Characterization of dental pulp stem cells from impacted third molars cultured in low serum-containing medium

We isolated and expanded stem cells from dental pulp from extracted third molars using an innovative culture method consisting of low serum-containing medium supplemented with epidermal growth factor and platelet-derived growth factor BB. We evaluated the differentiation potential of these cells when they were growing either adherently or as micromass/spheroid cultures in various media. Undifferentiated and differentiated cells were analyzed by flow cytometry, immunocytochemistry and immunoblotting. The flow cytometry results showed that the dental pulp stem cells (DPSCs) were positive for mesenchymal stromal cell markers, but negative for hematopoietic markers. Immunocytochemical and/or immunoblotting analyses revealed the expression of numerous stem cell markers, including nanog, Sox2, nestin, Musashi-1 and nucleostemin, whereas they were negative for markers associated with differentiated neural, vascular and hepatic cells. Surprisingly, the cells were only slightly positive for α-smooth muscle actin, and a heterogeneous expression of CD146 was observed. When cultured in osteogenic media, they expressed osteonectin, osteopontin and procollagen I, and in micromass cultures, they produced collagen I. DPSCs cultured in TGF-β1/3-supplemented media produced extracellular matrix typical of cartilaginous tissue. The addition of vascular endothelial growth factor to serum-free media resulted in the expression of endothelial markers. Interestingly, when cultured in neurogenic media, DPSCs exhibited de novo or upregulated markers of undifferentiated and differentiated neural cells. Collectively, our data show that DPSCs are self-renewing and able to express markers of bone, cartilage, vascular and neural tissues, suggesting their multipotential capacity. Their easy accessibility makes these cells a suitable source of somatic stem cells for tissue engineering.