Tunnelling nanotubes: Life's secret network

* 18 November 2008 by Anil Ananthaswamy * Magazine issue 2682

Tunnelling nanotubes seem to play a major role in anything from how our immune system responds to attacks, to how damaged muscle is repaired   after a heart attack (Image: Paul McMenamin / UWA).

HAD Amin Rustom not messed up, he would not have stumbled upon one of
the biggest discoveries in biology of recent times. It all began in 2000, when he saw something strange under his microscope. A very long, thin tube had formed between two of the rat cells that he was studying. It looked like nothing he had ever seen before.

His supervisor, Hans-Hermann Gerdes, asked him to repeat the experiment.
Rustom did, and saw nothing unusual. When Gerdes grilled him, Rustom
admitted that the first time around he had not followed the standard protocol of swapping the liquid in which the cells were growing between
observations.

Gerdes made him redo the experiment, mistakes and all, and there they
were again: long, delicate connections between cells. This was something
new - a previously unknown way in which animal cells can communicate with each other.

Gerdes and Rustom, then at Heidelberg University in Germany, called the
connections tunnelling nanotubes. Aware that they might be onto
something significant, the duo slogged away to produce convincing evidence and eventually published a landmark paper in 2004 (Science, vol 303, p
1007).

A mere curiosity?

At the time, it was not clear whether these structures were anything
more than a curiosity seen only in peculiar circumstances. Since their
pioneering paper appeared, however, other groups have started finding nanotubes in all sorts of places, from nerve cells to heart cells. And far from being a mere curiosity, they seem to play a major role in anything from how our immune system responds to attacks to how damaged muscle is repaired after a heart attack.

They can also be hijacked: nanotubes may provide HIV with a network of
secret tunnels that allow it to evade the immune system, while some cancers could be using nanotubes to subvert chemotherapy. Simply put, tunnelling nanotubes appear to be everywhere, in sickness and in health. "The field is very hot," says Gerdes, now at the University of Bergen in Norway.

(New Scientist)