Metamorph software version 6.3r5

Formalin-fixed, paraffin-embedded hearts from sham and HF mice were sectioned at 5 μm thickness, deparaffinized, and rehydrated. Histological staining was performed as previously described.^{6 (link), 21 (link), 23 (link)} Masson’s trichrome was used to evaluate tissue fibrosis and Alexa Fluor 488–conjugated wheat germ agglutinin (Invitrogen) to assess myocyte area, as quantified from 5 to 6 high-power fields per section in non-infarcted myocardium using Metamorph software version 6.3r5 (Molecular Devices).
To evaluate for tissue abundance of CD4⁺ and CD8⁺ T-cells, heart sections were embedded in OCT compound (Tissue-Tek OCT), and then kept at −80°C until sectioning. Sections (7 μm thickness) were fixed with 4% paraformaldehyde in PBS, and labeled with either rat anti-mouse CD4 (Clone GK1.5; eBiosciences) or CD8 antibody (Clone 4SM15; eBiosciences). Goat anti-rat antibody conjugated with Alex Fluor 555 and 488 (Life Technologies) were used as secondary antibodies for CD4 and CD8, respectively, and fluoroshield-containing DAPI (Sigma-Aldrich) was used as the mounting medium. CD4⁺ or CD8⁺ cells were quantified using confocal microscopy from 5–6 sections and 3–4 mice from each group. All measurements were conducted in a blinded manner. Confocal microscopy was performed on an LSM710 microscope (Zeiss).