The Long-Term Effects of Unloading on the Transdifferentiation of Condylar Chondrocytes

Abstract

Background

The role of chondrocyte transdifferentiation into bone cells during postnatal condylar growth remains unknown.

Purpose:

To quantify the long-term effects of masticatory forces on condylar chondrocyte transdifferentiation. Research Design: Chondrocyte tracing was performed in 12 Aggrecan-CreERT2;R26RTdTomato;2.3Col1a1-GFP and 12 Col10a1-Cre; R26RTdTomato;2.3Col1a1-GFP mice. After Tamoxifen injections at 3 weeks, they were randomly divided into soft and hard food diet groups and followed for 6 weeks. 2D and 3D µCT, H&E staining, cell proliferation, immunostaining for chondrogenic markers, and cell lineage tracing analyses were performed.

Results:

Mice on soft diet showed significantly (p<.05) smaller mandibular length, less chondrocyte proliferation and maturation, and fewer chondrocyte-derived bone cells in the condylar head (30% less) and mid-condylar process (28% less).

Conclusions:

Masticatory function affects condylar chondrogenesis and chondrocyte transdifferentiation, which may partially explain differences in postnatal condylar growth.