(a) Representative images of rat H9c2 cardiomyoblasts stained for senescence associated (SA) β-galactosidase: untreated cells (Ctrl), cells exposed to 0.1 μM Dox (Dox), and cells pre-incubated with 40 μg/ml of: the hAFS-CMNormo (hAFS-CMNormo + Dox), the hAFS-CMHypo (hAFS-CMHypo + Dox), the hNCTC-CMNormo (hNCTC-CMNormo + Dox), or the hNCTC-CMHypo (hNCTC-CMNormo + Dox) prior to Dox treatment. Scale bar 100 μm. (b) Percentage of H9c2 cells expressing SA β-galactosidase after exposure to Dox with or without pre-incubation with 40 μg/ml of the hAFS-CM or hNCTC-CM (mean ± s.e.m.). Ctrl: 11.7 ± 1.2%, Dox: 46.5 ± 1.7%, hAFS-CMNormo + Dox: 30.4 ± 4.5%, hAFS-CMHypo + Dox: 23.7 ± 1.8%, hNCTC-CMNormo + Dox: 46.9 ± 1.2%, and hNCTC-CMHypo + Dox: 46.4 ± 3.3%; ***p < 0.001 (p = 0.0004), ****p < 0.0001. (c) Representative images of H9c2 cardiomyoblasts stained for cleaved caspase-3 (Caspase-3): untreated cells (Ctrl), cells exposed to 1 μM Dox (Dox), and cells pre-incubated with 40 μg/ml of: the hAFS-CMNormo (hAFS-CMNormo + Dox), the hAFS-CMHypo (hAFS-CMHypo + Dox), the hNCTC-CMNormo (hNCTC-CMNormo + Dox), or the hNCTC-CMHypo (hNCTC-CMNormo + Dox) prior to Dox treatment. Scale bar 100 μm. (d) Percentage of H9c2 cells expressing cleaved caspase-3 (% Caspase-3+ cells) after exposure to Dox with or without pre-incubation with 40 μg/ml of the hAFS-CM or hNCTC-CM (mean ± s.e.m.). Ctrl: 1.1 ± 0.2%, Dox: 25.0 ± 1.1%, hAFS-CMNormo + Dox: 18.5 ± 0.8%, hAFS-CMHypo + Dox: 14.2 ± 1.4%, hNCTC-CMNormo + Dox: 32.0 ± 3.9%, and hNCTC-CMHypo + Dox: 28.3 ± 1.7%; *p < 0.05 (p = 0.0433), **p < 0.01 (p = 0.0014).