Specificity of RNA aptamers for vascular smooth muscle cells (VSMCs). (a) Secondary structure predictions of selected RNA aptamers (14 and 51) and of a nonselected, control aptamer (NSC). (b) VSMC-specific aptamers (150 nmol/l; 14 and 51), but not control aptamer (150 nmol/l; NSC), bind to denuded femoral arteries but not endothelium-intact arteries. Binding was measured using RT-qPCR in vessels of equal length derived from the same animal and normalized to NSC intact. *P < 0.05 versus intact for same aptamer, n = 3. (c) Binding selectivity of RNA aptamers (150 nmol/l) to various muscle types. *P < 0.05 versus NSC for same tissue, n = 3. RT-qPCR, reverse-transcription quantitative PCR.