Establishment and characterization of an immortomouse-derived odontoblast-like cell line to evaluate the effect of insulin-like growth factors on odontoblast differentiation.

Insulin-like growth factors (IGF-I and IGF-II) play important roles in regulating growth and differentiation of many different organs including teeth. The presence of these factors in the developing tooth has been demonstrated. In vitro studies using tooth explants grown in the presence of IGFs suggest that they promote differentiation of ameloblast and odontoblasts cells. This is achieved by inducing or repressing gene expression associated with these cells. Since some of the genes involved in tooth differentiation are expressed by both cells, to determine the effect of IGF on odontoblast cell differentiation we first need a cell line in which a controlled environment can be created. In this study, we report the establishment and characterization of an Immortomouse-derived odontoblast-like cell line. This conditional cell line can grow indefinitely under permissive conditions in the presence of INF-gamma at 33 degrees C, differentiate into odontoblast-like cells and produce a mineralized extracellular matrix when the INF-gamma is removed and cell maintained at 39 degrees C. Addition of exogenous IGFs to the media results in an accelerated production of a mineralized matrix. This is the result of increased transcription of genes associated with bone mineralization while down regulating genes associated with dentin formation like DSPP. This data suggest that IGFs induce dental papillae mesenchyme cells to produce a bone-like mineralized extracellular matrix.