After a cut, the bleeding usually stops when a scaffolding of molecules block the entry of the wound. These biochemical processes that build up a clot rely on a set of molecules that constantly flow through our veins and arteries, spring into action when needed, and dissolve back into the blood when the job is done.
Now for the first time, scientists have figured out how all these molecular components work together to block the flow of blood – and they hope to harness these principles to create new, self-healing synthetic materials to plug leaks. MIT News reports.
A team led by Alfredo Alexander-Katz at MIT found that the increased flow rate caused by a wound automatically triggers the reaction that plugs the hole: The faster the flow, the more effectively it works. (That seems counterintuitive, since faster flows usually stir things up rather than clump things together.)
The key molecule is a biopolymer called the von Willebrand factor (vWF): a long, chain-like structure that normally flows through the bloodstream in its inactive, coiled-up form.
- As soon as the vWFs are unfurled and stretched, they become sticky. It’s like exposing the adhesive part of tape when you pull it from the roll. (Watch a demo with scotch tape.)
- When an increased rate of flow stretches them out, they begin sticking to platelets (pictured).
- Then a network begins to take shape over the cut — a mixture of sticky molecules and platelets. This creates a plug within seconds, and as additional cells accumulate, a clot is formed.
- When the flow rate slows down, the plugs disaggregate anew.
Most biochemical materials, like shells or bones, form extremely slowly -- but clotting is rapid. The team hopes to create blood-clotting-inspired materials that can assemble quickly to control all sorts of liquid flows.
The work was published in Nature Communications this week.
[Via MIT News Office]
Image: Hsieh Chen via MIT News Office