Role of miR-21 in stretch-induced proliferation of HASMCs by regulating p27 and phosphorylated retinoblastoma (p-Rb) protein expression.

<p>HASMCs underwent elevated stretch (16% elongation, 1 Hz) or were cultured under static conditions for 12 hr; the effect of stretch on proliferation was determined by BrdU incorporation assay and cell counting. HASMCs were transfected with miR-21 inhibitor or negative control (NC) inhibitor 48 hr before stretch treatment. (A) Representative view of BrdU-positive cells under different conditions, BrdU-positive cells were indicated (white arrows), DAPI was used for nuclear staining. (B) Quantification of BrdU-positive cells. Data are mean ± SEM, n = 4 per group. **P<0.01, versus static control; # P<0.05, versus stretch. (C) Effect of miR-21 on stretch-induced HASMC proliferation determined by cell counting. Data are mean ± SEM, n = 4 per group. *P<0.01, vs. static control; # P<0.01, vs. stretch. (D) Representative western blot and quantification of protein level of p27 and p-Rb. β-actin was a loading control. Data are mean ± SEM, n = 4 per group. *P<0.01, vs. static control; # P<0.01, vs. stretch.