Surgery-Induced Stress Promotes SOX9 Nuclear Localization and Increases COL2A1 in Tracheal Cartilage

Airway reconstruction triggers a surgery-induced stress (SIS) response, but its effect on cartilage regeneration remains elusive. SOX9 regulates cartilage regeneration by promoting type II collagen production and may aid in repair; however, the role of SOX9 in response to SIS is unclear. We utilized a mouse model to validate SOX9 nuclear expression in tracheal chondrocytes and assess its localization after segmental tracheal replacement.

Tracheas from C57BL/6J mice were digested using Dispase-Collagenase-Trypsin, then collagenase II to isolate chondrocytes for primary culture. Syngeneic tracheal grafts were harvested from donor animals, and a 3 to 4 mm tracheal graft was implanted orthotopically to assess chondrocyte function in vivo. At 1 month, graft, anastomosis, and adjacent host tissues were harvested. Samples were stained for SOX9 and COL2A1, and their localization was analyzed with ImageJ.

Primary tracheal chondrocytes showed strong nuclear SOX9 and cytoplasmic COL2A1 expression. One month after orthotopic tracheal replacement, SOX9 nuclear colocalization increased in the host and anastomosis regions (P = .0269 and P = .0262, respectively), but not in the graft (P = .5958). COL2A1 intensity in the cartilage matrix was significantly higher in graft, host, and anastomosis compared to native cartilage (all P < .01), with no morphological differences.

After tracheal reconstruction, increased SOX9 and COL2A1 intensities indicate a potential chondrocyte response to SIS. SOX9 nuclear localization may be involved in regulating COL2A1 in tracheal chondrocytes during cartilage injury and repair. This supports a possible role for SOX9 in maintaining cartilage function and its potential as a therapeutic target to improve graft integration and airway stability.