Activation of αSMA expressing perivascular cells during reactionary dentinogenesis

To examine the contribution of perivascular cells expressing αSMA to reactionary dentinogenesis.

An inducible, Cre-loxP in vivo fate-mapping approach was used to examine the contribution of the descendants of cells expressing the αSMA-CreERT2 transgene to reactionary dentinogenesis in mice molars. Reactionary dentinogenesis was induced by experimental mild injury to dentine without pulp exposure. The Student's t test was used to determine statistical significance at *P ≤ 0.05.

The lineage tracing experiments revealed that mild injury to dentine first led to activation of αSMA-tdTomato⁺ cells in the entire pulp chamber. The percentage of areas occupied by αSMA-tdTomato⁺ in injured (7.5 ± 0.7%) teeth were significantly higher than in teeth without injury (2 ± 0.5%). After their activation, αSMA-tdTomato⁺ cells migrated towards the site of injury, gave rise to pulp cells and a few odontoblasts that became integrated into the existing odontoblast layer expressing Col2.3-GFP and Dspp.

Mild insult to dentine activated perivascular αSMA-tdTomato⁺ cells giving rise to pulp cells as well as a few odontoblasts that were integrated into the pre-existing odontoblast layer.