simple, because DNA cannot easily pass through cell

membranes; it needs a transporter, such as a virus, liposome, or

special peptide. A European team of researchers has now developed a

new approach: they have succeeded in slipping DNA into mammalian

cells by using modified carbon nanotubes.

Carbon nanotubes are tiny needle-shaped structures made exclusively

of carbon atoms. They can be pictured as one or more layers of a

rolled up sheet of graphite. They have become the focus of much

interest as materials for biomedicine as well as other technical

applications.

In order to work as gene transporters, however, the tiny " needles "

first need to be slightly modified. The Italian, French, and British

team led by Alberto Bianco (Strasbourg), Kostas Kostarelos (London),

and Maurizio Prato (Trieste) attached several chains made of carbon

and oxygen atoms to the outside of carbon nanotubes. The end of each

chain consists of a positively charged amino group (– NH3+). This

alteration makes the tiny needles water-soluble. More importantly,

the charged groups are very attractive to the negatively charged

phosphate groups in the DNA backbone. By using these electrostatic

attractive forces, the researchers were able to solidly anchor

plasmides, small, ring-shaped DNA fragments from bacteria, to the

outsides of the nanotubes. They then brought their DNA – nanotube

hybrids into contact with a cell culture of mammalian cells. The

result: the carbon nanotubes, together with their DNA cargo, entered

into the cells. Electron microscope images of thin sections of the

cells even showed how the thin needles make their way through the

cell membrane. They are not harmful to the cells because, unlike

several previous gene-transport systems, they do not destabilize the

membrane when passing through it. Once inside the cell, the genes

proved to be functional.

Carbon nanotubes are not limited to the transfer of genes; other

modifications should also allow for the attachment of other

pharmaceuticals, allowing them to enter cells as well.