Characterization of mouse incisor tooth mesenchymal stem cells

Objectives: The continuously growing mouse incisor provides an excellent model for studying molecular mechanisms of stem cell fate determination. This work aims to: (1) Define the molecular signatures of a mesenchymal stem cell (MSC) region within the mouse incisor; (2) Develop a methodology to culture MSCs in vitro.
Methods: Based on the Notch signalling pathway activation levels in the cells, we used Laser Capture Micro dissection to capture different regions of interest within the mouse incisor dental mesenchyme. A real time PCR screening of the cDNA from the cells was performed with specific probes targeting a group of known mesenchymal quiescent stem cell markers. The corresponding protein expression levels were evaluated using immunofluorescent microscopy. Furthermore, cell culture of dissected MSC containing incisor mesenchyme was performed and stem cell status manipulation has been attempted using an in vitro synchronisation assay.
Results: We have found that mouse incisor MSCs express many similar markers to MSCs contained in other organs, such as muscle and the hematopoietic system. These cells could be cultured in vitro. Cellular quiescence and activation can be simulated using a synchronization assay. Notch signalling pathway members express differently in the MSCs and transit amplifying (activated) cells.
Conclusions: Our study showed that mouse incisor MSCs are located in a distinct region and express specific markers even when cultured in vitro. Notch signalling may play a key role in incisor MSCs maintenance and differentiation. It is expected that the molecular mechanisms driving dental stem cell behaviour, can be applied to direct differentiation of stem cells into dental tissues and possibly even utilised to grow an entire adult tooth.