Peptide-based CE-SELEX enables convenient isolation of aptamers specifically recognizing CD20-expressing cells

The CD20 antigen is a key target for several diseases including lymphoma and autoimmune diseases. For over 20 years, several monoclonal antibodies were developed to treat CD20-related disorders. As many therapeutic proteins, their clinical use is however limited due to their nature with a costly biotechnological procedure and side effects such as the production of anti-drug neutralizing antibodies. Nucleic acid aptamers have some advantages over mAbs and are currently investigated for clinical use. We herein report the selection of DNA aptamer by using a peptide-based CE-SELEX (Capillary Electrophoresis-Systematic Evolution of Ligands by Exponential Enrichment) method. It was demonstrated that these aptamers bind specifically a CD20-expressing human cell line, with K_d estimated from isothermal titration calorimetry experiments in the micromolar range. This study demonstrates that the CE-SELEX is suitable as alternative method to the conventional Cell-SELEX to discover new cell-targeting compounds.