EFFECT OF AGE ON HUMAN PERIPHERAL-BLOOD STEM-CELLS

We evaluated the correlation between the number of peripheral blood st em cells (PBSCs) and aging by monitoring those of CD34(+) cells (PB-CD 34(+)), colony-forming unit granulocyte macrophages (PB-CFU-GM) per I mi 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.