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Fig. 7
VIM-positive fibroblasts and TNC localize at the border zone between the myocardium and fibrotic tissue. (A, C, E and G) Heart sections immunostained for a cardiac nuclear marker MEF-2 (red) and an intermediate filament marker Vimentin (VIM, green). (B, D, F and H) Heart sections immunostained for a cardiac sarcomeric marker TPM (red) and an extracellular de-adhesive protein Tenascin-C (TNC, green). (A′, B′, C′, D′, E′, F′, G′ and H′) Higher magnifications of the framed area in the left panels. (A-A′ and B-B′) In control, at 4 days after sham operation, no significant expression of VIM and TNC can be detected in the ventricle. (C-C′ and D-D′) At 7 dpci, the scar margin and the interface between the myocardium and post-infarct are highlighted by VIM- and TNC-expressing fibroblasts. (E-E′ and F- F′) At 14 dpci, protrusions of cardiomyocytes expand along VIM/TNC-expressing cells (arrows). (G-G′ and H-H′) At 30 dpci, the scar tissue is largely replaced by cardiomyocytes. A new compact myocardial wall (arrowheads) surrounds residual VIM and TNC. Dashed line encircle the post-infarct. Bars in (A-A′), 300 μm.