Wnt-directed CXCL12-expressing apical papilla progenitor cells drive tooth root formation

Area of Science:

• Dental Biology
• Stem Cell Biology
• Regenerative Medicine

Background:

• Tooth root formation is essential for tooth anchoring and involves the apical papilla (AP).
• The precise physiological coordination of AP cells in root development remains unclear.
• Mesenchymal stem cells from the AP hold potential for regenerative therapies.

Purpose of the Study:

• To identify and characterize cell populations within the apical papilla that drive tooth root formation.
• To elucidate the differentiation potential and regulatory mechanisms of these key AP cells.
• To explore the role of specific signaling pathways in maintaining dental progenitor cell fates.

Main Methods:

• Utilized Cxcl12-creER-based cell-lineage tracing in a mouse model.
• Investigated cell emergence under hypoxic conditions.
• Examined the effects of Wnt signaling inhibition and TGF-β receptor inhibition (galunisertib) on cell fate.

Main Results:

• CXCL12-expressing cells were identified in the AP during hypoxic conditions at the onset of root formation.
• These CXCL12+ cells differentiate into odontoblasts and cementoblasts, contributing to root elongation.
• CXCL12+ cells exhibited plasticity, differentiating into osteoblasts under regenerative conditions.
• Wnt pathway inactivation led to root truncation and aberrant fibroblast fates, which were mitigated by galunisertib.

Conclusions:

• CXCL12+ cells in the apical papilla are pivotal dental mesenchymal progenitor cells.
• These progenitors maintain odonto-cementogenic fates in a Wnt-dependent manner.
• The plasticity of these cells highlights their significant role in tooth root formation and regeneration potential.