Figure 4.

Collagen deposition and turnover in the old female and old male mouse heart in response to 5-aminoimidazole-4-carboxamide riboside (AICAR) treatment. A: gating strategy to identify the nonmyocyte/nonmyeloid/nonendothelial-cell cardiac fibroblast population (CD45^negCD31^negPDGFRα⁺) that was analyzed for expression of procollagen type I α, fibroblast-activated protein (FAP), periostin (Postn), and Gli1. B: mean fluorescence intensity (MFI) of procollagen type I α in CD45^negCD31^negPDGFRα⁺ cells isolated from control or AICAR-treated old female and male mouse hearts. C: graph depicting the MFI for periostin (left) and FAP (right) in the CD45^negCD31^negPDGFRα⁺ cells (n = 6–12/group). D: summary of the ex vivo experiments performed using bioreactor vessels. Fibroblasts were seeded on sex-matched matrices isolated from old mouse hearts. They were then incubated with 0.5 mM AICAR for 7 days. E: immunostaining for procollagen type 1α in cardiac fibroblasts seeded on sex-matched matrices in the bioreactor. Scale bar = 50 μm (n = 3). Brown–Forsythe and Welch one-way ANOVA was used to test the significant difference among the four groups, to determine the significant difference among the groups for B and C (n = 7–12).