Conditioned medium from human cord blood mesenchymal stem cells attenuates age-related immune dysfunctions

Aging is accompanied with progressive deterioration of immune responses and tissue's function. Using 12-month-old mice as model, we showed that conditioned medium of human cord blood mesenchymal stem cells (CBMSC-CM) significantly reduced the population percentage of CD3^-CD335⁺ NK and CD4⁺CD25⁺ regulatory T-cells in peripheral blood. The CBMSC-CM administration also increased naïve T-cells number and restored the ratio of naïve to memory T-cells in CD4⁺ T-cells population. These results indicated that CBMSC-CM improved the immune response efficiency of aged mice. Moreover, we also found CBMSC-CM treatment significantly reduced the number of senescenT-cells in kidney tissues. Finally, we demonstrated that CBMSC-CM remarkably attenuated hydrogen peroxide triggered T-cell response and ameliorated oxidative stress induced cellular senescence. All of these data suggest a prominent anti-aging effect of secretome of CBMSCs.