A collaboration between mathematicians and biologists has discovered “why platelets, the cells that form blood clots, are the size and shape that they are”, a better understanding of which “could have wide implications [for] healing wounds and in strokes and other conditions”.

A press release explains that platelets are

made by bone marrow cells called megakaryocytes. They bud off first as large, circular pre-platelets, form into a dumbbell-shaped pro-platelet, then finally divide into a standard-sized, disc-shaped platelet. A typical person has about a trillion platelets in circulation at a time, and makes about 100 billion new platelets a day, each living for 8 to 10 days.

The research  “developed a mathematical model of the forces inside the cells that turn into platelets, accurately predicting their final size and shape”. Paper author Alex Mogilner is quoted in his university’s press release saying the question is “a longstanding puzzle in platelet formation” and this paper offers “the first quantitative solution”.

Inside the pre- and pro-platelets is a ring of protein microtubules, which exerts pressure to straighten and broaden the nascent cells. But overlying the ring is a rigid cortex of proteins that prevents the platelets from expanding.
By tweaking the number of microtubules in the bundles, Mogilner, Zhu and Lee found that they could correctly predict how pro-platelets would flip into a dumbbell shape, as well as the size and shape of mature platelets.

Press release: Math predicts size of clot-forming cells.

Paper: Microtubule and cortical forces determine platelet size during vascular platelet production. (£22 to non-subscribers)