Short-Term Effect of Mechanical Loading on the Cell Transdifferentiation of Condylar Chondrocytes

Abstract

Chondrocytes transdifferentiate into bone cells during condylar growth, but the regulation mechanism is unclear.

We aimed to investigate how mechanical loading affects chondrocyte-derived osteogenesis in condylar modeling.

Thirty-three Aggrecan-CreERT2; R26RtdTomato; 2.3Col1a1-GFP compound mice received tamoxifen injections at four-weeks-old and were divided into control and experimental groups. Appliances were bonded to shift the mandibles to the left for five days. Condylar analysis was performed using two-dimensional radiography, microcomputed tomography, and histomorphometry.

The experimental group developed asymmetric mandibles, with the protrusive side being longer than controls and the retrusive being shorter. The protrusive condyle showed an increase in cartilage matrix and chondrocyte-derived osteoblasts, especially in the posterior third. The reverse was shown on the retrusive side.

Mechanical loading directly regulates condyle chondrogenesis and chondrocyte transdifferentiation, which affects the growth direction of the condyle.