The wound healing capacity of undifferentiated and differentiated airway epithelial cells in vitro

Congenital or acquired tracheal lesions alter airway epithelial structure and can lead to long-segment tracheal defects. Tissue engineered tracheal grafts (TETG) have the potential to cure such defects; however, clinical applications have been plagued with numerous complications including delayed graft epithelialization. The knowledge that epithelial cells migrate from native tissue to the TETG raises the possibility that TETG performance can be improved by increasing the rate of epithelialization.

We developed a model that can be used quantify epithelial migration in clinically-relevant conditions.

Existing histological analyses determined the differentiation status of the normal and injured human tracheal epithelium and were used to identify in vitro culture conditions that mimic these parameters. The classical scratch assay was adapted to permit analysis of migratory velocity as a function of differentiation status. Migration of undifferentiated (UD), partially-differentiated (PD), and well-differentiated (WD) epithelia was quantified.

The normal and injured epithelium can be modeled using human cells that are cultured using a modified air-liquid-interface culture system. PD cell cultures are similar to the remodeled epithelium; whereas; WD cultures are similar to the normal epithelium. Preliminary results indicate that PD cells migrate more rapidly than WD cells and that PD and WD cells migrate more rapidly than UD cells.

Pending verification of these results, we suggest that epithelial migration is significantly altered by differentiation status. Thus, efforts to improve TETG epithelialization should use model systems that faithfully-represent the differentiation state of the native tissue.