Hematopoietic stem cell and mesenchymal stem cell population size in bone marrow samples depends on patient's age and harvesting technique.

Mesenchymal stem cells (MSCs) are heterogeneous population of cells with great potential for regenerative medicine. MSCs are relatively easy to expand in a cell culture, however determination of their concentration in harvested tissue is more complex and is not implemented as routine procedure. To identify MSCs collected from bone marrow we have used two combinations of cell markers (CD45/CD73/CD90/CD105 and CD45/CD271) and fibroblast colony-forming unit (CFU-F) assay. Further, in donors of various ages, mesenchymal stem cell concentration was compared with the result of CFU-F assay and with hematopoietic stem cell concentration, determined by a standardized flow cytometric assay. A positive correlation of MSC populations to the CFU-F numbers is observed, the population of the CD45/CD271 cells correlates better with CFU-F numbers than the population of the CD45/CD73/CD90/CD105 cells. The relationship between the hematopoietic CD45/CD34 cell concentration and mesenchymal CFU-Fs or CD45/CD271 cells shows a positive linear regression. An age-related quantitative reduction of hematopoietic CD45/CD34, mesenchymal CD45/CD73/CD90/CD105 and CD45/CD271 stem cells, and CFU-F numbers were noted. Additionally, statistically significant higher CFU-F numbers were observed when bone marrow samples were harvested from three different sites from the anterior iliac crest instead of harvesting the same sample amount only from one site.