The purpose. Respiratory epithelium regeneration is studied in rats with tracheal damage induced by inhaling hydrochloric acid vapor. Method. Regeneration process after the chemical burn was activated by intratracheal administration of preparations obtained from the same-species mesenchymal stem cells (MSC). Results. Tracheal epithelium is shown to recover almost completely on day 3-7 after applying MSC compositions (MSCs). Closed structures containing ciliated cells similar to ciliated cells of the respiratory epithelium lining the trachea are formed in the submucosal epithelium during regeneration. These structures migrate towards epithelium and get incorporated into the damaged epithelium. This phenomenon is apparently indicative of the special mechanism of respiratory epithelium regeneration after HCl-induced injury. Conclusion. It is demonstrated in this study that cell-free MSCs instilled intratracheally promote the recovery of normal submucosal epithelium by either preventing or reducing necrosis and inflammation. Such topical MSCs administration significantly accelerates migration of ciliated cell towards the surface and de novo formation of the ciliary epithelium.

The aim of the study was to investigate a role of different antioxidant enzymes for tracheal epithelium regeneration after chemical burn. Methods. The study was conducted in a rat model of chemical burn of the upper airways caused by inhaled hydrochloric acid. Results. According to results of histological examination, to the 2nd day after the exposure approximately 70 % of the epithelial surface remained injured, mostly due to death of the ciliated cells. The degree of the damage was unchanged to the 4th day after the exposure. Visible regeneration of the tracheal epithelium began to the 7th day. The death of the tracheal epithelial cells was generally due to necrosis though cell apoptosis also occurred. The expression of all antioxidant enzymes was greatly decreased during the 1st day after the exposure followed by its growth to maximum to the 7th day and normal level to the 15th day after the burn. Exposition of superoxide dismutase to the trachea resulted in a significant epithelium destruction. On contrary, peroxiredoxin 6 and a chimeric protein containing peroxiredoxin / superoxide dismutase significantly protected the tracheal epithelium. Conclusion. Peroxiredoxins and their derivates could be used as highly efficient therapeutic agents with potent antioxidant action in patients with burn injury of the upper airways.