Effect of age on human peripheral blood stem cells

We evaluated the correlation between the number of peripheral blood stem cells (PBSCs) and aging by monitoring those of CD34⁺ cells (PB-CD34⁺), colony-forming unit granulocyte macrophages (PB-CFU-GM) per 1 ml of peripheral blood in normal volunteers (n=50) including 20 males and 30 females (median age 67, range 20-90). The numbers of PB-CD34⁺, PB-CFU-GM were monitored by flow cytometry and methylcellulose-based colony assay, respectively. An inverse correlation between the number of PB-CD34⁺ with age (r=-0.33, p=0.020) was found. Furthermore, the number of PB-CFU-GM also showed an inverse correlation with age (r=-0.58, p=0.003). Based on these results, it is suggested that the number of PBSCs decrease with age.