Donor Age and Cell Passage Affect Osteogenic Ability of Rat Bone Marrow Mesenchymal Stem Cells

Tissue engineering allows the restoration of pathologically damaged tissues such as cartilage and bone using bio-scaffolds containing functionally active cells. Bone-marrow-derived mesenchymal stem cells (BMSCs) are a promising source of cells for tissue engineering due to their multilineage differentiation potential. However, proliferative and osteogenic abilities of BMSCs, and quantity of stem cells decreases in the bone marrow in aged population. We cultured BMSCs isolated from rats of various ages and evaluated their morphology, activity, and differentiation potential. Cultured BMSCs formed monolayer of fibroblast-like cells and maintained their characteristic morphology for 7-10 generations. Flow cytometry showed that aging of the cultured cell population correlated with the decrease in the expression of mesenchymal and hematopoietic surface markers, such as CD44, CD45, CD90, and CD29. We detected strong correlation between the age of BMSC donor and ALP activity in BMSC culture induced with low doses of dexamethasone and vitamin C. Cells from 2- and 6-week-old donor SD rats exhibited markedly increased ALP activity that coincided with increased bone content and strong positive staining of mineralized nodules. In contrast, BMSCs isolated from 10-month-old donors showed the lowest ALP activity, and decreased bone content and mineralized nodules formation. Our results demonstrate that the increase in donor age negatively affects proliferation and differentiation capacity of BMSCs in culture.