Mosquito spit can bust blood clots in mice

Does your blood run thick? A bit of mosquito saliva might one day be just what the doctor ordered. That’s because scientists have found a new way to reinvigorate anticlotting factors in mosquito spit in the lab. The modified blood thinner has so far only been tested in mice; if it ever works in humans, it could help prevent—and even treat—the blood clots that can lead to hemorrhaging or thrombosis.

When a mosquito bites, it injects a potent mix of proteins called anophelins into its host, allowing the blood to flow more freely. These anophelins have long been a target of researchers trying to create new classes of blood thinners for human use. But once extracted and tested in the lab, anophelins do a poor job of thinning and unclotting the blood.

To revitalize tired mosquito spit, scientists added sulfate to the mix. Sulfate, which reacts with amino acids in the anophelins, strengthened the electrostatic forces between the proteins, making them better able to bind to the enzyme in blood plasma that causes clotting. Researchers injected three anaesthetized mice with the modified or original molecules and measured how much they bled from a tail wound. Mice treated with the modified proteins had much thinner blood—their anophelins were 100 times as effective in binding to the enzyme as the unmodified protein, the scientists reported last month in ACS Central Science.

The team also found that sulfated anophelins are more effective than hirudin, a blood-thinning molecule derived from the salivary juices of leeches, which is occasionally used in clinical settings. Given how well the modified anophelins performed—and the fact that they also stimulate a natural immune response—the researchers are planning to develop mosquito spit–based blood thinners that could eventually be used to prevent and treat blood clot formation in humans.