A new way to make platelets

Platelets play a key role in blood clotting, and their numbers often drop in people having chemotherapy or with some kinds of anaemia.

Platelets from blood donors carry a risk of infection and other side effects, especially for people who need repeated transfusions, so scientists have tried to make platelets from another source: embryonic stem cells.

So far there have been two obstacles: platelets made from embryonic stem cells are often removed by other cells produced from the stem cells, and these platelets don't work well in clotting. Scientists have overcome these problems in mice by starting with stem cells inclined to produce platelets and by blocking a type of enzyme that interferes with clotting. The next step is to apply this in humans. The research was published in the Journal of Experimental Medicine in July 2008.