αSMA-Expressing Perivascular Cells Represent Dental Pulp Progenitors In Vivo.

Area of Science:

• Dental Research
• Cell Biology
• Developmental Biology

Background:

• Odontoblasts are crucial for dentin formation and maintenance.
• The origin of odontoblasts during different stages of tooth development and repair is not fully understood.
• Perivascular cells are a potential source of progenitor cells in various tissues.

Purpose of the Study:

• To investigate the contribution of perivascular cells to the odontoblast lineage during dentinogenesis and repair.
• To identify the specific progenitor cell population involved in secondary odontoblast formation.
• To elucidate the role of alpha-smooth muscle actin (αSMA)-expressing cells in dentin formation.

Main Methods:

• Utilized an inducible Cre-loxP in vivo fate-mapping system in mouse molars.
• Employed lineage tracing by tracking αSMA-CreERT2 expressing cells and their descendants (αSMA-tdTomato+).
• Analyzed cell differentiation into odontoblasts (Dspp+) and osteoblasts (Bsp+) using reporter gene expression (Col2.3-GFP+).

Main Results:

• αSMA-tdTomato+ cells contributed to a small population of odontoblasts during primary dentinogenesis.
• αSMA-tdTomato+ cells were found to contribute to cells secreting reparative dentin after pulp exposure.
• These cells differentiated into Col2.3-GFP+ cells, including Dspp+ odontoblasts and Bsp+ osteoblasts.

Conclusions:

• Perivascular cells (αSMA-expressing) are a source of odontoblasts during primary dentinogenesis.
• A distinct population of mesenchymal progenitor cells, identified by αSMA expression, can generate a second generation of odontoblasts for reparative dentinogenesis.
• This study reveals a novel mechanism for dentin repair involving perivascular-derived progenitor cells.