miR-21 negatively regulates stemness-related properties of granulation tissue-derived cells. Passage 2 granulation tissue-derived cells (GTCs) were pretreated with microRNA (miR)-21 antagomir (50 nM) or control antagomir (50 nM) for 48 hours. (A) The proliferation ability was detected by CCK-8 every 2 days after seeding. (B) Colony-forming assay of GTCs pretreated with miR-21 antagomir and control antagomir. Colonies presented as mean ± standard deviation (n = 6 wells per group). Twenty colonies were randomly chosen in each group for analyzing (C) average colony sizes and (D) size distribution. (E) Representative migration photographs of GTCs pretreated with miR-21 antagomir and control antagomir at indicated time points. (F) Relative migration rate presented as mean ± standard deviation (n = 6 per time point for each group). (G) Adipogenic and (H) osteogenic differentiation of GTCs pretreated with miR-21 antagomir or control antagomir were measured by staining with Oil-Red O and Alizarin Red and quantifying them respectively. CFU, colony-forming units; d, days; h, hours; OD, optical density. *P < 0.05, **P < 0.01. Scale bar = 500 μm.