Technology : Catching blood clots before they do damage

2019-02-27 09:16:09

By David Bradley A MOLECULAR claw that grabs a radioactive label to turn an ordinary peptide into a marker for potentially fatal blood clots has been developed by researchers in the US and successfully tested on animals. Deep-vein thrombosis often only causes pain or discomfort, but when clots fragment and reach the lungs the result can be a potentially fatal embolism. Some 5.5 million people in the US suffer from thrombosis, and pulmonary embolism kills about 100 000 each year. Prompt treatment of thrombosis before it leads to a life-threatening embolism offers the best hope of survival. But early diagnosis can be time-consuming and expensive. Daniel Pearson and his colleagues at the biotechnology company Diatide in Londonderry, New Hampshire, realised that a quick, cheap, nonsurgical way of detecting clots was needed (Journal of Medicinal Chemistry, vol 39, p 1361). The Diatide researchers, like others before them, focused on the small peptides that bind to cell receptors involved in the clumping of blood platelets in clotting. They modified the amino acid sequence of the peptides to introduce a segment that grabs hold of the relatively cheap radioisotope technetium-99. Their idea was that the compound would seek out the clots, making them visible on a scanner. The researchers found that the compounds with the radioisotope marker bound to activated human blood platelets almost as well as the unmodified peptides. And in trials on dogs with thrombosis, they found that the radioactive claw binds to clot tissue but not to muscle tissue. “The key experiments to be carried out in human patients will be awaited with interest,” says David Parker, a chemist at Durham University who specialises in cancer radio-imaging. But he warns: “Very often animal models look really promising,