EXPRESSION OF ALKALINE PHOSPHATASE DURING OSTEOGENIC DIFFERENTIATION OF RAT BONE MARROW STROMAL CELLS

Introduction: Bone marrow contains a population of stem cells capable of differentiating to osteoblast and forming the bone nodule by dexamethasone. Material and Methods: The stromal cells of bone marrow obtained from 4 to 6 weeks old Spruge-Dawely male rats were grown in primary culture for 7 days and subcultured for 18 days. The cells were cultured in either DMEM medium containing 15% fetal calf serum and antibiotics as the controls or the above medium supplemented with osteogenic supplements (OS): include 10 mM Na-beta glycerophosphate (Na-betaGp), 10 nM dexamethasone (Dex) and 50 g/ml ascordic acid (AsA) as the examined cultures. After 6, 12 and 18 days of grow up in subculture, the cultures were examined for mineralization and alkaline phosphatase (Apase) expression. Results: Mesenchymal stem cells (MSCs) in examined cultures underwent a dramatic change in cellular morphology and a significat increase in Apase activity by day 12. The deposition of a calcified matrix on the surface of the culture flasks became evident between days 12 and 18. Conclusion: The addition of osteogenic supplements (OS) to MSCs cultures induced Apase expression that contributes to cellular differentiation and mineralization of extracellular matrix.