Characterization of vocal fold regeneration after adipose-derived mesenchymal stem cells implanting

Abstract

To investigate the treatment for injured vocal folds by implanting autologous adipose-derived mesenchymal stem cells (ADSC), and to observe the characteristics of lamina propria of the vocal folds and its major extracellular matrix (ECM), as well as the growth features of ADSC. The lamina propria was injured by localized resection in fifty-three vocal folds of thirty-four rabbits. Isolation, culture and identification of ADSC were performed in twenty rabbits. Three to five days after vocal folds injury, autogeneic ADSC were implanted into the injured vocal folds. As control, scaffolds (collagen or hyaluronic acid) and none were injected into eighteen and fifteen vocal folds respectively. Larynges were harvested at 15 days, 40 days and 3, 6, 12 months after operation. The growth and distribution of ADSC were detected by DAPI stain. Meanwhile, HE staining was performed for histopathologic research, Masson trichrome staining, Alcian Blue staining and immunohistochemical staining were used for collagen, hyaluronic acid and fibronectin respectively. ADSC showed a spindle-shaped adherent growth, with multi-differentiation potential. After implanting into the injured vocal fold, ADSC can survive in vocal fold lamina propria. In ADSC implanting group, the morphology and histologic structure of vocal folds were similar to normal in six and twelve months after ADSC implanting respectively. collagen had an increasing trend in three months, with the disorderly distribution in the vocal fold lamina propria, then it became decreasing until the twelveth month, when concentration closed to normal, however, distribution of collagen was a little irregular. The content of hyaluronic acid increased within forty days and distributed in the lamina propria, then gradually reduced to normal levels in the following twelve months, and limited in the superficial and middle layers of lamina propria, which closed to normal. Fibronectin in the lamina propria continued to scattered at the peak levels at fortieth day, then decreased in the later twelve months when the content became near normal. In the untreated group, vocal fold showed a local scar contracture at third month after injury, histology showed large number of fibrous tissue (mainly collagen fibers) hyperplasia with a tendency of increasing, disorders was also found in vocal fold lamina propria. In the scaffold implanting group, the changes were between the two groups above. ADSC are good source of seed cells for vocal fold tissue engineering, which have the ability for promoting injured rabbit vocal folds ECM secretion, rational distribution and part ordering arrangement. ADSC also play an important role in vocal folds reparation and regeneration.