Fig. 2: G-MDSCs from aging mice induce cardiac fibrosis.

Adoptive transfer of G-MDSCs (1 × 10⁷) was performed in young mice (6 weeks) every 5 days for 40 days. Echocardiography, pathological examination, and qPCR were performed in young mice, old mice (20 months), and young mice that were administered G-MDSCs. A–D Left ventricular ejection fraction (LVEF; A), LV end-systolic diameter (LVDs; B), LV dp/dTmax (C), and LV dp/dTmin (D) of the young mice, aging mice, and young mice with G-MDSCs; n = 5 per group. E WGA staining revealed the cardiomyocyte cross-sectional area of the young mice, aging mice, and young mice with G-MDSCs. Representative cytograms are shown on the left, and statistical data are shown on the right; n = 4 per group. Scale bars, 50 μm. F Masson staining revealed fibrotic tissue in the mouse hearts. Representative cytograms are shown on the left, and statistical data are shown on the right; n = 4 per group. Scale bars, 50 μm. G The ratio of α-SMA + fibroblasts detected by flow cytometry of the young mice, aging mice, and young mice with G-MDSCs. Representative cytograms are shown on the left, and statistical data are shown on the right; n = 4 per group. H–J The mRNA levels of fibrosis markers (Col1a1, Col3a1, Postn, and Acta2; H), fibrosis-related factors (Mmp2, Mmp9, Timp1, Lox, Lgals3, and Tcf21; I), and cytokines (IL6, IL1b, IL10, and Tgfβ1; J) in the hearts of the young mice, aging mice and young mice with G-MDSCs; n = 4 per group. The data are presented as the means ± SDs. Differences were determined by one-way ANOVA (for more than 2 groups), and Tukey’s HSD post hoc test was performed. *P < 0.05.