Abstract
Aging is one of the causative agents associated with heart failure. Cell-based therapies show potential in the treatment of cardiac aging due to the characteristics of stem cells, including differentiation and the paracrine effect. This study aimed to investigate in detail the mechanism related to biomolecules released from mesenchymal stem cells in the treatment of cardiac aging. In vitro and in vivo models were designed to explore the above hypothesis. Experimental results from the in vitro model indicated that the elevation of oxidative stress, the expression of aging marker p53, and the suppression of antioxidant marker SOD2 could be found in D-galactose-stressed H9c2 cardiomyoblasts. The co-culture of D-galactose-stressed H9c2 with mesenchymal stem cells significantly improved the above pathological signaling. An animal model revealed that the change in cardiac structure, the accumulation of fibrotic collagen, and the activation of the above pathological signaling could be observed in heart tissues of D-galactose-stressed rats. After the rats had received mesenchymal stem cells, all the pathological conditions were significantly improved in D-galactose-stressed hearts. Further evidence indicated that the release of the survival marker IGF-1 was detected in a stem-cell-conditioned medium. Significant increases in cell viability and the expression of SOD2, as well as a reduction in oxidative stress and the suppression of p53, were found in D-galactose-stressed H9c2 cells cultured with a stem-cell-conditioned medium, whereas the depletion of IGF-1 in stem-cell-conditioned medium diminished the antiaging effect on H9c2 cells. In conclusion, the paracrine release of IGF-1 from mesenchymal stem cells increases the expression of antioxidant marker SOD2, and the expression of SOD2 reduces oxidative stress as well as suppresses p53, leading to a reduction in cardiac senescence in D-galactose-stressed rats.