Structural requirements of mono- and multivalent L-selectin blocking aptamers for enhanced receptor inhibition in vitro and in vivo

Activity screening in vitro of L-selectin specific DNA aptamer variants led to a significant reduction in size and detected invariant bases essential for high affinity target recognition. Trimerization of the optimized aptamer sequence increased receptor binding and contributed to leukocyte shielding up to 90-fold, which was comparable to the activity of neutralizing antibodies. Blockade of leukocyte extravasation in vivo was monitored by intravital microscopy and confirmed activity of the trivalent assembly.96