Disease‐specific biomarker discovery by aptamers

RNA and DNA aptamers developed by an in vitro selection process, Systematic Evolution of Ligands by EXponential enrichment (SELEX), comprise a novel class of high‐affinity and specific capture agents, which can be easily modified for cytometry and in vivo applications. A novel application of this technique (Cell SELEX) explores the expression of cell surface epitopes that differ between two given cell types or between healthy and diseased cells. Using whole cells as targets, aptamer libraries can be identified that bind to biomarkers expressed by target cells and not by any other cells. Aptamers have been developed that specifically interact with cell surface epitopes of trypanosomes or distinguish between the differences in molecular signature of somatic and cancer cells. Aside from its use for target cell identification by image and flow cytometry and laser‐scanning microscopy, aptamers can be used for ligand‐mediated purification and identification of their binding proteins in target cell membranes. In this review, we discuss an approach for the development of aptamers targeting parasite‐derived surface proteins of Trypanosoma and Plasmodium. © 2009 International Society for Advancement of Cytometry