It’s long been known that cells can navigate towards chemicals that attract them by following concentration gradients. This process is known as chemotaxis.

But this simple form of navigation isn’t equal to the task of guiding cells over long distances (more than 1 mm) or along a tortuous, branched paths - which is exactly what we see, for example, when an embryo is developing, during an immune response or when a tumour is metastasising.

So how is any of that possible?

New research suggests that it depends on a process called ‘self-generated chemotaxis’.

The idea is that, rather than passively responding to the presence of a chemical attractant, some cells actively alter their environment by breaking the attractant down as they move along. The local depletion of the attractant results in diffusion of fresh attractant towards the cells from its source. This dynamic flux, rather than the absolute amount of attractant around the cells, seems to be the key to the whole process. In effect, the cells create their own local chemical gradients and use these as a basis for choosing their direction of travel.

Luke Tweedy and his colleagues set a tough pathfinding challenge for cells of an organism called Dictyostelium discoideum (known for its long-range navigational ability), as well as metastatic pancreatic cancer cells. They had to find their way through a variety of mazes, some of which were quite complex. One of them was actually based on the famous maze at Hampton Court Place.

Remarkably enough, the cells could efficiently find optimal routes, detect dead ends before they reached them, and could sense an approaching junction, even when it was around a corner!

Significantly, these experimental results were accurately predicted by a computer model - which means that they probably apply to any system in which an attractant is degraded by cells that are drawn towards it.

The authors believe that self-generated chemo-attractant gradients ‘could offer answers to many unexplained physiological behaviors’.