Methods: hOMSC were cultured at high density for 2 weeks on fibrin membrane. Part of these cultures was processed for qRT-PCR assessment of Oct4, Sox2 and Nanog and markers of the osteogenic lineage. Cultures at day 0 served as controls. The remaining fibrin membranes + hOMSC were implanted between the skin and calvaria bones in 10 scid mice. After 10 weeks the animals were sacrificed and the implants were analyzed by soft x-rays and light and fluorescent microscopy.
Results: The qRT-PCR analysis revealed: a slight increase in the expression of Oct4, Sox2 and Nanog at 2 weeks compared to controls; an increase of 3 folds in the early master skeletal progenitor marker Runx2, appearance and strong expression of the osteogenic progenitor marker Osterix and of the cementoblastic marker cementum attachment protein (CAP). Macroscopic and soft x-rays examination revealed mineralized tissue-tumors formation, which on light microscopy examination consisted of bony tissue comprising lacunae of acellular matrix. Immunofluorescence demonstrated that these acellular matrices consisted of molecules characteristic to bone, cartilage, enamel and cementum.
Conclusions: The results indicate that hOMSC have the constitutive potential to develop into most of the mineralized tissue of the human body (except dentin which was not tested) pointing to their therapeutic potential in the treatment of skeletal and dental defects and diseases.