Age and stress related phenotypical changes in bone marrow CD34+ cells

Phenotypical changes in the human bone marrow (BM) due to age and stress have not so far been properly addressed in the literature. In the present study, we compared CD34(+) BM cells between older and young volunteers. The influence of stress on CD34(+) cell phenotype in older patients was investigated in an age-matched group with acute myocardial infarction (AMI). Cytokines thought to influence BM CD34(+) cell homeostasis were also analysed.

BM mononuclear cells of 10 older volunteers and of 7 young volunteers (18-25 years), as well as 22 AMI patients, were analysed by flow cytometry for the following markers: CD34, CD38, CD117 (c-kit) and CD133. Blood samples were analysed for CRP, IL-6, MCP-1, IL-8, MMP-9, TIMP-1 and TNFalpha by ELISA methods.

Significantly higher numbers of CD34(+) CD38(-) cells (both absolute and relative) were observed in older volunteers than in young volunteers and AMI patients. Higher numbers of immature progenitors, namely CD34(+)CD38(-) cells and CD34(+)CD38(-)CD117(+)CD133(+) cells, were observed among older volunteers compared to the other groups. However, the relative number of CD34(+) cells lacking CD38 expression or expressing CD133 was higher in the old volunteers and AMI patients. None of the circulating factors investigated correlated with any of the cell population yields.

In this study, we found that the absolute and relative numbers of BM CD34(+)CD38(-) progenitor cells increase with age. The increment is attenuated in patients with AMI.