Induction of embryonic mouse stem cells by osteogenic stimuli

Objectives: Embryonic mouse stem cells have been chosen as a working model and were subjected to growth conditions with different osteogenic substances. The development of osteoblast-like features has subsequently been analysed by means of histological and molecular methods. Methods: BMP2 as a potent inductor of ectopic bone formation in animal models as well as a mixture of Dexamethasone, ß-Glycerophosphate and Ascorbic acid (DAG) were used as inductive supplements in the cell culture experiments. Results: Histological staining revealed that BMP-2 treatment lead to the deposit of Calcium salts in the extracellular matrix to a much lower extent than found in DAG-treated cultures. The expression of bone-specific marker genes was assessed by measuring mRNA levels in a real time PCR assay for Alkaline Phosphatase, Collagen I, Osteopontin and Osteonectin. All transcripts were present already in undifferentiated cells, but each supplement lead to substantial changes of mRNA levels. Osteogenic differentiation seems to possess several trigger points along the bone forming cascade that can be addressed by different inductive substances. Conclusion: The study contributes to the formulation of an optimised environment for osteogenic differentiation, which will be transferred to other progenitor cells as well for future use in bone graft development.