The repair process of airway epithelium involves cell migration, spreading, proliferation and re-differentiation. Objective: Cellular and molecular responses to tracheal brush induced injury were investigated using a rabbit model. Methods: Eighteen New Zealand white rabbits were divided into uninjured and injured groups. After tracheal brushing, the animals were maintained in the laboratory before being sacrificed at given time points (1, 12 hours, 3, 7, and 21 days). The trachea of each rabbit was retrieved and preserved before being subjected to haematoxylin and eosin staining and real time PCR. Results: After injury, the remained epithelial cells underwent an instant response by proliferating and migrating into the damaged site. This finding was in accordance with the proliferative and migration activity-related gene expression results (MMP-9, TIMP1, vimentin, and ß-integrin). The increased activity of these genes was crucial at the early time points, as it encouraged the remaining cells to repopulate the damaged area. Conclusions: Continuous regulation of MMP-9, vimentin and ß-integrin plays important roles in promoting cellular homing especially the cells bordering the lesion to migrate and repair of the damaged ECM. Thus, this activation enhanced regeneration and repair of the damaged tracheal epithelium as early as 1 h and complete at 21 d following injury.
No single animal model can reproduce all of the human features of both acute and chronic lung diseases. However, the rabbit is a reliable model and clinically relevant facsimile of human disease. The similarities between rabbits and humans in terms of airway anatomy and responses to inflammatory mediators highlight the value of this species in the investigation of lung disease pathophysiology and in the development of therapeutic agents. The inflammatory responses shown by the rabbit model, especially in the case of asthma, are comparable with those that occur in humans. The allergic rabbit model has been used extensively in drug screening tests, and this model and humans appear to be sensitive to similar drugs. In addition, recent studies have shown that the rabbit serves as a good platform for cell delivery for the purpose of stem-cell-based therapy.