Recruitment patterns of side population cells during wound healing in rat vocal folds

Abstract

Despite big advances in understanding the mechanisms of wound healing in vocal fold injury, it still remains unclear which are the decisive factors that lead to a complete restoration or to scarring. Among several other factors, stem cells are believed to play an important role in vocal fold restoration. Side population (SP) cells are considered to contain high numbers of stem cells and have gained great interest in the tissue engineering community. The aim of the following study was to investigate the recruitment pattern of SP cells in a rat vocal fold injury model. Experimental animal study. Unilateral vocal fold scarring was performed in Sprague Dawley rats. Larynges were harvested 1, 3, 5, 7, 14, 21, and 35 days after initial injury and were examined immunohistochemically for the presence of SP cells. This was done in coronal sections of the posterior and anterior macula flava as well as in the midportion of the vocal fold investigating the lamina propria. The number of SP cells peaked significantly after 7 days in the midportion of injured vocal folds, with a return to pre-injury levels after 14 days. No increase was detected throughout the observed time in the contralateral side. The number of SP cells increased slightly but not significantly in both anterior and posterior macula flava. Our findings suggest that SP cells may play an important role in early vocal fold wound healing and may serve as a possible therapeutic target.