αSMA-Expressing Perivascular Cells Represent Dental Pulp Progenitors In Vivo

The goal of this study was to examine the contribution of perivascular cells to odontoblasts during the development, growth, and repair of dentin using mouse molars as a model. We used an inducible, Cre-loxP in vivo fate-mapping approach to examine the contributions of the descendants of cells expressing the alpha SMA-CreERT2 transgene to the odontoblast lineage. In vivo lineage-tracing experiments in molars showed the contribution of alpha SMA-tdTomato(+) cells to a small number of newly formed odontoblasts during primary dentinogenesis. Using an experimental pulp exposure model in molars to induce reparative dentinogenesis, we demonstrate the contribution of alpha SMA-tdTomato(+) cells to cells secreting reparative dentin. Our results demonstrate that alpha SMA-tdTomato(+) cells differentiated into Col2.3-GFP(+) cells composed of both Dspp(+) odontoblasts and Bsp+ osteoblasts. Our findings identify a population of mesenchymal progenitor cells capable of giving rise to a second generation of odontoblasts during reparative dentinogenesis. This population also makes a small contribution to odontoblasts during primary dentinogenesis.