What happens when you accidentally cut your finger and make it bleed? First off, the blood begins to clot, thanks to your platelets; then, the wound becomes inflamed as the white blood cells consume the dead cells and debris. Lastly, new tissue is grown, and the wound contracts, just as skin cells begin to migrate over the wound.
This is all well known to medical researchers, but there’s one detail that has escaped them for some time: How exactly do the skin cells move towards the cut in the first place? This has been incredibly difficult to try and view under a microscope, but a new study published in the journal FASEB has finally captured the event on camera, so to speak.
“And they walk,” Jonathan Jones, director of Washington State University’s (WSU) School of Molecular Biosciences and lead author of the study, said in a statement. It appears as if skin cells dissolve the protein bonds that keep them in place, before shifting from side to side and using their outer edges as feet-like platforms to push themselves along.
Although it’s not yet completely clear how a skin cell's outer edges gain traction on the surface, the team thinks that it uses an additional protein to push itself along, somewhat like an incredibly small paddle being used to push a boat along a river. “It’s using its internal muscle-related proteins to be able to generate these forces to allow the cell to use its feet and move along in step-wise fashion,” Jones added.
Normally, skin cells cannot be seen in motion with this much accuracy. In separate studies, researchers have used animal analogues like the multicolored zebrafish, whose illuminated scales can be seen moving around their bodies towards wounds with remarkable precision.
For this particular piece of research, the team embedded the skin cell surface with fluorescent microbeads, which allowed them to see with unprecedented resolution how the cells were actually moving. Looking through a high-powered confocal microscope, they could see the skin cells shimmying across the beady surface by contracting and expanding their outer rims.
Apart from being very cool from a visual point of view, this research may lead to techniques that increase the mobility of skin cells. As we age, our body’s ability to heal worsens, and wounds take longer to disappear. Perhaps finding out precisely how they “walk” could one day reverse this decline.
Gif in text: A skin cell “walking” across a surface. The colored arrows track its displacement. WSU