The aptness of aptamers

Aptamers are nucleic acid ligands selected to interact with specific proteins with high affinity. In the September 5 Nature, Rusconi et al. describe the elegant design of a drug-antidote pair to control blood clotting using aptamer technology (Nature 2002, 419:90-94). They screened a nucleic-acid combinatorial library for aptamers specific for coagulation factor FIXa. They selected a high-affinity aptamer and demonstrated that it could inhibit FIXa activity and acted as an anti-coagulant. Rusconi et al. also created antidote oligonucleotides that blocked binding of the aptamer. The drug and antidote could effectively control clotting times in the plasma of patients with heparin-induced thrombocytopenia. This strategy presents a promising approach for the development of safe aptamer-antidote pairs as therapeutics.