Figure 5.

miR-221 Reduces Post-infarct Fibrosis and Inhibits myoFB Activation at Days 2 and 7 Post-MI

Rats with MI received 1 mg/kg miR-221 mimic or PBS injection right after coronary artery ligation and were harvested at day 2 post-MI, or they received another injection after 72 h and were harvested at day 7 post-MI (miR-221 or MI +miR-221 and MI-Ctrl). qRT-PCR measurements of (A) Col1a1 mRNA and (B, i) Smad3 mRNA; (B, ii and iii) western blot measurement of SMAD2/3 at day 2 post-MI. (C) miRNA Taqman qPCR measurement of miR-221 levels at day 7 post-MI. (D) Picro-sirius red staining to quantify tissue collagen content at day 7 post-MI. Representative images of heart cross-sections are shown for each group. Results are expressed as the percentage of positive staining over the area of LV. (E) Immunohistochemistry with anti-α-SMA (green) and DAPI (blue) nuclei staining at day 7 post-MI. Scale bar, 150 μm. Results are expressed as the percentage of α-SMA⁺ cells over the total number of nuclei. *p < 0.05, **p < 0.01, ***p < 0.001 versus sham; #p < 0.05 versus MI-Ctrl. n = 4, 6, and 4 for sham, MI-Ctrl, and MI +miR-221, respectively.