A novel method to generate aptamers against recombinant targets displayed on the cell surface

Isolation of anti-protein aptamers is typically carried out against purified recombinant protein. Thus, certain cell surface proteins including pharmacologically important receptors do not become targets of aptamers due to the difficulties encountered in their purification. In order to overcome this limitation, we developed a new SELEX procedure in which cells displaying the target protein on the cell surface are used, thereby precluding the need for target purification. As a model experiment, CHO cells expressing human transforming growth factor-beta type III receptor (TbRIII) were used as the target for SELEX, resulting in the successful isolation of a specific, high-affinity aptamer.