Adult stem cells (ASCs) are maintained in a slow cycling and quiescent state under normal physiological conditions. This state could be awakened by certain factors, such as injury signals. Previously, we have shown that dental follicle stem cells (DFSCs) appear to grow more rapidly than their non-stem cell counterparts at elevated temperatures. This study aimed to (a) elucidate the optimal temperature to grow DFSCs, (b) determine if the elevated temperatures could enhance the differentiation capability of DFSCs, and (c) characterize the stem cell and osteogenic markers expression in DFSCs under elevated temperatures.
Materials and methods
DFSCs obtained from rat first molar were cultured at 37 (control), 38, 39, 40, and 41°C. Cell proliferation was evaluated by Alamar blue reduction assay and mean number of viable dissociated cells. Osteogenic differentiation was evaluated after 7 or 14 days of osteogenic induction. Expression of selected marker genes was also assessed during proliferation and differentiation of the DFSCs.
Increased cell proliferation was seen at heat-stress temperatures of 38, 39 and 40 °C, DFSCs showed maximal osteogenesis when cultured at 39 and 40°C. Moreover, some stem cell and osteogenic associated markers increased their expression under heat-stress conditions.
Under proper heat-stress conditions, DFSCs increased proliferation, osteogenic differentiation, and expression of some marker genes. Thus, it is likely that elevated temperature could serve as a factor to activate ASCs.